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The present study evaluated the potentials of phytoremediation and the biomonitoring of potentially toxic metals (PTMs) (Zn, Ni, Fe, Pb, and Cu) in the mangrove leaves of Rhizophora apiculata from the tropical mangrove ecosystem in the Sepang Besar River and Lukut River, Peninsular Malaysia. Overall, the present studies concluded that (a) the levels of essential Fe, Cu, and Zn in lamina are significantly (p < 0.05) higher than in MP, (b) the levels of Pb and Ni in MP are significantly (p < 0.05) higher than in lamina, (c) the lamina has better potential as a phytoremediator of Cu, Zn, and Fe, while MP is a better potential phytoremediator of Pb and Ni, (d) lamina is a potential biomonitoring agent of potentially toxic metals based on better correlation coefficients with the surface sedimentary geochemical fractions, and (e) metal uptake in the mangrove leaves and comparative levels of metals is low with reported studies. Specifically, based on bioconcentration factors (BCF), their most obtained values were considered low (<1), suggesting that R. apiculata can be considered as a low-efficiency plant for the bioaccumulation of PTM. However, the present findings also suggested that R. apiculata may be classified as a potential phytoremediator for Zn, Cu, Pb, and Ni in the leaves, as indicated by higher metal accumulation in the MP, with BCFEFLE values > 1.0; BCFAR > 1.0 for Cu, Pb, and Ni. The mangrove leaves are potential biomonitors of PTMs since positive correlations of PTMs were found between the leaves and their habitat surface sediments. Having been identified as a potential phytoremediator and biomonitor of PTMs, the present study emphasized the possibility of establishing a framework for managing the coastal aquatic ecosystems along the mangrove ecosystems of Sepang and Lukut. [ABSTRACT FROM AUTHOR]

It is of great significance to study the distribution characteristics and transport of heavy metals in complex sedimentary environments and areas with intensive human activities. This study analyzed sediment size, heavy metal contents (Cu, Zn, Cd, Cr, and Pb), organic carbon content, and sulfide content in surface sediments collected from 27 sites in Chengbei Sea. The main controlling factors of the distribution and transport of heavy metals were discussed from the perspective of sediment dynamics. The concentrations of Cu, Zn, Cd, Cr, and Pb in surface sediments were 7.9–20.5 mg/kg, 33.8–94.6 mg/kg, 0.08–0.26 mg/kg, 6.3–62.3 mg/kg, and 3–13.4 mg/kg, respectively. According to the geoaccumulation index, the study area was not polluted by the heavy metals, except for Cd, which did not pollute only areas with relatively coarse-grained sediments. Combining the results of correlation analysis, tidal residual current analysis, sediment transport trend analysis, and principal component analysis confirmed that Cu, Zn, and Cd originate from natural sources, and their distribution characteristics are mainly controlled by the grain size of surface sediments. Cr and Pb could be attributed to human activities, such as oil exploration, and their distribution characteristics were affected by sediment transport and tidal residual current. Zonation of the sedimentary dynamic environment also provided reference for the relationship between the distribution of heavy metals in surface sediments and sedimentary environments. [ABSTRACT FROM AUTHOR]

Interest in the study of microplanktonic organisms in the Arctic has increased owing to their direct participation in the process of sedimentation and sensitive response to changes in environmental and climatic factors. This study presents new data on the taxonomic diversity and content of radiolarian skeletons and agglutinated tintinnid ciliate loricae in the Upper Holocene sediments of the Laptev Sea, East Siberian Sea, and the adjacent part of the Arctic Ocean. We traced the spatial distribution of representative microfauna of these groups in surface sediments and sediment cores. Radiolarian skeletons were found in the surface sediments of the continental slope of the Laptev Sea and adjacent parts of the Arctic Ocean. These belong to the following six species: Stylatractus (?) sp., Actinomma leptoderma leptoderma, Actinomma leptoderma longispina, Streblacantha circumtexta, Spongotrochus glacialis, and Cycladophora davisiana. The radiolarian fauna detected was in deep sea and close to the fauna of the Nansen Basin (Central Arctic). Furthermore, we found tintinnid ciliate loricae belonging to the following seven species: Tintinnopsis ventricosoides, Tintinnopsis fimbriata, Tintinnopsis turbo, Tintinnopsis nitida, Tintinnopsis sp. cf. fusus (?), Tintinnopsis sp., and Stenosemella nivalis. In the study area, the tintinnid ciliate loricae of these species were discovered for the first time and traced mainly in the coastal shelf zone, which can be explained by their ecology. The only exception is that of T. nitida, which was found only on the continental slope of the Laptev Sea. Our findings advance knowledge on the biodiversity of Arctic seas and can be used to monitor ecological and paleoceanographic changes in the Arctic region. [ABSTRACT FROM AUTHOR]

Our research was motivated by significant warming in the Arctic in recent decades and the influence of this warming on diatoms, which are the main producers in the seas of the Eastern Arctic. For this purpose, we studied the qualitative concentrations and quantitative ratio of diatoms from the surface sediments of the Laptev Sea (LS), the East Siberian (ESS) and Chukchi seas (ChS), and the Arctic Ocean (AO), obtained by box corers in 2016 and 2018. The ecological structure of the diatom assemblages of these sediments, reflecting the current environmental conditions, was also analyzed. Compared with the end of the last century, there were significant changes in species composition and quantitative ratio of the diatom assemblages in the sediments from the AO and the LS and ESS. In contrast, the diatom assemblages in the sediments from the ChS had not significantly changed in terms of species composition or quantitative ratio over the same three decades. The observed transformations in the diatom assemblages of the surface sediments were associated with substantial changes in water temperature, current flow, salinity, ice melting, and prolonged ice-free periods associated with global warming in the Northern Hemisphere in recent decades. The foregoing processes have clearly had strong impacts on the environment and the biota of the Arctic region. [ABSTRACT FROM AUTHOR]

Residence time of an element in the ocean is a consequence of its chemical behaviour and the various biogeochemical processes governing its distribution, sources, and sinks. Precise estimation of the residence time of beryllium(Be) is necessary for its application as a tracer for understanding present and paleo-environmental processes. We utilise cosmogenic 10Be and terrestrially derived 9Be measurements from surface sediments to estimate the residence time of Be in the Indian Ocean. Significant variation in Be residence time is observed, which ranges between 370 and 620 years in the central Indian Ocean, 64–205 years in the Bay of Bengal, 41–117 years in the Andaman Sea, and 179–443 years in the Arabian Sea. Large heterogeneity in the residence time of Be can be attributed to its variable scavenging efficiency in different regions. Active scavenging of Be by sediment particles contributed through various major rivers draining into the northern Indian Ocean results in short residence time of Be. The results of this study have significant implications for the selection of sample sites and the use of Be as a tracer in paleo reconstructions. • Residence time of Be in the Indian Ocean was estimated. • Significant spatial variation in Be residence time was observed. • Scavenging of Be from the water column largely controls the residence time. [ABSTRACT FROM AUTHOR]

Benthic eukaryotic microalgae were analyzed by metabarcoding the partial 18S rRNA gene in Daya Bay bi-monthly in 2021. Altogether 941 eukaryotic microalgal OTUs were detected, belonging to 27 classes of 8 phyla. Dinophyta and Chlorophyta were the dominant phyla. Microalgal community in the mariculture zone differed significantly from those in non-mariculture zone, reflected by low alpha diversity indexes and increasing abundance and richness of chlorophytes and correspondingly decreasing of dinoflagellates. The abundant occurrences of the pico- and nano-sized taxa such as the chlorophyte Picochlorum in the mariculture zone suggested that nutrient enrichment might result in the miniaturization of the benthic eukaryotic microalgae. The co-occurrence network suggested more negative interactions between taxa in the mariculture zone. A total of 41 algal bloom and/or harmful algal bloom (HAB) species were detected in this study, suggesting a high potential risk of HABs in Daya Bay, especially for the recurrent bloom species Scrippsiella acuminata. [Display omitted] • Benthic eukaryotic microalgae in Daya Bay were analyzed by metabarcoding. • Mariculture led to differences in microalgal community and co-occurrence network. • Nutrient enrichment resulted in miniaturization of the benthic microalgal community. • More negative interactions were between taxa in the mariculture zone. • Abundant and diverse HAB species suggested a high potential rick of HABs. [ABSTRACT FROM AUTHOR]

Cold seeps are highly productive chemosynthetic ecosystems in the deep-sea environment. Although microbial communities affected by methane seepage have been extensively studied in sediments and seawater, there is a lack of investigation of prokaryotic communities at the surface sediments and bottom seawater. We revealed the effect of methane seepage on co-occurrence networks and ecological niches of prokaryotic communities at the surface sediments and bottom seawater in the Haima cold seep. The results showed that methane seepage could cause the migration of Mn and Ba from the surface sediments to the overlying seawater, altering the elemental distribution at seepage sites (IS) compared with non-seepage sites (NS). Principal component analysis (PCA) showed that methane seepage led to closer distances of bacterial communities between surface sediments and bottom seawater. Co-occurrence networks indicated that methane seepage led to more complex interconnections at the surface sediments and bottom seawater. In summary, methane seepage caused bacterial communities in the surface sediments and bottom seawater to become more abundant and structurally complex. This study provides a comprehensive comparison of microbial profiles at the surface sediments and bottom seawater of cold seeps in the South China Sea (SCS), illustrating the impact of seepage on bacterial community dynamics.

In order to strengthen the environmental control of Minjiang River Basin and support the management and control of heavy metal pollution in Minjiang Estuary, based on the measured data of 14 sampling stations in Minjiang Estuary, this paper systematically evaluated the distribution of heavy metals and their potential ecological risks in surface sediments of Minjiang Estuary by using the methods of correlation analysis, principal component analysis and potential ecological risk index. The results showed that there were significant differences in the content of heavy metals in the surface sediments of Minjiang Estuary. Except for Zn and Hg at individual stations, the concentrations of other heavy metals were accorded with first class of the national marine sediment quality. The main factor affecting the distribution of lead was industrial sewage, while the main factors affecting the distribution of other heavy metals were organic matter and sedimentary environment. The proportion of low risk and medium risk of potential ecological risk of heavy metals in surface sediments of Minjiang Estuary was 71.43% and 28.57%, respectively. Among them, the east and south of Langqi Island were medium risk areas, and the north and northeast of Langqi Island and the outside of Chuanshi waterway were low risk areas. Cd and Hg were the main heavy metal elements with potential ecological risks, which had reached a high risk level, and risk monitoring work should be strengthened.

Abstract Background Trace metals pollution in the coastal and estuarine sediment could harm water quality and aquatic organisms, leading to potential long-term health risks on the environment and humans. Thus, the purpose of this study was to conduct an assessment of selected trace metals in surface sediments of the coastal and in four rivers estuary in the Sarawak State of Malaysia to investigate their distribution, environmental risk, and potential source distribution. Results Average concentrations of trace metals in sediment increased in the following order: Cd ˂ As ˂ Co ˂ Cu ˂ Ni ˂ Cr ˂ Zn ˂ Mn ˂ Mg ˂ Fe. The enrichment, contamination, and geo-accumulation index results showed that surface sediments were polluted with Zn and Mg. In contrast, the other metals (i.e., As, Fe, Mn, Ni, Cr, Cu, Co, and Cd) indicated background concentration to minor contamination. Generally, the pollution load index values showed that almost all the sampling sites were unpolluted with the selected trace metals. Sediment quality guidelines (SQGs) and risk indexes were employed to assess the ecotoxicological risk of trace metal contamination in the sediments. The results proved that studied trace metals are not likely to have a deleterious impact on bottom-dwelling organisms. Still, a further accumulation of trace metals such as Zn, Ni, and Cr with time may adversely affect bottom-dwelling organisms. The risk index results showed a low ecological risk to the study sites. The correlation analysis and principal component analysis indicated that nine studied trace metals have strong interrelationships, suggesting common pollution sources or similar geochemical characteristics. Conclusions The study highlights the need to make tremendous efforts to monitor and control trace metal pollution in the coastal and estuarine areas.

Phosphorus (P) is an essential element for the metabolism, growth, and development of living organisms, and it often limits primary production in freshwater ecosystems. During flood events, rivers can transport considerable amounts of particulate organic P (org-P) and inorganic P from the basin to the ocean. Understanding the transport mechanisms and changes in P distribution from upstream to downstream areas of rivers is crucial to estimate its flux to the ocean. However, the processes involved in P transformation and cycling among different forms in rivers are not well understood. To better understand P transformation and total P (TP) concentrations in river basins, this study examined various P forms in bottom sediments, river bank sediments, parent rock material, and soil samples along the Tone River, Japan. P forms such as org-P, Ca-bound phosphorus (apatite, Ca-P), P bound with iron oxides/hydroxides (Fe-P), bio unavailable non-apatite inorganic P (NAIP), and TP were analyzed. The results showed an increase in TP concentration in bottom and bank sediment samples along the course of the Tone River. This change in TP was mostly due to the increases in Fe-P and bioavailable org-P, while Ca-P and NAIP decreased toward the downstream area. Analysis of parent rock in three main mountain group areas (Mount Tanigawa, Mount Akagi, and Mount Tsukuba) showed their downstream impacts on TP and the distribution of P forms. Sediment grain size distribution analysis suggested that Fe-P and org-P fractions increased with decreasing sediment particle size, while Ca-P and NAIP were relatively evenly distributed among all grain sizes. The data revealed the transformation of P forms in sediments of the largest river in the Kanto region, Japan, which influence its flux to the Pacific Ocean. The results suggest that Fe-P and org-P may play a more significant role in P transport from river basins to the ocean than previously thought. The findings of this study can be useful for estimating P fluxes to the ocean and for the management of freshwater ecosystems.

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heavy metal pollution is a global concern. Targeting at the surface sediments in western Chaohu Lake and using metagenome sequencing, we probed into the mechanism of how microbes adapted to heavy metal‐polluted sediments under natural conditions. It was found the heavy metal pollution intensity of the three typical sampling places ranked as estuary of Nanfeihe River (NFH) > Zhongmiao Town (HZ) > Hongshizui (HSZ). Totally 129 phyla, 2631 genera and 12 989 species were detected in the sediment samples, and HSZ, HZ and NFH had 35, 51 and 67 exclusive genera, respectively. The bacterial biomass and virus quantity from NFH accounted for 22·84 and 70·69% of total quantities, respectively, and the microbial community compositions in NFH were also different from those in HSZ and HZ. Metagenomics sequencing and functional gene annotation showed NFH contained many functional genes related to nucleic acid transport and metabolism, ribosome structures and biological origin, replication recombining and repair and inorganic ion transport and metabolism. Kyoto Encyclopedia of Genes and Genomes analysis suggested the sediments from NFH were rich in enzymes correlated with heavy metal transport and reduction. Our findings offer some scientific basis for Chaohu Lake control and microbe resource utilization. [ABSTRACT FROM AUTHOR]

The epicontinental seas to the east of China have become highly anthropogenically impacted due to rapid economic development in recent decades, resulting in various environmental problems, including heavy metal pollution. The Bohai Strait, as a key junction connecting the material-energy exchange between the Bohai and Yellow Seas, is extremely critical in regional pollution prevention and control. To ascertain the spatial distribution and contamination levels of heavy metals in the surface sediments of the northern Bohai Strait, a systematic investigation was conducted. Geochemical analysis revealed that the concentrations (in ppm) of heavy metal elements in surface sediments vary in the range of 4.19–77.6 for As, 0.04–0.21 for Cd, 5.1–65.7 for Pb, 0.30–39.40 for Cu, 7.77–46.50 for Ni, 1.50–86.60 for Cr, 11.70–91.80 for Zn, and 0.005–0.038 for Hg. Ecological statistics indicate that the northern Bohai Strait suffers from prominent heavy metal pollution primarily induced by As, Cd, and Pb, accompanied by relatively weak pollution of Cu and Ni. Sediments collected from the submarine depressions and the southeast region exhibit higher heavy metal concentrations, and as a consequence, more serious ecological risk. Correlation analysis indicated that the accumulations of Hg, Cr, and Zn were associated with the deposition of organic matter. Preliminary provenance discrimination suggested that the pollutants were mainly derived from the eastern parts of the North Yellow Sea, rather than the Bohai region. [ABSTRACT FROM AUTHOR]

In order to study the speciation, contamination statues, and distribution characteristic of heavy metals in the surface sediments of cascading dams, the reservoir regions of Manwan and Dachaoshan cascading dams were sampled and investigated. The speciation and its contents of heavy metals (As, Cd, Cr, Cu, Pb, and Zn) were analyzed by the modified European Community Bureau of Reference (BCR) sequential method. The ecological risk assessment of heavy metals was performed by the ratio of secondary phase and primary phase (RSP) method. The source identification of heavy metals was performed by correlation analysis (CA) and principal component analysis (PCA). The results indicated that the values of RSPcd were from heavy pollution (IV level), and those of RSPZn were from light pollution (II level) to moderate pollution (III level) in the lacustrine zone of the upper-stream Manwan dam. The values of the RSP were no pollution (I level) in the downstream of the Dachaoshan dam. The ecological risk assessment of heavy metals (Cd, Zn, and As) at the upper stream of the Manwan dam was generally higher than that at the downstream Dachaoshan dam. Cascading dams operation showed significant accumulation effects on heavy metals in surface sediments. The source identification of heavy metals showed that Cd and Zn were mainly from anthropogenic activities; As, Cu, and Pb were affected by both natural processes and anthropogenic activities; and Cr was mainly from natural processes. [ABSTRACT FROM AUTHOR]

Paleolimnological records from temperate South-Central Chilean lakes revealed a recent and marked increase in the relative abundances of the key-planktonic diatom species Asterionella formosa and Aulacoseira distans. To better understand these changes, we studied the ecological niches of planktonic diatoms in 42 temperate Chilean lakes (36–43°S). We used morphological analysis of spring and early summer diatom communities, as well as sub-fossil sedimentary assemblages along gradients in mixing regime, light climate, and water chemistry. For Asterionella formosa and the species belonging to the genus Aulacoseira, morphology based enumerations were combined with molecular phylogenies using the 18S rDNA and rbcL genes to determine their taxonomic position and explore potential hidden diversity. Analysis of extant and sub-fossil communities revealed similar patterns, with small Discostella species (D. mascarenica and D. pseudostelligera) and Urosolenia eriensis being characteristic for large, well-mixed lakes, whereas Aulacoseira pusilla (previously erroneously identified as A. distans in Chile) is more dominant in smaller, warmer, and stratified water bodies. This suggests that recent increases in the latter taxon might be related to changes in the physical lake properties in the region, rather than a recent increase in nutrient concentrations. By contrast, Asterionella formosa occurred in lakes with a high Si concentration. Phylogenetic data of the most common species belonging to the genera Aulacoseira and Asterionella showed little evidence for hidden diversity in most of the taxa, except for the Aulacoseira granulata complex. This indicates that the Chilean strains are closely related to populations in the Northern Hemisphere. The results of this study will allow for more accurate diatom-based reconstructions of limnological changes in South-Central Chilean lakes. This is crucial to better understand climate dynamics in the region, as these lakes are known to be sensitive to alterations in windiness and precipitation in response to changes in the intensity and latitudinal position of the Southern Hemisphere Westerlies and the El Niño-Southern Oscillation. [ABSTRACT FROM AUTHOR]

Background: Heavy metals and total petroleum hydrocarbons (TPHs) are important pollutants in the aquatic ecosystem, and their long-term resistance, bio-accumulation, and bio-magnification during the food chain may cause adverse ecological and health risks., Methods: In here, the distribution and risk assessment of six heavy metals Cd, Pb, Ni, Cu, Zn, Cr, and TPHs were performed in the sediments of 32 regions situated in two mangroves (Tiab and Azini estuaries, Hara Mangrove forest protected area) and coral habitats (Larak and Hengam Islands) in Northeast of the Persian Gulf during 2020-2021. An atomic absorption device was used to determine the concentrations of heavy metals. Ecological risk of heavy metals is assessed through indices contamination factor (CF), contamination degree (CD), modified contamination degree (MCD), pollution load index (PLI), potential ecological risk index (PERI), and geoaccumulation index (Igeo). The spatial distribution of heavy metals was mapped through the inverse distance weighting (IDW) method in ArcMap., Results: The concentration of heavy metals indicated significant differences in spatial distribution. The maximum concentration of Cd 1.64 ± 0.001, Cr 18.41 ± 0.41 and Cu 40.5 ± 0.28 µg/g was observed at the regions situated in the Hara Mangrove forest protected area. Azini estuary had the maximum value of Zn 94.61 ± 30.74 and TPHs 4.47 ± 1.93 µg/g and finally, the highest value of concentration Ni 135.22 ± 1.85 µg/g and Pb 17.87 ± 2.17 g/gµ was found in Tiab estuary. The studied regions in the Tiab estuary and Hara Mangrove forest protected area were more contaminated than others and had considerable risks of Ni and Cd. Average ecological indices indicated the sediments of these areas especially Tiab, Hara Mangrove forest protected area, and Azini are moderately to considerably contaminated with Cd and Ni. Tiab was identified as the most contaminated area and all stations except Hengam Island were exposed to considerable ecological risks. Cadmium was found to be the riskiest heavy metal in the investigated region. The distribution of TPHs indicated there is no pollution of TPHs in the region. In all studied stations, the PELq (Toxicity of TPHs) and CF values showed the absence of potential risks of TPHs in sediments., Conclusions: The findings indicated considerable contamination of Cd and Ni in the mangrove areas, especially Tiab, and it seems necessary to identify, manage, and control possible sources of contamination., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

This study aims to explore persistent microorganic pollutants (Poly chloro byphneyls (PCBs) and Organochlorine Pesticides (OCPs)) in sediment and mud clams (Polymesoda erosa) in Segara Anakan Lagoon (SAL). In addition, polycyclic aromatic hydrocarbons (PAHs) in the mud clams were evaluated their risk consumption and Bioaccumulation factor in sediment. Concentrations of seven PCBs in the sediment were found in the range 0.11 ± 0.05 to 2.63 ± 0.1 μg kg−1 sed dw. OCPs levels were found in the range of 0.2 ± 0.05 and 2.9 ± 0.01 μg kg−1 sed dw. In P. erosa, 16 Polycyclic Aromatic Hydrocarbons (PAHs) (USEPA) were found in the range from 103.34 ± 2.01 to 1348.31 ± 18.21 μg kg−1 tissue dry weight (dw), PCBs content was found only in one station at concentration 2.34 ± 1.72 μg kg−1 tissue dw and OCPs content was found in the range 0.87 ± 0.03 to 24.79 ± 1.30 μg kg−1 tissue dw. The disturbance matrices have been evaluated with the appropriate samples according to the extraction yield and yield analysis. Several guidelines evaluate the quality of sediment on PCBs and OCPs (i.e. pp-DDE). The consumption evaluation shows that this mud clam P. erosa has been contaminated of PAHs and not recommended for human consumption. They were potentially as site-specific bioaccumulation in sediment for organic micropollutants which receives from any untreated sewage, industrial waste discharge into the canal system of river of Segara Anakan Lagoon. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lakes in protected or remote regions are not immune to anthropogenic impacts and face a variety of stressors ranging from atmospheric deposition of pollutants to global climate change. Monitoring programs in these lakes can be limited in scope due to sampling logistics, leaving an incomplete picture of how the systems may be impacted by environmental stressors. Here, we used diatoms as early indicators of change in relatively undisturbed lakes from five national park units in the US Great Lakes region. Surface sediment samples were collected repeatedly over more than a decade to analyze the diatom community turnover. This diatom community assemblage data were compared with the measured water quality data collected over the same period in order to identify the predominant drivers of ecological change. Even though the parks in this study span two biomes, and lake characteristics vary between and within parks, we found synchronicity in measured water quality trends and diatom responses. Changes in the thermal regime and water‐column mixing appeared to drive much of the change across parks, although much of the diatom turnover also followed a sulfate or pH gradient. Nutrients did not appear to play a major role in diatom community change. This method of using diatoms in conjunction with water quality monitoring allows for an integrated response over a number of years and provides managers with a complementary tool to determine which environmental parameters are having the biggest effect on lake ecology. [ABSTRACT FROM AUTHOR]

Current mass balances of C, N, and P were estimated using a model (Fluxin = Fluxout + Δ Flux) from Gamak Bay, Korea, in August 2017, where eutrophication and reducing conditions are prevalent. To examine the current fluxes of particulate organic carbon (POC), nitrogen (PON), and phosphorus (POP), sinking and re-floating sediment traps were deployed, a sediment oxygen demand (SOD) chamber experiment and ex-situ nutrient incubation experiment were conducted, and Fick's first law of diffusion was applied. The principal component analysis and cluster analysis were performed to identify the three groups of water masses based on the characteristics of the bay, including the effects of the reducing environment due to the anoxic water mass using 14 bottom water quality parameters. In the reducing environment (sampling point GA4), the SOD20 flux was 3047.2 mg O2/m2/d. Additionally, the net sinking POC flux was 861.0 mg C/m2/d, while 131.8% of the net sinking POC flux (1134.5 mg C/m2/d) was removed toward the overlying water. This indicates that the organic matter that had been deposited was decomposed as a flux of 273.6 mg C/m2/d. The net sinking PON flux was 187.9 mg N/m2/d, whereas 15.8% of the net sinking PON flux was eluted, and 84.2% remained in the surface sediments. The dissolved inorganic nitrogen (DIN) elution flux from the surface sediments consisted of NH4+ elution (33.7 mg N/m2/d) and NOx− elution (− 4.1 mg N/m2/d) fluxes. Despite the net sinking POP flux being 26.0 mg P/m2/d, the 47.7 mg P/m2/d of DIP elution flux (179.5% of the net sinking POP flux) was eluted to the overlying water. Similar to C mass balance, the additional elution flux occurred. Therefore, severe eutrophication (16.5 of the Okaichi eutrophication index) with the lowest N:P ratio (2.6) in GA4 was noted. This indicates that not only the freshly exported organic matter to the surface sediments but also the biochemical processes under anoxic conditions played an essential role as a remarkable nutrient source–particularly P–for eutrophication in Gamak Bay, Korea. [ABSTRACT FROM AUTHOR]

The pollution of water bodies by pharmaceuticals and personal care products (PPCPs) has attracted widespread concern due to their widespread use and pseudo-persistence, but their effects on sediments are less known. In this study, solid-phase extraction-high performance liquid chromatography–tandem mass spectrometry (SPE-LC/MSMS) was used to investigate the occurrence and ecological risks of five typical pharmaceuticals and personal care products (PPCPs) in thirteen key reservoirs, sluices, dams, and estuaries in the Haihe River Basin. At the same time, the PPCP exchanges of surface water, groundwater, and sediments in three typical sections were studied. Finally, the PPCP's environmental risk is evaluated through the environmental risk quotient. The results showed that the five PPCPs were tri-methoprazine (TMP), sinolamine (SMX), ibuprofen (IBU), triclosan (TCS), and caffeine (CAF). The average concentration of these PPCPs ranged from 0 to 481.19 μg/kg, with relatively high concentrations of TCS and CAF. The relationship between PPCPs in the surface sediments was analyzed to reveal correlations between SMX and TMP, CAF and IBU, CAF and TCS. The risk quotients (RQ) method was used to evaluate the ecological risk of the five detected PPCPs. The major contributors of potential environmental risks were IBU, TCS and CAF, among which all the potential environmental risks at the TCS samples were high risk. This study supplemented the research on the ecological risk of PPCPs in sediments of important reaches of the North Canal to reveal the importance of PPCP control in the North Canal and provided a scientific basis for pollution control and risk prevention of PPCPs. [ABSTRACT FROM AUTHOR]

BACKGROUND Anning is an important industrial and mining city in the upper reaches of the Yangtze River Economic Belt. It is a fulcrum for economic development and ecological civilization construction in the Central Yunnan New Area. The investigation of geochemical water system sediments and hydrogeology in the Anning area was last performed in the 1970s and the 1980s. In recent years, the impact of human production and life on the ecological environment remains unclear. OBJECTIVES Surface sediment samples from the Anning area were investigated to reveal their pollution status, spatial distribution characteristics, and potential ecological risks of river sediments. METHODS X-ray fluorescence spectroscopy, inductively coupled plasma optical mass spectrometry, gas chromatography-mass spectrometry, and other methods were used to systematically analyze the contents and distribution characteristics of major elements, trace elements, and 16 priority-controlled PAHs. Geoaccumulation index, Hankanson ecological risk index, and sediment quality criteria were used to assess the ecological risk of eight typical heavy metals (As, Cd, Cr, Cu, Ni, Zn, Pb, and Hg) and PAHs. RESULTS Results showed that the heavy metal content in the river sediments from the Anning area was higher than the background values of the national and southern rivers. The spatial distributions of the heavy metals were highly variable and uneven. Additionally, Cd, Hg, and Ad showed medium to severe potential ecological risks. The average content of ∑PAHs was 20856ng/g, and the detection rate of the 16 monomers was ~100%. The overall ecological risk of PAHs was low, and their main sources were petrochemical industry and combustion of petroleum fuels. The major risks of pollutants in the river sediments of the Anning area were mainly concentrated in the vicinity of steel plants and chemical factories in the Tanglangchuan River. CONCLUSIONS This research provides a scientific basis for local governments to strengthen key industrial point source pollution control, and reduce and control industrial sewage discharge.

Sediment samples collected from the river Shitalakhya, Bangladesh, were analyzed using atomic absorption spectroscopy (AAS) to investigate site-to-site (spatial) and seasonal (i.e., dry, pre-monsoon, post-monsoon) variation of Cr, Mn, Ni, Cu and Zn. The mean concentrations of Cr, Mn, Ni, Cu and Zn were 22.37 ± 6.09, 612.59 ± 160.08, 54.11 ± 11.21, 50.36 ± 9.40 and 103.62 ± 62.74 mg/kg in the dry, 31.58 ± 5.22, 569.71 ± 112.16, 58.35 ± 7.82, 49.93 ± 17.36 and 110.88 ± 95.83 mg/kg in the pre-monsoon and 18.09± 6.32, 567.02 ± 115.55, 50.89 ± 6.58, 39.75 ± 4.56 and 55.22 ± 11.33 mg/kg in the post-monsoon, respectively. Based on the metals’ concentrations, no considerable difference was observed among the three seasons, but the concentrations were slightly elevated in the dry and pre-monsoon compared to that in the post-monsoon with respect to site-to-site variation. Among the metals examined, concentrations of Ni and Cu were elevated because of the use of oxides of these heavy metals as catalysts in the ammonia plant. The following statistical indices i.e., Pearson correlation matrix, geo-accumulation index (Igeo), contamination factor (Cf), degree of contamination (Cd), pollution load index (PLI) and ecological risk potential (RI) factors were taken into account to assess the heavy metals contamination of the sediments. According to the values of the statistical indices for Cr, Mn, Ni, Cu and Zn, it is concluded that the study area was with low contamination while concentrations of Ni and Cu were higher than the Threshold Effect Level (TEL) and Toxicity Reference Value (TRV) values suggesting unsafe to use the sediments for vegetation and other uses.

Background: Heavy metals due to their ecological risks and high toxicity to living organisms are considered as one of the most dangerous pollutants. Therefore, the present study was conducted to investigate the level of pollution, toxicity and the ecological risks of heavy metals in the coastal surface sediments of Bushehr province using systematic review. Methods: To conduct this review study, the concentration level of heavy metals in the surface sediments of Bushehr coastal was obtained by searching for published studies during the 9 years (2012-2020) through databases (Springer, Google Scholar, ProQuest, Web of Science, SID, Magiran). Finally, a comprehensive description of heavy metal pollution, toxicity and risks in coastal sediments was investigated using various indicators. Results: As a result of reviewing the extracted studies from the databases, 24 papers were selected. The survey results showed that the order of mean concentration of heavy metals in sediments was as Zn>Ni>Cr>Cu>Pb>Cd, and the amount of metals Pollution load index in different coastal sediments ranged from 0.15 to 1.99. The order of ecological risks for metals was observed as Cd>Pb>Ni>Cu>Cr>Zn, and the potential ecological risks for metals was obtained in the range of 3.76-257.38. In addition, the results of Toxic unit analysis and modified Hazard quotient of metals showed that the degree of toxicity and risk of contamination varies from very low to severely contaminated. Conclusion: Based on the findings from the perspective of toxicity control and ecological risks of metals, it is necessary to prevent the transfer of heavy metals, especially Cd, Pb and Ni due to dominant human activities in the coastal areas of Bushehr. Also, due to the maximum pollution load and ecological risks in Bidkhon (Assaluyeh) coasts, pollution sources should be determined to effectively control and manage the entry of pollutants in this area.

• The phytoplankton structure from Prydz Bay was determined from lipid biomarkers. • Phytoplankton succession driven by sea ice controls organic matter composition. • Sea ice retreat induces diatom to flourish and so increases biological pump efficiency. The coastal zones in Antarctica play an important role in the polar carbon cycle through the efficiency of the biological pump. In this study, Prydz Bay in East Antarctica was selected to investigate factors controlling organic matter composition in sediments using source-dependent biomarkers. The results show that fatty acids are the most abundant biomarkers in sediments, followed by sterols, fatty alcohols, and alkanes. Although microalgae are well known to be the main source of sedimentary organic matter in Prydz Bay, the distribution of low molecular weight branched alkanes and alkenes with an even–odd predominance suggest the importance of bacteria during organic matter transformation, and its contribution to sedimentary organic matter. High concentrations of highly branched isoprenoid alkenes (HBIs) with a distinctive enriched 13C signature indicate substantial inputs of ice algae to sediments. Principal component analysis of source-dependent biomarkers reveals that the spatial heterogeneity of organic composition in sediments of Prydz Bay is mainly controlled by the distribution of sea surface phytoplankton community in different geographical zones. Redundancy analysis demonstrates that seasonal sea-ice cover is the main driver for blooms of distinctive algae in each geographical zone as a result of spatial succession of the phytoplankton community. The result clearly exhibits that, at least in Prydz Bay, spatial succession of the sea surface phytoplankton community in austral summer can be recorded in sediments, suggesting that a high-resolution sediment record of source-dependent biomarkers can be used to reconstruct the evolution of sea surface phytoplankton community structure during geological history in Antarctic coastal zones. [ABSTRACT FROM AUTHOR]

Surface sediment samples were collected from the surrounding sea areas of the two largest tourist islands in Sanya City, China, to compare and assess the sources, distribution, and ecological risks of 16 polycyclic aromatic hydrocarbons (PAHs). The total PAHs concentrations ranged from 31.16 to 163.3 ng/g, with an average concentration of 102.46 ng/g, which is still lower than the levels detected in most other sediment studies worldwide. PAHs from coal combustion (Flu, Pyr, Fl, Phe) showed positive correlations with TOC, Silt, and Clay, indicating that these PAHs are easily adsorbed in muddy and silty sediments. Sanya Bay is primarily composed of mud and silt, whereas Haitang Bay is mainly sandy. This corresponds to the significantly higher concentrations of Fl, Phe, and Pyr in Sanya Bay compared to Haitang Bay. The main industrial activities in the study area are related to power and heat production and supply. The results indicate that the primary sources of sediment PAHs are high-temperature combustion during heavy industrial production, followed by maritime transportation and petroleum sources. Overall, the PAHs pollution levels in the study area range from slight to moderate. Sediment quality assessments show that only Ace and Phe have higher individual risk values. Six stations in Sanya Bay have higher adverse impact risks, while in Haitang Bay, only HT07 poses a high risk to biological impact. These two areas require enhanced monitoring and pollution source control. • Studied the distribution, sources, and potential ecological risks of polycyclic aromatic hydrocarbons (PAHs). • PAHs generated from coal combustion are prone to adsorption onto fine particulate sediment. • The main sources of PAHs are heavy industrial production and ship transportation in the area. • Sanya Bay exhibits a relatively high risk value for adverse effects on organisms, while Haitang Bay has only one location with a relatively high risk value. [ABSTRACT FROM AUTHOR]

The investigation along the Coromandel coastline of South-east India focused on assessing microplastics abundance using Simpson's diversity index (D I M P) , Degradation-carbonyl index (D g C I M P ), Pollution load index (P L I M P) and Ecological risk fraction (R f M P ). These indices evaluated the dissemination and transportation of MPs across a 1076 km stretch divided into five zones from Chennai to Kanyakumari. During the wet season, average microplastics abundance (101 ± 36.6 items/kg dw) was lower compared to the dry season (143 ± 56.2 items/kg dw). Notably, 54% and 45% of microplastics were found in the 0.1–0.5 mm size range, with 45% and 64% being colored microplastics, and 80% and 71% being fibers during the wet and dry seasons respectively. Micro-Fourier-transform infrared spectroscopy (μFTIR) analysis showed rayon (34%) and PE (64%) dominance in ports and estuaries during both seasons. Kottaipattinam Port exhibited higher diversity indices ( D I M P s h = 0.56 , D I M P s z = 0.66 , D I M P c o = 0.50 a n d D I M P p o = 0.65) compared to other zones, with an overall diversity index I D I M P of 0.57. Notably, among the D g C I M P values (n = 96), only 12 fell within the moderate photo-chemical oxidation range (0.16–0.35), while the majority (n = 60) surpassed 0.35 indicating higher oxidation levels, with some (n = 24) exceeding 0.50, signifying extreme oxidation. P L I M P revealed that 42% of sampling stations had very low to negligible MP contamination levels in ports and estuaries. However, ecological risk fraction R f M P values ranged from 10.2 to 13,670, with 27% of values exceeding 1500, indicating higher coastal ecological risk in 13 sampling stations. [Display omitted] • Highest mean ± std. dev of MPs recorded in ports of 210 ± 103.1 items/kg dw. • The coastline is enriched with PE (64%) as highest polymer counts in the ports. • Abundancy and lower inventory of microplastics are found during flash flood. • The intertidal zones are found with low P L I M P and the R f M P (below 15-Category I). [ABSTRACT FROM AUTHOR]

Heavy metals contamination in sediments may endanger ecosystems and human health via the food chain. In fact, there is little to no understanding about heavy metal accumulation in surface sediment of one of the most economically important marine bodies for Vietnam, the Thai Binh Coast, where five large rivers co-discharge into the Gulf of Tonkin. Twenty-seven surface sediment samples were collected from the intertidal regions and analyzed for: arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), and zinc (Zn) using inductively coupled plasma mass spectroscopy (ICP-MS). The studied area exhibited a large spatial variation in the concentration of heavy metals, e.g., the dry sediment concentration of Cd was the least (0.05–0.49 mg.kg−1), whereas that of Zn was the greatest (45.4–252 mg.kg−1). Based on the geoaccumulation index ( I geo ), most of the studied heavy metals were accumulated at low pollution levels, except four locations exhibited moderately and highly polluted levels of Hg with I geo Hg values from 1.92 to 2.66. However, the high contamination factor value implicated that not only Hg but also all other detected heavy metals in this area resulted from anthropogenic activities along the coast and the river upstream. This implied the need for quick action from the government. In addition, numerous analytical methods were used to see the association between metals, total organic carbon (TOC), and particle size distribution, including Pearson correlation coefficient (P) and principal component analysis (PCA). Hg demonstrates lowest connection with TOC (PHg-TOC ~ 0) but individual heavy metal correlations are largely positive, with many reaching 1.0 (e.g., PNi-Cr = 0.89, PCd-As = 0.72, PNi-Cu = 0.76, and PCu-Cr = 0.72). From the PCA diagram, we can observe that those sampling points in the positive direction of PC1 were expected to have a high concentration of Cu, Zn, As, Ni while having extremely little sand content. [ABSTRACT FROM AUTHOR]

Mercury is highly toxic and persistent in the environment and is one of the global environmental pollutants. As an important part of the ecosystem, lakes are the gathering place of many pollutants. In this paper, two typical lakes in Zhanjiang were used as the study area, and the vertical distribution characteristics of mercury and effective state mercury in the overlying water, pore water, sediment and their bioavailability were analyzed based on thin film diffusion gradient (DGT) and high resolution dialysis technique (HR-Peeper), and their effects on mercury distribution were discussed with several environmental factors such as iron and manganese content and pH value. The total mercury content in the sediments of the typical lake area of Zhanjiang ranged from 21.26 to 76.65 µglkg, and the methylmercury content ranged from 0.11 to 1.11 µglkg, which exceeded the environmental background value (19 µglkg) for soils in Shandong Province; the total mercury content in the overlying water bodies of Zhanj iang ranged from 1.50 to 5.63 ng/L, and the mean dissolved mercury content in pore water was The mean value of dissolved mercury in pore water was 12.95 ng/L, which was higher than that of total mercury in the overlying water bodies; the effective mercury content in the overlying water bodies of Zhanj iang ranged from 1.41-3.81 ng/L, and the effective mercury content in sediments ranged from 3.58- 18.97 ng/L. The influence of several environmental factors on the distribution of effective mercury in sediments of typical lakes in Zhanjiang was discussed. The decrease in the content of Fe-Mn, total nitrogen and organic carbon in the sediment reduces the adsorption capacity of the sediment to Hg, so the effective state of Hg shows surface enrichment. pH, DO and Eh are negatively correlated with the effective state of Hg, and the decrease in pH at the interface reduces the negative charge on the surface of clay minerals, hydrated oxides and organic matter, which increases the content of the effective state of Hg released from the solid phase into the water col4507 umn; the trends of dissolved oxygen and redox potential indicate that This is a reducing environment, and the rate of mercury desorption is faster under anaerobic conditions, which makes the effective state of mercury in the sediment increase. [ABSTRACT FROM AUTHOR]

With the entry of various effluents into aquatic ecosystems such as wetlands, pollutants containing heavy metals are deposited in the sediments. The aim of this study was to determine the level of heavy metal contamination of surface sediments in Salehieh Wetland, Karaj, Alborz Province. For this purpose, samples were taken from the sediments of six stations along with the wetland in May 2020. After preparation and chemical digestion of the samples, the concentration of heavy metals was determined by the flame atomic absorption instrument. Mean concentrations with standard deviation of lead, cadmium, nickel and chromium in wetland bed sediments were 14.11 ± 1.52, 1.14± 0.17, 19.87± 2.67 and 64.1± 7.03 µg/g, respectively and the accumulation pattern of heavy metals obtained was Cr> Ni> Pb> Cd. The highest concentration of metals was observed in station number 1. Comparison of metal concentrations with the values ​​of international standards showed that the mean concentrations of lead 14.11, cadmium 1.14 and chromium 64.1 µg/g were higher than LAL standards for lead (2), cadmium (0.04) and chromium (26 µg/g), respectively. The mean concentration of nickel was 19.87 µg/g, which is more than the HAL standard (15.9 µg/g). The amount of cadmium and chromium was higher than the ISQGS standards (0.7 and 43 µg/g for cadmium and chromium respectively). Therefore, increasing the concentration of these metals, especially cadmium and chromium, if not monitoring and controlling the discharge of effluent from the industrial town adjacent to the wetland, can lead to a threat to the health of ecosystems and the region.

Microplastic pollution is an emerging topic in environmental science. However, information about its prevalence in the freshwater ecosystems is still scarce. This study quantified and identified microplasticform and polymer types from surface sediments of the Molawin River. Sediment samples were collected from the upstream, midstream, and downstream stations of the river. Isolation of microplastics was performed through a modified granulometric approach, density separation, and filtration. Stereoscopic microscopy and Fourier-transform infrared spectroscopy (FTIR) were conducted to quantify and describe microplastics and identify the polymer types based on the infrared spectrum of absorption, respectively. Thehighest concentration of microplastics was found in the downstream station, with an average number of 97±12 items/100 g and 47.33±11.39 items/100 g sediment dry weight in the bank and channel, respectively. The isolated microplasticswere dominated by ≥100 to ≤200 μm size range. Based on stereoscopic microscopy, microfragments and microfibers were the most common microplastic type, while polyethylene (PE) and polypropylene (PP) were the polymer types identified based on FTIR analyses.This study revealed the presence of microplastics and confirmed the microplastics polymers present in the Molawin Watershed of Makiling Forest Reserve.

The Meliane River, the second longest and most important river in Tunisia, is one of the major rivers that flow into the Gulf of Tunis. However, it is known by its significant discharges of urban and industrial activities that have seriously affected the quality of the aquatic ecosystem. The highest amounts of Cadmium (Cd), Copper (Cu), Lead (Pb), Zinc (Zn), Nickel (Ni), Chromium (Cr) and Manganese (Mn) in the surface sediments of the Meliane River indicate that the downstream part is the most polluted area. The chemical speciation shows that the majority of the trace metals are bound to a reducible fraction (Zn, Mn, Cr and Ni) and the Pb and Cu are bound to the oxidizable fraction. The Cd is linked to the exchangeable fraction, which indicates its high mobility and toxicity. Both the contamination and enrichment factors values of some trace metals are elevated in the downstream part of the Meliane River. The percentage of the risk assessment code in Cd is 59.8%, which presents a very high environmental risk. Therefore, the spatial distribution of trace elements in the surface sediments is characterized by its high concentration of metals in the downstream part of the Meliane River. These concentrations decrease as a function of change in the physicochemical parameters from the freshwater-saltwater mixing zone to marine stations. [ABSTRACT FROM AUTHOR]

Lake Sevan (Armenia) is one of the large freshwater high-mountain lakes of Eurasia. Detailed information about the extent and fate of trace elements on lake sediment and water quality has not been published yet. For this reason, surface sediment and water samples were collected from the southern and northern basins of Lake Sevan to determine trace element concentrations and assess the trace element behaviour. Geo-accumulation index, potential ecological risk index, and hazard index were calculated to estimate the environmental risk potential. In comparison to reference values, the investigated sediment samples contained elevated concentrations frequently for V, Cr, Co, Ni, Mo, Cd, Be, Ti, Rb, Sr, Se, Hf, and Th and occasionally for Cu, As, Li, B, Ag, Sb, Tl, Bi, U, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm. An overall potential ecological risk posed by all the investigated trace elements in the sediments was assessed to be moderateconsiderable, however, Mo, Hg, and Cd were the elements with the highest ecological risk potential. The two basins of the lake showed significantly different behaviour according to the investigated trace element contents in the sediments to be higher in the bigger basin compared to the smaller basin. In comparison to reference concentrations in water samples according to the use of the adapted geoaccumulation index, elevated values for Ti, Cr, Cu, Cd, and Pb were observed. Elevated concentration was also observed in the case of B in nearly all water samples in comparison with literature values. Nevertheless, several water samples can be seen as not strongly anthropogenic influenced by Co, Ni, Sn, Sb, Ag, Hg, and Bi. The concentrations of trace elements in the lake water caused health risks to humans particularly children in the case of lake water used for drinking purposes, moreover, As was the main element posing health hazards. The results point out further attention to the sources of elevated trace elements in Lake Sevan, including anthropogenic influences and geological characteristics. [ABSTRACT FROM AUTHOR]

A survey of 60 high mountain lakes of Colombia's Eastern Range was performed to evaluate the response of surface-sediment diatoms to environmental variables. In each one of these lakes, water samples were taken for physical and chemical characterization, and diatoms were collected from the superficial bottom sediment at the deepest part. Multivariate statistical analyses were made to determine the relationships between environmental and biological data, specifically which environmental variables explain the diatom distribution. For each of these significant environmental variables, optima and ecological tolerances were calculated using the weighted-average method, which allowed for the classification of the species according to their environmental preferences. The lakes showed a wide range of environmental gradients in variables such as pH, alkalinity, and nutrients. In addition, the depth of the lakes was a direct determinant of the light environment of the water column. A total of 339 diatom taxa were identified belonging mainly to the genera Eunotia and Pinnularia. Variables related to pH-alkalinity gradient, trophic condition (nitrates and phosphorus), and physical factors (radiation at the bottom) had a significant effect on diatom composition. Despite the fact that the total organic carbon environmental range was high, the effect of this variable on diatom species composition was not significant. In conclusion, the diatoms of the studied lakes showed a significant ecological relationship with environmental variables which are potentially important in environmental reconstruction. Diatoms in the study sites can provide useful and independent quantitative information to investigate the recent impacts of global change on tropical high mountain ecosystems. [ABSTRACT FROM AUTHOR]

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Rivers, as the living artery of the watershed, have caused its life and have long determined the extent and establishment of civilizations, especially in the coastal plains. The Tajan River in the coastal plain of Sari has been directly polluted by water and sediment resources as a result of industrialization, agricultural development, and towns, and villages. The aim of this study was to determine the quality of surface sediments of Tajan River in the city to sea range based on the concentration of toxic elements As, Cr, Cd, Cu, Ni, Pb, Zn and to detect the level of pollution caused by them. The sampling strategy was designed to collect 25 surface sediment samples based on the distribution of point and non-point pollution sources and river morphology. Samples were conditioned and concentration of toxic elements and sulfur were measured using ICP-MS at dry weight with accuracy of mg/kg and percentage of total organic carbon. Using enrichment factor and sediment quality standards (ISQGs, PEL, SEL), the level of contamination caused by toxic elements was detected. The results well identified the polluted and clean ranges of the Tajan River. Accordingly, the southeast and downstream of the urban area of Sari were polluted by the toxic metal of As and upstream of the urban area, and adjacent to the effluent of industrial estates to the river were contaminated considerably by the toxic metal of chromium. Finally, superficial sediments of the Tajan River along the studied range were polluted significantly by the toxic metal of Ni at a risky level. Also, Pb enrichment was proven in the downstream sediments of the urban area due to fossil fuels. The research results emphasize the effect of urban-rural pollution (surface water drainage, construction waste and rubbish), industrial and agricultural effluents and sand mines on the pollution of water resources and sediment of Tajan River.

Peatlands form environmental archives of trace element deposition. In this regard they are particularly valuable for areas such as the Arctic, where regular pollution monitoring is either impossible or extremely costly. The aim of this study was to assess pollution in the Solovetsky Islands (65° 05' N, 35° 53' E) by examining the spatial variability in trace element content of the uppermost layer of peat, immediately below the surface layer of green vegetation. We evaluated Cr, Cd, Ni and Pb contents in samples taken from ombrotrophic (raised bog) and mesotrophic (transitional) mires and in different microtopographical settings (hummock/hollow), and calculated the following pollution indices: geoaccumulation index (Igeo), contamination factor (Cf) and degree of contamination (Cdeg). The contents of these elements were markedly lower in the Solovetsky Islands than reported from other parts of central and northern Europe. Depending on the pollution index considered, the studied peat samples could be classified as unpolluted to considerably polluted. The local spatial patterns showed the highest values of Cd in samples collected near the sea, while the highest contents of Cr and Ni were noted at sampling points located farther inland. Moreover, Cr and Pb concentrations were higher in raised bogs than in transitional mires, and this contrast was accentuated if raised bog was represented by hummocks alone. These patterns are consistent with the likely sources of Cr, Ni and Pb being atmospheric pollution; and with higher mobility of Cd in seawater, which periodically floods the transitional mires. Amongst the trace elements determined, the most consistent values across peat types and sampling locations were found for Ni, which could be successfully used for pollution monitoring even in transitional mires.

The ecological functions and biogeochemical processes of continental marginal seas are important for the global carbon cycle. In the eastern China marginal seas (ECMS), phytoplankton productivity has increased significantly in recent decades, but the sources and burial processes of marine organic carbon (OC) remain under-studied. We analyzed the contents of marine lipid biomarkers (brassicasterol, dinosterol, and C37 alkenones) in surface suspended particles obtained from seven cruises between 2010 and 2015, and in surface sediments from eight cruises between 2006 and 2012 in the ECMS, to estimate marine OC sources and burial. The correlations between lipid biomarkers and environmental factors were quantified to reveal controlling factors. The study area was divided into four regions according to cluster analysis conducted based on sediment parameters. Our results showed that the concentrations of marine lipid biomarkers in surface water were high near large estuaries such as the Changjiang River Estuary and the Yellow River Estuary, but those in surface sediments were high in mud areas. Nutrient concentration was a key factor controlling phytoplankton biomass in surface water, with high nutrients enhancing the growth of diatoms and dinoflagellates, while haptophytes were more abundant in low-nutrient, high-salinity and cold environments. High marine OC contents calculated from total OC δ13C were mainly associated with fine sediments transported by coastal currents, and finally deposited in mud areas. The proto-burial efficiency of marine OC in the ECMS (7–19%) was markedly higher than the mean value in global marginal seas, with high values being located in the western coast of the ECMS. The proto-burial efficiency of total marine lipid biomarkers (6–24%) was quantified for the first time in our study, with overall values and spatial patterns similar to that of marine OC. A key parameter for marine OC and marine biomarker proto-burial efficiency was sediment grain size. The smaller the sediment grain size was, the better the marine OC and marine biomarker were retained. Our study provides an important basis to elucidate spatial distribution patterns and forcing mechanisms of marine OC in surface water (production process) and surface sediments (burial process), and to estimate carbon budgets in large marginal seas.

This study investigated the concentration of trace metals in surface sediments of Parishan Lake. Parishan Lake is one of the biggest freshwater lakes in the Middle East, situated in Kazerun area (Fars Province, Iran). This preliminary study concerns the mineralogy, enrichment level, and trace elements source identification in surface sediment of this lake. The geochemical Enrichment Factor (EF) and Geo-accumulation index (Igeo) and sedimentological approaches were applied to characterize the contamination by heavy metals, comparing with Average Shale. Multivariate statistical analysis was also used to identify probable studied elements sources in collected samples. The XRD and microscopic analysis show that main mineral of surface sediments is aragonite with small amounts quartz and nepheline. Chemical analysis of sediments showed that the mean concentrations of As, Cd, Cr, Cu, Ni, Pb, Zn, and Sr were 1.88, 27.2, 32.4, 18.6, 8.1, 38.4, and 3934.9 mg/kg, respectively, and average concentrations of Cd, Cu, and Sr exceeded the corresponding values of upper continental crust (UCC) values. The outcomes of this study indicate that geochemical indices (EF and Igeo) revealed an extremely high enrichment for Sr, whereas other elements had minimal enrichment. The levels of potential ecological risk index (RI) for studied trace elements in all sampling locations were 41.13 and 23.76, lower than baseline value (150), signifying that ecological risks displayed by those elements in sediments were moderate. The multivariate statistical analysis indicated that Sr had a geogenic source (natural source), while As and Cd came probably from Industrial source (chemical fertilizers), Ni and Cr were likely derived from vehicle emissions, particularly agricultural machinery, and Pb originated from exhaust and non-exhaust traffic emissions. [ABSTRACT FROM AUTHOR]

Deciphering the source(s) of sediment deposited in Hugunagyan Lake in South China using magnetic properties will advance our understanding of the evolution of East Asian monsoon systems. However, the source of magnetic minerals in the surface sediments of this lake is unknown, still needing further exploration. Due to simple hydrological systems, the Hugunagyan Lake provides a unique record for investigating the magnetic property of sediments and surface processes. In this study, based on the magnetic properties of 43 surface sediment, 12 surface soil, and 7 volcanic rock samples from the catchment, we demonstrate that the magnetic minerals in sediments were dominated by fine super paramagnetic magnetic particles, with coexistence of pseudo‐single‐domain states minerals. There are no signatures showing the presence of biogenic and authigenic magnetite. The magnetic properties of surface sediments display significant differences between the potential sources of aeolian dust from the loess in North China and modern surface soils in Central Asia, suggesting that the magnetic minerals mainly originate from the weathered materials in the catchment, and there are no further signals of winter monsoon‐driven aeolian dust input. [ABSTRACT FROM AUTHOR]

In order to understand the distribution characteristics, sources and potential ecological risks of heavy metals in Yunmeng Lake, surface sediment samples were analyzed in August 2018. Concentrations of six heavy metals, including Cr, Ni, Cu, Zn, Cd and Pb were determined by inductively coupled plasma mass spectrometry. The spatial distribution of heavy metals were analyzed by geo?statistics method and GIS technology, then risks of these heavy metals were evaluated by geo-accumulation index and potential ecological risk index and the sources were investigated by using principal component analysis and correlation analysis. The results indicate that the average contents of Cr, Ni, Cu, Zn, Cd and Pb are 62.91, 9.66, 56.79, 93.14, 0.09 and 11.07 mg / kg respectively. The Igeo shows that the pollution status of heavy metals is unpolluted and slightly polluted. According to the potential ecological risk indicators, the average value of RI in the reservoir is 50.12, suggesting a lower ecological risk. The analysis of heavy metal sources shows that Cr, Cd and Pb are greatly affected by industrial and agricultural activities and Zn and Cu are mainly from aquaculture. [ABSTRACT FROM AUTHOR]

Hydrothermal venting has a profound effect on the chemical and biological properties of local and distal seawater and sediments. In this study, lipid biomarkers were analyzed to examine the potential influence of hydrothermal activity on the fate of organic matter (OM) in surface sediments around Tianxiu Hydrothermal Field in the Carlsberg Ridge (CR), Northwest Indian Ocean. By comparing the biomarker distributions of the samples with that of other typical hydrothermal sediments in the mid ocean ridge, it is shown that the location of the samples is not affected by the hydrothermal activity. The relatively low abundances of terrestrial n-alkyl lipids and riverine 1,15-C32 diol suggested a minor contribution of terrigenous OM to the study area. The bacteria contributed predominantly to sedimentary marine OM; however, other marine source organisms, e.g., eukaryotes (i.e., phytoplankton and fungi) could not be completely neglected. The marine-originated biomarkers showed significantly variable distributions between the two sediments, suggesting different dynamic physical and biogeochemical processes controlling the fate of marine OM. This study identified various diagnostic biomarkers (5,5-diethyl alkanes, diols and β-OH FAs), which may have significant environmental implications for future works in this region. [ABSTRACT FROM AUTHOR]

The study aimed to determine the level of mercury (Hg) and its labile and stable forms in the surface sediments of the Baltic Sea. The work considers the impact of current and historical sources of Hg on sediment pollution, together with the influence of different environmental parameters, including water inflows from the North Sea. Surface sediments (top 5 cm) were collected in 2016–2017 at 91 stations located in different areas of the Baltic Sea, including Belt Sea, Arkona Basin, Bornholm Basin, Gdańsk Basin, West Gotland Basin, East Gotland Basin, and the Bothnian Sea. Besides, the particulate matter suspended in the surface and near-bottom water was also collected. The analysis of total Hg concentration and individual Hg forms in collected samples was carried out using a 5-step thermodesorption method. This method allows for the identification of three labile and thus biologically available, fractions of Hg, which are mercury halides, organic Hg, mercury oxide and sulphate. Two stable fractions, mercury sulphide and residual Hg, were also determined. The highest Hg concentrations, reaching 341 ng g−1, were measured in the highly industrialised Kiel Bay, which was additionally a munition dumping site during and after World War II. High Hg level, ranging from 228 to 255 ng g−1, was also recorded in the surface sediments of the Arkona Basin, which was a result of the cumulative effect of several factors, such as deposition of Hg-rich riverine matter, favourable hydrodynamic conditions and military activities in the past. The relatively elevated Hg concentrations, varying from 60 to 264 ng g−1, were found in the Gdańsk Basin, a region under strong anthropopressure and dominated by soft sediments. The sum of labile Hg in sediments was high and averaged 67% (with the domination of organic Hg compounds), which means that a large part of Hg can be released to the water column. It was found that the water inflows from the North Sea intensify the remobilisation of Hg and its transformation into bioavailable labile forms. As a consequence, the load of Hg introduced into the trophic chain can increase. Despite the significant reduction of Hg emission into the Baltic in the last decades, surface sediments can be an important secondary Hg source in the marine ecosystem. This is especially dangerous in the case of the western Baltic Sea. [ABSTRACT FROM AUTHOR]

BACKGROUND: Anning is an important industrial and mining city in the upper reaches of the Yangtze River Economic Belt. It is a fulcrum for economic development and ecological civilization construction in the Central Yunnan New Area. The investigation of geochemical water system sediments and hydrogeology in the Anning area was last performed in the 1970s and the 1980s. In recent years, the impact of human production and life on the ecological environment remains unclear. OBJECTIVES: Surface sediment samples from the Anning area were investigated to reveal their pollution status, spatial distribution characteristics, and potential ecological risks of river sediments. METHODS: X-ray fluorescence spectroscopy, inductively coupled plasma optical mass spectrometry, gas chromatography - mass spectrometry, and other methods were used to systematically analyze the contents and distribution characteristics of major elements, trace elements, and 16 priority - controlled PAHs. Geoaccumulation index, Hankanson ecological risk index, and sediment quality criteria were used to assess the ecological risk of eight typical heavy metals (As, Cd, Cr, Cu, Ni, Zn, Pb, and Hg) and PAHs. RESULTS: Results showed that the heavy metal content in the river sediments from the Anning area was higher than the background values of the national and southern rivers. The spatial distributions of the heavy metals were highly variable and uneven. Additionally, Cd, Hg, and Ad showed medium to severe potential ecological risks. The average content of ∑ PAHs was 20856ng/g, and the detection rate of the 16 monomers was -100%. The overall ecological risk of PAHs was low, and their main sources were petrochemical industry and combustion of petroleum fuels. The major risks of pollutants in the river sediments of the Anning area were mainly concentrated in the vicinity of steel plants and chemical factories in the Tanglangchuan River. CONCLUSIONS: This research provides a scientific basis for local governments to strengthen key industrial point source pollution control, and reduce and control industrial sewage discharge. [ABSTRACT FROM AUTHOR]

Spatial patterns, potential origins, and ecotoxicological risk of alkylated (APAH) –and parent –(PPAH) polycyclic aromatic hydrocarbons (PAHs) were studied in mangrove surface sediments along the northern coasts of the Persian Gulf, Iran. The mean total concentrations (ngg−1dw) ∑ 32 PAH, ∑PPAHs and ∑APAHs in sediments were 3482 (1689–61228), 2642 (1109–4849), and 840 (478–1273), respectively. The spatial variability was similar among these PAH groups, with the highest levels occurring in Nayband National Marine Park (NNMP). Physicochemical environmental factors, such as sediment grain size, and total organic carbon (TOC) contents, are significant factors of PAH distribution. These findings suggest that PAH pollution level is moderate-to-high, supporting the current view that mangrove ecosystems are under intensive anthropogenic impacts, such as petrochemical, oil and gas loads, port activities, and urbanization. Non-parametric multidimensional scaling (NPMDS) ordination demonstrated that NNMP mangrove is the critical site exhibiting high loading of PAH pollutants. Here, for the first time in this region, Soil quality guidelines (SQGs), Toxic equivalency quotient (TEQ), Mutagenic equivalency quotient (MEQ), and composition indices comprising Mean maximum permissible concentration quotient (m- MPC-Q), and Mean effect range median quotient (m- ERM-Q) methods were used to have a comprehensive risk assessment for PAH compounds and confirmed medium-to-high ecological risks of PAHs in the study area, particularly in the western part of the Gulf, highlighting the industrial impacts on the environment. [Display omitted] • First spatial accumulation distribution of PAHs in mangroves of the Persian Gulf. • Mangroves can be divided into several groups based on pollution levels and sources. • The most polluted mangrove was observed in NNMP site. • TOC and clay revealed an effective role on the spatial distribution of PAHs. • The overall ecological risk is medium to high with adverse biological effects. [ABSTRACT FROM AUTHOR]

The distribution, characteristics, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and hopanes in the surface sediments collected along the Qatar coast were investigated. Concentration of ∑ 14 PAHs and hopanes ranged between 0.076 and 7.04 ng g−1 (mean: 2.60 ng g−1), 100 and 700 ng g−1 (mean: 205 ng g−1), respectively. Sediment samples were dominated by high molecular weight PAHs composition (4–6 rings). Diagnostic ratios of PAH concentrations showed both petrogenic and pyrogenic origins of PAHs, with a higher percentage of pyrogenic sources. The ecological risk levels of PAHs were estimated using sediment quality guidelines (SQG), mean probable effect level quotient values (PEL-Q), carcinogenic toxic equivalent quantity (TEQ), and risk quotient (RQ) evaluation methods. The calculated TEQ values (0.00012–0.85 ng g−1) were lesser than those in other locations around the globe, and were also within the safe level (600 ng g−1) suggested by the Canadian soil quality guidelines. • PAHs and hopanes ranged from 0.076 to 7.04 and 100 to 700 ng g−1, respectively. • PAHs dominated with HMW and origins are from pyrogenic and petrogenic. • Calculated ecological risks of PAHs showed low ecological risk in Qatar sediments. [ABSTRACT FROM AUTHOR]

The Ledong Sea Area is located on the southwest side of Hainan Island. In recent years, with the development of industrialization and urbanization, the problem of heavy metals in marine sediments has gradually become a global problem, and research on this topic is of great significance for nearshore environmental protection and coastal management. This paper analysed the heavy metal content of 97 surface sediments in the Ledong Sea, indicating unpolluted to moderately polluted and low to moderate risk. Cu, Zn, Hg, Pb, Cr, and Cd are highly correlated, with similar origins, and originate from rivers carrying industrial wastewater, domestic sewage, and weathered material from the parent rocks, which are subsequently redistributed under the action of ocean dynamics. The distribution of Hg is mainly influenced by feed and biological metabolites during the farming process. As originates from rivers carrying large amounts of agricultural pesticide and fertilizer residues. • The ocean hydrodynamics can redistribute heavy metal elements imported from rivers. • Coastal aquaculture is one of the main causes of heavy metal enrichment. • The study of heavy metal transport process is very important for pollution control measures. • The concentrations of heavy metals in the Ledong Sea area had little risk to Marine organisms. [ABSTRACT FROM AUTHOR]

ABSTRACT: Based on the 39 surface sediment samples collected in the flood season and the dry season in 2012 respectively and the measured hydrological data in October 2012, the sediment grain size characteristics has been analyzed and the response mechanism of surface sediments to estuarine hydrodynamics was revealed by calculating the range of waves and tidal currents. The results show that: (1) The grain size of the surface sediment samples decreased gradually from land to sea in the flood season. The fine sediment was redistributed under marine hydrodynamics in the dry season and the sediments showed coarser tendency ingeneral; (2) tidal current stirring sediment was very obvious in Dagu River estuary area, and wave stirring sediments mainly occurred in the tidal flat area and estuary sand bar area; (3) in the flood season, surface sediment sat the estuary were transported towards south and southeast. In the dry season, surface sediments were transported towards southwest at the north area of Jiaozhou Bay Bridge, and sediments were transported towards northeast area at the south of Jiaozhou Bay Bridge.

Background and Objective: This study conducted to assess ecological risk of an important group of pollutants called polycyclic aromatic hydrocarbons (PAHs) in offshore sediment of the Persian Gulf deposits in Bushehr province. The aim of this study was to model the toxicity of PAHs for aquatic organisms in the study area. Materials and Methods: In the first step of the applied risk assessment model in this study, the unit of toxicity for each PAH and solubility were calculated by Quantitative Structure-Activity Relationships (QSAR) model. In the second step, the pore water concentration of all compounds in sediment was calculated as an available fraction. Finally, the proposed model was used to evaluate the offshore sediments of the Persian Gulf. Sediments in 19 stations and 7 transects were studied to assess the ecological risk of 21 PAHs. The extraction and clean up method was based on pressurized liquid extraction (PLE) with packed clean up cell. Compounds were analyzed by GC-MS. Results: The toxicity and solubility of PAHs were modeled. The Pearson correlation for the predicted and measured data was more than 0.93. The amount of total toxicity was introduced as a risk index. The maximum and minimum total toxicity values for the sediments were found as 0.018 and 0.147, respectively. The results from this study indicated that although the concentration of PAHs in the sediments may not cause significant concern in the study area, they may affect benthic organism at the sub-lethal levels. According to the applied risk assessment model for 21 unsubstituted PAHs, the offshore sediments of Bushehr are in low-risk range. Conclusion: The result of this study indicated a low risk of the sediments. The hazard index decreased as the distance from coastal and oil and gas industry increased, indicating the high impact of anthropogenic activities on the contamination of the study area.

Large amount of anthropogenic mercury (Hg) emitted from China has been transported and deposited in the northwestern Pacific marginal seas; in particular, the Yellow Sea adjacent to China is immediately affected by Chinese-high Hg emissions [1,2]. This article presents the comprehensive baseline dataset on the mercury concentrations and their controlling factors in surface sediments from the entire Yellow Sea shelf, including Korean and Chinese rivers and coastal zones. These data supported the research article entitled “Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese High-Hg emissions: source-to-sink, mass inventory, and accumulation history” Kim et al. [1]. Some of the data was used in Kim et al.’s research paper [3] with the reference [1]. A total of 492 surface sediments were collected from the Yellow Sea shelf and coastal zones, and the rivers around the Sea. All sediment samples were freeze-dried and ground by agate mortar for analyzing total mercury (THg) and related elemental components (total nitrogen, total carbon, total inorganic carbon, total organic carbon, and aluminum). Most previous studies on the sedimentary Hg were conducted locally, mainly in the river-dominated coastal and inner shelf zones of the Yellow Sea, which are associated with riverine Hg inputs. Thus, the quality and quantity of available sedimentary Hg data, on which we rely for mass inventories of Hg in the Sea, are limited. In this respect, our large dataset may contribute significantly to a better understanding of the behaviors of riverine and atmospheric Hg from Chinese sources and will help to further refine global estimates of Hg discharge to ocean margins and open oceans in East Asia. Additionally, the dataset will be essential for improving numerical model for global budget calculation and prediction.