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As a non-invasive imaging technique, this study explores the application of Computed Tomography (CT) in microplastics research, assessing its potential to distinguish different types and sizes of microplastics (polypropylene, polyethylene terephthalate, polyethylene, and polyvinyl chloride) from homogenised river-estuarine sediment. When examined in layers within artificial cores, all microplastic types could be observed by CT imagery, with good contrast in X-ray attenuation (based on image gray level intensity) against background sediments. Large microplastics (4 mm diameter) were also detectable when distributed randomly amongst the sediment. These spiked cores had sufficient difference in attenuation to allow segmentation between type, and therefore isolate individual microplastics. Due to limitations on scan resolution, smaller microplastics (≤125 μm diameter) could not be detected in spiked cores. Scans of two sediment cores from a Thames River tributary (UK) revealed two distinctive sediment structures which could influence microplastic accumulation. This information would be lost using conventional recovery procedures. [Display omitted] • A new application of Computed Tomography (CT) in microplastics research is proposed. • CT scans reveal non-invasive study of microplastics in sediments could be possible. • Larger microplastics in artificial cores were digitally recovered and isolated. • Scans of environmental cores show data on sediment structure lost by other methods. [ABSTRACT FROM AUTHOR]

Hyperspectral imaging has recently emerged in the geosciences as a technology that provides rapid, accurate, and high-resolution information from lake sediment cores. Here we introduce a new methodology to infer particle size distribution, an insightful proxy that tracks past changes in aquatic ecosystems and their catchments, from laboratory hyperspectral images of lake sediment cores. The proposed methodology includes data preparation, spectral preprocessing and transformation, variable selection, and model fitting. We evaluated random forest regression and other commonly used statistical methods to find the best model for particle size determination. We tested the performance of combinations of spectral transformation techniques, including absorbance, continuum removal, and first and second derivatives of the reflectance and absorbance, along with different regression models including partial least squares, multiple linear regression, principal component regression, and support vector regression, and evaluated the resulting root mean square error (RMSE), R-squared, and mean relative error (MRE). Our results show that a random forest regression model built on spectra absorbance significantly outperforms all other models. The new workflow demonstrated herein represents a much-improved method for generating inferences from hyperspectral imagery, which opens many new opportunities for advancing the study of sediment archives.

Sediment cores were collected from Kota Kinabalu and Labuan ports to determine the distribution of natural uranium isotopes, calcium (Ca), aluminium (Al) and total organic matter (TOM). A strong statistical correlation value between 234U/238U and Ca contents were shown at Kota Kinabalu (r2 = 0.811), and Labuan (r2 = 0.833) ports. Good statistical correlation r2 > 0.8 was also obtained between uranium isotopes and TOM at Kota Kinabalu port. Most activity ratio values of 234U/238U found in sediment cores from Kota Kinabalu port were more than 1.0; the major input of uranium at Kota Kinabalu port may be related to the sorptive process of authigenic uranium that occurs in the water column. In this case, the mobile U(VI) was reduced to immobile U(IV) by organic matter and scavenged to the sediment with co-precipitation of organic matter and calcium carbonate. On the other hand, a low activity ratio of 234U/238U (≤ 1) from Labuan was of detrital origin and also showed positive statistical correlation between calcium and aluminium.

Anthropogenic activities release large quantities of heavy metals into the atmosphere. In China, the input of these heavy metals through local and trans-boundary atmospheric deposition is poorly understood. To assess this issue, herein, we use Pb and Zn isotopes to constrain the sources of Pb and Zn in a 210 Pb-dated sediment core collected from the enclosed lake in South China. We observed a progressive shift toward higher 208 Pb/ 206 Pb and Pb fluxes (0.79-4.02 μg·cm -2 ·a -1 ) from 1850 to 1950 and a consistent decrease in δ 66 Zn IRMM (as low as -0.097 ± 0.030‰) coupled with an increase in Pb (1.74-3.36 μg·cm -2 ·a -1 ) and Zn (8.07-10.44 μg·cm -2 ·a -1 ) fluxes after 1980. These distinguished isotopic signals and flux variations reveal the presence of trans-boundary Pb since 1900, with the addition of local industrial Pb and Zn pollution after 1980. Up to 72.3% of Pb deposited at our site can be attributed to long-distance transportation from previously industrialized countries, resulting in a noteworthy legacy of Pb in China since 1900. Despite the phasing out of leaded gasoline, Chinese gasoline still contributes an average of 20.9%. The contribution of China's mining and smelting activities to Pb has increased steadily since 1980 and remained stable at an average of 25.1% since 2000.

The effects of and the interplay between natural and anthropogenic influences on the composition of benthic communities over long time spans are poorly understood. Based on a 160-cm-long sediment core collected at 44 m water depth in the NE Adriatic Sea (Brijuni Islands, Croatia), we document changes in molluscan communities since the Holocene transgression ~11,000 years ago and assess how they were shaped by environmental changes. We find that (1) a transgressive lag deposit with a mixture of terrestrial and marine species contains abundant seagrass-associated gastropods and epifaunal suspension-feeding bivalves, (2) the maximum-flooding phase captures the establishment of epifaunal bivalve-dominated biostromes in the photic zone, and (3) the highstand phase is characterized by increasing infaunal suspension feeders and declining seagrass-dwellers in bryozoan-molluscan muddy sands. Changes in the community composition between the transgressive and the highstand phase can be explained by rising sea level, reduced light penetration, and increase in turbidity, as documented by the gradual up-core shift from coarse molluscan skeletal gravel with seagrass-associated molluscs to bryozoan sandy muds. In the uppermost 20 cm (median age <200 years), however, epifaunal and grazing species decline and deposit-feeding and chemosymbiotic species increase in abundance. These changes concur with rising concentrations of nitrogen and organic pollutants due to the impact of eutrophication, pollution, and trawling in the 20th century. The late highstand benthic assemblages with abundant bryozoans, high molluscan diversity, and abundance of soft-bottom epi- and infaunal filter feeders and herbivores represent the circalittoral baseline community largely unaffected by anthropogenic impacts. [ABSTRACT FROM AUTHOR]

The impacts of anthropic activities have had profound effects on the nitrogen (N) and phosphorus (P) cycles in many aquatic ecosystems. We investigated the spatial and temporal distributions of carbon (C), N, and P in the sediments of a tropical Paiva Castro Reservoir (São Paulo, Brazil), as well as their release and retention in the system. In 2010, surface sediments were collected at nine sites in the reservoir, and a core was obtained in the limnetic zone, in 2010. The core was dated using the 210Pb technique. The organic C content was estimated from organic matter concentration, which was measured by the loss-on-ignition method, and the concentrations of P and N were determined by spectrophotometry. Marked spatial heterogeneity in the Paiva Castro sediments associated with both natural variations in the water body and variations induced by human impacts was observed. Heterogeneity was evidenced by a decrease in the allochthonous contribution of organic matter (C/N) in the upstream-downstream direction and increases of N and P, mainly associated with water flows in the different compartments of the reservoir. In the core, C and N concentrations display significant positive correlations with increases in population and agricultural activities in the drainage basin through time. The C/P molar ratios in surface sediments are indicative of human impacts in the region, as C:P ratios in the sediment are low (7.8:1) compared to the Redfield ratio (C:P = 108:1). Predominance of oxic conditions at the sediment surface and particles sizes < 63 μm provided favorable conditions for P retention in the sediments, which helps prevent eutrophication. Approaches used in this research should be extended to other locations, especially in mesotrophic and oligotrophic reservoirs, to provide information on historical impacts in such aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this article is to study, result of metal concentration in two-sediment cores from Persian Gulf. Age of sediment is determined by C14 isotope method and bulk concentration is determined by ICP. This research output shows that, age of BandareAbbas core back to 9660 and Bushehr core to 15,600 years ago. Also,concentration in BandareAbbas and Bushehr cores respectively change as, As (1.08–11.76 Vs 5.2–13.09), Ba (15.03–129.5 Vs 73.9–120.4), Cd (0.09–0.46 Vs 0.09–0.18), Li (5.66–58.5 Vs 15.3–33.4), Mo (0.3–0.75 Vs 0.3–0.8), Mg (7928.4–15,503.9 Vs 13,102.8–17,227.8), Mn (110.6–566.4 Vs 279.3–429.1), Na (8905.47–27,993.3 Vs 9357.7–27,541.4), Ni (13.3–110.3 Vs 37.1–88.4), Pb (0.5–42.5 Vs 2.5–13.6), Sr (407.5–1773.2 Vs 440.3–1596.9), Zn (13.05–71.2Vs22.4–50.5), Fe (0.46–4.07 Vs 1.7–3.18), Ca (9.25–23.3 Vs 13.8–19.2) and Al (0.62–8.15 Vs 2.48–4.65). Moreover different pollution index investigation represent that except Ca, the rest of the metal elements do not show pollution. Highlights • Two sediment cores dating back to 9660 and 15,600 years are indicative of sedimentation rates between 0.66 and 1.2 mm/Yr. • Oil transportation through striate of Hurmuz might have led to the higher concentration of some elements. • Higher concentrations of Ca could be indicative of higher biological production rate in the Persian Gulf. • Conventional pollution indices do not depict elemental pollution in the sediment of the Persian Gulf. [ABSTRACT FROM AUTHOR]

Abstract A sediment core, spanning from the year 1925 ± 3.03 to 2012, was collected for analyzing historical distribution of mercury (Hg) in the Old Yellow River Estuary (OYRE), China. The Hg concentrations in the sediment core ranged from 14 to 351 ng g−1, with the high values occurred in the middle layers (1960–1996), which may be resulted from intensive human activities during this period, such as oil exploitation and booming of petrochemical industry, salt chemical industry and chlor-alkali plants. A significant positive correlation was found between THg and loss on ignition (LOI). The main fraction of Hg existed in residual part while the fraction that was easy to leach out from sediments accounted for only a small portion according to the results of BCR sequential extraction procedure. Multiple ecological risks indices and guidelines of Hg indicated that the sedimentary record presented an "intermediate state" for Hg contamination in the OYRE. Highlights • High mercury (Hg) concentrations in studied core sediments were consistent with intensive human activities. • A significant positive correlation was found between THg and loss on ignition (LOI). • The major part of Hg in sediments was not bioavailable. • The sediments of the Old Yellow River Estuary presented an "intermediate state" for ecological risks of Hg contamination. [ABSTRACT FROM AUTHOR]

A 157-cm-long sediment core from Longemer Lake in the Vosges Mountains of France spans the past two millennia and was analyzed for trace metal content and lead isotope composition. Trace metal accumulation rates highlight three main input phases: Roman Times (cal. 100 BC-AD 400), the Middle Ages (cal. AD 1000-1500), and the twentieth century. Atmospheric contamination displays a pattern that is similar to that seen in peat bogs from the region, at least until the eighteenth century. Thereafter, the lake sediment record is more precise than peat records. Some regional mining activity, such as that in archaeologically identified eighteenth-century mining districts, was detected from the lead isotope composition of sediment samples. Compositional data analysis, using six trace metals (silver, arsenic, cadmium, copper, lead and zinc), enabled us to distinguish between background conditions, periods of mining, and of other anthropogenic trace metal emissions, such as the recent use of leaded gasoline. [ABSTRACT FROM AUTHOR]

High-altitude lake sediments can be used as natural archives to reconstruct the history of pollutants. In this work, the temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was determined in a sediment core collected from the southern Tibetan Plateau (TP), which was dated by using the 210Pb dating method and validated with the 137Cs fallout peak. The concentrations of the anthropogenic PAHs (Σ8PAH) in the sediment core ranged from 0.83 to 12 ng/g dw, and the fluxes of the Σ8PAH were in the range of 2.1-27 g/cm2/year. The temporal variations in the concentration and input flux of anthropogenic PAHs were low with little variability before the 1950s, and then gradually increased from the 1950s to the 1980s, and an accelerated increase was observed after the early 1980s. The content of total organic carbon played an insignificant role in affecting the time trends of PAHs in the sediment core. Diagnostic concentration fractions of PAH components indicate PAHs in the lake sediment of the southern TP which are mainly from biomass burning and/or from long-range atmospheric transport. [ABSTRACT FROM AUTHOR]

In studies of environmental change of the past few centuries, 210Pb dating is often used to obtain chronologies for sedimentary sequences. One of the most commonly used approaches to estimate the age of material at different depths in a sequence is to assume a constant rate of supply (CRS) or influx of ‘unsupported’ 210Pb from the atmosphere, together with a constant or varying amount of ‘supported’ 210Pb. Current 210Pb dating models do not use a proper statistical framework and provide poor estimates of the uncertainties. Here, we develop a new model for 210Pb dating, where ages and values of supported and unsupported 210Pb form part of the parameters. We apply our model to a case study from Canada as well as to some simulated examples. Our model can extend beyond the current CRS approach, deal with asymmetric errors and mix 210Pb with other types of dating, thus obtaining more robust, realistic and statistically better defined age estimates. [ABSTRACT FROM AUTHOR]

Long-term trends of sediment compositions are important for assessing the impact of human activities on the sediment and protecting the sediment environment. In this study, based on the contents of heavy metals and the Pb isotope ratios in lake sediments, atmospheric dustfall and soil in Yixing, China, the representative heavy metals (Zn, Pb, Cr and Cd) in lake sediments from western Taihu Lake were studied. The evolution history of heavy metals in the local environment was constructed for the past 100 years. From 1892 to the 1990s, the anthropogenic fluxes of the representative heavy metals were negligible, indicating minimal anthropogenic emissions of heavy metals. Since the 1990s, anthropogenic fluxes of the representative heavy metals began to increase, concurrent with the economic growth and development in the western Taihu Lake Basin after the Chinese economic reform. The maximum flux percentage of the heavy metals in the sediments, caused by human activities, is 23.0% for Zn, 31.6% for Pb, 39.5% for Cr and 85.3% for Cd, indicating that most of the Cd comes from human activities. The Cd content in the western Taihu Lake Basin was significantly higher than that in the other areas, and the rapid development of the industry in the western Taihu Lake Basin and ceramics in Yixing led to the enrichment of heavy metals in local sediments. Since the 21st century, measures have been taken to control the pollution of heavy metals, including the increase in local government attention and the deployment of environmental monitoring technology. However, heavy metal content remains high, and the Pb content is still increasing. The ratios of Pb isotopes show that the main sources of heavy metals in the western Taihu Lake sediments, the local soil of Yixing and the atmospheric dustfall are coal combustion, leaded gasoline combustion, industrial wastewater and domestic sewage. [ABSTRACT FROM AUTHOR]

The residues of organochlorine pesticides (HCHs and DDTs) in a dated (137Cs and 210Pb) sediment core from the Küçükçekmece Lagoon, an urban lake at the southern entrance of the future Canal Istanbul Project, an artificial watercourse, were analyzed with the gas chromatograph equipped with electron capture detector (GC 63Ni-ECD). Concentrations of ∑HCH and ∑DDT along the core varied between 0.4 and 469.4 (average 51.4) ng g−1 dw, and between 0.5 and 72.0 (average 7.4) ng g−1 dw, respectively. α-HCH was the predominant isomer (98%) and followed by γ-isomer (2%). The highest concentrations of technical HCH were found in the sediments dated 1963-1972, whilst the DDT concentrations had their maximum around 1945. The highest concentrations of γ-HCH and p,p′-DDT exceeded probable-effect level values which can lead to frequently cause adverse effects on aquatic biota. [ABSTRACT FROM AUTHOR]

Mountain lakes are sensitive to natural perturbations and human activities. Profiles of anthropogenic polycyclic aromatic hydrocarbons (PAHs) in lake sediments serve as a natural archive from which human impacts on lakes can be reconstructed. Two parallel sediment cores (34 cm long) were extracted from Lake Sayram in the Tianshan Mountains of arid northwest China and dated using 210 Pb and 137 Cs. PAHs in the sediments were used to infer the past ∼150 years of anthropogenic impact on the lake. Results showed that PAH concentrations in the lake sediments were generally low, but nevertheless reflect some human activity. Benzo(ghi)perylene (BghiP) and indeno(1, 2, 3-cd)pyrene (IcdP) are typical markers of vehicular traffic, so significant correlations between PAH (especially BghiP and IcdP) and metal concentrations suggest that PAHs in sediments are effective proxies for anthropogenic activities. Furthermore, constrained cluster analysis revealed that the vertical profile of PAHs was characterized by three periods that correspond to changes in human activities. Prior to the 1960s, low PAH concentrations in the sediments generally indicate that the lake was virtually unaffected by human impact. BghiP and IcdP concentrations, however, displayed a minor peak in the 1950s, possibly reflecting transport from a remote polluted region via prevailing westerly winds. From the 1960s through the 1990s, relatively high values of PAHs, especially high molecular weight (HMW) PAHs BghiP and IcdP, and heavy metal enrichment factors (EFs), were related to increasing anthropogenic activities. After the 1990s, maxima of PAHs, HMW PAHs, BghiP, IcdP, EFs, together with highest total phosphorus (TP) and total organic carbon (TOC) values, reflect intensive human-related impact on the lake. The coincidence of limnological changes and local socio-economic development suggest that sedimentary PAHs record recent anthropogenic impact on Lake Sayram. [ABSTRACT FROM AUTHOR]

A novel approach was proposed to evaluate the potential risk of organic enrichment in marine aquaculture farms without obvious environmental degradation. The approach was based on historical environmental records preserved in sediment cores, and potential risk of organic enrichment can be effectively evaluated by comparing burial fluxes of marine organic carbon (OCM) during times before and after large-scale aquaculture. A case study was conducted in Sanggou Bay. The change trends on burial fluxes of organic carbon in sediment over the past 150 years were rebuilt. OCM burial fluxes have greatly increased since the beginning of large-scale aquaculture in 1980s, reaching 16.0~16.5 times higher than that before large-scale aquaculture. The results indicate that aquaculture activities have resulted in obvious accumulation of aquacultural organic matters, although sedimental environment has not degraded seriously. Besides, if the OCM burial fluxes further increase to 3.5~7.0 times higher than that in present, sedimental environment may degrade obviously. Therefore, potential risks of organic enrichment still exist with aquaculture development in Sanggou Bay. [ABSTRACT FROM AUTHOR]

There are very few data available of 236 U in marine sediment cores. In this study we present the results from the first oceanic depth profile of 236 U in a sediment core sampled in the North Atlantic Ocean, at the PAP site (4500 m depth, Porcupine Abyssal Plain (PAP) site, 49°0′ N, 16°30′ W). Additionally, the sediment core was radiologically characterized through the measurement of anthropogenic 137 Cs, 239 Pu, 240 Pu, 129 I and 14 C and natural 210 Pb, 40 K and 226 Ra. The measured 236 U concentrations decrease from about 90·10 6 at g −1 at the seafloor down to 0.5·10 6 at g −1 at 6 cm depth. They are several orders of magnitude lower than the reported values for soils from the Northern Hemisphere solely influenced by global fallout (i.e. from 2700·10 6 to 7500·10 6 at g −1 ). 236 U/ 238 U atom ratios measured are at least three orders of magnitude above the estimated level for the naturally occurring dissolved uranium. The obtained inventories are 1·10 12 at m −2 for 236 U, 80 Bq m −2 for 137 Cs, 45 Bq m −2 for 239+240 Pu and 2.6·10 12 at m −2 for 129 I. Atomic ratios for 236 U/ 239 Pu, 137 Cs/ 236 U and 129 I/ 236 U, obtained from the inventories are 0.036, 0.11 and 2.5 respectively. Concentration profiles show mobilization probably due to bioturbation from the abundant detritivore holothurian species living at the PAP site sea-floor. The range of 236 U, 137 Cs, 239+240 Pu and 129 I values, inventories and ratios of these anthropogenic radionuclides are more similar to the values due to fall-out than values from a contribution from the Nuclear Fuel Reprocessing Plants dispersed to the south-west of the North Atlantic Ocean. However, signs of an additional source are detected and might be associated to the nuclear wastes dumped on the Eastern North Atlantic Ocean. [ABSTRACT FROM AUTHOR]

Over the past century, numerous discoveries throughout East Africa have advanced our understanding of hominin evolution and provided substantive evidence that climatic and environmental variability played a critical role in evolutionary developments. Stratigraphic records with high temporal resolution aid in testing evolutionary hypotheses that invoke changes in climate and environment at various timescales as drivers of hominin evolution. Olduvai Gorge, Tanzania has a rich history of hominin fossil discoveries from its ~2.0 Ma sedimentary sequence, which includes multiple deep lake intervals. In 2014, the Olduvai Gorge Coring Project (OGCP) recovered a sequence of sediment cores that provide an extensive record of the Pleistocene sedimentary history, including paleolacustrine systems in this area. With >94% core recovery, these cores are ideally suited for high-resolution analyses of organic geochemical proxies and provide an exceptional opportunity to build on previously published outcrop-based paleoenvironmental data from Olduvai. The OGCP core 2A section between 76.6 and 86.9 m depth is considered as a time-stratigraphic equivalent of strata that host the hominin fossils OH24 and OH56 at the Olduvai DK archaeological site. This depositional interval age-bracketed between ~1.88 Ma (Bed I Basalt) and ~1.85 Ma (Tuff IB) was sampled for organic geochemical analyses. The carbon isotopic composition of organic matter (δ 13 C TOC ) from this section varies between values representative of more forested and open grassland ecosystems over ~21 kyr. This observation is consistent with the Milankovitch precession cycle driving the availability of water, which was previously observed in lower resolution studies of outcrop samples. Complementary organic geochemical proxies provide further evidence of these shifts in environmental conditions and record sub-Milankovitch scale changes superimposed on the precession cycle. This suggests the occurrence of short-term fluctuations in the environments inhabited by hominins, which opens new lines of investigation on how environmental scenarios may affect particular evolutionary mechanisms that drove various evolutionary responses. [ABSTRACT FROM AUTHOR]

A total of 21 surface sediments from the Yellow River Estuary (YRE) and a sediment core from the abandoned Old Yellow River Estuary (OYRE) were analyzed for n -alkanes using gas chromatography-mass spectrometry (GC-MS). n -Alkanes in the range C 12 -C 33 and C 13 -C 34 were identified in the surface sediments and the core, respectively. The homologous series were mainly bimodal distribution pattern without odd/even predominance in the YRE and OYRE. The total n -alkanes concentrations in the surface sediments ranged from 0.356 to 0.572 mg/kg, with a mean of 0.434 mg/kg on dry wt. basis. Evaluation of n -alkanes proxies indicated that the aliphatic hydrocarbons in the surface sediments were derived mainly from a petrogenic source with a relatively low contribution of submerged/floating macrophytes, terrestrial and emergent plants. The dated core covered the time period 1925–2012 and the mean sedimentation rate was ca. 0.5 cm/yr. The total n -alkanes concentrations in the core ranged from 0.0394 to 0.941 mg/kg, with a mean of 0.180 mg/kg. The temporal evolution of n -alkanes reflected the historical input of aliphatic hydrocarbons and was consistent with local and regional anthropogenic activity. In general, the investigation on the sediment core revealed a trend of regional environmental change and the role of anthropogenic activity in environmental change. [ABSTRACT FROM AUTHOR]

The historical trend of pollution sources of Pb in Tokyo Bay, Japan was investigated on the basis of Pb isotope ratios in a sediment core. The isotope ratios of anthropogenic Pb decreased gradually with increasing Pb concentration in the 1900s–1970s, suggesting a combination of Pb sources with various isotope ratios. In contrast, the isotope ratios of anthropogenic Pb in the 1980s–2000s showed no significant trend, and corresponded to the Pb isotope ratios in the three principal rivers flowing into the bay. It is probable that river bottom sediments contaminated with Pb are principal sources of anthropogenic Pb in Tokyo Bay. [ABSTRACT FROM AUTHOR]

Psychrotolerant yeast Rhodotorula sp. Y‐23 was isolated from the sediment core sub‐samples of Nella Lake, East Antarctica. Isolate was screened for lipase production using plate assay method followed by submerged fermentation. Production optimization revealed the maximum lipase production by using palmolein oil (5% v/v), pH 8.0 and inoculum size of 2.5% v/v at 15 °C. The potential inducers for lipase were 1% w/v of galactose and KNO3, and MnCl2 (0.1% w/v). Final productions with optimized conditions gave 5.47‐fold increase in lipase production. Dialyzed product gave a purification fold of 5.63 with specific activity of 26.83 U mg−1 and 15.67% yields. This lipase was more stable at pH 5.0 and −20 °C whereas more activity was found at pH 8.0 and 35 °C. Stability was more in 50 mM Fe3+, EDTA‐Na (20 mM), sodium deoxycholate (20 mM), H2O2 (1% v/v), and almost all organic solvents (50% v/v). Tolerance capacity at wider range of pH and temperature with having lower Km value i.e., 0.08 mg ml−1 and higher Vmax 385.68 U mg−1 at 15 °C make the studied lipase useful for industrial applications. Besides this, the lipase was compatible with commercially available detergents, and its addition to them increases lipid degradation performances making it a potential candidate in detergent formulation. [ABSTRACT FROM AUTHOR]

Results of analyses of a shallow marine sediment vibrocore from the Atlantic seafloor just west of the Aran Islands, western Ireland, are presented. The sediments range from ~16,000 to younger than 9,000 cal BP in age, based on 14C dating of foraminifers and molluscs. One sample within the core is dated at 12804 ± 125 cal BP and lies a very short distance stratigraphically below a conspicuous horizon containing isolated pebbles and sand‐size clasts, in what is an otherwise fine‐grained sequence of sediment. These outsized clasts are interpreted to be ice‐rafted debris. Approximately coeval with this horizon, the diversity and abundance of foraminifers decrease significantly and the foraminifer Nonionellina labradorica makes its first appearance in the core sediment. Stable isotope analysis shows a significant increase in values of δ18O approaching the horizon containing ice‐rafted debris. These results show the effects of a relatively sudden cooling of this part of the Atlantic Ocean at middle latitudes coincident with, or just after, the onset of the Younger Dryas event and demonstrate the extent of floating icebergs and probable later pack ice as a result of this temperature decrease. [ABSTRACT FROM AUTHOR]

Information is scarce on historical trends of perfluoroalkyl substances (PFASs) in the coastal environment. In this study, four sediment cores were collected from semi-enclosed bays of Korea to investigate the pollution history, contamination profiles, and environmental burden of PFASs. The total PFAS concentrations in sediment cores ranged from 6.61 to 821 pg/g dry weight. The highest concentrations of PFASs were found in surface or sub-surface sediments, indicating on-going contamination by PFASs. Historical trends in PFASs showed a clear increase since the 1980s, which was consistent with the global PFAS consumption pattern. Concentrations of PFASs were dependent on the organic carbon content in sediment cores. PFOS and longer-chain PFASs were predominant in all of the sediment cores. In particular, a large proportion of longer-chain PFASs was observed in the upper layers of the sediment cores from industrialized coastal regions. Inventories and fluxes estimated for PFASs were similar to those for PCDD/Fs. [ABSTRACT FROM AUTHOR]

Salem, MA, located north of Boston, has a rich, well-documented history dating back to settlement in 1626 ce, but the associated anthropogenic impacts on Salem Sound are poorly constrained. This project utilized dated sediment cores from the sound to assess the proxy record of anthropogenic alterations to the system and compared the proxy records to the known history. Proxies included bulk stable isotopes of organic matter, magnetic susceptibility, and trace metal concentrations. Our data reveal clear changes in organic matter composition and concentration associated with land use changes and twentieth century sewage disposal practices. Further, metal data correspond with local industrial activity, particularly the historic tanning industry in Peabody, MA. Although conservation practices of past decades have improved the state of Salem Sound, the stratigraphic record demonstrates that the environment is still affected by anthropogenic influences, and has not attained conditions consistent with pre-anthropogenic baseline. The approach and results of this study are applicable to coastal embayments that are being assessed for remediation, especially those with scant historic or monitoring data. [ABSTRACT FROM AUTHOR]

Vertical profiles of radiocesium concentrations were measured in sediment cores collected at various times after the 2011 Fukushima nuclear accident in five Japanese lakes (Hinuma, Kasumigaura, Kitaura, Onogawa and Sohara) with different morphological and trophic characteristics in order to investigate the sedimentation-diffusion processes. In lakes where sediments had high porosities and experienced considerable wave action due to shallowness, we observed rapid penetration of radiocesium to a certain depth just after the accident, followed by downward movement of the peak depths. In contrast, gradual downward transfers of distinct peaks were found in other types of lakes. A one-dimensional differential sediment model with water-sediments interaction processes was constructed to describe the vertical shift of radiocesium profiles. Our proposed submodels relating to the length scales of the mixing using wind-induced stress and porosity of sediments were constructed based on one measurement of the vertical distribution of radiocesium in three lakes (Hinuma, Kasumigaura and Sohara). This model was then validated using samples from those lakes in different years, as well as from two other lakes. Good agreement was obtained. We discuss our findings, the limits of model application, and future research targets. [ABSTRACT FROM AUTHOR]

Abstract: The monitoring of fecal contamination (human and animal) is an incessant challenge. In this approach, microbiological methods play an important role, though with substantial limitations. Organic compounds, such as sterols, are often used to trace fecal contamination. Although the fecal sterols profiles of some animals are already known, capybara, a typical mammal from South America, is a significant contributor to aquatic fecal contamination because of its water dependence; and still there is no one way, scientifically speaking, to trace its fecal contribution. The aim of the present study was to provide a tool to measure the temporal fecal contribution of capybara in aquatic systems. We examined the sterol content of capybara feces and compared with another species (sheep, cow, horse, pig, hen, duck, cat, dog, opossum, and human). From numerical relationships among fecal sterols, 6 ratios were delineated and tested to assess their potential to identify the capybara feces contribution in contaminated environments. Statistical analysis showed that 3 ratios were able to differentiate capybara feces from other sources. Such ratios were applied in samples of a sediment core from an urban area in south Brazil with a large capybara population. The temporal trend showed a significant contribution of capybara feces in the last 100 yr. Environ Toxicol Chem 2018;37:353–361. © 2017 SETAC [ABSTRACT FROM AUTHOR]

In the present study, the spatial distributions and vertical variations of PFASs in the sediments of the Dalian Bay were investigated. The total concentrations of PFASs (∑ PFASs) in surface sediments of Dalian Bay ranged from 1.49 to 2.66 ng g − 1 dw. The predominant PFASs in surface sediments were PFOA, PFBS and PFBA with the concentration ranges of 0.50 to 0.95, 0.21 to 0.94, and 0.035 to 0.32 ng g − 1 dw, respectively. For the two sediment cores, ∑ PFASs ranged from 1.20 to 2.00 and from 1.37 to 2.06 ng g − 1 dw, respectively. There was a maximum ∑ PFASs concentration value near the surface. In general, ∑ PFASs gradually decreased with increasing sampling depth after reaching the maximum. PFOA, PFBS and PFBA were also the predominant PFASs in the two sediment cores. It is recommended that the monitoring and risk assessment of short-chain PFAS should be taken into consideration, and further researches are needed to understand the transportation and fate of these chemicals in the aquatic environment. [ABSTRACT FROM AUTHOR]

Sediment cores from four lakes across the Tibetan Plateau were used as natural archives to study the time trends of organochlorine pesticides (OCPs). The total concentrations of dichlorodiphenyltrichloroethane (ΣDDT) and hexachlorocyclohexane isomers (ΣHCH) were in the range of 0.04–1.61 and 0.08–1.88 ng/g based on dry weight (dw), while the input fluxes were in the range of 0.3–236 and 0.7–295 pg/cm2/y in the core sediments, respectively. The input fluxes of ΣDDT and ΣHCH generally peaked in sediment layers corresponding to the 1970s–1990s and peaked in top sediment layers. The ratio of α/γ-HCH decreased in the top layer sediments, implying that the contribution of lindane (pure γ-HCH) has been increasing in recent years. In addition, the ratio of o,p′-DDT/p,p′-DDT increased significantly over the last 15–20 years, suggesting that dicofol (characterized by high ratio of o,p′-DDT/p,p′-DDT about 7.0) has recently become a relatively more important source of DDT compared to technical DDT itself. The time trends of OCPs recorded in lake sediments examined the impact on such remote alpine regions by human activities. [ABSTRACT FROM AUTHOR]

Kaohsiung Ocean Dredged Material Disposal Site (KODMDS) that located in the southwest offshore of Taiwan, has been annually disposed about 500,000 ton dredged sediments of Kaohsiung Harbor from 2003 to 2012. Five sediment cores collected from KODMDS and three from nearby reference sites were analyzed to evaluate their sedimentation rates, vertical profiles of heavy metal, and heavy metal pollution indices to assess the impact of dumping harbor dredged sediments into the ocean on the sediment quality in KODMDS. The sedimentation rate of 0.24 cm/y was estimated by the 210 Pb method, which means that the effected depth of the top layer of a core of D1 was affected in the period of dumping dredging sediments. The vertical distribution of heavy metals in the sediment cores from KODMDS showed the concentrations of most heavy metals were slightly elevated in the top layers of the sediment cores, which may be affected by the dumping of harbor dredged sediments. According to the analyzed results of the heavy metal pollution indices, the level of heavy metal pollution, the potential eco-toxicity and the potential ecological risk of the sediments in KODMDS exhibited only a slight increase, which indicated that the increase in concentration of heavy metals may potentially pose the insignificant impact on benthos inhabiting the disposal site. [ABSTRACT FROM AUTHOR]

Resurrection ecology ( RE) is a very powerful approach to address a wide range of question in ecology and evolution. This approach rests on using appropriate model systems, and only few are known to be available. In this study, we show that Artemia has multiple attractive features (short generation time, cyst bank and collections, well-documented phylogeography, and ecology) for a good RE model. We show in detail with a case study how cysts can be recovered from sediments to document the history and dynamics of a biological invasion. We finally discuss with precise examples the many RE possibilities with this model system: adaptation to climate change, to pollution, to parasites, to invaders and evolution of reproductive systems. [ABSTRACT FROM AUTHOR]

To evaluate the contribution of the long-range transport of heavy metals from the Asian continent to the enrichment of surface sediments in western Japan, heavy-metal (Cd, Cu, Pb, Sb, and Zn) concentrations were measured in sediment cores collected at three sites each in Lakes Shinji and Nakaumi. Sedimentation fluxes of these metals were calculated on the basis of their concentrations in excess of their background concentrations. Pb showed similar sedimentation fluxes in the sites, suggesting a predominant contribution of atmospheric deposition of Pb transported from the Asian continent to the input to the lakes. In contrast, the sedimentation fluxes of heavy metals other than Pb in the surface sediments were markedly high near the estuary of a principal river flowing into Lake Nakaumi. A highly positive correlation was observed between the Cd and Zn concentrations in the cores at each site ( r = 0.84-0.97). The Cd/Zn ratios in the surface sediments (1990-2007) indicated that Lake Shinji sediments have ratios of 0.0067-0.0074, higher than those of Tokyo Bay sediments (0.0054 on average in 1990-2003), which have been polluted primarily by effluent discharges. In contrast, the ratios in Lake Nakaumi sediments (0.0053-0.0060) were close to those in Tokyo Bay sediments. Rainwater and aerosols, which were strongly affected by air pollutants from the Asian continent, have much higher Cd/Zn ratios of 0.014-0.016. This suggests that the Lake Shinji sediments with higher Cd/Zn ratios are less affected by effluent discharges. Hence, Lake Shinji sediments may be suitable for assessing the environmental impact of the long-range transport of heavy metals from the Asian continent. [ABSTRACT FROM AUTHOR]

The molluscan assemblages in a sediment core from the north-eastern Adriatic show significant compositional changes over the past 10,000 yrs related to (1) natural deepening driven by the post-glacial sea-level rise, (2) increasing abundance of skeletal sand and gravel, and (3) anthropogenic impacts. The transgressive phase (10,000–6000 BP) is characterized by strongly time-averaged communities dominated by infaunal bivalves. During the early highstand (6000–4000 BP), the abundance of epifaunal filter feeders and grazers increases, and gastropods become more important. Epifaunal dominance culminates during the late highstand (4000–2000 BP) with the development of extensive shell beds formed by large-sized Arca noae and Ostrea sp. bivalves. This community persists until the early 20th century, when it falls victim to multiple anthropogenic impacts, mainly bottom trawling, and is substituted by an infauna-dominated community indicative of instability, disturbance and organic enrichment. The re-establishment of this unique shell-bed ecosystem can be a goal for restoration efforts. [ABSTRACT FROM AUTHOR]

Concentrations and vertical distributions of organophosphate esters (OPEs) were investigated in the sediment cores collected from the Laizhou Bay, Bohai Sea of China. The total concentrations of OPEs in the sediment core (CA) collected near the Yellow River Estuary were in the range of 11.8–102 ng/g, while the total concentrations in the sediment core (CB) near a mariculture area were 6.65–41.5 ng/g. Significantly high concentrations of OPEs were found in the sediments near the Yellow River Estuary than those in the mariculture area. Vertical distributions in the sediment cores demonstrated a recent increase of OPE emissions, especially for tri- n -butyl phosphate (TnBP), tris (2-chloroethyl) phosphate (TCEP), and tris (2-chloroisopropyl) phosphate (TCPP). Generally, TCEP and TCPP were the dominant congeners in the sediment cores, while the profiles of TnBP were increase in the surface 0–20 cm layers of the CA core. OPEs in the CA core may be remarkably influenced by the discharge of Yellow River, whereas OPEs in the CB core may originate from the transport through seawater. The remarkable increase of OPE flame retardants in the surface sediments raises the concern about their emissions and risks to the environment and indicates the need for further monitoring. [ABSTRACT FROM AUTHOR]

The Southern Yellow Sea (SYS) is an important reservoir of anthropogenic organic contaminants, such as polybrominated diphenyl ethers (PBDEs). To reconstruct the historical records of PBDEs and examine their relationships with the human activities and organic matters, a 210 Pb-dated sediment core was collected from the central mud area in the SYS. The concentrations of tri-to hepta-BDEs (∑ 7 PBDEs) and BDE-209 ranged from 9.8 to 99.8 pg g −1 d.w. and from 12.1 to 855.4 pg g −1 d.w., respectively, both displaying the increasing trends from the bottom to the surface. More importantly, there was a faster increase for PBDEs since the 1990s, especially for BDE-209, which responded well with the rapid economic growth, and the increases of urbanization and industrialization in the local areas of the SYS. The analogously vertical patterns and significant relationships between PBDEs and total organic carbon (TOC) implied the TOC-dependent deposition of PBDEs in the core. Furthermore, multiple biomarker-based proxies of terrestrial organic matter (TOM) and marine organic matter (MOM) were introduced to systematically investigate the different effects of TOM and MOM on PBDE deposition in the SYS. The similarly down-core profiles and significant correlations were found between PBDEs and the MOM proxies (sum of rassicasterol, dinosterol and C 37 alkenones (∑A + B + D) and marine TOC) as well as the branched and isoprenoid tetraether (BIT), but not for TOM proxies (∑C 27 +C 29 +C 31 n -alkanes, terrestrial and marine biomarker ratio (TMBR) and terrestrial TOC), indicating that MOM was an important factor driving PBDE deposition in the sediment core from the SYS. [ABSTRACT FROM AUTHOR]

Seafloor sediments are an important sink for microplastics (MPs), and the vertical profile of MP accumulation in a sediment core represents historical pollution trends. In this study, MP (20–5000 μm) pollution in surface sediments of urban, aquaculture, and environmental preservation sites in South Korea was evaluated, and the historical trend was investigated using age-dated core sediments from the urban and aquaculture sites. The abundance of MPs ranked in the order of urban, aquaculture, and environmental preservation sites. Polymer types were more diverse at the urban site compared to other sites, and expanded polystyrene was dominant in the aquaculture site. An increase in MP pollution and polymer types was observed from bottom to top of cores, and historical trends of MP pollution reflect local influences. Our results indicate that the characteristics of MPs are determined by human activities, and MP pollution should be addressed according to the characteristics of each site. • The abundance of microplastic was in order of urban, aquafarm, and reference sites. • Characteristics of microplastic pollution well reflect the sea area use patterns. • Polymer composition of fiber was different between urban and aquafarm sites. • Increasing trend of microplastic pollution levels reflected surrounding sources. [ABSTRACT FROM AUTHOR]

Simeulue waters are adjacent to the northern part of Sumatra Island, which is undergoing massive land-use transformations; moreover, the waters are located in an active tectonic region. Land changes and tectonic activity might affect the metal pollution profile in this deep sea area. Thus, this study aimed to investigate the vertical profile and assess the sediment quality from the deep-sea marine sediment around Simeulue Island based on metal concentration. Seventy-six bottom sediment samples were collected from eight cores at a water depth of up to 2800 m in the Simeulue waters, Indonesia, in November 2017. Metals Cd, Cu, Fe, Ni, Pb, and Zn were quantified from the cores and multivariate analyses were carried out to understand the process. Metals distributions are analogous to the grain size parameters and LOI 550 distribution pattern, while Sumatra and Simeulue islands influenced grain size and LOI 550 spatial distribution. The vertical grain size profile exhibited no extreme oscillation in the investigated cores. Thus, sediment transport from the Island was the main suspect for these metals' profiles in the deep water, and the tectonic activity had a minor impact. Cu, Ni, Pb, and Zn tend to rise in the collected cores, suggesting that the accumulation of the metals is growing. While Fe tended to be stable and Cd oscillated in the cores. Indices were computed to assess the metal contamination profile. The cores were dominated by EF class 1 (none to slight enrichment) status and I geo class 1 (unpolluted). Cd was the metal of concern in the study since a high Cd was observed in some layers (maximum EF = 26.45 and maximum I geo = 3.81). Thus, this study can be used as a database to improve the regulation formulation for improved environmental managerial efforts in the region. • The Simeulue basin has higher Cd, Cu, Pb, Ni, and Zn levels in sediment than the deeper waters. • The vertical profile of metals fluctuated in the cores, with Cu, Pb, Ni, and Zn inclining. • The land sediment supply was the main suspect in the metal distribution pattern. • The distribution of metals was less affected by tectonic activity. • Cd was the metal of concern in this study, leading to degrading environmental condition. [ABSTRACT FROM AUTHOR]