Search

The present study aimed to evaluate multi-element concentrations (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr) in suspended particulate material (SPM) collected from Ensenada de La Paz (ELP) lagoon, Baja California Sur, Mexico in two different periods (September and May) to comprehend their origin, geochemical behavior, mass transfer and associated ecotoxicological risks. The 24 hr variation coefficient of volumetric SPM levels were found to be 51.7% in September and 40.5% in May, signifying the effects of oceanic waters. The calculated enrichment factor (EF) values for all the studied elements were of higher magnitude because of the high surface area and oxide nature of SPM, and in this study, Mo had the highest EF of 46.77 probably due to its origin from continental weathering. From the ecotoxicological perspective, the integrated toxic risk index revealed low toxic risk to the benthic community. However, the mean-ERM-Quotient calculated using the particulate concentrations of As, Cd, Cr, Cu, Ni, Pb indicated 9% probability of toxicity to biota. The comprehensive geochemical and ecotoxicological assessment of particulate metal concentrations in the ELP lagoon signify low to moderate 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 article., (Copyright © 2022. Published by Elsevier B.V.)

The quality of life and human survival is dependent on sustainable development and sanitation of water bodies in an environment. The present research focuses on cyclicity data of more than 750,000 records of parameters associated with the water quality from a rural-urban river monitoring stations in real-time from River Atoyac in Central Mexico. The events detected in the instrumental records correlated with 2528 laboratory and instrumental determinations. The 64 polluting compounds were grouped into inorganic compounds (metals and metalloids) and organic compounds (pesticides, herbicides, hydrocarbons). Metal associated compounds were grouped along mechanical, pharmaceutical and textile industries which associates itself with the entry of polluting components. The cyclicity of the events was detected through Discrete Fourier Transformation time series analysis identifying the predominant events in each station. These highlight the events at 23-26 h corresponding to a circadian pattern of the metabolism of the city. Likewise, pollution signals were detected at 3.3, 5.5, and 12-14 h, associated with discharges from economic activities. Multivariate statistical techniques were used to identify the circadian extremes of a regionalized cycle of polluting compounds in each of the stations. The results of this research allow pollution prevention using a mathematical analysis of time series of different quality parameters collected at monitoring stations in real-time as a tool for predicting polluting events. The DFT analysis makes it possible to prevent polluting events in different bodies of water, allowing to support the development of public policies based on the supervision and control of pollution., 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 © 2023 Elsevier Ltd. All rights reserved.)

Efficient management of land use/land cover (LULC) features is vital for a balanced sustainable ecosystem. Thus, this work aimed to document the LULC changes in the less studied El Peñol-Guatapé reservoir, Antioquia, Colombia, especially in the reservoir area due to the construction of a hydro-electric power plant. For this study, Landsat images of 1977, 1986, 1997, and 2017 were used and the results indicated an increase in the settlement area and road networks by 0.10 and 0.60%, respectively, while during 1986 to 2017, cropland, plantation, dense forest, and open forest areas presented an increase of 0.52, 1.06, 2.87 and 2.61%, respectively. However, the marshy vegetation, scrub forest and fallow land decreased to - 0.51, - 3.79 and - 4.29%, respectively, in the same period. The water body before and after the completion of reservoir project denoted an increase from 13.1 km 2 in 1977 to 45.7 km 2 in 1986. This study provides a first-hand report on LULC dynamics in this tourism dominated municipalities that will serve as a reference for ecosystem management to reconcile the conflicts between different LULC classes in ecologically enriched regions., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This study is a baseline data on the presence of MPs from the gastro-intestinal tracts (GITs) in Coryphaena hippurus Linnaeus, from eastern Baja California Sur, México. 878 MPs items (in %) of fibers (29%), fragments (68%) and films (1.3%) were detected from 51 GITs of Coryphaena hippurus. Transparent, white, blue and black were the prevalent colours. Morphological features observed through SEM analysis, the presence of heavily weathered MPs is due to the mechanical, microbiological and chemical weathering process. PP (29%), Nylon (29%), PS (17%), PE (11%), PET (6%) and HDPE (8%) presence indicates their source from regional anthropogenic stress. Trophic level transition is enforced by polymer derivative, permitting the sinking behavior of MPs and increased ingestion probability. Fishes were classified as slim despite their higher feeding capabilities and ingested MPs indicates a relationship with environmental contaminants. Current study emphasizes the health risk linked to biological aspects of MPs ingestion., 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 © 2023 Elsevier B.V. All rights reserved.)

Microplastic (MP) pollution is a major global issue that poses serious threats to aquatic organisms. Although research on MP pollution has been extensive, the relationship between MPs and water quality parameters in estuarine water systems is unclear. This work studied the spatiotemporal distribution and characteristics of MPs in the Karnaphuli River estuary, Bangladesh. MP abundance was calculated by towing with a plankton net (300 μm mesh size) at three river gradients (up-, mid- and downstream) and the association between physicochemical parameters of water (temperature, pH, salinity, electrical conductivity, total dissolved solids, and dissolved oxygen) and MP distribution patterns was also investigated. Mean MP abundance in water was higher during the wet season (April) (4.33 ± 2.45 items per m 3 ) compared to the dry season (September) (3.65 ± 2.54 items per m 3 ). In descending order, the highest MP abundance was observed downstream (6.60 items per m 3 ) > midstream (3.15 items per m 3 ) > upstream (2.22 items per m 3 ). pH during the wet season (April) and temperature during the dry season (September) were key physicochemical parameters that correlated with river MP abundance ( r = -0.74 and 0.74 respectively). Indicating that if the Karnaphuli River water has low pH or high temperature, there is likely to be high MPs present in the water. Most MP particles were film-shaped, white in color, and 1-5 mm in size. Of the six polymers detected, polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and cellulose were predominant, comprising roughly 17-19% each. These results can be used to model MP transport in the freshwater ecosystem of the Karnaphuli River estuary in Bangladesh to help develop future mitigation strategies.

Sharks are top predators and play an important role in the regulation of marine ecosystems at lower trophic position. Mustelus californicus, Sphyrna zygaena, and Isurus oxyrinchus prove to be important fishery resources along the western coast of Baja California Sur and cohabit the same coastal areas, probably sharing resources. However, our knowledge about ecological dynamics of multiple species coexisting and sharing similar habitat resources is still limited, particularly for predators such as sharks. Therefore, this study focuses on the analysis of trophic ecology of the sharks species, using carbon ( 13 C) and nitrogen ( 15 N) stable isotope values in muscle tissues coupled with trace element concentration (Hg, Se, and Cd) in muscle and hepatic tissues of sharks. The values of δ 13 C (M. californicus -17.3 ± 1.1‰, S. zygaena -17.9 ± 0.5‰, and I. oxyrinchus -18.3 ± 0.3‰) and δ 15 N (M. californicus 18.2 ± 1.1‰, S. zygaena 18.4 ± 0.9‰, and I. oxyrinchus 17.8 ± 1.1‰) indicated that these species feed in the Gulf of Ulloa all throughout the year, and for extended periods with similar habitat use and trophic niche. The above-mentioned statement is also a conclusion supported by the significant correlation between isotopic and trace element concentrations in the muscular tissues in all studied species. Thus, the results of the present study emphasize the habitat and niche characteristics of three sympatric sharks off the coast of Baja California Sur, Mexico., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Mercury (Hg) is a global pollutant that is a major public health concern due to its mobility, stability and toxicity behavior in the environment. In this study Hg concentrations were determined in beach sediment samples (n = 43) collected from the South Durban Coast, South Africa. A human health risk assessment was also carried out to comprehend the potential health effects of incidental ingestion/direct contact with contaminated sediments in a recreational setting. Hg concentrations ranged between 0.62 and 4.88 mg kg -1 dw., exceeding all background and regulatory limits. Numerical values of calculated exposure pathways represented dermal contact with the sediments as one of the potential paths in both adults and children. Hazard Index (HI) values were found to be less than unity signifying no adverse health effects. This study validates the critical need for long-term monitoring of Hg in various scenarios in order to incorporate better public health management strategies., (Copyright © 2022. Published by Elsevier Ltd.)

Investigation on freshwater MPs has increased gradually across the world, since they are main trajectory for the transportation of MPs from inland to ocean. The present study aims to identify the presence, distribution and the type of MPs in the lake Hawassa, Ethiopia. Twenty-five shoreline surface sediments were separated using ZnCl 2 solution and was microphotographed using SEM and type of MP was identified using FTIR spectra. The abundance of MPs was in range of 11-74 items/m 3 near the catchment area of the lake in the eastern side. Fiber (90%), fragments (5%) and pellets (5%) were the commonly observed form with varied colour such as white, black, blue, red and others. Our results infer that the common polymer detected in the study area were polyester (82%), polyethylene (15%) and polystyrene (3%) infer their origin from fishing nets, ropes and plastics bags. The industries near the lake contributes more MPs, where the waste water effluents are drained directly into the lake. Spearman's correlation matrix applied among the MPs characters endorses the fate of MPs in the lake environment indicating the weathering process (especially due to bleaching process). Comparative studies with other lake regions around the globe indicate higher values which is entirely and it depends on various factors surrounding the study area. Being, highly polluted lake in Ethiopia, this study extremely acclaims that some monitoring studies in fresh water components in the lake Hawassa helps to mitigate the prevailing MPs pollution., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study focuses on the presence of MPs in the sediment beds around coral reefs of MPNPs in Baja California Sur, México. Based on seasonal sampling results, comparison of MPs from Cabo Pulmo (avg. 680.25 items/100 g -1 d.w) recorded higher values than Espiritu Santo Island (avg. 321.75 items/100 g -1 d.w) from backshore/foreshore regions. Fibrous MPs are the dominant morphotypes followed by fragments and spheres. SEM/EDS analysis revealed that the MPs are altered texturally in surface and is bioavailable to marine organisms independent of size/shape. FTIR analysis indicate different polymers (in %) in the form of PP (70), PET (65), HDPE (59), LDPE (50), PS (30), PC (18), PU (10) and RYN (10). Most of the MPs are secondary in origin resulting from man-made and tourist's activities controlled by wave transportation and tidal currents. Existence of MPs in sediment beds around the coral reefs signals the ways for future investigations., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Cadmium, selenium, and mercury concentrations were measured in muscle and liver of juvenile blue (Prionace glauca) and smooth hammerhead (Sphyrna zygaena) sharks caught on the west coast of Baja California Sur, Mexico, to evaluate the human health risk associated with its consumption. Cd and Hg were lower than the maximum allowable limit for human consumption established by the Mexican government (Hg = 1.0 μg g -1 and Cd = 0.50 μg g -1 ). Interspecific differences in trace elements accumulation denoted diet variations and physiological requirements of each shark species. Calculated biomagnification factor (BMF) values confirmed a prey-predator trophic transfer of elements. Not significant results of Selenium health benefit Index value (P. glauca = -0.46; S. zygaena = -0.02) signify no potential risks for human health. However, calculated Hazard Index values displayed possible health hazards to the children who consume blue shark meat regularly. The local population is advised regarding the ingestion rates of shark., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Baseline data on concentration, fractionation, pollution level and ecological risk index for seventeen beach sediments from Santa Rosalia mining region of Baja California Sur, Mexico were assessed. Higher concentrations of Rare Earth Elements (REEs) (mean. 341.49 μg/g) indicated that it is higher than most of the mining regions around the world. Normalization pattern showed enrichment of Eu (>4) and calculated geochemical indices revealed that light and middle REEs are moderately polluted with most of the sampling points located closer to the river discharge. Potential Ecological Risk Index (PERI) showed that Eu (20.2), Tb (20.88), and Lu (28.57) pose moderate ecological risk to the soil at selected stations (10, 11, 15 and 16) with a risk index value ranging from 245 to 359. Pearson's correlation matrix suggested that all REEs are highly correlated (r 2 0.95) with each other having similar geochemical characteristics and indicating identical source due to continuous mining activity., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A study on mercury (Hg) and selenium (Se) concentrations in the liver and muscle of brown smooth-hound shark Mustelus henlei and its principal prey items, was conducted in the western coast of Baja California Sur, Mexico. Average Hg concentrations were found to be high in the muscle than in the liver; however, Hg concentrations were below the maximum permissible limits, and hence, the consumption of this species does not constitute a risk to human health. The mean Se concentrations were higher in the liver than in the muscle. The results of Hg: Se molar ratio revealed that Se counteracts the toxicity of Hg in hepatic tissues, whereas the contrary occurs in the muscle. Significant differences in Hg and Se accumulation were observed between females and males. Biomagnification factor values >1 demonstrate a biomagnification process from its principal prey species (i.e., red crab, Pleuroncodes planipes and Pacific mackerel, Scomber japonicus)., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The study evaluated the spatial and seasonal variations of microplastic abundances in water, sediments, and commercial fishes of a semi-urban tourist impacted estuary in the Gulf of Mexico, Mexico. The prevalence of microplastics (MPs) elucidated diffuse sources namely long-range transport, domestic, agricultural, fishing, industrial and recreational activities and the local climatic conditions. Seasonally, the mean abundances of MPs in both water and sediments were high during Nortes (strong winds) followed by the dry and rainy seasons. Overall, black and blue colored MPs dominated the region and all the recovered plastics were fibers. The commercial fishes (n = 187) contained 881 MPs in their gastrointestinal tracts, suggesting that the food web of the estuary is highly prone to microplastic contamination. SEM images of extracted plastic fibers presented surface morphologies that are impacted by physical strains. Further, the elemental characterization of fibers using EDX displayed significant peaks of Al, As, Cl, Cr, Cu, Pb, and Zn that were used as additives during the production of plastics. The main types of polymers included low-density polyethylene, polyester, polypropylene, polycarbonate, rayon, polyvinyl chloride, polyacrylonitrile, polyamide, nylon and polyethylene terephthalate. MP abundances demonstrated in this study elucidate that estuaries are a major conduit for land-derived plastics to the ocean and the results will aid in implementing remedial/clean up actions of the estuary for better conservation of the ecosystem., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Total mercury (THg), methylmercury (MeHg) in water, sediments, macrophytes, fish and human health risks were analyzed and assessed from abandoned gold mining ponds (AGMPs)/ mining areas in Western Colombia to know its present environmental condition. Concentrations of THg in water (avg. 13.0 ± 13.73 ng L -1 ) was above the EPA threshold level (12 ng L -1 ), suggesting possible chronic effects. Sediment sample revealed that the ponds are methylated (%MeHg: 3.3-11). Macrophyte Eleocharis elegans presented higher THg content in the underground biomass (0.16 ± 0.13 µg g -1 dw) than in the aerial biomass (0.05 ± 0.04 µg g -1 dw) indicating accumulation of THg. MeHg was the most abundant chemical species in fish (MeHg/THg: 83.2-95.0%), signifying higher bioavailability and its risk towards human health. Fish samples (15%) indicate that THg were above WHO limit (0.5 µg g), particularly in Ctenolucius beani, Hoplias malabaricus and lowest in Sternopygus aequilabiatus and Geophagus pellegrini. Bioaccumulation and biomagnification of MeHg were higher in the carnivores representing a source of exposure and potential threat to human health. Fulton's condition factor (K) for bioaccumulation indicate a decrease with increasing trophic level of fishes. Overall results suggest, mercury species found in different AGMPs compartments should be monitored in this region., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Microplastics (MPs) existence, identification and source were investigated by studying a total of 2539 particles in 349 sediment samples from nine different tourist beaches [(Sodwana & Richard Bays; Ballito, Mtunzini, Tugela, Zinkwazi, Ballito (north & south) and Durban north & south)] of southeastern coast of South Africa. They are more abundant in the beaches of the Durban city, followed by the Sodwana & Richards Bays, Ballito and Mtunzini. The black particles prevailed over the blue, white, pink, brown, red and green MPs. Supremacy of MPs in the Durban city is mainly due to the longshore coastal Agulhas current in the South eastern side of African coast aiding the degradation of primary plastics coming both from continent and sea. SEM images provided the evidences of weathering/degrading process through grooves, cracks, deep fissures, sharp edges and layered degradation showing signs of oxidation due to long term exposure in the coastal environment. EDS results suggested presence of elements (i.e. C, -O, Si, Al, Fe, Ca, Mg, Na, K, S, Ti, Cu and Zn introduced during the production of plastics as additives. FTIR spectral matches identified from all samples infer polypropylene (PP) (62%), rayon (RY) (17.2%), polycarbonate (PC) (29.8%), nylon (NY) (18.92%), polyester (PES) (31.2%), polyacrylonitrile (PAN) (11.21%) and polystyrene (PS) as well as low (28.9%) & high (36.1%) polyethylene terephthalate (PET). Higher abundance of MPs in the beaches of South Africa in comparison with studies around the world emphasizes the need of dispersal monitoring and use of plastic materials/polymers., Competing Interests: Declaration of competing interest The authors certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Total mercury (THg) and methylmercury (MeHg) were studied in sediments from 27 abandoned gold mining ponds (AGMPs) through small-scale artisanal gold mining in the district of San Juan in Chocó region of Colombia. The AGMPs were abandoned in the last century (1997) and were grouped into three distinct groups (2-6; 7-12; 13-20 years). Overall concentration (in ng g -1 ) pattern of THg in sediments varied from 39.06 to 1271.32 (avg. 209.57) with 174.81 (13-20 years), 205.56 (7-12 years) and 248.33 (2-6 years) respectively. MeHg concentrations accounted for 3.3-10.9% (avg. 6.5%) of THg and were significantly correlated with THg during all periods. Correlations between organic matter (OM) vs MeHg and THg were negative in the oldest pools, signifying a "dilution effect" or "natural burial" of THg and MeHg. Results for sequential extraction indicate that the fraction of elemental Hg (Hg-e) and organo chelated Hg (Hg-o) represent the main chemical forms of Hg in the sediments, regardless of the abandonment period, whereas the bioavailable fraction was only 0.12-1.65% of THg. The significant statistical relationship between MeHg, THg and OM suggests that these parameters control the distribution, mobility, toxicity and bioavailability of Hg in the sediments of these abandoned ponds. Evaluation of THg with sediment quality guidelines indicates that the values are on the higher side for Threshold effect concentration and Upper continental crust. Comparing of MeHg with many other regions outside Colombia is a worrying factor and needs immediate attention to protect the human health., Competing Interests: Declaration of competing interest The authors do not have any conflict of interest in this study., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study aims to report the short-term coastline dynamics and inundation limits of coastal cities along the Eastern Pacific due to the sea swell events that occurred during April to May 2015. The multi-temporal satellite datasets from Landsat such as Enhanced Thematic Mapper (L7 ETM+) and Operational Land Imager/Thermal Infrared Sensor (L8 OLI/TIRS) of different periods before and after the swell events were used to identify the shoreline changes. The satellite images were pre-processed using ERDAS imagine 9.2, and the coastline was digitized in ArcGIS 10.4.1 for ten cities spread across from Mexico to Chile (in Pacific coast) using the spectral water indices, and the shoreline change rate and erosion/accretion pattern at each transect were estimated using the statistical parameters embedded in Digital Shoreline Analysis System (DSAS). The maximum erosion and accretion were observed in El Salvador (268 m) and Huatulco (Mexico) (115 m), respectively. Likewise, the maximum inundation was observed in El Salvador with 268 m and Acapulco (Mexico) with 254 m, and the tide gauge data suggest a possible relation to the bathymetry and the geomorphological conditions of the coast. Overall, the results indicate that the Eastern Pacific Ocean side sea swell events has led to extreme coastal flooding in recent years due to the increase in the mean sea level and the unpredictable variation in El Niño/Southern Oscillation events. Graphical abstract.

Pelagic thresher shark (Alopias pelagicus) is a circumglobal species with high ecological and economic importance. Concentrations of mercury, selenium and cadmium in the muscle and liver tissues of A. pelagicus captured from Baja California Sur, Mexico were determined for assessing the potential human hazard. Results revealed that the average concentrations of Hg (0.76 mg kg -1 ) and Cd (0.18 mg kg -1 ) in muscle tissues were below the maximum permissible limits for human consumption. Se in the muscles were relatively low (mean: 0.30 mg kg -1   -1 ) resulting in a molar excess of Hg over Se. Average levels of hepatic Cd were extremely higher than the maximum limit for consumption. Organotropism of Hg was muscle > liver, whereas Se and Cd presented an order of liver > muscle. Biomagnification Factor (BMF) emphasized the trophic transfer of elements. Selenium Health Benefit value was negative (-3.76) posing potential health risks demanding regular monitoring for health risks., Competing Interests: Declaration of competing interest We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The present work represented first study of the spatio-seasonal distribution of the multi-elements in the suspended particulate matter (SPM) of the tropical Hooghly river estuary (HRE), eastern part of India. The high load of SPM (20-3460 mg/l) might have induced negative impact on the phytoplankton density. The relative abundance of the studied elements exhibited the following decreasing trend (concentration in μg/g and %): Si(26.44 ± 3.75%) > Al(7.94 ± 1.52%) > Fe(6.17 ± 1.9%) > K(3.05 ± 1.5%) > Ca(1.97 ± 1.11%) > Mg(1.57 ± 1.71%) > Na(1.45 ± 8.40%) > Mn(1273 ± 2003) > Zn(178.43 ± 130.95) > V(151.54 ± 27.13) > Cr(147.08 ± 32.21) > Cu(62.06 ± 14.03) > Ni(49.64 ± 12.09) > Pb(21.5 ± 10.45). The accumulation of Ni, Cr, Pb, and Cu is mainly controlled by the formation of Fe hydroxides along with particulate organic carbon (POC) and salinity. The average geo-accumulation index (I geo ) and enrichment factor (EF) endorsed the substantial input of Cr (I geo  = 0.037; EF = 1.61) and Zn (I geo  = 0.123; EF = 2.07) from diffused pollution sources. From ecotoxicological point of view, the quality guidelines (QGs) suggested that Cr and Ni might possess frequent adverse biological effects. However, the mean probable effect level (PEL) quotient values revealed 49% probability of toxicity to the aquatic biota for five toxic elements (Cr, Ni, Cu, Zn, and Pb). The geochemical approaches, pollution indices, and statistical evaluation together revealed low to moderate contamination in the estuary. This baseline data would be beneficial in adopting proper management strategies for sustainable utilization and restoration of the water resources. The authors strongly recommend continuous systematic monitoring and installation of treatment plants for management of this stressed estuary.

Mercury- Selenium concentrations were determined in 136 samples of Carcharhinus falciformis (Silky shark) sampled from the Chiapas coast, Gulf of Tehuantepec, Mexico during August 2014 - January 2015. Average Hg concentrations in neonates and juveniles (all values in μg g -1 w.w.) were found to be 0.115 and 0.129 respectively, below the maximum permissible limit of 1 μg g -1 set by the Mexican government. However, excess Se values (all values in μg g -1 d.w.) observed in neonates (5.366) and juveniles (2.815) prove to maintain antioxidant ability by inducing Hg excretion and reducing its toxicity. Calculated Biomagnification Factor (BMF TL ) denoted high values for the prey C.hippurus, signifying absolute magnification of Hg and Se along the food chain. This study provides key toxicological evidences of Hg- Se interaction and their effects in marine systems and human health., (Copyright © 2020. Published by Elsevier Ltd.)

A study on cadmium concentration in Mustelus henlei (liver and muscle) was carried out in an area influenced by natural phosphorite deposits and coastal upwelling. Our results indicate that liver (0.96 μg/g) concentrations were higher compared to the muscle (0.040 μg/g) suggesting it is on the safer level for human consumption. The male/female ratio indicates higher values (based on liver & muscle) in males (0.899 μg/g), which contributes to these differences in concentration. Higher values in the liver (0.96 μg/g) is due to the influence of phosphorite deposits in the region as well as the high metabolic activity. The other important factor responsible for these high Cd values are the prey, which also poses high values and is well supported by the biomagnification (1.08 & 4.57) of this element. The study also benefited in evaluating the environmental conditions for this particular species and elemental concentration in relation to human health., (Copyright © 2019. Published by Elsevier Ltd.)

Sediment metal concentrations were assessed in five different beach regions (n = 183) of KwaZulu-Natal (KZN) province in South Africa. Metal distribution revealed that Cr, Cu, Mo, Cd, Zn, Hg and As exceed the background upper continental crust values suggesting their anthropogenic origin (mining, agricultural and industrial) apart from natural geological inputs (gold placer deposits and heavy minerals). Various geochemical indices (Geoaccumulation index, Enrichment factor and Degree of contamination) confirmed that the sediment samples are extremely contaminated with Cr, Cd and Hg. Further, Hg and Cd were main contributors (60-90%) to the ecological threat in sediments. Hazard index estimated a high hazard potential of Hg in near future. Finally, present study together with our previous results portray the status of KZN coast with special significance to Hg contamination/enrichment. Thus, future researches are recommended to investigate the environmental and human health implications of mercury exposure in this coastal province., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The aim of the article is to evaluate the national adaptation to climate change in the energy generation sector in Colombia via a composite index. To build an index, a framework by stages is used, which includes the definition of the main concepts that supports the measurements; the selection of the relevant indicators using a subject matter experts; standardization of the indicators using a mathematic formula regarding the relationship between the variables that represent the adaptation to climate change; and establishment of the weights using an analytic hierarchical process of paired comparisons and the aggregation of indicators to obtain the following three sub-indexes: reactive adaptation, wherein the replacement of hydraulic energy by thermal energy is evaluated; anticipatory adaptation, which measures the gap between the generation of total energy and the demand of the national energy system; and planned adaptation, which considers indicators such as the sectoral plan for adapting to climate change, the law of alternative energies, and the generation of alternative energies as a percentage of generation capacity. By adding these sub-indices, the climate change adaptation index (CCAI) is obtained. The results of CCAI show that progress was made from a reactive adaptation scenario in which the system vulnerability was high to an anticipatory adaptation scenario wherein the vulnerability was average, indicating that the foundations for this sector to build a planned adaptation are currently being laid., (Copyright © 2019. Published by Elsevier Ltd.)

Metal/metalloid concentrations in water sediment and commercial fishes of Loreto Maritime National Park (MNP), Baja California Sur, Mexico were determined for a comprehensive geochemical study. In-situ physical characteristics (pH, conductivity, redox potential, dissolved oxygen, turbidity) of water clearly indicated the unique oceanographic properties of the Gulf of California. Likewise, the distribution pattern of metals/metalloid in water, sediments and fishes denoted the influences of local geology, longshore currents, upwelling process, natural hydrothermal vents and the 100-year old mining activities of Santa Rosalia region, situated to the north of Loreto. Calculated carcinogenic indices in commercial fish species showed safe human consumption. Thus, the present research validates a comprehensive geochemical study of protected areas upholding the need for continuous monitoring for a better conservation of coastal ecosystems., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

River Atoyac is considered to be one of the most polluted rivers in Mexico due to the discharges of untreated or partially treated wastewater from industrial and municipal activities. In order to improve the river water quality, it is obligatory to identify the possible contaminant sources for upholding a well-balanced ecosystem. Henceforth, the present study incorporates the application of a continuous real-time monitoring system to identify the provenance of pollutants of the river mainly from anomaly events. Four monitoring stations were installed all along the River Atoyac in the State of Puebla, Central Mexico. The real-time monitoring systems have an ability to measure various water quality parameters for every 15 minutes such as Temperature (T), pH, Conductivity (EC), turbidity (TURB), Dissolved Oxygen (DO), Oxidation Reduction Potential (ORP) and Spectral Absorption Coefficient (SAC). In total, eight water samples of anomaly events (i.e.) 2 per monitoring station during rainy (August-September) and winter seasons (November-December), that were detected using the parameters previously mentioned were procured and also analyzed in the laboratory for evaluating almost 54 physicochemical, inorganic and organic characteristics. Statistical results of factorial analysis explained that 30% of the total variance corresponded to textile effluents, 23% related to discharges produced by automobile and petrochemical industries, and 18% of the total variance defined the agricultural activities. Additionally, indices like Overall Index Pollution, Heavy Metal Evaluation Index, Screening Quick Reference Table and Molecular ratios of hydrocarbons for PAH sources was also calculated to estimate the grade of pollution and associated ecotoxicological risks. The present study also enlightens the fact that the assessed results will definitely provide valuable information for the management of river water quality by developing stringent public policies by governmental agencies for the sustainable conservation of Atoyac River., (Copyright © 2019. Published by Elsevier B.V.)

Trace element (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, As, Hg) concentrations were assessed in marine organisms (n = 52) sampled from the Magdalena Bay lagoon complex in Baja California Sur, Mexico, a pristine marine environment. The overall trend of metal concentrations (dry weight) in the organisms was found to be Fe > Zn > Cd > Cu > Mn > Pb > As > Hg > Ni > Cr > Co. Bivalve mollusks (53.83 mg kg -1 ) contained twofold higher levels of metals than the finfishes (20.77 mg kg -1 ). Calculated BioConcentration Factor (BCF) values showed that dissolved Mn is readily bioavailable to the organisms, whereas Biota Sediment Accumulation Factor (BSAF) indicated high values for Zn, Cu and Cd. Cd and As levels were observed to be increasing with the trophic levels. Toxic elements, namely Pb, Cd and As in the studied fish species were found to be higher than the values recommended for human seafood consumption. The study provides a comprehensive baseline report on trace element bioaccumulation in several marine organisms that will aid in developing effective conservation strategies of the highly biodiverse lagoon complex.

Microplastics (MPs) are contaminants of emerging concern in aquatic environments. The abundance, distribution and characteristics (color, morphology, texture) of MPs from Atoyac River basin, a highly urbanized river system located in Central Mexico were investigated in this study. The sediment samples were collected from 29 different sites along the Atoyac River basin in four different zones: Zahuapan River, Atoyac River, Confluence zone and Valsequillo dam and processed for MPs extraction using ZnCl 2 density separation method. The total number of MPs in Zahuapan River, Atoyac River, Confluence zone and Valsequillo dam was 1633.34 ± 202.56, 1133.33 ± 72.76, 833.33 ± 80.79 and 900 ± 346.12 items kg -1 respectively. It was found that the concentration of MPs is higher in the downstream section of the river (confluence zone: 833.33 ± 80.79 & Valsequillo dam: 900 ± 346.12 items kg -1 ), revealing significant impacts of dense population and industrial complex of Puebla City. Colored MPs were predominant accounting for 51% and white MPs for 49% of the total MPs. Films (25.9%) and fragments (22.2%) were the most abundant type followed by fibers (14.8%). Scanning electron microscope images revealed varying disintegration features and energy-dispersive X-ray spectra demonstrated the presence of different metal elements on the surface of MPs. The results highlighted the widespread distribution of MPs in the sediments of Atoyac River basin, Mexico., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Thirty-four water samples were collected all along the course of River Yautepec, Morelos State, Central Mexico, in three different zones based on the physical and anthropogenic setting. In situ measurements of physical characteristics (temperature, pH, conductivity, and turbidity) were also performed at each sampling station. Likewise, total/dissolved metal concentrations (Fe, Mn, Cr, Cu, Ni, Pb, Zn, Cd, As, and Pb) were determined using an atomic absorption spectrophotometer. Located in a peri-urban and volcanic zone of Central Mexico, the river system presented impacts of both natural and anthropogenic activities. Results revealed differences in pH values (6.7-8.23) in all the three zones probably due to the influences of volcanic ash and local geological formations, whereas conductivity levels (635-1098 μs/cm) were high indicating the effect of agricultural and industrial activities. The relative order of the concentrations of metals in both the total and dissolved fractions was observed to be in the following order: zone I, Fe > Zn > Mn > Cu > Pb > Ni > Cr > As > Cd > Hg; zone II, Fe > Zn > Pb > Ni > Mn > Cu > Cr > Cd > As > Hg; zone III, Fe > Pb > Zn > Mn > Ni > Cu > As > Cd > Cr > Hg. Calculated heavy metal evaluation index (HEI) values indicated less contamination. However, concentrations of Fe and Pb were observed to be higher than the permissible limits set forth by the Mexican government for human consumption. Henceforth, the prerequisite for maintaining and improving the health of a river system depends on continuous long-term monitoring of the dynamic ecosystem for sustainable management.

Thirty sediment samples from four different beaches along Bahia Solano and Nuquí (Department of Chocó) of eastern Colombia, with tourism and gold mining activities, were analysed to estimate the concentrations of fourteen different acid leachable metals. Metal distribution patterns showed elevated concentrations of Co, Cr, Cu, Pb and Zn compared with the upper continental crust values. Calculation of geochemical indices confirmed that the enrichment is due to periodic gold mining activities (severe to extremely severe enrichment of Cu, Zn, V, Co, Cr and Pb) along with natural (geological) contributions (minor and moderate enrichment of Ca, Mg, Fe, Ti, Mn and Li). Potential ecological risk index revealed that Pb posed the highest risk. Our results together with a global comparison suggest that the observed metal enrichments are mainly caused by mining and to a lesser extent by tourism in this region, thus instigating continuous monitoring of metal concentrations in this region., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A biomonitoring study was carried out to examine the adverse impacts of total mercury in the blood (HgB), urine (HgU) and human scalp hair (HgH) on the residents of a mining district in Colombia. Representative biological samples (scalp hair, urine and blood) were collected from volunteered participants (n=63) to estimate the exposure levels of THg using a Direct mercury analyzer. The geometric mean of THg concentrations in the hair, urine and blood of males were 15.98μg/g, 23.89μg/L and 11.29μg/L respectively, whereas the females presented values of 8.55μg/g, 5.37μg/L and 8.80μg/L. Chronic urinary Hg (HgU) levels observed in male workers (32.53μg/L) are attributed to their long termed exposures to inorganic and metallic mercury from gold panning activities. On an average, the levels of THg are increasing from blood (10.05μg/L) to hair (12.27μg/g) to urine (14.63μg/L). Significant positive correlation was found between hair and blood urinary levels in both male and female individuals. Thus the present biomonitoring investigation to evaluate the Hg levels and associated health issues would positively form a framework for further developmental plans and policies in building an ecofriendly ecosystem., (Copyright © 2017. Published by Elsevier B.V.)

A baseline study on metal concentrations in sediments was initiated from the Sodwana Bay and St. Lucia, adjacent to marine protected areas (MPAs) of South Africa. They were analysed to identify the acid leachable metal (ALM) (Fe, Mg, Mn, Cr, Cu, Mo, Ni, Co, Pb, Cd, Zn and Hg) concentration pattern. Metal distribution in 65 sediment samples exhibits higher abundances of Cr, Mo, Cd and Hg compared to the Upper Continental Crust. We relate the enrichment of these metals to beach placer deposits and activities related to former gold mining. Geochemical indices affirmed that Cr and Hg caused contamination, and Hg posed ~90% harmful effect on the biological community. These beach sediments, however, host lower metal concentrations compared to many worldwide beaches and other beaches in South Africa. This study suggests that it is largely unaffected by human activities, however, the overabundance of Hg demands regular monitoring., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The spatial and seasonal distribution of trace elements (TEs) (n=16) in surficial sediment were examined along the Hooghly River Estuary (~175km), India. A synchronous elevation of majority of TEs concentration (mgkg -1 ) was encountered during monsoon with the following descending order: Al (67070); Fe (31300); Cd (5.73); Cr (71.17); Cu (29.09); Mn (658.74); Ni (35.89). An overall low and homogeneous concentration of total Hg (T Hg =17.85±4.98ngg -1 ) was recorded in which methyl mercury (MeHg) shared minor fraction (8-31%) of the T Hg . Sediment pollution indices, viz. geo-accumulation index (I geo ) and enrichment factor (EF) for Cd (I geo =1.92-3.67; EF=13.83-31.17) and Ba (I geo =0.79-5.03; EF=5.79-108.94) suggested high contamination from anthropogenic sources. From factor analysis it was inferred that TEs primarily originated from lithogenic sources. This study would provide the latest benchmark of TE pollution along with the first record of MeHg in this fluvial system which recommends reliable monitoring to safeguard geochemical health of this stressed environment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The present work investigated the spatial distribution and ecological risk assessment of total and mild acid-leachable trace elements in surface sediments (top 0-10 cm; grain size ≤ 63 μm) along the Hooghly (Ganges) River Estuary and Sundarban Mangrove Wetland, India. The trace elements, analyzed by ICPMS, showed wide range of variations with the following descending order (mean values expressed in milligrams per kilogram): Fe (25,050 ± 4918) > Al (16,992 ± 4172) > Mn (517 ± 102) > Zn (53 ± 18) > Cu (33 ± 11) > Cr (29 ± 7) > Ni (27 ± 6) > Pb (14 ± 3) > As (5 ± 1) > Se (0.37 ± 0.10) > Cd (0.17 ± 0.13) > Ag (0.16 ± 0.19) > Hg (0.05 ± 0.10). In the acid-leachable fraction, Cd (92%) is dominated followed by Pb (81%), Mn (77%), Cu (70%), and Se (58%) indicating their high mobility, imposing negative impact on the adjacent benthos. The sediment pollution indices (both enrichment factor and contamination factor) suggested severe pollution by Ag at the sampling site Sajnekhali, a wildlife sanctuary in Sundarban. The mean probable effect level quotient indicated that surface sediments in the vicinity of the studied region have 21% probability of toxicity to biota. The result of multivariate analyses affirms lithogenic sources (e.g., weathering parent rocks, dry deposition) for As, Pb, Cr, Cu, and Ni, whereas Cd and Hg originated from anthropogenic activities (such as urban and industrial activities). Both human-induced stresses and natural processes controlled trace element accumulation and distribution in the estuarine system, and remedial measures are required to mitigate the potential impacts of these hazardous trace elements.

The study accentuated the trace metal accumulation and distribution pattern in individual organs of 13 native mangrove plants along with rhizosediments in the Indian Sundarban Wetland. Enrichment of the essential micronutrients (Mn, Fe, Zn, Cu, Co, Ni) was recorded in all plant organs in comparison to non-essential ones, such as Cr, As, Pb, Cd, Hg. Trunk bark and root/pneumatophore showed maximum metal accumulation efficiency. Rhizosediment recorded manifold increase for most of the trace metals than plant tissue, with the following descending order: Fe>Mn>Zn>Cu>Pb>Ni>Cr>Co>As>Cd>Hg. Concentrations of Cu, Ni, Pb and Hg were found to exceed prescribed sediment quality guidelines (SQGs) indicating adverse effect on adjacent biota. Both index of geoaccumulation (I geo ) and enrichment factor (EF) also indicated anthropogenic contamination. Based on high (>1) translocation factor (TF) and bioconcentration factor (BCF) values Sonneratiaapetala and Avicenniaofficinalis could be considered as potential accumulators, of trace metals., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The aim of the study was to evaluate the bioavailability of trace metals (Chromium, Copper, Nickel, Lead, Zinc, Cadmium, Arsenic, and Mercury) in the commercially consumed Crassostrea gigas oysters collected over a 12-month growth period (2011-12) from an experimental cultivation farm in La Pitahaya, Sinaloa State, Mexico. Sediment and water samples were also collected from four different zones adjacent to the cultivation area to identify the concentration patterns of metals. The results revealed that sewage disposals, fertilizers used for agricultural practices and shrimp culture are the major sources for the enrichment of certain toxic metals. The metal concentrations in oysters presented a decreasing order of abundance (all values in mg Kg -1 ): Zn (278.91 ± 93.03) > Cu (63.13 ± 31.72) > Cr (22.29 ± 30.23) > Cd (14.54 ± 4.28) > Ni (9.41 ± 11.33) > Pb (2.22 ± 1.33) > As (0.58 ± 0.91) > Hg (0.04 ± 0.06). Bioconcentration Factor (BCF) and Biota Sediment Accumulation Factor (BSAF) exhibited that C. gigas in the region are strong accumulators for Zn and Cd respectively. Thus, the present study proves to fulfill the gap in understanding the rate of bioaccumulation of metals in C. gigas which is regarded as the most sought after oyster species globally., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

South Durban basin of South Africa has witnessed tremendous urban, industrial expansion and mass tourism impacts exerting significant pressure over marine environments. 43 sediment samples from 7 different beaches (Bluff beach; Ansteys beach; Brighton beach; Cutting beach; Isipingo beach; Tiger Rocks beach; Amanzimtoti beach) were analyzed for acid leachable metals (ALMs) Fe, Mg, Mn, Cr, Cu, Mo, Ni, Co, Pb, Cd, Zn and Hg. The metal concentrations found in all the beaches were higher than the background reference values (avg. in μgg -1 ) for Cr (223-352), Cu (27.67-42.10), Mo (3.11-4.70), Ni (93-118), Co (45.52-52.44), Zn (31.26-57.01) and Hg (1.13-2.36) suggesting the influence of industrial effluents and harbor activities in this region. Calculated geochemical indexes revealed that extreme contamination of Cr and Hg in all the beach sediments and high Cr and Ni levels poses adverse biological effects., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The feasibility of a potential bioindicator based on functional groups of microzooplankton tintinnids for bioassessments of water quality status was studied during southwest monsoon (June to September) along the coastal waters of Kalpakkam, India during 2012-2015. The work highlights the following features (1) tintinnid community composed of 28 species belonging to 11 genera and 9 families, revealed significant differences among the four study sites (2) maximum numerical abundance (2224±90ind. l -1 ) and species diversity (H'=2.66) of tintinnid were recorded towards Bay of Bengal whereas minimum abundance (720±35ind. l -1 ) and diversity (H'=1.74) were encountered in the backwater sites, (3) multivariate analyses [RELATE, Biota-environment (BIOENV) and canonical analysis of principal coordinates (CAP)] reveal that chl a, nitrate and phosphate were the potential causative factors for tintinnid distribution. Based on the results, we suggest that tintinnids may be used as a potential bioindicator of water quality status in marine ecosystem., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The rapid urban expansion and presence of volcanoes in the premises of Puebla River basin in central Mexico exert significant influences over its aquatic environments. Twenty surface sediment samples from Puebla River basin consisting of R. Alseseca, R. Atoyac, and Valsequillo dam were collected during September 2009 and analyzed for major (Al, Fe, Mg, Ba, Ca, and K) and trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V, and Zn) in order to identify the metal concentrations and their enrichment. R. Atoyac sediments presented higher concentrations of Ba (1193.8 μg g -1 ) and Pb (27.1 μg g -1 ) in comparison with the local reference sample values. All the metal concentrations except Sr for R. Alseseca sediments were within the range of local reference sample values indicating no significant external influence, whereas Valsequillo dam sediments had elevated concentrations of all the metals suggesting both natural and external influences in the study region. The magnitude of metal contamination was assessed using several indices such as geoaccumulation index (I geo ), enrichment factor (EF), degree of contamination (C d ), and pollution load index (PLI). The results suggest that As, Pb, and Zn were predominantly enriched in the Puebla River basin sediments. Comparing with sediment quality guidelines and ecotoxicological values, it is revealed that Cd, Cr, Cu, and Ni have possible harmful effects on the biological community. The present study provides an outlook of metal enrichment in Puebla River basin sediments, highlighting the necessity to conserve this river ecosystem for the near future.

The presence and impacts of plastic marine debris (PMD) have been documented in the oceans worldwide, and they deserve special attention. This study is the first to report the presence of microplastics in tourist beaches located in Huatulco Bay, southern Mexico. A total of 70 beach sediment samples (for 2 distinct seasons) were collected from Huatulco Bay in April 2013 and December 2014. The samples were subsequently extracted by scanning electron microscopy (SEM) to identify the fibrous microplastics (diameter<5mm). The maximum number of fibrous materials was found in April 2013 and December 2014 in the Rincón Sabroso beach (48/30g sediment) and the Cuatunalco beach (69/30g sediment), respectively. Overall, a high amount of microplastics is present in the Conejos, Tangolunda, Santa Cruz, and San Agustin beaches. The microplastics are mainly derived from tourism-based activities and effluents discharged from the hotels and restaurants located along the beaches., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Cadmium concentrations were determined in the tissues of muscle and liver of Carcharhinus falciformis (silky shark) sampled in Todos Santos, Baja California South, Mexico. This is one of the main shark species for human consumption in Mexico. Results indicate that accumulation of Cd varied in both sexes, based on its metabolism, sex, maturity and other biological characteristics. High Cd values were observed in the liver of adults of male (529.61μgg(-1)) and female (457.43μgg(-1)), whereas, in muscular tissues it was low (0.37μgg(-1)) than the prescribed permissible limits for seafood (0.5μgg(-1)). Substantial correlations were observed between body length and Cd values in adults except young male due to faster growth rate and its metabolism. The study indicated the impact of environmental conditions in the accumulation of Cd and its risk to the food web structure in the marine environment and health hazard for humans., (Published by Elsevier Ltd.)

Acid Leachable Trace Metal (ALTMs) concentrations in tourist beaches of Richards Bay, Kwazulu-Natal, South Africa were assessed. 53 surface sediment samples were collected from five different beaches (Kwambonambi Long Beach; Nhlabane Beach; Five Mile Beach; Alkanstrand Beach and Port Durnford Beach). The results of ALTMs (Fe, Mn, Cr, Cu, Ni, Co, Pb, Cd, Zn, As, Hg) suggest that they are enriched naturally and with some local industrial sources for (avg. in μgg(-1)) Fe (3530-7219), Mn (46-107.11), Cd (0.43-1.00) and Zn (48-103.98). Statistical results indicate that metal concentrations were from natural origin attributed to leaching, weathering process and industrial sources. Comparative studies of metal concentrations with sediment quality guidelines and ecotoxicological values indicate that there is no adverse biological effect. Enrichment factor and geoaccumulation indices results indicate moderate enhancement of Fe (Igeo class 1 in FMB), Cd (EF>50; Igeo classes 2-4) and Zn (Igeo classes 1 & 2)., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We analyzed the total (Zn, Pb, Ni, Hg, Cr, Cd, Cu, As) and partially leachable metals (PLMs) in 25 ash and soil samples from recent (2012-2013) eruptions of the Popocatépetl Volcano in Central Mexico. More recent ash and soil samples from volcanic activity in 2012-2013 had higher metal concentrations than older samples from eruptions in 1997 suggesting that the naturally highly volatile and mobile metals leach into nearby fresh water sources. The higher proportions of As (74.72%), Zn (44.64%), Cu (42.50%), and Hg (32.86%) reflect not only their considerable mobility but also the fact that they are dissolved and accumulated quickly following an eruption. Comparison of our concentration patterns with sediment quality guidelines indicates that the Cu, Cd, Cr, Hg, Ni, and Pb concentrations are higher than permissible limits; this situation must be monitored closely as these concentrations may reach lethal levels in the future.

Concentrations of 11 trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, As, Hg) in 40 fish species from Santa Maria Bay, Baja California Sur, Mexico, the strategically important area for marine mammals and organisms were analyzed. Based on their concentrations the ranking of metals Fe>Zn>Ni>Cr>Mn>Pb>Cu>Co>As>Cd>Hg suggests that organism size, metabolism and feeding habits are correlated with metal concentrations. Local geological formations affect the concentrations of different metals in the aquatic environment and are subsequently transferred to fishes. The correlation analysis suggests that metabolism and nurturing habits impact the concentration of metals. Concentrations of Fe and Mn appear to be influenced by scavenging and absorption processes, which vary by species. The considerable variability in the metal concentrations obtained in different species underscores the importance of regular monitoring., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The study first illustrates a comprehensive account of large-scale changes in water quality characteristics and plankton community structure due to occurrence of Annual Gangasagar Festival (AGF) at Sagar Island, western part of Indian Sundarban megadelta for 3-year duration (2012-2014; n=36). About 1 million pilgrims across India converge to take their holy bath at the confluence of Hooghly estuary and Bay of Bengal during January each year. This mass scale bathing results negative impact on water quality due to high turbidity (14.02 ± 2.34 NTU) coupled with low chlorophyll a (1.02 ± 0.21 mg m(-3)) and dissolved oxygen (3.94 ± 1.1 mg l(-1)). A marked decrease in abundance (from 4140 to 2997 cells l(-1)) and diversity (H'=2.72-1.33) of phytoplankton and microzooplankton tintinnids (from 450 to 328 ind l(-1); H'=4.31-2.21) was recorded. The festival acts as multiple stressors modifying natural functions of the delta. Sound and sustainable management strategies are to be adopted to maintain the protection-usage equilibrium., (Copyright © 2015 Elsevier Ltd. All rights reserved.)