Distribution of mercury and other trace metals in the sediments of Cochin estuary (a Ramsar site), Kerala, India

Sediment quality data provide essential information for evaluating ambient environmental quality conditions. Sediments are important carriers of trace metals in the environment and reflect the current quality of the system. In the present study, distribution of mercury, lead, cadmium, copper, zinc, chromium and manganese in Cochin estuary were studied. The distribution of oxides of metals and textural quality were also studied in detail. It was found that the concentration of metals in the sediments near the industrial belt was extremely high. Correlation of different metals and metal oxides were analysed. It was found that all the alloys were correlated significantly (α?<?0.01) but in case of metals, correlation was only among certain metals.     

Statistical apportionment and risk assessment of selected metals in sediments from Rawal Lake (Pakistan)

The present study was carried out in order to evaluate the statistical apportionment and risk assessment of selected metals (Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, Sr, and Zn) in freshly deposited sediments in Rawal Lake, Pakistan. Composite sediment samples were collected, oven-dried, grounded, homogenized, and processed to assess the water-soluble and acid extractable concentrations of the metals in the water extract and acid extract of the sediments using flame atomic absorption spectrophotometer. Statistical methods were used to identify the possible sources of the metals. Sediment quality guidelines and potential acute toxicity were used to evaluate the ecotoxicological sense of selected metals. Non-carcinogenic health risk assessment was also carried out to determine the potential adverse health risks to the inhabitants. Relatively higher concentration was noted for Ca, Fe, Mg, Na, K, Mn, and Sr in the sediment samples. Principal component analysis and cluster analysis revealed anthropogenic contributions of Cd, Pb, Cr, Mn, Fe, and Li in the sediments. Enrichment factors of the metals in sediments showed severe to moderate enrichment of Cd, Pb, Ca, Fe, Li, Mn, and Sr. Geoaccumulation indices and contamination factors evidenced significant contamination by Cd and Pb, although, on the whole, low degree of contamination was noted. The levels of some metals exceeded the sediment quality guidelines, which revealed frequently adverse biological effects to the dwelling biota in the aquatic ecosystem. The sediments were found to be significantly contaminated by Cd, Pb, Cr, Mn, Fe, and Li.     

Assessment of water quality parameters of the Harike wetland in India, a Ramsar site, using IRS LISS IV satellite data

This study aims at the classification and water quality assessment of Harike wetland (Ramsar site) in India using satellite images from the Indian Remote Sensing satellite, Resourcesat (IRS P6). The Harike wetland is a converging zone of two rivers, Beas and Sutlej. The satellite images of IRS Linear Imaging Self Scanner (LISS) IV multispectral sensor with three bands (green, red, and near infrared (NIR)) and a spatial resolution of 5.8 m were classified using supervised image classification techniques. Field points for image classification and water sampling were recorded using a Garmin eTrex Global Positioning System. The water quality parameters assessed were dissolved oxygen, conductivity, pH, turbidity, total and suspended solids (SS), chemical oxygen demand, and Secchi disk transparency (SDT). Correlations were established between turbidity and SS, SS and SDT, and total solids and turbidity. Using reflectance values from the green, red, and NIR bands, we then plotted the water quality parameters with the mean digital number values from the satellite imagery. The NIR band correlated significantly with the water quality parameters, whereas, using SDT values, it was observed that the green and the red reflectance bands were able to distinguish the waters from the two rivers, which have different water qualities.     

Study of seasonal variations and health risk assessment of heavy metals in Cyprinus carpio from Rawal Lake,Pakistan

This study was carried out to find out the comparative distribution of heavy metals (Fe, Cu, Mn, Zn, Co, Cr, Cd and Pb) in various tissues (muscles, gills, liver, stomach and intestine) of Cyprinus carpio from Rawal Lake, Pakistan, during summer and winter. Relatively higher concentrations of Cd, Co, Cr, Cu, Fe and Zn were found in the stomach samples, while the highest Pb and Zn levels were noted in muscle and intestine samples, respectively. Correlation study exhibited diverse relationships among the metals in various tissues. Generally, the metal concentrations found during the summer were comparatively higher than the winter. Potential non-carcinogenic and carcinogenic health risks related to the metals in C. carpio were evaluated using the US Environmental Protection Agency approved cancer risk assessment guidelines. The calculated daily and weekly intakes of Pb, Cd, Cr and Co through the fish consumption were significantly higher than the permissible limits. In relation to the non-carcinogenic risks to human, Pb, Cd, Cr, Co and Zn levels were higher than the safe limits; however, carcinogenic risks related to Cr (3.9?×?10^?3 during summer and 1.1?×?10^?3 during winter) and Pb (2.6?×?10^?4 during summer and 1.5?×?10^-4 during winter) clearly exceeded the safe limit (1?×?10^?6). Consequently, the consumption of C. carpio from Rawal Lake on regular basis was considered unsafe.     

Sorbed metals fractionation and risk assessment of release in river sediment and particulate matter

Fractionation of metals in natural sediment and suspended particulate matter (SPM) of Tadjan River is investigated. Competitive sorption, sorption capacities of sediment and SPM as well as fractionation of metal-loaded sediment and SPM are also examined. A risk assessment code (RAC) is applied to estimate the risk of heavy metals release into the environment during the sorption process. Results revealed that sediments and SPM containing more than 25 % of clay minerals and higher amounts of calcite have great capacity of metal sorption, particularly for Cu, Ni, and Mn. Assessing the risk of metals release prior to and following sorption tests indicates that RAC of metals would significantly increase from the level of no or low risk in natural sediment and SPM to high or very high risk after sorption. The Langmuir model reveals that the highest affinity for Cu, Mn, and Ni in sediment is the organic fraction. The classic isotherm models of Freundlich and Langmuir can fit the data from chemical extraction studies of adsorbed metals, indicating that although sorption was apparently a physical and chemical process in the river, isotherm models can be used to simulate the sorption and accumulation in different geochemical phases within the particulate matter.     

Groundwater arsenic contamination in Brahmaputra river basin: a water quality assessment in Golaghat (Assam), India

Distribution of arsenic (As) and its compound and related toxicology are serious concerns nowadays. Millions of individuals worldwide are suffering from arsenic toxic effect due to drinking of As-contaminated groundwater. The Bengal delta plain, which is formed by the Ganga?CPadma?CMeghna?CBrahmaputra river basin, covering several districts of West Bengal, India, and Bangladesh is considered as the worst As-affected alluvial basin. The present study was carried out to examine As contamination in the state of Assam, an adjoining region of the West Bengal and Bangladesh borders. Two hundred twenty-two groundwater samples were collected from shallow and deep tubewells of six blocks of Golaghat district (Assam). Along with total As, examination of concentration levels of other key parameters, viz., Fe, Mn, Ca, Na, K, and Mg with pH, total hardness, and SO $_{4}^{2-}$ , was also carried out. In respect to the permissible limit formulated by the World Health Organization (WHO; As 0.01 ppm, Fe 1.0 ppm, and Mn 0.3 ppm for potable water), the present study showed that out of the 222 groundwater samples, 67%, 76.4%, and 28.5% were found contaminated with higher metal contents (for total As, Fe, and Mn, respectively). The most badly affected area was the Gamariguri block, where 100% of the samples had As and Fe concentrations above the WHO drinking water guideline values. In this block, the highest As and Fe concentrations were recorded 0.128 and 5.9 ppm, respectively. Tubewell water of depth 180 ± 10 ft found to be more contaminated by As and Fe with 78% and 83% of the samples were tainted with higher concentration of such toxic metals, respectively. A strong significant correlation was observed between As and Fe (0.697 at p < 0.01), suggesting a possible reductive dissolution of As?CFe-bearing minerals for the mobilization of As in the groundwater of the region.     

Metal concentrations in water, sediment, and fish from sewage-fed aquaculture ponds of Kolkata, India

The concentrations of lead, cadmium, chromium, copper, and zinc were investigated in the sewage-fed pond water, sediment, and the various organs of Labeo rohita, Catla catla, Cirrhinus mrigala, Oreochromis mossambicus, and Cyprinus carpio cultured in sewage-fed ponds, Kolkata, India. Among the metals, cadmium, lead, and zinc were detected in water and, except lead, were below the water quality guideline levels for the protection of freshwater aquatic life proposed by CEQG (Canadian Environmental Quality Guidelines) and AENV (Alberta Environment). Therefore, lead could pose danger to aquatic organisms. All the five metals were detected in the sediment and, except cadmium and lead, were below the sediment quality guideline levels for aquatic life proposed by EPA (Environmental Protection Agency). Therefore, these two metals could be toxic to aquatic organisms. Significant (P > 0.05) differences were observed among the five fish species for all these metals accumulation. Also, significant (P > 0.05) differences were noticed among these metals accumulation in fish organs. Cadmium showed the least bioaccumulation, while zinc showed the highest bioaccumulation in all the fish species. Though the metal concentration in the different fish tissues was variable, the highest concentration was found in kidney and the lowest in the muscle. Concentrations of these metals in the muscle tissue of all the fish species were well below the consumption safety tolerance in fish set by WHO/FAO, and thus, so far as these metals are concerned, these sewage-fed cultured fishes are safe and suitable for human consumption.     

Spatial and temporal variability of metals in inter-tidal beach sediment of Mumbai, India

Nine metals were monitored in the beach sediment in Mumbai from May 2011 to March 2012 to evaluate the spatial and temporal distributions. The average heavy metal concentrations exhibited the following order: Fe > Mn > Cr > Co > Ni > Pb > Zn > Cu > Cd for the four sampling sites. The mean concentrations (± SD) of Fe, Mn, Cr, Co, Ni, Pb, Zn, Cu and Cd were estimated to be 31.15?±?10.02 g kg^?1, 535.04?±?76.42, 151.98?±?97.90, 92.76?±?14.18, 67.52?±?11.32, 59.57?±?15.19, 54.65?±?15.01, 32.24?±?8.07 and 18.75?±?1.76 mg kg^?1, respectively. The results indicated that the sediments were polluted with Cd, Cr, Co and Pb due to high anthropogenic influences. Spatial variation of metals revealed that most of the metals were high in Dadar beach and low in Aksa beach. Cd was the highest contaminant metal studied with a mean contamination factor of 93.75. The pollution load indices of the studied beaches ranged from 1.63 (Aksa) to 1.91 (Dadar) and indicated that the beach sediments were polluted with heavy metals. The heavy metal contents increased in relation to monsoon, and most of the heavy metals showed significantly high concentrations in November during the post-monsoon. The statistical analysis revealed significant effect of study site on all the metals studied. Further, there was a significant difference on metal accumulation on bimonthly basis in relation to weather pattern in Mumbai beaches.     

Persistent organic pollutants in sediment from the southern Baltic: risk assessment

The concentrations of organochlorine pesticides, PCBs, and PCDD/Fs were measured in sediment samples collected from the Gulf of Gdańsk, the Gdańsk Deep, the Vistula Lagoon and the off-shore waters in the southern Baltic Sea. The determinations were conducted in the fraction <63 μm. The highest levels of pollutants were found in sediments from the Gulf of Gdańsk and the Gdańsk Deep. In these sediments, concentrations of pp'-DDT and its metabolites (pp'-DDE and pp'-DDD) ranged from 2 to 11 μg kg(-1) dw. Concentrations of HCB were between 0.1 and 1.0 μg kg(-1) dw. Concentrations of the sum of α-, β-, γ-HCH were between 0.3 and 2.58 μg kg(-1) dw. Concentrations of marker PCBs ranged from about 2 to 11 μg kg(-1) dry weight. Total TEQ PCDD/F/dl-PCB values in the studied samples varied between 1 and 18 ng kg(-1) dw. The data were evaluated in terms of ecotoxicological criteria based on the environmental impact of the pollutant effects. Our research indicated that in the sediment from the southern Baltic Sea, the PCDD/F and PCBs occurred at concentrations which could be dangerous to marine organisms.     

Fraction distribution and risk assessment of heavy metals and trace elements in sediments of Lake Uluabat

To examine the status and risk of heavy metal pollution, the distribution of As, Cd, Cr, Ni, and Pb in the sediment of Lake Uluabat was characterized. The present study used a four-stage method to assess the ecotoxicological effects of the heavy metal and trace elements fractions in the sediment of Lake Uluabat. Total Cr and Ni concentrations in the sediment were determined to have exceeded the severe effect level (SEL) limit values. The percentages of the variable fractions of Cr and Ni were below 10%. Because of this reason, they were not defined to have a high risk. The relationships among the physicochemical parameters, heavy metals and trace elements in water and sediment were determined statistically. Pb, Cd, and As in the water were found in relation with some of the fractions. Moreover, it was thought that the amounts of the elements of As releasing into the water might be increased due to their relations with the physicochemical parameters.     

Bioaccumulation of selected metals in bivalves (Unionidae) and Phragmites australis inhabiting a municipal water reservoir

Urbanization can considerably affect water reservoirs by, inter alia, input, and accumulation of contaminants including metals. Located in the course of River Cybina, Maltański Reservoir (Western Poland) is an artificial shallow water body built for recreation and sport purposes which undergoes restoration treatment (drainage) every 4 years. In the present study, we demonstrate an accumulation of nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in water, sediment, three bivalve species (Anodonta anatina, Anodonta cygnea, Unio tumidus), and macrophyte Phragmites australis collected before complete drainage in November 2012. The mean concentrations of metals in the sediment, bivalves, and P. australis (roots and leaves) decreased in the following order: Fe > Mn > Zn > Cu > Cr > Ni > Pb > Co > Cd. A considerably higher bioconcentration of metals was observed in samples collected from the western and southern sites which undergo a higher degree of human impact. Sediments were found to be a better indicator of metal contamination than water samples. Interspecific differences in levels of metal accumulation were found between investigated unionids. U. tumidus accumulated higher levels of Cr, positively correlated with ambient concentrations, predisposing this species as a potential bioindicator of this metal in aquatic environments. On the other hand, species of Anodonta genus demonstrated higher accumulation of Cu and Cd. Positive correlations were found between Pb content in the sediments and tissues of all three bivalve species. In P. australis, metals were largely retained in roots except for Cd and Pb for which higher concentrations were found in leaves suggesting additional absorption of these metals from aerial sources. P. australis and bivalve from the Maltański Reservoir may be a potential source of toxic metals for animals feeding upon them and contribute to further contamination in the food chain.     

Characterization of heavy metals in water and sediments in Taihu Lake, China

To explore a comprehensive status of heavy metals in the Taihu Lake, which is one of the most important waters in China, water and sediment samples were taken throughout the lake during April to May of 2010, and metal elements (Cu, Cd, Cr, Ni, Pb, Sn, Sb, Zn, Mn) were analyzed in the water column, interstitial water and sediment. Relevant standards were used to assess the sediment and water quality. Results show that, in the lake water column, the average concentration of all metals ranged from 0.047 μg/l (Cd) to 8.778 μg/l (Zn). The concentration in the river water was usually higher than in the lake water for many metals. In the interstitial water Mn was significantly higher than that in water column, and other metals had no significant difference between the two media. In the surface sediment, average metal content ranged from 1.325 mg/kg (Cd) to 798.2 mg/kg (Mn). Spatially, contents of many metals were higher in Zhushan Bay than in other lake areas, and there existed a clear content gradient from the river to the lake for both water and sediment. On the sediment profiles, many metals presented an increasing trend from the depth of 15-20 cm to the top, which is indicative of the impact of increasingly intensive human activities from that period. Quality assessment indicates that metals in water phase are generally safe compared with USEPA "National Recommended Water Quality Criteria," with the exception of Mn in the interstitial water and Sb in the river water. Whereas the sediment is widely contaminated with metals to some extent compared with the "Consensus-Based Sediment Quality Guidelines," and Cu, Cr, and Ni are more likely to raise ecological risks. This work could be a basis for the ongoing China's criteria strategy.     

Heavy metals in water,periphytonic algae,detritus, and insects from two streams in Shillong,Notheastern India

Cadmium, copper, manganese, lead and zinc concentrations were determined in water, periphytonic algae, detritus, and larvae of three aquatic insects, viz. Baetis sp. (Ephemeroptera: Baetidae), Hydropsyche sp. (Trichoptera: Hydropsychiidae), and Chironomus ramosus Choudhury and Das (Diptera: Chironomidae), during two surveys from an unpolluted and a polluted stream in Shillong, Meghalaya State, Northeastern India. Metal concentrations were higher in all the samples from the polluted stream, possibly reflecting the contributions from various non-point sources of metal contamination present in its catchment. Among the three insects, Baetis sp. was found to accumulate cadmium, copper, and zinc, and Hydropsyche sp. manganese, to concentrations significantly higher than those found in the other taxa. The concentrations of all the metals were higher in fine detritus than in C. ramosus, although Cd and Zn concentrations were elevated in Baetis as compared to those in periphytonic algae and fine detritus, indicating possible bioconcentration of these metals by this animal.     

Bioaccumulation and translocation of metals in the natural vegetation growing on fly ash lagoons: a field study from Santaldih thermal power plant, West Bengal, India

A field study was conducted in the fly ash lagoons of Santandih Thermal Power Plant located in West Bengal (India) to find out total, EDTA and DTPA extractable metals in fly ash and their bioaccumulation in root and shoot portion of the naturally growing vegetation. Fly ash sample has alkaline pH and low conductivity. The concentration of total Cu, Zn, Pb and Ni were found higher than weathered fly ash and natural soil, where as Co, Cd and Cr were found traces. Five dominant vegetation namely, Typha latifolia, Fimbristylis dichotoma, Amaranthus defluxes, Saccharum spontaenum and Cynodon dactylon were collected in the winter months (November–December). Bioaccumulation of metals in root and shoot portions were found varied significantly among the species, but all concentration were found within toxic limits. Correlation between total, DTPA and EDTA extractable metals viz. root and shoot metals concentration were studied. Translocation factor (TF) for Cu, Zn and Ni were found less than unity, indicates that these metals are immobilized in the root part of the plants. Metals like Mn have TF greater than unity. The study infers that natural vegetation removed Mn by phytoextraction mechanisms (TF > 1), while other metals like Zn, Cu, Pb and Ni were removed by rhizofiltration mechanisms (TF < 1). The field study revealed that T. latifolia and S. spontaenum plants could be used for bioremediation of fly ash lagoon.     

Heavy metals in two fish species (Carangoidel malabaricus and Belone stronglurus) from Pulicat Lake, North of Chennai, Southeast Coast of India

We present the results from a detailed study based on five metals (Cr, Cd, Zn, Pb and Fe) measured in four organs (gills, liver, intestine and muscle) of two fish species (Carangoidel malabaricus and Belone stronglurus) from Pulicat Lake in southeast coast of India. The results show marked differences between the two species and organs as well as significant variations within the five analyzed metals. Although the metal concentrations measured in fish muscle are low, high levels of Pb and Fe were observed in the liver and gills of the two fish species. The concentrations of heavy metals in edible parts (muscle) of fish were within the permissible levels and are safe for the human consumption.     

Distribution of heavy metals in sediment and water of river Gomti

Gomti river receives industrial as well as domestic wastes from various drains of Lucknow city. In the process the water and sediment of the river Gomti get contaminated with heavy metals and other pollutants. In the present study, impacts of domestic/industrial wastes on the water and sediment chemistry of river Gomti with special reference to heavy metals have been investigated in different seasons (summer, winter and rainy). For this, seven sampling sites: Gaughat, Mohan Meakin, Martyrs Memorial, Hanuman Setu, Nishatganj bridge, Pipraghat and Malhaur, in the river Gomti in Lucknow region were identified and samples of water and sediments were collected in all the three seasons. In the collected water and sediment samples, six metals (Cd, Cr, Cu, Ni, Pb, and Zn) were analyzed on ICP-AES (Inductively coupled plasma emission spectroscopy) Labtam Plasmalab 8440. High concentrations of all the metals were noticed in water and sediment in rainy season compared to summer and winter. Because in rainy season runoff from open contaminated sites, agricultural field and industries, directly comes into the river without any treatment. In both the cases, the concentration of zinc was maximum (0.091 g/ml in water and 182.13 g/g in sediment) and the concentration of cadmium (0.001 g/ml in water and 17.26 g/g in sediment) was minimum. Higher concentration of metal in water and sediment during rainy season could be due to the industrial/agricultural/domestic runoff coming into the river.