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.     

Heavy metals concentration in edible fishes from coastal region of Kalpakkam, southeastern part of India

Concentrations of Cu, Mn, Zn, Fe, Cr, and Pb were estimated using ICP-MS in nine commercially important and locally consumed fish species (Sarda orientalis, Scomberomorus commerson, Rastrelliger kanagurta, Sardinella longiceps, Paraplagusia bilineata, Cynoglossus lida, Cynoglossus macrostomus, Lepturacanthus savala, and Siganus javus) collected from coastal waters of Kalpakkam, eastern part of India. Their concentration (μg g(-1)) in the examined fish species ranged as follows: Cu (0.8-6.5), Zn (14.3-27.9), Mn (0.5-8.8), Fe (17.6-117.0), Cr (0.24-1.78), and Pb (0.18-2.29). Concentrations of most of the metals in the fish species studied were found to be safe for human consumption barring Mn.     

Eutrophication induced changes in benthic community structure of a flow-restricted tropical estuary (Cochin backwaters), India

The influence of anthropogenic loading on the distribution of soft bottom benthic organisms of a tropical estuary (Cochin backwaters) was examined. The industrial activities were found to be high in the northern and central part of the estuary, where dissolved inorganic nitrogen (DIN > 210 ??M) and phosphorus (DIP > 6.5 ??M) have caused high abundance of chlorophyll a (up to 73 mg m^???3) and accumulation of organic carbon in sediments (up to 5%). Principal component analysis distinguished three zones in the estuary. The central zone (Z1) was characterized by organic enrichment, low species diversity, and increased number of pollution tolerant species. Long-term deterioration of the estuary is indicated by an increase in the nutrients and chlorophyll a levels by sixfold during the last few decades. Flow restrictions in the lower estuary have lead to a fourfold increase in sediment organic carbon over the period of three decades. The reduced benthic diversity followed by an invasion of opportunistic polychaetes (Capitella capitata), are indicative of a stress in the estuary.     

Impact of eutrophication on the occurrence of Trichodesmium in the Cochin backwaters, the largest estuary along the west coast of India

Phytoplankton studies in early 1970s have shown the annual dominance of diatoms and a seasonal abundance of Trichodesmium in the lower reaches of the Cochin backwaters (CBW) and adjacent coastal Arabian Sea during the pre-summer monsoon period (February to May). Surprisingly, more recent literature shows a complete absence of Trichodesmium in the CBW after 1975 even though their seasonal occurrence in the adjacent coastal Arabian Sea continued without much change. In order to understand this important ecological feature, we analyzed the long-term water quality data (1965–2005) from the lower reaches of the CBW. The analyses have shown that salinity did not undergo any major change in the lower reaches over the years and values remained >30 throughout the period. In contrast, a tremendous increase was well marked in levels of nitrate (NO₃) and phosphate (PO₄) in the CBW after 1975 (av. 15 and 3.5 μM, respectively) compared with the period before (av. 2 and 0.9 μM, respectively). Monthly time series data collected in 2004–2005 period from the lower reaches of the CBW and coastal Arabian Sea have clearly shown that the physical characteristics like salinity, temperature, water column stability, and transparency in both regions are very similar during the pre-summer monsoon period. In contrast, the nutrient level in the CBW is several folds higher (NO₃, 8_; PO₄, 4; SiO₄, 10; and NH₄, 19 μM) than the adjacent coastal Arabian Sea (NO₃, 0.7; PO₄, 0.5; SiO₄, 0.9; and NH₄, 0.6 μM). The historic and fresh time series data evidences a close coupling between enriched levels of nutrients and the absence of Trichodesmium in the Cochin backwaters     

Analysis of mercury and other heavy metals accumulated in lichen Usnea antarctica from James Ross Island,Antarctica

The study was designed to investigate the content and distribution of selected heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Fe, Pb and Zn) in samples of fruticose macrolichen Usnea antarctica from James Ross Island. A special emphasis was devoted to mercury and its species (elemental mercury and methylmercury). It was found that mercury contents were relatively high (up to 2.73 mg kg^?1 dry weight) compared to other parts of the Antarctic Peninsula region, while the concentrations of most other elements were within reported ranges. Mercury contents in lichens originating from the interior were higher than those from the coast, which is probably the result of local microclimate conditions. Similar trends were observed for Hg⁰ and MeHg⁺, whose contents were up to 0.14 and 0.098 mg kg^?1 dry weight, respectively. While mercury did not show a significant correlation with any other element, the mutual correlation of some litophile elements probably refers to the influence on thalli of resuspended weathered material. The influence of habitat and environmental conditions could play an essential role in the bioaccumulation of contaminants rather than just the simple presence of sources. Thus, the study of the thalli of this species can bring a new perspective on the interpretation of contaminant accumulation in lichens of the polar region.     

Potential Vulnerability Implications of Sea Level Rise for the Coastal Zones of Cochin, Southwest Coast of India

This study presents the results of the impact assessment analysis of the coastal zones of Cochin along the southwest coast of India. The climatological cycle of sea level derived for the region for the period 1939–2003 has shown a range of about 17 cm. From the results obtained on the coastal sedimentary environments, it is found that climate-induced sea level rise scenarios will bring profound effects. It is also revealed that the mean beach slope and relief play a vital role in land loss of the region. The local relief of coastal zone will decrease as sea level rises, thus increasing the percentage of land above mean sea level subjected to episodic inundations. Results of the yearly probability of damages indicated the urgency to upgrade the existing designs of coastal protection structures. A brief characterisation of the issues on infrastructure and uncertainties in policy planning also are attempted.     

Biomonitoring of trace metal pollution using the bivalve molluscs, Villorita cyprinoides, from the Cochin backwaters

Trace metal concentrations in the muscle of the bivalve Villorita cyprinoides from the Cochin backwaters (southwest coast of India) were investigated during the monsoon, post-monsoon and pre-monsoon periods. The seasonal average ranges of metals (μg g^?1, dry weight) in the bivalve were as follows: Fe (18,532.44–28,267.05), Co (23.25–37.58), Ni (10.56–19.28), Cu (3.58–11.35), Zn (48.45–139.15), Cd (1.06–1.50) and Pb (3.05–4.35). The marginally elevated metal concentrations in bivalve muscles are probably related to high influx of metals as a result of pollution from the industries and agricultural fields with consequent increased bioavailability of metals to the bivalve. Evaluation of the risks to human health associated with consumption of the bivalves suggested that there is no health risk for moderate shellfish consumers. A regular and continuous biomonitoring program is recommended to establish V. cyprinoides as a bioindicator for assessing the effects of trace metal pollution and to identify future changes to conserve the “health” of this fragile ecosystem.     

Concentration of heavy metals in Karanja reservoir, Bidar district, Karnataka, India

In this study, some heavy metals concentrations (Zn, Pb, Fe, Mn, Cu, Ni) and other physico-chemical parameters were studied during October 2001 to September 2003 in Karanja reservoir, Bidar district. Water quality parameters were collected monthly basis whereas heavy metals were analyzed by Atomic Adsorption Spectrometer (AAS). Heavy metals have shown within the permissible limits, except Fe and Ni were recorded higher values in southwest monsoon, where as Mn has showed higher concentration in northeast monsoon in and summer. All other physico-chemical parameters are with in the permissible limit. Water is moderately hard and reservoir is productive.     

Diurnal variations in bacterial and viral production in Cochin estuary, India

Microbes play a central role in the decomposition and remineralization of organic matter and recycling of nutrients in aquatic environments. In this study, we examined the influence of physical, chemical, and biological parameters on the rate of bacterial production (BP) and viral production (VP) with respect to primary production over a diurnal period in Cochin estuary. Time series measurements were made every 2 h for 12 h (6 a.m.–6 p.m.) during periods of low and high salinities. The light intensity as photosynthetically active radiation, temperature, salinity, nutrients like NO₃–N, SiO₄–Si, and PO₄–P, and chlorophyll a (Chl a) were measured along with BP, VP, and net primary production (NPP). NPP showed a strong positive correlation with light and Chl a (r ²?=?0.56 and 0.47, respectively), while VP showed a strong positive correlation with light, salinity, and Chl a (r ²?=?0.37, 0.58, and 0.37, respectively) and a negative correlation with BP (r ²?=??0.39) at P?≤?0.05. We observed a diurnal pattern in BP but did not have any significant correlation with light. Similar diurnal pattern was seen in VP, the peak of which was in succession with BP, suggesting that virus-mediated lysis plays an important role in loss processes of bacteria in Cochin estuary. The results of our study highlight the light-dependent and physicochemical-dependent diurnal variation in virioplankton production in a tropical estuarine ecosystem.     

Enrichment and fractionation of heavy metals in bed sediments of River Narmada, India

A metal fractionation study on bed sediments of River Narmada in Central India has been carried out to examine the enrichment and partitioning of different metal species between five geochemical phases (exchangeable fraction, carbonate fraction, Fe/Mn oxide fraction, organic fraction and residual fraction). The river receives toxic substances through a large number of tributaries and drains flowing in the catchment of the river. The toxic substances of particular interest are heavy metals derived from urban runoff as well as municipal sewage and industrial effluents. Heavy metals entering the river get adsorbed onto the suspended sediments, which in due course of time settle down in the bottom of the river. In this study fractionation of metal ions has been carried out with the objective to determine the eco-toxic potential of metal ions. Although, in most cases (except iron) the average trace/heavy metal concentrations in sediments were higher than the standard shale values, the risk assessment code as applied to the present study reveals that only about 1–3% of manganese, <1% of copper, 16–19% of nickel, 4–20% of chromium, 1–4% of lead, 8–13% of cadmium and 1–3% of zinc exist in exchangeable fraction and therefore falls under low to medium risk category. According to the Geo-accumulation Index (GAI), cadmium shows high accumulation in the river sediments, rest of other metals are under unpolluted to moderately polluted class.     

Assessment of heavy metals in some wild edible mushrooms collected from Yunnan Province, China

Eight heavy metals (Cu, Zn, Fe, Mn, Cd, Cr, Ni, and Pb) in 14 different wild-growing edible mushroom species (Coprinus comatus, Voluariella volvacea, Pleurotus nebrodensis, Hypsizigus marmoreus, Hericium erinaceus, Agrocybe aegerita, Lenfinus edodes, Collybia velutipes, Agaricus bisporus, Russula albida, Clitocybe conglobata, Pleurotus eryngii, Lepista sordida, and Pleurotus ostreatus) collected from Yunnan province, China, were determined by inductively coupled plasma-atomic emission spectrometry after microwave digestion. All element concentrations were determined on a dry weight basis. The ranges of element concentrations for copper, zinc, iron, manganese, cadmium, chromium, nickel, and lead were 6.8-31.9, 42.9-94.3, 67.5-843, 13.5-113, 0.06-0.58, 10.7-42.7, 0.76-5.1, and 0.67-12.9 mg/kg, respectively. In general, iron content was higher than other metals in all mushroom species. The levels of zinc, cadmium, and lead in some edible mushroom samples were found to be higher than legal limits. The relative standard deviations were found below 10%. The accuracy of procedure was confirmed by certified reference material.     

Total and methyl mercury in the water,sediment, and fishes of Vembanad,a tropical backwater system in India

Mercury contamination in the water bodies of developing countries is a serious concern due to its toxicity, persistence, and bioaccumulation. Vembanad, a tropical backwater lake situated at the southwest coast of India, is the largest Ramsar site in southern India. The lake supports thousands of people directly and indirectly through its resources and ecosystem services. It is highly polluted with toxic pollutants such as heavy metals, as it receives effluent discharges from Kerala’s major industrial zone. In the present study, water, pore water, sediment, and fish samples collected from Vembanad Lake were analysed for total mercury (THg) and methyl mercury (MHg) contents. The maximum concentrations of THg and MHg in surface water samples were31.8 and 0.21 ng/L, respectively, and those in bottom water samples were 206 and 1.22 ng/L, respectively. Maximum concentration of THg in surface sediment was observed during monsoon season (2850 ng/g) followed by that in the pre-monsoon season (2730 ng/g) and the post-monsoon season (2140 ng/g). The highest sediment concentration of MHg (202.02 ng/g) was obtained during monsoon season. The spatial variation in the mercury contamination clearly indicates that the industrial discharge into the Periyar River is a major reason for pollution in the lake. The mercury pollution was found to be much higher in Vembanad Lake than in other wetlands in India. The bioaccumulation was high in carnivorous fishes, followed by benthic carnivores. The THg limit in fish for human consumption (0.5 mg/kg dry wt.) was exceeded for all fish species, except for Glossogobius guiris and Synaptura orientalis. The concentration of THg was five times higher in Megalops cyprinoides and four times higher in Gazza minuta. Significant variation was observed among species with different habits and habitats. Overall, risk assessment factors showed that the mercury levels in the edible fishes of Vembanad Lake can pose serious health impacts to the human population.     

Fractionation of heavy metals and phosphorus in suspended sediments of the Yamuna river,India

The Yamuna river is the largest tributary of the Ganges river system. It originates in the Himalayas and flows through a varied geological terrain encompassing a large basin area. Metals Fe, Mn, Pb, Zn, Cu in different chemical fractions of suspended sediments such as exchangeable, carbonates, Fe–Mn oxides, organics and residual fractions were studied. Phosphorus associated with different chemical forms are discussed. The metals are mostly associated with residual fractions in the sediments followed by organics, Fe–Mn oxides, exhangeable and carbonates. Intensive use of chemical fertilizers and pesticides in agriculture in the basin affects the high inorganic phosphorus content in sediments.     

Soil contamination of heavy metals in the Katedan Industrial Development Area, Hyderabad, India

Studies on quantitative soil contamination due to heavy metals were carried out in Katedan Industrial Development Area (KIDA), south of Hyderabad, Andhra Pradesh, India under the Indo-Norwegian Institutional Cooperation Programme. The study area falls under a semi-arid type of climate and consists of granites and pegmatite of igneous origin belonging to the Archaean age. There are about 300 industries dealing with dyeing, edible oil production, battery manufacturing, metal plating, chemicals, etc. Most of the industries discharge their untreated effluents either on open land or into ditches. Solid waste from industries is randomly dumped along roads and open grounds. Soil samples were collected throughout the industrial area and from downstream residential areas and were analysed by X-ray Fluorescence Spectrometer for fourteen trace metals and ten major oxides. The analytical data shows very high concentrations of lead, chromium, nickel, zinc, arsenic and cadmium through out the industrial area. The random dumping of hazardous waste in the industrial area could be the main cause of the soil contamination spreading by rainwater and wind. In the residential areas the local dumping is expected to be the main source as it is difficult to foresee that rain and wind can transport the contaminants from the industrial area. If emission to air by the smokestacks is significant, this may contribute to considerable spreading of contaminants like As, Cd and Pb throughout the area. A comparison of the results with the Canadian Soil Quality Guidelines (SQGL) show that most of the industrial area is heavily contaminated by As, Pb and Zn and local areas by Cr, Cu and Ni. The residential area is also contaminated by As and some small areas by Cr, Cu, Pb and Zn. The Cd contamination is detected over large area but it is not exceeding the SQGL value. Natural background values of As and Cr exceed the SQGL values and contribute significantly to the contamination in the residential area. However, the availability is considerably less than anthropogenic contaminants and must therefore be assessed differently. The pre- and post-monsoon sampling over two hydrological cycles in 2002 and 2003 indicate that the As, Cd and Pb contaminants are more mobile and may expect to reach the groundwater. The other contaminants seem to be much more stable. The contamination is especially serious in the industrial area as it is housing a large permanent residing population. The study not only aims at determining the natural background levels of trace elements as a guide for future pollution monitoring but also focuses on the pollution vulnerability of the watershed. A plan of action for remediation is recommended.     

Dynamics and quantification of dissolved heavy metals in the Mahanadi river estuarine system,India

Dynamics of heavy metals such as Fe, Mn, Zn, Cr, Cu, Co, Ni, Pb, and Cd in surface water of Mahanadi River estuarine systems were studied taking 31 different stations and three different seasons. This study demonstrates that the elemental concentrations are extremely variable and most of them are higher than the World river average. Among the heavy metals, iron is present at highest concentration while cadmium is at the least. The spatial pattern of heavy metals suggests that their anthropogenic sources are possibly from two major fertilizer plants and municipal sewage from three major towns as well as agricultural runoff. The temporal variations for metals like Fe, Cu, and Pb exhibit higher values during the monsoon season, which are related to agricultural runoff. Concentrations of Ni, Pb, and Cd exceed the maximum permissible limits of surface water quality in some polluted stations and pose health risks. Dissolved heavy metals like Fe, Mn, Cr, Ni, and Pb exhibit a non-conservative behavior during estuarine mixing, while Zn, Cu, and Co distribution is conservative. Distribution of cadmium in the estuarine region indicates some mobilization which may be due to desorption. The enrichment ratio data suggest that various industrial wastes and municipal wastes contribute most of the dissolved metals in the Mahanadi River. The Mahanadi River transports 18.216 × 10³ t of total heavy metals into the Bay of Bengal and the calculated rate of erosion in the basin is 128.645 kg km^− 2 year^− 1.     

Speciation of heavy metals in biosolids of wastewater treatment plants at Mysore,Karnataka, India

Urban wastewater treatment leads to the generation of large quantities of biosolids. Accumulation of biosolids is a problem of environmental relevance due to the existence of heavy metals in the biosolids. Determination of total metal in biosolid provides information relating pollution levels. Determination of their mobilization capacity and behaviour in the environment is an important task. An experimental approach commonly used for studying the mobility, transport and bioavailability of metal in biosolids is the use of selective sequential extraction procedure. In the present study an attempt has been made to study the heavy metal properties in biosolid samples collected from urban wastewater treatment plants located at Mysore, Karnataka. Few heavy metals selected for the present study are cadmium, chromium, copper, iron, nickel and zinc. The concentration of these metals in biosolids and their partition in different fractions are studied. The speciation of metals based on the sequential extraction scheme was carried out. The concentration of heavy metals is lower than that established by European legislation. The residual fraction has the maximum percentage of heavy metals whereas, only a small fraction of heavy metals (Fe, Zn and Cd) are extracted in the most soluble fractions, exchangeable and carbonate fractions.     

Total concentrations, fractionation and mobility of heavy metals in soils of urban area of Guwahati, India

This work describes the results of assessment of the heavy metals, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn in urban soil of Guwahati City, India from 31 sites of five different land use types covering residential, commercial, industrial, public utilities, and roadside. Sequential extraction procedure was used to evaluate the relative distribution of the eight metals in exchangeable, carbonate, reducible (Fe?CMn oxide), organic and sulfide, and residual fractions. Of the eight metals, Cd and Co occur in lower concentrations (Cd <?< Co) in all types of land, and concentration variation from one type of land use to another is not much significant for both the metals. Ni presence is more than Co, and the concentrations show some variation depending on land use status. Average Cr and Cu concentrations are ??100?mg/kg, but Cr has a significantly higher presence in industrial land use. The results are similar in case of Pb. The two metals, Mn and Zn have domination over the other metals, and the values are ??300?mg/kg. Industrial and roadside soil contains much more Mn, while commercial soil is most enriched with Zn. Of the metals, Ni has the largest proportion (~42%) bound to the exchangeable fraction and Co, Cr, and Pb also have appreciable proportion bound to the same fraction. A significant amount of Co is associated with carbonates. The reducible fraction has bound considerable quantity of Mn and Zn, while most of Cu is associated with the organic and sulfide fraction. Both Cd and Pb are dominantly associated with the residual fraction. Computation of the mobility factor of the metals indicates Mn to be the most mobile metal present in the soil samples.     

Distribution of heavy metals in surface water of Ranipet industrial area in Tamil Nadu, India

Ranipet industrial area is about 120 km from Chennai on Chennai-Bangalore highway and is a chronic polluted area identified by Central Pollution Control Board of India. It is one of the biggest exporting centers of tanned leather in India. The total number of industries located in and around Ranipet town are 240 tanneries along with ceramic, refractory, boiler auxiliaries plant, and chromium chemicals. Studies were carried out to find out the contamination of surface water bodies due to industrial effluents. The results reveal that the surface water in the area is highly contaminated showing very high concentrations of some of the heavy/toxic metals like Cadmium ranging from 0.2 to 401.4 μg/l (average of 51.1 μg/l), Chromium 2.4–1,308.6 (average of 247.2 μg/l), Copper 2.1–535.5 μg/l (average of 95.5 μg/l), Nickel 1.6–147.0 μg/l (average of 36.7 μg/l), Lead 6.4–2,034.4 μg/l (average of 467.8 μg/l) and Zinc 20.8–12,718.0 μg/l (average of 3,760.4 μg/l). The concentration levels of these metals are much above the permissible limits in surface water and are health hazards especially for the people working in the tannery industries. It was observed that the people in the area are seriously affected and suffering from occupational diseases such as asthma, chromium ulcers and skin diseases. Distribution of metals, their contents at different locations, and their effects on human health are discussed in this paper.     

Accumulation of heavy metals in Spinacia oleracea irrigated with paper mill effluent and sewage

The present study on heavy metal contamination in soil and their accumulation in edible part (leaves) and roots of Spinacia oleracea (Spinach) on irrigation with paper mill effluent (PME)/sewage revealed that there was significant increase in the nickel (Ni, +227.17 %) content of the soil irrigated with PME, whereas in the soil irrigated with sewage chromium (Cr, +274.84 %), iron (Fe, +149.56 %), and cadmium (Cd, +133.39 %), contents were increased appreciably. The value of enrichment factor (EF) for Ni (3.27) indicated moderate enrichment in PME-irrigated soil. The EF of Fe, zinc (Zn), Cd, and Cr were <2 in PME effluent-irrigated soil which showed deficiency of minimal enrichment. In sewage irrigated soil, EF value for Cr, Fe, and Cd indicated moderate enrichment, while the values for Zn and Ni indicated deficiency of minimal enrichment. Among various metallic concentrations, the maximum concentration of Fe was observed in leaves (400.12?±?11.47 mg/kg) and root (301.41?±?13.14 mg/kg) of S. oleracea after irrigation with PME, whereas the maximum concentrations of Fe was found in leaves (400.49?±?5.97 mg/kg) and root (363.94?±?11.37 mg/kg) of S. oleracea after irrigation with sewage for 60 days. The bioaccumulation factor value was found maximum for Cd (2.23) in the plants irrigated with PME while that of Fe (0.90) in the plants irrigated with sewage. The undiluted use of PME/sewage for irrigation increased the concentration of Cr, Cd, Zn, Ni, and Fe metals which were accumulated in S. oleracea, posing a potential threat to human health from this practice of irrigation.