Lead, cadmium, nickel, and zinc contamination of ground water around Hussain Sagar Lake, Hyderabad, India

A pair of cadmium-exposed zebrafish affect social behavior of the un-exposed majority

To account for global contamination events, we must identify direct and indirect pollutant effects. Although pollutants can have direct effects on individuals, it is unknown how a few contaminated individuals affect groups, a widespread social organization. We show environmentally relevant levels of cadmium (Cd) can have indirect social effects revealed in the social context of a larger group. Cd-contaminated individuals had poor vision and more aggressive responses, but no other behavioral effects. The presence of experienced Cd-exposed pairs in the groups had an indirect effect on the un-exposed individual's social interactions leading to the shoal becoming bolder and moving closer to a novel object than control groups. Because a few directly affected individuals could indirectly affect social behavior of the un-exposed majority, we believe that such acute but potentially important heavy metal toxicity could inform reliable predictions about the consequences of their use in a changing world.

Wastewater irrigation in India: Current status, impacts and response options

Wastewater generated from urban agglomerations in India is estimated to be 26.4 km³ annually and 28% of it is treated. This has a potential to irrigate about 2.1 million-ha agricultural land, contribute 4 million Mg of plant nutrients, generate 2.8 million person-days of employment and reduce green house gas (GHG) emission by 73.7 million Mg CO₂-e. Farmers in peri-urban areas depend largely on raw and partially treated wastewater for livelihood via raising high value crops such as vegetable, fodders and fruits. Both controlled and uncontrolled disposal of waste waters leads to progressive and irreversible contamination of soils, surface and ground waters with pathogens, heavy metals and organic micro-contaminants and consequently their bio-transfer through the chain: sewage-soil-vegetation-animal-humans. This has led to the development of a considerable assortment of regulatory measures and guidelines aimed at reducing or eliminating wastewater related health risks. Because conventional treatment technologies are cost prohibitive, alternate methods based on biological and land treatment systems are being advocated. Since soils are the most logical sinks for wastewater, efforts are to optimise rates and methods of water application, quantify the sink capacity of soils to immobilise contaminants and protect the quality of produce. Reuse of diluted or undiluted wastewaters improves crop productivity by 10-36% though production sustainability depends on soil type, climatic conditions, crop grown, irrigation techniques and socio-political factors. Disposal of wastewater in tree plantations and constructed wetlands with consequent removal of toxic metals/compounds using hyper-accumulators/accumulators plants provide for a possible alternative. Ignoring the associated risks, using pisciculture for sewage disposal is quite popular in high rainfall areas. With growing water scarcities, it is utmost important to recognise wastewaters as a valuable resource and formulate appropriate policy initiatives considering the health and livelihood issues of the per-urban farmers and consumers of food as well as risks to environment.

Heavy Metals in the Soils of Placer Small-Scale Gold Mining Sites in Myanmar

BACKGROUND

Artisanal and small-scale mining activities are widely practiced globally. Concentrations of heavy metals associated with gold, such as copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) can increase in the environment as a result of mining activities, leading to environmental pollution and pose toxicity risks to humans and animals.

OBJECTIVES

The aim of the present study was to investigate soil concentrations of toxic heavy metals in placer small-scale gold mining operations in Myanmar.

METHODS

Soil samples were collected from three placer small-scale gold mining sites: Site A located in the Hmawbon public protected forest, Site B and Site C, situated in the Nant-Kyin reserved forest around Nar Nant Htun village. At each site, soil samples were collected from four gold mining stages (ore processing, sluicing, panning, and amalgamation). Atomic absorption spectroscopy was utilized to examine the concentrations of As, Cd, Pb, and Hg.

RESULTS

The highest heavy metal concentrations were generally found in the amalgamation stages across all the gold mining sites. Across the three mining sites, the maximum heavy metal concentrations in the amalgamation stage were 22.170 mg.kg^-1 for As, 3.070 mg.kg^-1 for Cd, 77.440 mg.kg^-1 for Hg, and 210.000 mg.kg^-1 for Pb.

CONCLUSIONS

The present study examined the concentrations of As, Cd, Hg and Pb in the soil of several small-scale gold mining sites in Banmauk Township, Myanmar. The results demonstrated the presence of high concentrations of heavy metals in the soil of the gold mining sites. Miners in this area work without proper personal protective equipment, and frequent exposure to heavy metals in the soil may cause adverse health effects. The present study provides baseline data for future risk assessment studies of heavy metal contamination in gold mines.

COMPETING INTERESTS

The authors declare no competing financial interests.

Heavy metal assessment in surface sediments off Coromandel Coast of India: Implication on marine pollution

The present study investigates the distribution of heavy metals (Fe, Cd, Co, Cr, Cu, Ni, Zn and Pb) in the surface sediments along the Coromandel Coast of Bay of Bengal as an indicator of marine pollution. Pollution indices such as Contamination factor (CF), Enrichment factor (EF) and Geo-accumulation index (I) were performed to assess the spatial distribution and pollution status of the study area. The heavy metal concentration in the study area is closely associated with grain size and organic matter. Both geoaccumulation index and metal contamination factor indicate that the sediments are free from contamination with regards to the metals Cr and Ni, followed by uncontamination to moderate contamination of Co, Cu and Zn. However, sediments are found to be extremely polluted with respect to Cd and Pb. Factor analysis reveals that the accumulation of these heavy metals in the shelf sediments are due to anthropogenic inputs from the adjacent land area.

A scientometric examination of the water quality research in India

Water quality has emerged as a fast-developing research area. Regular assessment of research activity is necessary for the successful R&D promotion. Water quality research work carried out in different countries increased over the years, and the USA ranked first in productivity while India stands in the seventh position in quantity and occupies the ninth position in quality of the research output. India observes a steady growth in the water quality research. Four thousand six hundred sixteen articles from India assessed from the aspect of citations received distributions of source countries, institutes, journals, impact factor, words in the title, author keywords. The qualitative and quantitative analysis identifies the contributions of the major institutions involved in research. Much of the country's water quality research is carried out by universities, public research institutions and science councils, whereas the contribution from Ministry of water resources not so significant. A considerable portion of Indian research is communicated through foreign journals, and the most active one is Environmental Monitoring and Assessment journal. Twenty-one percent of work is reported in journals published from India and around 7% ages in open access journals. The study highlights that international collaborative research resulted in high-quality papers. The authors meticulously analyse the published research works to gain a deeper understanding of focus areas through word cluster analyses on title words and keywords. When many papers deal with 'contamination', 'assessment' and 'treatment', enough studies done on 'water quality index', 'toxicity', considerable work is carried out in environmental, agricultural, industrial and health problems related to water quality. This detailed scientometric study from 1,09,766 research works from SCI-E during 1986-2015 plots the trends and identifies research hotspots for the benefit to scientists in the subject area. This study comprehends the magnitude of water quality research also establishes future research directions using various scientometric indicators.

Cadmium-induced oxidative stress tolerance in cadmium resistant Aspergillus foetidus: its possible role in cadmium bioremediation

Toxic effects of cadmium (Cd) were examined on a cadmium-resistant strain of Aspergillus foetidus isolated from wastewater. The Cd removal potential was analyzed. The results indicated that the strain could tolerate up to 25 mM and 63 mM Cd in liquid and solid Czapek-Dox media, respectively. It efficiently removed Cd from liquid growth media and industrial wastewater by mycelial biosorption. The strain produced oxalic acid for the purpose of Cd bioleaching as confirmed by the presence of cadmium oxalate crystals on the mycelial surface. Intracellular proline contents and the antioxidative enzyme activities increased up to a certain level to detoxify the overproduced free radicals. These data indicate that the strain has inherent mechanisms to grow in Cd contaminated environment, tolerate high Cd doses and high Cd uptake potential which are pre-requisite for acting as a suitable candidate for Cd bioremediation.

Seasonal variations of lead, arsenic, cadmium and aluminium contamination of groundwater in Dhemaji district, Assam, India

Seasonal variations in the concentrations of groundwater with respect to arsenic, lead, cadmium and aluminium has been studied in Dhemaji district of Assam, India. The water samples were collected from 20 different sites in both dry and wet seasons. The metals were analysed by using atomic absorption spectrometer, Perkin Elmer AAnalyst 200 model. The concentrations of aluminium, lead and cadmium in groundwater were found to be significantly elevated. High concentrations of all the metals were recorded in the dry season than in the wet season. Univariate statistics along with skewness, kurtosis and confidence limit have been calculated for both the seasons to test the distribution normality for each metal. Statistical analyses of the data reveal non-uniform distribution of the metals in the area. The metal contamination of groundwater in the district follows the trend Al>Pb>Cd>As in both the seasons.

Ecotoxicological effects of aluminum and zinc on growth and antioxidants in Lemna minor L

The present study aimed at investigating effects of zinc and aluminum (0.15 and 0.3mM) in duckweed (Lemna minor L.) over a 15-day period. High bioaccumulation of both metals was accompanied by an increase in dry weight under higher metal treatments. Antioxidant response was observed under both metal stresses, with large increases in superoxide dismutase and peroxidases. Catalase activity declined only in duckweed exposed to Zn while lipid peroxidation as well as H(2)O(2), proline and ascorbate levels increased. The results suggest induction of oxidative stress under both aluminum and zinc toxicity, and also demonstrate duckweed's capacity to upregulate its antioxidative defense. Additionally, Zn was found to be more toxic than Al to duckweed for the concentrations applied. Due to its high bioaccumulation potential and tolerance via increased antioxidant capacity, duckweed has a potential for phytoremediation of water bodies polluted by low levels of zinc and aluminum.

The contamination with organochlorine pesticides and heavy metals in surface water in Küçük Menderes River in Turkey, 2000-2002

This study was conducted from 2000 to 2002 to determine the residues of organochlorine pesticides (OCP) and metals in surface water of Küçük Menderes River in Turkey. The results showed that Küçük Menderes River was still polluted with organochlorine pesticide despite the existence of bans over a long time. The concentrations of pesticides depended on the sampling season and the tendency was not the same for all detected pesticides. The DDTs (DDT, DDD, DDE) were detected in most water samples. DDD showed a high concentration among DDTs. The highest concentration among organochlorine pesticides was heptachlor epoxide by 281 ng/l. However, the residues were lower than most polluted water from other sources in the world. In most cases, they were not detectable. The studied surface water metals varied from not detected to 0.258 mg/l, and the residues were low except for Ni, Cu, and Zn.

Organochlorine and heavy metal residues in the water/sediment system of the Southeast Regional Park in Madrid, Spain

A study into levels of contamination by organochlorine compounds (insecticides and PCBs) and heavy metals (Cd and Pb) in the water/sediment system of the Southeast Regional Park (SERP) in Madrid, Spain, has been carried out. Residue levels of xenobiotics were determined in surface and underground waters and sediments from selected sites throughout the protected area. The results showed these contaminants to be widespread throughout the studied area. p,p'-DDT concentration levels were consistently higher than its metabolite p,p'-DDE, indicating a recent use of this organochlorine insecticide in the area. PCB levels exceeded, in the majority of the cases, the levels taken as the maximum (100 ng/microl) for highly polluted waters. Cd and Pb levels found in water samples were under the detection limits of the methodology used. Pb levels found in sediment samples were higher than Cd.

Drinking water contaminants (arsenic, cadmium, lead, benzene, and trichloroethylene). 1. Interaction of contaminants with nutritional status on general performance and immune function in broiler chickens

The objective of this study was to examine possible interactions between drinking water contaminants and suboptimal nutritional status for performance and immune function in male broiler chickens. Experimental drinking water contained a mixture of arsenic, benzene, cadmium, lead, and trichloroethylene (TCE) at low concentrations (0.80, 1.3, 5.0, 6.7, and 0.65 ppm) and high concentrations (8.6, 13, 50, 67, and 6.5 ppm). These chemicals were selected because they are among the most common contaminants found in ground water near hazardous waste sites. The experimental diets included feed containing 50% added vitamins and minerals (V&M) and feed without added V&M. Increasing levels of drinking water contaminants and decreasing levels of V&M in diet resulted in significantly (P < or = 0.05) decreased water and feed intake, decreased weight gain, and suppression of natural, humoral, and cell-mediated immune response. In a paired-water study, feed consumption, body weight, and immune function were decreased in chickens provided low and high concentrations of the chemical mixture in drinking water compared with chickens given control drinking water equal to the volumes consumed by the chickens given the low and high concentration of mixture, respectively. A deficiency of dietary V&M caused increased sensitivity to adverse effects of drinking water contaminants.