The effects of municipal wastewater irrigation on the accumulation of heavy metals (Pb, Zn, Cd, Cr, Cu and Ni) in soil and vegetables were investigated by monitoring wastewater-irrigated agricultural field of Titagarh, 24-Parganas (North), West Bengal, India. The mean concentrations of Pb, Ni, Cu in the irrigation water and the mean Cd content in soil were much above the recommended level. The concentrations of Pb, Zn, Cd, Cr and Ni in all the examined vegetables were beyond the safe limits. The study reveals that heavy metal-contaminated vegetables grown in wastewater-irrigated areas may pose public health hazards.

Ganga-Meghna-Bramhaputra basin is one of the major arsenic-contaminated hotspot in the world. To assess the level of severity of arsenic contamination, concentrations of arsenic in irrigation water, soil, rice, wheat, common vegetables, and pulses, intensively cultivated and consumed by the people of highly arsenic affected Nadia district, West Bengal, India, were investigated. Results revealed that the arsenic-contaminated irrigation water (0.318-0.643 mg l -1 ) and soil (5.70-9.71 mg kg -1 ) considerably influenced in the accumulation of arsenic in rice, pulses, and vegetables in the study area. Arsenic concentrations of irrigation water samples were many folds higher than the WHO recommended permissible limit for drinking water (0.01 mg l -1 ) and FAO permissible limit for irrigation water (0.10 mg l -1 ). But, the levels of arsenic in soil were lower than the reported global average of 10.0 mg kg -1 and was much below the EU recommended maximum acceptable limit for agricultural soil (20.0 mg kg -1 ). The total arsenic concentrations in the studied samples ranged from <0.0003 to 1.02 mg kg -1 . The highest and lowest mean arsenic concentrations (milligrams per kilogram) were found in potato (0.654) and in turmeric (0.003), respectively. Higher mean arsenic concentrations (milligrams per kilogram) were observed in Boro rice grain (0.451), arum (0.407), amaranth (0.372), radish (0.344), Aman rice grain (0.334), lady's finger (0.301), cauliflower (0.293), and Brinjal (0.279). Apart from a few potato samples, arsenic concentrations in the studied crop samples, including rice grain samples were found not to exceed the food hygiene concentration limit (1.0 mg kg -1 ). Thus, the present study reveals that rice, wheat, vegetables, and pulses grown in the study area are safe for consumption, for now. But, the arsenic accumulation in the crops should be monitored periodically as the level of arsenic toxicity in the study area is increasing day by day.

No abstract

No abstract

In the present study, the magnitude of contamination of vegetables with heavy metals (Pb, Zn, Cd, Cr, Cu and Zn) was determined in a long-term wastewater-irrigated agricultural land. Heavy metal concentrations in vegetables were several folds higher in wastewater-irrigated site compared to clean water-irrigated area. The wastewater-irrigated crops analysed in this study are heavily contaminated with heavy metals. Concentrations of Pb, Zn, Cd and Cr in all the sewage-fed vegetables were beyond the safe limit of FAO/WHO and Indian standard. Contamination is at its highest level in radish and spinach. Daily intake values of Pb, Cd and Ni through consumption of sewage-fed vegetables exceeded the recommended oral dose of metal for both adult and children. The study concludes that wastewater irrigation led to accumulation of heavy metals in vegetables causing potential health risk to consumers.

The presence of arsenic in irrigation water and in paddy field soil were investigated to assess the accumulation of arsenic and its distribution in the various parts (root, straw, husk, and grain) of rice plant from an arsenic effected area of West Bengal. Results showed that the level of arsenic in irrigation water (0.05-0.70 mg l -1 ) was much above the WHO recommended arsenic limit of 0.01 mg l -1 for drinking water. The paddy soil gets contaminated from the irrigation water and thus enhancing the bioaccumulation of arsenic in rice plants. The total soil arsenic concentrations ranged from 1.34 to 14.09 mg kg -1 . Soil organic carbon showed positive correlation with arsenic accumulation in rice plant, while soil pH showed strong negative correlation. Higher accumulation of arsenic was noticed in the root (6.92 ± 0.241-28.63 ± 0.225 mg kg -1 ) as compared to the straw (1.18 ± 0.002-2.13 ± 0.009 mg kg -1 ), husk (0.40 ± 0.004-1.05 ± 0.006 mg kg -1 ), and grain (0.16 ± 0.001-0.58 ± 0.003 mg kg -1 ) parts of the rice plant. However, the accumulation of arsenic in the rice grain of all the studied samples was found to be between 0.16 ± 0.001 and 0.58 ± 0.003 mg kg -1 dry weights of arsenic, which did not exceed the permissible limit in rice (1.0 mg kg -1 according to WHO recommendation). Two rice plant varieties, one high yielding (Red Minikit) and another local (Megi) had been chosen for the study of arsenic translocation. Higher translocation of arsenic was seen in the high yielding variety (0.194-0.393) compared to that by the local rice variety (0.099-0.161). An appreciable high efficiency in translocation of arsenic from shoot to grain (0.099-0.393) was observed in both the rice varieties compared to the translocation from root to shoot (0.040-0.108).

We examined the relationship between distribution of actinomycetes and antagonistic behaviour with the physico-chemical characteristics of the Sundarbans, off the Bay of Bengal, India. Soil/sediment samples were collected from three regions: near to the sea, intertidal regions and mangrove forests. For the enumeration of actinomycetes, four treatments combining dilution with distilled or sea water with or without heating followed by plating onto starch-casein, glycerol-arginine and starch-nitrate media were done. Dilution with seawater, heating and plating onto starch-casein yielded maximum number of actinomycetes. The highest number of actinomycetes was isolated from an intertidal region having alluvial soil and the lowest from a site containing sandy sediments. Antimicrobial activity was dependent upon seawater. Antimicrobial score of an actinomycetes strain was calculated allotting maximum points to the isolate showing activity against all the test bacteria, next lower point to the isolate showing activity against one less the total and so on. The antagonistic potential (AP) of a sampling site was the ratio of total antimicrobial score of the isolates and their number. The high AP sites were influenced by tides, while the low AP sites were not. Pearson's correlation between soil chemical parameters and microbiological parameters revealed soil nitrogen as the key factor determining the antagonistic activity.

No abstract