Replacing winter rice in non-traditional areas by strawberry reduces arsenic bioaccumulation, and improves water productivity and profitability.

Use of huge amount (1450-1650 mm) of arsenic contaminated (14.0-24.5 mg l-1) ground water to irrigate winter rice resulted in high deposition of arsenic (As) in the topsoil and in rice grains, posing a serious threat to soil and human health of the Bengal basin. Strawberry (Fragaria × ananassa Duch.) requires 250 mm irrigation and fetches 3.5 times more net return over the winter rice, and can be grown as an alternate crop in place of winter rice to save the environment. In comparison to rice As load in edible parts of strawberry reduced from 865 to 39 µg kg-1. Deficit irrigation (0.8 and 0.6 crop evapotranspiration, ETc) to strawberry further reduced total as well as different As species load in fruits. Jute and straw mulches recorded lower As in fruits over other mulches. Drip irrigation to recharge full or 80% of ETc loss and use of jute agrotextile surface mulch maximized root growth and yield in strawberry, benefit:cost ratio, and energy efficiency and productivity. Results demonstrate that strawberry cultivation in non-traditional winter rice growing areas of Bengal basin can potentially benefit millions of people by reducing As load in food chains, ensuring higher returns, and aid in reviving the local jute agrotextile industry.

Arsenic accumulating bacteria isolated from soil for possible application in bioremediation.

Twenty six arsenic (As) resistant bacterial strains were isolated from As contaminated paddy soil of West Bengal, India. Among them, 10 isolates exhibited higher As resistance capacity and could grow in concentration of 12000 mg I-1 of arsenate (AsV) and 2000 mg l-1 of arsenite (Aslll) in growing medium. Maximum growth was observed at 1000 mg I-1and 100 mg I-1 in case of AsV and Asll respectively. Results of incubation study carried out in basal salt minimal media (BSMY) containing 25 mg l-1 of AsV and Aslll separately showed that the isolates could accumulate 1.03 - 6.41 mg I-1 of AsV and 2.0 - 7.6 mg l-1 of Aslll from the media. The bacterial isolate AGH-21 showed highest As accumulating capacity both for AsV (25.64%) and Aslll (30.4%) under laboratory conditions. The isolates AGH-21 (NCBI accession no: HQ834295) showed highest sequence similarity (98%) with Bacillus sp. and could be used as a potential bioremediator in future to combat with arsenic toxicity.

Arsenic contamination in sesame and possible mitigation through organic interventions in the lower Gangetic Plain of West Bengal, India.

BACKGROUND: The widespread geogenic arsenic contamination of groundwater in the Gangetic Delta of West Bengal, leading to toxicities through the food chain-principally through irrigated rice-drew due attention from researchers. Oilseeds such as sesame might be a remunerative alternative to rice and can be grown with small quantities of contaminated groundwater. RESULTS: The present study was conducted to explore the efficiency of organic matter in reducing arsenic accumulation in sesame. Accumulation of total arsenic in sesame seed and available arsenic in post-harvest soils varied from 0.08 to 0.58 mg kg(-1) and from 3.87 to 8.89 kg ha(-1) , respectively. The organic manures added as soil amendment significantly reduced the accumulation (concentration) of arsenic in sesame seed to a maximum extent of 65.5% (vermicompost), 50% (phosphocompost), 42% (mustard cake) and 40% (farmyard manure (FYM)) compared with the control counterpart. The risk associated with dietary exposure to arsenic-contaminated sesame oil reached a value of 15.55% of provisional tolerable weekly intake for arsenic at the maximum accumulation of arsenic in sesame oil. CONCLUSION: Substantial accumulation of arsenic in the soil-plant system was found. Risks of exposure to arsenic-contaminated oil remained considerably high. Irrigation through surface water and organic amendments both significantly reduced arsenic accumulation in sesame.