Comparison of pesticide residues in surface water and ground water of agriculture intensive areas.

The organochlorines (OClPs) and organophosphates (OPPs) pesticides in surface and ground water having intensive agriculture activity were investigated to evaluate their potential pollution and risks on human health. As per USEPA 8081 B method, liquid-liquid extraction followed by Gas-Chromatographic technique with electron capture detector and mass selective detector (GC-MS) were used for monitoring of pesticides. Among organochlorines, α,ß,γ,δ HCH's, aldrin, dicofol, DDT and its derivatives, α,ß endosulphan's and endosulphan-sulphate were analysed; dichlorovos, ethion, parathion-methyl, phorate, chlorpyrifos and profenofos were determined among organophosphates.As compared to ground water, higher concentrations of OClPs and OPPs were found in surface water. Throughout the monitoring study, α - HCH (0.39 µg/L in Amravati region),α - endosulphan (0.78 µg/L in Yavatmal region), chlorpyrifos (0.25 µg/L in Bhandara region) and parathion-methyl (0.09 µg/L in Amravati region) are frequently found pesticide in ground water, whereas α,ß,γ-HCH (0.39 µg/L in Amravati region), α,ß - endosulphan (0.42 µg/L in Amravati region), dichlorovos (0.25 µg/L in Yavatmal region), parathion-methyl (0.42 µg/L in Bhandara region), phorate (0.33 µg/L in Yavatmal region) were found in surface water.Surface water was found to be more contaminated than ground water with more number of and more concentrated pesticides. Among pesticides water samples are found to be more contaminated by organophosphate than organochlorine. Pesticides in the surface water samples from Bhandara and Yavatmal region exceeded the EU (European Union) limit of 1.0 µg/L (sum of pesticide levels in surface water) but were within the WHO guidelines for individual pesticides.

Dioxin formation in pulp and paper mills of India.

Samples of effluents, sludge, pulp, final products (paper) and soil were collected from the identified pulp and paper mills in India. The samples were analysed for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and other dioxin congeners and precursors. Pulp and paper mills using chlorine for the bleaching process showed the presence of 2,3,7,8-TCDD in effluent samples. In the effluent and pulp samples from mills where chlorine dioxide was used as a bleaching agent, the 2,3,7,8-TCDD congener ranged from below the detection limit 0.05 to 0.12 ngL(-1)/ngg(-1). The relative standard deviation of reproducibility and the percent recovery of 2,3,7,8-TCDD were 2.07 and 82.4% in pulp and 2.8 and 92% in effluent, respectively. The 1,3,6,8-TCDD was the only other major dioxin congener found in the treated and untreated effluent and sludge samples. However, dichlorobenzene, trichlorophenyl, and hexachlorobiphenyl were detected in all samples. The formation of dioxins can be minimised by replacing chlorine with chlorine dioxide in bleaching processes in pulp and paper mills.

Hydrogen peroxide and ultraviolet irradiations in water treatment.

Trihalomethanes (THMs) the by-products of chlorination in water treatment are recognised as a threat to public health due to their carcinogenicity. The photodegradation of THMs using hydrogen peroxide has been found to give increased removal efficiency and the outcome of the study may find, its application in designing a unit process for water treatment. Batch experiments were carried out using UV lamp of 83 W and 40% w/w Hydrogen peroxide (H(2)O(2)) in test waters between 2.5-10 pH range of chloroform, bromodichloromethane, dibromochloromethane and bromoform at 50-200 microg L(-1) initial concentration. 92-100% removal of chloroform, bromodichloromethane, dibromochloromethane and bromoform were found with 0.1% of H(2)O(2) and 90 min of UV exposure.

Trihalomethane formation potential and concentration changes during water treatment at Mumbai (India).

The treated water at the outlet of treatment plants and representative service reservoirs of Mumbai city have been evaluated for trihalomethane formation potential in 1995-1996. Chloroform, dichlorobromomethane, chlorodibromomethane and bromoform have been monitored during monsoon, winter and summer. The levels of chloroform are found above the regulated WHO guideline value of 200 microg L(-1) in final water during postmonsoon at Ghatkopar (226 microg L(-1)), Malbar (210.3 microg L(-1)) and Tulsi (231.26 microg L(-1)).