Insecticide pollution of Indian rivers

Summary Rivers are the main source of water in India, and are particularly used for agricultural irrigation and drinking water supply. As most of the rivers pass through agricultural fields, they are subject to contamination with the different insecticides used for crop protection. Residues of persistent organochlorines, which are still used in large quantities in India, are found in water from many Indian rivers. In certain rivers, the concentrations of DDT, aldrin and heptachlor are often present in excess of their guideline limits. Although the concentration level of gamma-HCH is well below the guideline limit, the accumulation of the carcinogenic beta isomer is a matter of great concern. A few organophosphorus insecticides have also been detected in river water. Recently, some organochlorine insecticides have been banned from use in India. The use of new, readily biodegradable insecticides and biocides in agriculture and public health programmes offers some optimism.Drs Satya P. Mohapatia, Vijay T. Gajbhiye and Narendra R. Agnihotri all work within the Division of Agricultural Chemicals at the above address. Dr Manju Raina is employed by the Ganga Project Directorate of the Ministry of Environment and Forests, New Delhi 11003, India.     

In situ treatment of metals in contaminated soils with phytate

Batch experiments were conducted to evaluate the ability of various forms of phytate, the hexaphosphoric form of myo-inositol (IP6), to immobilize U, Ni, and other inorganic contaminants in soils and sediments. A Ca-phytate precipitate (Ca(n)-IP6), dodeca sodium-phytate (Na12-IP6), and hydroxyapatite (HA) were added to contaminated soil at rates of 0, 10, 25, and 50 g kg(-1) and equilibrated in 0.001 M CaCl2. The samples were then centrifuged, the solution pH was measured, and the supernatants were filtered prior to analysis for dissolved organic carbon (DOC), U, Ni, P, and other inorganic contaminants, such as As, Cr, Se, and Pb. The residual sediments were air-dried prior to characterization by analytical electron microscopy and extraction with the Toxicity Characteristic Leaching Procedure (TCLP). The solubility of several metals (e.g., U, Pb, Cu) increased with increasing Na12-IP6 when compared with the nonamended control. In some cases immobilization was observed at the lowest Na12-IP6 application rate (10 g kg(-1)) with an increase in solubility observed at the higher rates, demonstrating the importance of metal to ligand ratio. In contrast, Ca(n)-IP6 and HA decreased the solubility of U, Ni, Al, Pb, Ba, Co, Mn, and Zn. For example, soluble U decreased from 2242 to 76 microg kg(-1) and Ni from 58 to 9.6 mg kg with the Ca(n)-IP6 addition, similar to the results observed for HA. Arsenic and Se solubility increased for HA and both forms of IP6, but to a much greater degree for Na12-IP6, suggesting that the increase in pH observed for HA and Na12-IP6, combined with added competition from PO4 and IP6 for sorption sites, resulted in the release of sorbed oxyanion contaminants. The analytical electron microscopy results indicated that metals such as U and Ni were closely associated with secondary Al-rich precipitates in the HA-treated soils, rather than unreacted HA. The analytical electron microscopy results were less definitive for the Ca(n)-IP6-treated soil, although the residual P-containing material was enriched in Al, with lesser amounts of U and Ni.     

Groundwater resources in India: an arena for diverse competition

There is evidence of a looming groundwater crisis in India. Unlike in the case of surface water, competition around groundwater generally does not result in open conflicts. Measurability and visibility of surface water accord a clearer public perception of water quantities, which leads to conflicts. Groundwater in an aquifer is sourced in a dispersed manner, and boundaries, quantities and interdependencies are less visible or measurable. Hence, groundwater resources go through intense and intricate competition between users and uses before open conflicts begin. Competition occurs with reference to sources rather than around the resource. The interdependency of sources is a function of changing patterns of usage as intricacies of aquifer characteristics come into play. Governance institutions and regulatory frameworks of groundwater need to be sensitive to the various forms in which groundwater competition manifests in different hydrogeological settings, and the consequences of this in terms of access and rights, in relation to issues of equity and justice.     

Calcium carbonate phosphate binding ion exchange filtration and accelerated denitrification improve public health standards and combat eutrophication in aquatic ecosystems.

Cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. The process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. Especially in Madrona Marsh, one of the last remaining vernal marshes in the greater Los Angeles area, California, cultural eutrophication has become a major problem. In this study, calcium carbonate was found to be an excellent phosphate binder, reducing up to 70% of the phosphates in a given sample of water, and it posed relatively negligent ecological repercussions. This study involved the testing of this principle in both the laboratory and the real ecosystem. A calcium carbonate lacing procedure was first carried out to determine its efficacy in Madrona Marsh. Through this, ammonia was found to interfere with the solubility of calcium carbonate and therefore to be a hindrance to the reduction of phosphate. Therefore, various approaches for reduction of ammonia were tested, including aeration, use of fiber growth media, and plants, mainly Caulerpa verticellata, chosen for it hardiness, primarily in an attempt to increase population of Nitrobacter and Nitrosomonas. All were successful in moderately reducing ammonia levels. In addition, soil sampling, sediment analysis, microscopic plant analysis, microorganism and macroinvertebrate identification, and rate law formulations were conducted. The effect of phosphate and ammonia reduction on the populations of enterobacteria was also an important focus of this experiment. Varying concentrations of phosphate, ammonia, and calcium carbonate in conjunction with phosphate were tested in Madrona Marsh to determine their effects on the populations of enteropathogens on nonspecific blood agar, MacConkey agar, and Hektoen agar. Initial analyses suggest a strong correlation between phosphate concentrations and bacterial populations; a 66% decrease in phosphate resulted in a 35% reduction in bacterial populations and a 45% reduction in enteropathogenic populations. Likewise, a strong correlation was shown between calcium carbonate concentrations and bacterial reduction greater than that which can be attributed to the phosphate reduction alone. This was followed by the construction of various phosphate binding calcium carbonate filters, which used the ion exchange principle, including a spring loading filter, PVC pipe filter, and a galvanized filter. All were tested with the aid of Stoke's law formulation. The experiment was extremely successful in designing a working phosphate-binding and ammonia-reducing filter, and a large-scale agitator-clarifier filter system is currently being planned for construction in Madrona Marsh; this filter will reduce phosphate and ammonia levels substantially in the following years, bringing ecological, economical, and health-related improvements to the overall ecosystem and habitat.     

Phosphorus adsorption by functionalized biochar: a review

Environmental Chemistry Letters - Phosphorus is essential element for agricultural production, yet phosphorus ore resources are non-renewable and become depleted. Moreover, phosphate release from...     

Using plants for health: Indigenous knowledge in health care in a tribal region of Bihar,India

While the potential of indigenous knowledge for health care is fully recognised in the literature and by many health professionals, the practices of so many indigenous peoples go unrecorded and untested. Indigenous knowledge remains essentially untapped, an unwritten resource involving information, language and skills in many groups, languages, cultures and environments. An attempt is made in this paper to identify selected indigenous health technologies in a tribal area of Bihar State, India; to describe the treatments, their application and preparation; and to link the traditional practice with the relevant scientific information to test or determine the validity of the practices. These practices were found to be effective in the treatment of a variety of health problems, and most were also scientifically confirmed. The paper argues, however, that other plant uses practised by tribal people still need to be explored: in order to popularise more widely the authenticated practices; to preserve indigenous knowledge; to integrate or blend it with scientific knowledge so that health professionals and healthcare users may benefit from a wider range of healthcare strategies which are environmentally unthreatening.     

Synthesis of nanoparticles using microorganisms and their applications: a review

Environmental Chemistry Letters - Nanoparticles synthesis under green conditions has been performed using natural resources to diminish the use of toxic chemicals. For instance, microbial synthesis...