Surfactant-enhanced release of carbaryl and ethion from two long-term contaminated soils

The potential of five nonionic surfactants, Triton X-100, Brij35, Ethylan GE08, Ethylan CD127, and Ethylan CPG660 for enhancing release of carbaryl and ethion from two long-term contaminated soils was evaluated using the batch method. Incorporation of the surfactants into soils enhanced the release of both pesticides to various extents, which could be related to the type of pesticides and type and the amount of surfactants added. Release of ethion was dramatically enhanced by aqueous concentrations of surfactants above their critical micelle concentration values. This was attributed to solubility enhancement through incorporation of the highly hydrophobic compound within surfactant micelles. A concentration of 10 g L(-1) of various surfactants released >70% of the total ethion from the soil irrespective of the surfactant. For carbaryl, the surfactants were effective at low concentrations and dependence on concentration was lower than in the case of ethion. The ethylan surfactants (GE08, CD127, and CPG660) had a higher potential than Triton X-100 and Brij35 for releasing the pesticides. However, there was still a significant portion of carbaryl (11% of the total) and ethion (17% of the total) left in the soil. Our study also showed that there must be an optimal concentration of each surfactant to maximize the mass transfer of pesticides. At some threshold concentration level, additional surfactant started to inhibit the mass transfer of solute from the soil into the water. The results suggested that surfactants could help remediation of soils polluted by pesticides. The choice of surfactant should be made based on the properties of pesticides.     

Soil, water and nutrient conservation in mountain farming systems: case-study from the Sikkim Himalaya

The Khanikhola watershed in Sikkim is agrarian with about 50% area under rain-fed agriculture representing the conditions of the middle mountains all over the Himalaya. The study was conducted to assess overland flow, soil loss and subsequent nutrient losses from different land uses in the watershed, and identify biotechnological inputs for management of mountain farming systems. Overland flow, soil and nutrient losses were very high from open agricultural (cropped) fields compared to other land uses, and more than 72% of nutrient losses were attributable to agriculture land use. Forests and large cardamom agroforestry conserved more soil compared to other land uses. Interventions, like cultivation of broom grass upon terrace risers, N2-fixing Albizia trees for maintenance of soil fertility and plantation of horticulture trees, have reduced the soil loss (by 22%). Soil and water conservation values (> 80%) of both large cardamom and broom grass were higher compared to other crops. Use of N2-fixing Albizia tree in large cardamom agroforestry and croplands contributed to soil fertility, and increased productivity and yield. Bio-composting of farm resources ensured increase in nutrient availability specially phosphorus in cropped areas. Agricultural practices in mountain areas should be strengthened with more agroforestry components, and cash crops like large cardamom and broom grass in agroforestry provide high economic return and are hydroecologically sustainable.     

Modulation of cadmium uptake and toxicity in Spirodela polyrrhiza (L.) schleiden due to malathion

Fronds of Spirodela polyrrhiza were treated with different concentrations of Cd and malathion singly and in combinations. Results showed that Cd toxicity was more than malathion. The chlorophyll content was more severely affected by Cd (EC-50 of >1.0 µg ml^–1); however, its toxicity was ameliorated in the presence of malathion (EC-50 of 2.0 µg ml^–1). Although biomass and frond numbers were least affected by these toxicants, at initial treatment durations fronds multiplication was more severely affected than biomass with an increase in treatment durations. The importance of these findings have been discussed in relation to metal abatement and biomonitoring.NBRI Publication No. (432) NS.     

An analysis of the himalayan environment and guidelines for its management and ecologically sustainable development

Summary The impacts of human activities on the bio-geophysical and socio-economic environment of the Himalayas are analysed. The main man-induced activities which have accelerated ecological degradation and threatened the equilibrium of Himalayan mountain ecosystems are stated as: unplanned land use, cultivation on steep slopes, overgrazing, major engineering activities, over-exploitation of village or community forests, lopping of broad leaved plant species, shifting cultivation (short cycle) in north-east India, tourism and recreation. Monoculture in forests, erosion and landslides have resulted in one–third of the total Himalayan land area becoming environmentally derelict. Cold desert conditions prevail in 41,500 km² of north-west Himalayas and are encouraged by traditional pasturalism. The geo-morphological conditions are major factors responsible for landslides which cause major havoc every year in the area. Other physical problems exist, such as eutrophication, drying up of the natural springs, the recession of the glaciers and changes in surface and ground water hydrology. Wild fauna, like musk deer (Moschus mischiferus) and the snow leopard (Panthera uncia), are now under threat partially due to changes in their habitat and the introduction of exotic plant species. Population pressure and migration are major factors responsible for poverty in the hills. The emigration of the working male population has resulted in the involvement of women as a major work-force. This work includes trekking for hours to collect fodder, timber and drinking water in addition to household duties. Guidelines, with special emphasis on the application of environmental impact assessments for the management of the Himalayas, are proposed.Drs Ahmad and Rawat are scientists, and Dr Rai is a research associate, at the Government of India, Ministry of Environment and Forests, G.B. Pant Institute of Himalayan Environment and Development. Correspondence should be addressed to Dr Afroz Ahmad.     

Sorption of nano-C60 clusters in soil: hydrophilic or hydrophobic interactions?

We studied the sorption behaviour of fullerene nano-C(60) particles (nC(60)) in soil from binary solvent mixtures of ethanol-water in order to critically evaluate the previous reports in the literature that the partitioning mechanism explains the soil sorption of fullerene C(60) as hydrophobic molecules. The sorption of nC(60) particles was studied in a range of solvent mixtures by changing volume fractions of ethanol from 20 to 100 percent. Sorption and particle characteristics were found to be very different in ethanol : water mixtures above and below 60% ethanol. In the range of 20-60% ethanol, sorption increased from 1.2 to 14.6 L kg(-1) accompanied by a change in zeta (ζ) potential from -32.4 to -7.2 mV. This observation can be attributed to hydrophilic interactions that negatively charged nC(60) particles undergo with soil colloids and water molecules. From 60% to 100% ethanol volume fractions, hydrophobic interactions of weakly charged nanoparticles may control the overall extent of soil sorption. The findings of this study indicate the importance of hydrophilic forces in controlling the sorption behaviour of nC(60) particles which are stabilized in water dominated solvent mixtures. The validity of the partitioning mechanism and K(OC) modelling approach in describing and estimating the sorption of nC(60) particles in soil (previously suggested in the literature) are, therefore, questioned.     

Designing a community-based insurance scheme to reduce human–wildlife conflict

Environment, Development and Sustainability - Globally, human–wildlife conflict (HWC) is a burning issue, which the conservationists have attempted to address through various conservation...