Electro kinetic remediation of contaminated habitats

Electrokinetics (EK) is a process that separates and extracts heavy metals, radionuclides and organic contaminants from saturated or unsaturated soils, sludge, and sediments. A low intensity direct current is applied across electrode pairs that have been implanted in the ground on each side of the contaminated soil mass. The electrical current causes electroosmosis and ion migration (electromigration) and electrophoresis, which move the aqueous phase contaminants in the subsurface from one electrode to the other. Contaminants in the aqueous phase or contaminants desorbed from the soil surface are transported towards respective electrodes depending on their charge. The results of several laboratory studies have demonstrated excellent contaminant removal efficiencies by the use of the electrokinetic process (Pamukcu and Wittle, 1992; Probstein and Hicks, 1993). However, recent field applications of the electrokinetic technology have also shown anomalous results (Guzman et al., 2000; Lageman, 1993), which have been attributed mainly to the interaction of the contaminants with naturally occurring electrolytes, humic substances and mixed wastes which are present in the subsurface (Lageman, 1993; Acer et al., 1994). In order to use electrokinetic remediation in the field successfully, the different geochemical interactions that occur in the field soils under induced electricity must first be accurately determined. In addition, mechanisms and their effects can be altered in order to enhance the removal efficiency of lock in non-critical contaminants in the soil by immobilization. Numerous field studies have proven the commercial viability and technical effectiveness of the electrokinetic remediation. However, there is still a lot of scope and avenues to cover in this newly developed technology which are subject to further research.Key words: Electorkinectics, electromigration, electrolysis, electroosmosis

sessment of ground water contamination in Erode District, Tamilnadu

A systematic study has been carried out to assess the water contamination and the effect of the tanneries and dyeing industries effluents on Erode District, Tamil Nadu. Ten (10) sampling locations were selected in and around industries. The water samples were collected from the selected sampling points. The samples were analyzed for major chemical water quality parameters like pH, EC, Ca, Mg, Cl, SO4, Na, CO3 and HCO3. The present investigation shows a constant variation in different parameters in different locations. So it is highly important to take periodical monitoring of the ground water quality in this region for future sustainability.Key words: Erode district, Tamilnadu, contamination assessment, tanneries and dyeing industries

Influence of soil properties on street tree attributes in Singapore

Soil quality is thought to be a primary driver of street tree performance and thus a major concern for urban forest growth, health and longevity. This research was conducted to evaluate the influence of soil physical, chemical and biological properties on Singapore's street trees. In total, 338 plots, 1014 trees and 32 species across Singapore's five regions were sampled. Singapore's street trees are skewed towards smaller diameters (-3), P (1.52 to 2.87 mg kg-1), organic C (7.8 to 11.4 %), Ca (924 to 1772 mg kg-1), Mg (313 to 631 mg kg-1), Na (130 to 208 mg kg-1), Cr (143 to 212 mg kg-1), Pb (55 to 74 mg kg-1), Ni (15 to 30 mg kg-1) and microbial biomass C (265 to 457 mg kg-1). Soil pH (6.04 to 7.63) is not as acidic as the humid-tropical soil commonly found in Singapore. Soil K (23 to 130 mg kg-1) was found to be relatively low and potentially limiting. Individual soil properties and multi-factor models were poor predictors of urban tree attributes across Singapore, but models improved when examined at regional scales. Relatively high soil quality, uniformity of streetscape soils and fast growth rates of these trees are proposed as explanations for why soil properties appear to poorly predict street tree attributes in Singapore

Not Available

Not AvailableSewage sludge (SS), a highly heterogeneous semisolid fraction of sewage water (about 1% of the sewage water), contains various amounts of nitrogen (N) and phosphorus (P) as well as trace elements such as cadmium (Cd), lead (Pb), copper (Cu), nickel (Ni) and zinc (Zn) with extremely variable physical and chemical compositions. Application of SS improves soil properties, increases yield and simultaneously increases trace metal content in soil and plants. The difficulty in handling, transporting and applying SS and its adverse effect, especially trace metal content in soil and plant, can be overcome by SS–coir pith pelletization (SSCP) or mixing with sewage sledge–coir pith mixture (SSCM). A study was undertaken to evaluate the prepared SSCM and SSCP (1:1 ratio of SS and coir pith) along with SS on dry matter yield, trace metal content in soil and plant parts. The results showed that increased rates of application of SS or SSCM or SSCP increased the green and dry fodder yield of forage maize. Application of SS as either SSCM or SSCP at 1.2 and 2.4 g pot−1 significantly reduced the trace metal content diethylene triamine pentaacetic acid (DTPA extractable) in soil and plant parts (leaves steam and root) compared to SS application. Therefore, in order to reduce the bioavailability of trace metal in soil and its uptake by plant, application of SSCM or SSCP at 1.2 or 2.4 g pot−1 proved to be a better option than SS applicationNot Availabl