Development of a Two-Phase Cosolvent Washing-Fungal Biosorption Process for the Remediation of DDT-Contaminated Soil

A bench scale, two-phase soil washing-biosorption process was developed for the remediation of p,p′-DDT-contaminated soil (containing 990 and 7750 mg kg^-1 of p,p′-DDT). Removal of p,p′-DDT from contaminated soil was achieved by washing the soil with low molecular weight primary alcohols (ethanol or 1-propanol). An improved efficiency of p,p′-DDT removal was observed with increasing C-chain length of the cosolvent and by increasing the cosolvent volume fraction. When 40 or 80% 1-propanol were used, greater than 93% of p,p′-DDT was desorbed from the respective soils. p,p′-DDT was partitioned from the cosolvent solutions using biomass of Cladosporium sp. strain AJR³18,501 as the sorptivematrix. When studies were conducted using a cosolvent-recycling regime (with 80% 1-propanol) greater than 95% of p,p′-DDT was removed from Soil A (990 mg kg^-1 p,p′-DDT) and Soil B (7750 mg kg^-1 p,p′-DDT) with the majority of the desorbed organochlorine repartitioning onto the fungal biomass. Less than 2.4 μg mL^-1 p,p′-DDT was detected in the cosolvent wash solution of Soil A after 80 hr: potentially the cosolvent could be further reused to treat other soil. A higher concentration of p,p′-DDT was detected in the cosolvent wash solution of soil B after 120 hr (13.3 μg mL^-1) indicating that the p,p′-DDT sorption sites on the fungal biomass were fully saturated.     

In situ Remediation of DDT-contaminated Soil Using a Two-Phase Cosolvent Flushing-Fungal Biosorption Process

The effectiveness of cosolvent soil flushing and fungal biosorption for the remediation of p,p′-DDT-contaminated soil was evaluated usingpacked soil columns in order to simulate an in situ soil flushing technique. Greater than 95% of p,p′-DDT (940 mg kg^-1) was desorbed from the soil by flushing with 40 or 80% 1-propanol. Increasing the cosolvent volume fraction increased the rate of p,p′-DDT removal from the soil, however, the extent of p,p′-DDT removal was not enhanced. A further enhancement in therate of p,p′-DDT removal was achieved by increasing the cosolventflow rate from 6 ml hr^-1 to 12 ml hr^-1 (pore water velocity from 18.9 to 37.8 cm hr^-1). The desorbed p,p′-DDT was removed from cosolvent wash solutions by partitioning onto fungal biomass. Biosorption of p,p′-DDT resulted in low concentrations of the organochlorine (3.3 μg ml^-1) remaining in thecosolvent effluent indicating that the cosolvent could be reused for further p,p′-DDT desorption. Using this technique, between 53 and 95 pore volumes were required to reduce p,p′-DDT concentrationsfrom 990 mg kg^-1 to below Australian and New Zealand Environmentaland Conservation Council (ANZECC) guidelines (50 mg kg^-1).     

Studies on antioxidant activity of pomegranate (Punica granatum) peel extract using in vivo models

Pomegranate (Punica granatum) peel extracts have been shown to possess significant antioxidant activity in various in vitro models. Dried pomegranate peels were powdered and extracted with methanol for 4 h. The dried methanolic extract was fed to albino rats of the Wistar strain, followed by carbon tetrachloride (CCl4), and the levels of various enzymes, such as catalase, peroxidase, and superoxide dismutase (SOD), and lipid peroxidation were studied. Treatment of rats with a single dose of CCl4 at 2.0 g/kg of body weight decreases the levels of catalase, SOD, and peroxidase by 81, 49, and 89% respectively, whereas the lipid peroxidation value increased nearly 3-fold. Pretreatment of the rats with a methanolic extract of pomegranate peel at 50 mg/kg (in terms of catechin equivalents) followed by CCl4 treatment causes preservation of catalase, peroxidase, and SOD to values comparable with control values, wheres lipid peroxidation was brought back by 54% as compared to control. Histopathological studies of the liver were also carried out to determine the hepatoprotection effect exhibited by the pomegranate peel extract against the toxic effects of CCl4. Histopathological studies of the liver of different groups also support the protective effects exhibited by the MeOH extract of pomegranate peel by restoring the normal hepatic architecture.     

Degradation of bifenthrin,chlorpyrifos and imidacloprid in soil and bedding materials at termiticidal application rates

Organophosphorus, pyrethroid and chloronicotinyl insecticides have been used to control termites in building structures in recent years. We investigated the degradation behaviour of three insecticides (bifenthrin, chlorpyrifos and imidacloprid) at termiticidal application rates under standard laboratory conditions (25 °C, 60% field moisture capacity and darkness) for 24 months. The study was carried out on one soil and two bedding materials (sand-dolomite and quarry sand), which are commonly used under housing in Australia. Experiments were also conducted to examine the effect of soil moisture on the degradation of these insecticides. Insecticide residues in the samples collected at different days after application were measured by high performance liquid chromatography (HPLC). The rate of degradation of bifenthrin and imidacloprid insecticides was adequately described by a first-order kinetic model (r² = 0.93–0.97). However, chlorpyrifos degradation was biphasic, showing an initial faster degradation followed by a slower rate. Therefore, the degradation data during the slower phase only (after a two-month period) followed the first-order law (r² = 0.95). Soil moisture had little effect on degradation of imidacloprid and bifenthrin. Among the three insecticides, bifenthrin and imidacloprid were most stable and chlorpyrifos the least. Chlorpyrifos showed a major loss (75–90%) of residue during the 24 months incubation period. In the bedding materials, simultaneous accumulation of the primary metabolite of chlorpyrifos, TCP (3,5,6-trichloro-2-pyridinol) was observed. Hydrolysis appeared to have caused the observed rapid loss of chlorpyrifos, especially in the highly alkaline bedding materials (sand-dolomite and quarry sand). © 1999 Society of Chemical Industry     

Bioavailability of cadmium-organic complexes to soil alga--an exception to the free ion model

It is generally considered that cadmium bioavailability shows a considerable dependence on chemical speciation of Cd in solution, correlates best with the activity of free metal ion (Cd2+) in solution, and is largely indifferent to soluble metal complexes. The role of soluble organic matter (DOM) and soluble metal-organic complexes in metal bioavailability and toxicity, however, is not clear. Growth studies with a soil alga (Chlorococcum sp.) were conducted on a growth medium and pore water of Cookes Plain soil (Paleuxeralf), spiked with Cd as Cd(NO3)2. Speciation of the Cd in pore water, and in growth medium with and without citrate, was performed using the MINTEQA2 computer model incorporating updated values of the stability constants of Cd-DOM complexes, as well as using anode stripping voltammetry. Analysis of the toxicity data showed that Cd-citrate, as well as the Cd-DOM complexes, is bioavailable and contributes toward the toxicity to alga. These data contradict the long-held notion that Cd-DOM complexes are not bioavailable to soil biota although they may increase the mobility of Cd.     

Effects of Varying Concentrations of l-carnitine-incorporated Diets on Growth and Body Composition of Fry of Cirrhinus mrigala (Hamilton, 1822)

Experiment was conducted to ascertain the effect of l ‐carnitine on growth and body composition of Cirrhinus mrigala fry (0.342 ± 0.03 g) using five different concentrations (0.25, 0.50, 0.75, 1, and 0%) of l ‐carnitine‐incorporated diets for 120 d. At the end of trial, weight gain, feed conversion efficiency, and protein efficiency of fishes fed with 0.25% l ‐carnitine diet were observed to be significantly higher. Poor growth was recorded in the fry fed diet with no carnitine, while intermediate growth was observed when fed with 0.50, 0.75, and 1% l ‐carnitine‐incorporated diets. The analysis of body composition of C. mrigala fry indicated that there is no significant difference (P > 0.05) in moisture, protein, and ash contents, but significant difference (P < 0.05) was found in body lipid content of fry, fed with different concentrations of l ‐carnitine. Decrease in viscerosomatic and hepatosomatic indices were observed in fishes fed with l ‐carnitine‐incorporated diets. Results of this study indicated that diet containing 0.25% l ‐carnitine can promote higher growth in C. mrigala fry.     

Antioxidant activities of grape (Vitis vinifera) pomace extracts

Antioxidant-rich fractions were extracted from grape (Vitis vinifera) pomace using ethyl acetate, methanol, and water. The extracts were screened for their potential as antioxidants in different models. The ethyl acetate, methanol, and water extracts showed 76, 87.1, and 21.7% antioxidant activities at 100 ppm, respectively, using the 1,1-diphenyl-2-picrylhydrazyl model system. As the methanol extract of grape pomace showed maximum antioxidant activity among all of the extracts, it was selected to determine its effect on lipid peroxidation, hydroxyl radical scavenging activity, and human low-density lipoprotein (LDL) oxidation. The methanol extract showed 71.7, 73.6, and 91.2% inhibition using the thiobarbituric acid method, hydroxyl radical scavenging activity, and LDL oxidation, respectively, at 200 ppm. Treatment of albino rats of the Wistar strain with a single dose of CCl(4) at 1.25 mL/kg of body weight decreases the activities of catalase, superoxide dismutase (SOD), and peroxidase by 81, 49, and 89%, respectively, whereas the lipid peroxidation value increased nearly 3-fold. Pretreatment of the rats with the methanolic extract of grape pomace at 50 mg/kg (in terms of catechin equivalents) followed by CCl(4) treatment causes restoration of catalase, SOD, and peroxidase by 43.6, 73.2, and 54%, respectively, as compared with control, whereas lipid peroxidation was restored to values comparable with the control. Histopathological studies of the liver of different groups also support the protective effects exhibited by the methanol extract of grape pomace by restoring the normal hepatic architecture. Owing to this property, the studies on grape pomace can be further extended to exploit its possible application for the preservation of food products as well as a health supplement and neutraceutical.