Effect of arsenic-phosphorus interaction on arsenic-induced oxidative stress in chickpea plants

Arsenic-induced oxidative stress in chickpea was investigated under glasshouse conditions in response to application of arsenic and phosphorus. Three levels of arsenic (0, 30 and 60 mg kg−1) and four levels of P (50, 100, 200, and 400 mg kg−1) were applied to soil-grown plants. Increasing levels of both arsenic and P significantly increased arsenic concentrations in the plants. Shoot growth was reduced with increased arsenic supply regardless of applied P levels. Applied arsenic induced oxidative stress in the plants, and the concentrations of H2O2 and lipid peroxidation were increased. Activity of superoxide dismutase (SOD) and concentrations of non-enzymatic antioxidants decreased in these plants, but activities of catalase (CAT) and ascorbate peroxidase (APX) were significantly increased under arsenic phytotoxicity. Increased supply of P decreased activities of CAT and APX, and decreased concentrations of non-enzymatic antioxidants, but the high-P plants had lowered lipid peroxidation. It can be concluded that P increased uptake of arsenic from the soil, probably by making it more available, but although plant growth was inhibited by arsenic the P may have partially protected the membranes from arsenic-induced oxidative stress

Metal (Loid)s in Farmland Soils and Strategies to Reduce Bioavailability

High concentrations of heavy metal (loid)s (HMs) in farmland soils reduces crop yield and contaminates the food chain. Exposure to HMs in the diet results in several adverse health effects such as cancer, reproductive health problems and cardiovascular diseases. Understanding the origin and fractionation of these toxic substances will provide direction for reducing their bioavailability in contaminated farmland soils. HMs are added to farmland soils through activities such as irrigation, organic and inorganic fertilization, pest control, and mining. Weathering of parent material and atmospheric deposition can also increase the levels of HMs in the soil. Fractionation of HM contaminated soils provides information on availability of HMs such as Pb, Cd, As, Cr and Cu to soil biota and plants. Several studies have reported that Pb is mostly associated with Fe and manganese oxides (reducible fraction) while Cd is mostly associated with the most mobile fraction (exchangeable fraction). The application of organic and inorganic soil amendments such as vermiculite, zeolite, composts and crop residue to contaminated farmland soils converts HMs from the plant available fractions to the less mobile fractions. HM resistant microbes can change HMs to a less mobile fraction or less mobile oxidation state. The combination of HM resistant microbes, HM tolerant plants, and soil amendments can be used to reduce mobility of HMs in contaminated farmlands.</p

Arsenic and heavy metal accumulation by Pteris vittata L. and P-umbrosa R. Br

This study compared the accumulation of arsenic, copper and chromium by Pteris vittata and Pteris umbrosa grown in a glasshouse in soil from a timber treatment facility. Soil was collected from three locations. Accumulation (as percentage removed) varied between these soils but was not related to soil concentration. P. vittata was more efficient than P. umbrosa, both in accumulating As and metals in the below-ground plant parts and in translocating As to the fronds. Under the experimental conditions, only P. vittata could be effectively used in soil from one location for phytoremediation purposes