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An investigation was carried out to monitor Pb and Cd contamination in grazing land located near a highway. Environmental media at different distances from highway (soil, grass, water, cow's forage, fertilizer, manure and milk samples) were collected from three sampling locations. Soil and grass were characterized by high metal mobility (soil with Pb: 5.25 +/- 0.71-14.59 +/- 1.17 mg kg(-1), dry mass and Cd: 0.038-0.33 +/- 0.04 mg kg(-1), dry mass and grass with Pb: 0.76 +/- 0.05-6.62 +/- 0.18 mg kg(-1), dry mass and Cd: 0.17+/- 0.01-0.73 +/- 0.09 mg kg(-1), dry mass). One-way analysis of variane (ANOVA) was applied to find out the correlation between metal (total and bioavailable) concentrations in the soil and the distance from roadside. In most cases, the finding showed that plants growing nearer to the highway are usually exposed to more heavy metal accumulations than those away from the highway. In addition, a correlation was established between plant available metal concentrations and plant metal uptake concentrations. Analysis of fertilizer and manure showed considerable amount of metals (fertilizer with Pb: 1.53 +/- 0.06 mg kg(-1) and Cd: 0.038 mg kg(-1) and manure with Pb: 2.55-3.34 mg kg(-1) and Cd: 0.14-0.31 mg kg(-1)). Long-.term simultaneous application of fertilizer and manure on the commercial farm showed higher metal accumulation in the soil and plants than those of co-operative farm. Considerable concentrations of metals (Pb: 1.60-2.94 mg kg(-1) and Cd: 0.025-0.19 mg kg(-1)) were observed in fodder. The finding clearly demonstrated that there are seasonal variation in total daily metal intake by individual cow (Pb: 109.37 mg day(-1) (dry), 273.47 mg day(-1) (rainy) and Cd: 2.02 mg day(-1) (dry), 19.62 mg day(-1) (rainy)). The provisional tolerable weekly intake of heavy metals in cows is 390 microg Pb and 28 microg Cd per kg body weight in the rainy season and 156 microg Pb and 2 microg Cd per kg body weight in the dry season. The levels of metals (Pb: 0.014 mg L(-1) and Cd: not detectable) and bio-transfer factor (10(-5)-10(-4)) in raw milk were found to be well below the Codex Alimentarius Commissions Draft (1997). Our analysis revealed that improvements on farm management give significant reduction in elevated levels of Pb and Cd in soil and plants, and however leads to minimize the amount of Pb and Cd in consumed milk.

This study was conducted to assess the potential of river sediment for amendment of agricultural land with respect to heavy metal mobilization. The mobility and concentration of bioavailable heavy metal containing in the sediment were evaluated with the use of DTPA (diethylenetriamine pentaacetic acid) extraction techniques. Sum of metals in exchangeable and carbonate fractions obtained from sequential extraction scheme was used to evaluate the potential plant available. Four land blocks of size (1 m x 5.8 m) were prepared for cabbage field experiment and applied with different loading rates of sediment (approximately 28 and 42 ton/ha or equivalent to 100 kgN/ha and 150 kgN/ha). In parallel test, land blocks treated with fertilizer at similar nitrogen loading rates were also conducted for comparisons. Pure soil plot was used as a control system. Results show that both plant available and total heavy metal concentration were found higher in those plots treated with higher loading rates of sediment (42 ton/ha). The concentrations of heavy metals (Cu,Zn,Pb) in soil were decreased with time after crop harvesting and the residues remain in the soil were well below those of the UK, USA and Germany standards. Simple linear regression was used to show the correlation between the DTPA extractable metals and the plant metals fractions (root and shoot) resulting from fertilizer and sediment applications in the amended soils. In most cases, plant available metal concentrations showed positively correlated with plant metal uptake concentrations (R2 = 0.01-0.95, n = 3). Concentration of metals in the cabbage tissue detected: Zn at 131.53+/-10.43 mg kg(-1) DM, Cu at 20.84+/-1.62 mg kg(-1) DM, Pb at 0.09+/-0.01 mg kg(-1) DM, Cd at 0.21+/-0.09 mg kg(-1) DM and Ni at 0.44+/-0.05 mg kg(-1) DM. None of these metals concentration exceeded the tolerable limits of plant. One-way analysis of variance (ANOVA) was applied to find out the effect of different soil amendments on cabbage yield in term of fresh and dry weights. The sequence of crop yields in this field studies for amended soils is chemical fertilizer > sediment > control soil.

This study investigated the potential leachability of toxic heavy metals and pathogenic reduction in sewage sludge using chitosan and zeolite as adsorbing materials. Experiments were conducted on chitosan-sludge and zeolite-sludge mixtures in the application ratio of 0.1:10, 0.5:10, 1.0:10, 2.0:10, 3.0:10, and 4.0:10, respectively, and examined their capacities to bind some heavy metals (Zn, Cu, Ni and Pb) deriving from sewage sludge. Acrylic columns packed with chitosan and zeolite-sewage sludge mixtures in optimum ratio 1.0:10 and 3.0:10, respectively, were leached with tap water and sewage effluent at different pH levels. Seven eluate fractions were collected from the leaching test at leachant/dry sludge (L/S) ratio fixed to 0.48, 0.95, 1.43, 1.90, 2.38, 2.85, and 3.33 L/kg, respectively, and monitored for heavy metal and fecal coliform reductions. Results from leaching test studies for amended sludge showed that the variation of the observed heavy metal contents were influenced by the pH and eluate fractions of leachants. It was found that from neutral to acid conditions, the mobility of heavy metals in amended sludge mixtures was increased with the decrement of pH value in leachants. Zeolite-sludge was found to have higher percentage of reduced metal bioavailability than chitosan-sludge. It can be seen in column studies, pathogenic reduction in amended sludge mixtures were dependent with eluate fractions and type of amended materials. It was also revealed that chitosan can reduce greater fecal coliform counts in sewage sludge than that of zeolite.