Metal phytotoxicity thresholds in copper smelter-contaminated soils

Environmental problems associated with non-ferrous smelter operations are a problem in many countries around the world. Copper production Armenia has resulted metal contamination of soils and general degradation environmental quality. In this study we attempted to determine thresholds phytotoxicity metals contaminated by copper Armenia. The studied were sampled Alaverdi valley, located ~200 km north Yerevan. range concentrations was very wide, e.g., total soil 87-5885 mg kg-1. Most had nearly neutral pH (6.9 士 0.57), average organic matter content (6.3 1.9). Some saline. Perennial ryegrass root elongation used as an operational method assess phytotoxicity. We calculated index for each plotted length function index. Root growth mainly affected based on concentration, while extractable concentration proved be weak predictor. Soil stimulatory (positive) effect, whereas electrical conductivity toxic (negative) effect growth. Despite these confounding factors, able derive (EC10, EC25, EC50) conclusion, discuss practical importance future research needs concerning Valley.