Copper Concentrations Found from Drinking Water, Soils, and Vegetables

Abstract

Humans, animals, and plants need copper for growth and development, but it can be an irritant to humans. The daily maximum limit of copper for humans is 10-12 µg day^-1 and excess concentrations of copper can cause nausea, diarrhea, and anorexia. In plants, excess copper concentrations cause chlorosis, stunted growth, and denaturing of macromolecules. Only 10 mg kg^-1 of copper can be accumulated by plants. The maximum allowable concentration in agricultural soils is 6.6 mg kg^-1. The concentration of copper in drinking water should not exceed 1 mg L^-1. When copper concentrations exceed an action level of 1.3 ppm in more than 10% of customer taps sampled, several additional controlling measures must be undertaken. In waste, the allowable concentration is 16 mg kg^-1. The hypothesis of the study was that copper would be found in the vegetables grown from the agricultural soils. Cabbage, green pepper, spinach, and tomato were grown for thirteen weeks. The soil and vegetables were digested, and the copper concentrations were measured using an Atomic Absorption Spectroscopy (AAS). The highest total and extractable copper concentrations found in the soil were 73 mg kg^-1 and 26 mg kg^-1, respectively. More than 20 and 32 mg kg^-1 of copper was found in the shoot and roots of the vegetables, respectively. More than 11 mg L^-1 of copper was found in the tap water. The results indicated that the copper concentrations from the soil, water, and vegetables exceeded the allowable concentrations.