Evaluación de la capacidad del pasto ryegrass anual (lolium multiforum) para depurar soluciones y suelo agrícola contaminado con plomo.

Abstract

Phytoremediation is a method of botanical treatment or green remediation, friendly to the environment, efficient and less expensive than alternative techniques. The present investigation seeks to evaluate the purification capacity, by phytoremediation, of solutions and agricultural soil contaminated with lead, using annual ryegrass grass (Lolium multiflorum). For this purpose, the percentage of metal absorption and the adaptability (mortality, wilting and growth) of this species, developed by hydroponic means, to synthetic solutions of lead 5 mgL-1 are quantified. The removal of lead in solution, after 5 days of treatment, was 87.9 %, with rates of mortality and wilting of the plant below 5 %. The remediation capacity of annual ryegrass grass in agricultural soil from the Machachi area (Mejía canton), contaminated with lead at a concentration of 200 mgKg-1 , was also evaluated for a period of 7 weeks, reaching removal values of 55,3 %. In both cases, after treatment, concentrations lower than those defined by the TULSMA (2003) standard are obtained, the value of 0,5 mgL-1 as the maximum allowable lead limit for discharges to the public sewer system. In the case of agricultural soils, the maximum permissible value of lead is 100 mgKg-1 according to soil restoration criteria. Additionally, it is determined that the annual ryegrass grass is a hyperaccumulating plant, due to its great capacity to store heavy metals in the aerial zone such as the stem and leaves.