Phytotoxicity of industrial contaminated soils

Abstract

Soil is the principal component of the terrestrial ecosystem on which is exercited the most of the industrial pollution. Even if soil have an increased biodegradation potential, the intensive antropogenic activities cause serious imbalances in biodiversity maintaining which ensure this process. Fate and bioavailability of contaminants in soil is often assessed through bioassays, biomonitoring and ecotoxicological testing of soil quality in order to identify negative processes. In this context, the aim of the study was to investigate the phytotoxicity of some soil samples contaminated with heavy metals (mining area Certejul de Sus, Hunedoara county) and with petroleum products (extraction area Poieni Teleorman and deposit area Constanta). Soil toxicity was assessed using the microbiotest Phytotoxkit with Sorghum saccharatum, Lepidium sativum and Sinapis alba, where seeds germination and roots growth inhibition were set as endpoints. Soil samples contaminated with heavy metals (As, Cu, Ni, Zn, Co, Cd, Cr) showed inhibition of germination in the range of 0 to 16.66% (insignificant compared to control) and roots growth inhibition in the range of 0.34 to 31.58%, indicating a moderate toxicity. Soil sample contaminated with petroleum products showed a different toxicity due to different sampling sections. The soil sampling from the extraction area highlighted a severe phytotoxicity on all plants (inhibition of germination in range of 45.5% - 90% and roots growth inhibition in 49.63% - 92.62%), toxicity was caused by significant loading of petroleum products (> 2500 mg / kg d.m). The soil sample from Constanta deposit showed no phytotoxicity on mustard and cress plants, but a low effect was observed on roots growth in case of sorghum plants (9.27%). Our experiments emphases the utility of the use of phytotoxicity microbiotest which can provide relevant information's about soil toxicity necessary in environmental risk assessment. The method protocol is easily to understand and apply, economical regarding the space use, maintenance and obtaining relevant results in a short time and easier to interpret.