Ecological Approach to Evaluate Effects of Chemical Pollutants in Soil and Groundwater

Abstract

Soil is the foundation of the entire biosphere, and the most important complex interface for the global transformation and interchange of matter and energy. Only a healthy, i.e., biologically active soil warrants the Sufficient production of food for the growing human population. Under stress conditions caused, e.g., by a long-term dissemination of chemical pollutants, the development and biochemical activities of soil microorganisms which play a key role in ecologically important biogeochemical processes undergo several alterations. To prevent negative ecological consequences, microbiologically-related parameters Should be involved in the indication of soil quality. After evaluation of more than 20 individual parameters we made a conclusion that nitrogen-fixing bacteria, total microbial biomass, soil respiration (CO) release), enzymatic activity (dehydrogenase), and in part also the humification activity of microorganisms Could be used as indicators of soil quality. However, seasonal oscillations in the values of the individual parameters Occurred, and should be appropriately respected in the evaluation of results achieved. Since groundwater represents a capital resource of drinking water in many Countries, there is also a growing public concern with contamination of groundwater aquifers by different health relevant chemicals. Based oil ail expected ability of autochthonous microbial Populations and other natural factors over time to bring about reduction or even elimination of health hazard for humans and animals, natural attenuation might stand for the remedy of contaminated aquifers. To be effective in transformation or degradation of chemicals, however, microorganisms indigenous to groundwater must be capable of resisting to chemical Pollutants. In Our laboratory experiments, microorganisms indigenous to all unpolluted deep groundwater aquifer were enriched, and ill portions, the microbial biomass obtained was exposed to different organic chemicals in samples of groundwater. The effect of the chemicals on the size of biomass (ATP contents), and metabolic activities (dehydrogenase, and respiratory activity) was measured. The results indicate toxic effects to be predominantly caused by very high concentrations of the chemicals, sometimes even near to the full water saturation capacity. On the other hand, a few chlorophenols, anilines and some nitrated aromatic hydrocarbons demonstrated a high degree of toxicity at rather low concentrations.