Ecotoxicological status and prognosis of the state of an urbanized hydroecosystem (on the example of the reservoir "Ternopil pond")

Abstract

As a result of a complex hydroecological research on the reservoir “Ternopil Pond”and comparison of these data with environmental and quality water standards we assessed the environmental threat posed by the content of certain substances, and the ecotoxicological state of the pond in general. A high concentration of HCO3 - was found, but the critical factor of water pollution is the significant concentration of ammonia, as well as the excess over the permissible levels of sodium ions. Moreover, we found polymetallic contamination of the bottom sediments with a high ratio of biologically dangerous mobile forms, with the exception of iron, and the excess over permissible levels (MPS), which in some places was ten times higher than the norm. The high level of the content of mobile metals forms was found at sampling areaswith a considerable sedimentation.The content of the mobile form of copper exceeded the norm by 24-86 times, nickel - from 2 to 17 times, cobalt – 4-8 times. The content of the mobile form of cadmium exceeded the permissible norm by 5-80 times, and lead – by 4.5-12 times. It was established that the content of the metals of the essential group in the water of the reservoir wasbelow the permissible values, and in the places where active flushing waters are flowing high concentrations of copper wasfound. Among the nonessential metals, cadmium and lead were found with fairlyhigh cadmium content , which is biologically dangerous because of the toxicity of this metal. In case of changes in the hydrochemical balance, the mobility of metals may increase, which will substantially worsen the almost disastrous pollution of the reservoir with highly toxic and biologically hazardous metals.Economic-mathematical modeling and statistical methods based on correlation-regression analysis using Matlab software were used to investigate the influence of ammonium content on the water pH index. The correlation index is ststistically significant and amounts to 0.86. This research will allow us to predict pH index of the water depending on the content of ammonium. The calculated elasticity coefficient shows that with an increase in ammonia by 10%, the pH index of the water will vary by 8%. In order to study the environmental situation in the near future, namely the content of metals in the bottom sediments, a forecast of the content of such metals as magnesium and cobaltfor the next two seasonal periods according to the theory of Markov chains has been made. This theory allows us to make predictions of the factor, taking into account the possibility of random effects on the environment, and investigates the greatest probability of presence of a factor in a certain numerical parameter.