The use of two microbiotests to evaluate the toxicity of sediment from Mpumalanga, South Africa

Abstract

Rapid urbanisation throughout the world has resulted in numerous ecological and environmental problems. The release of contaminants into the aquatic environment and the subsequent accumulation in sediment is a specific area of concern due to the potential re-release of the contaminants into solution. The responses of two microbiotests designed to evaluate sediment toxicity (the Ostracodtoxkit F and Phytotoxkit test) were compared once exposed to three samples collected in the vicinity of a power station in Mpumalanga, South Africa. Sediment characterisation and chemical analyses were conducted in order to determine possible correlations with the expressed results. Where possible, the concentration of chemicals in the sediment was compared to available sediment guidelines. The study showed that whilst the Phytotoxkit test results did not indicate any acute toxicity (< 50% inhibition), the Ostracodtoxkit F test indicated 100% mortality at the upstream site, with increased growth inhibition at the remaining two sites. The concentration of chrome at all three sites exceeded the interim sediment quality guidelines (37 mg/kg), with the sample collected at the upstream site exceeding the probable effect level (90 mg/kg). The findings from this study indicated that the Phytotoxkit and Ostracodtoxkit F test kits are sensitive enough to evaluate sediment toxicity.

Assessment of water quality contaminated with arsenic using diatoms and Ostracodtoxkit F test

“…The mining and industrial activities could be contributing to the probable high levels of As in sediments at all three sites therefore the mortality and growth inhibition occurred at all studied sites. Ostracods have been found very sensitive to metal contamination than other freshwater crustaceans [3]. The comparison of the results of the biological assessment of three streams which were conducted on the basis of two different methods showed slight differences in the quality of streams.…”

“…These findings coincide with the results obtained for multimeric diatom index (IO), but in all cases the mortality and growth inhibition of ostracods was recorded. The mobility of sediment is slow, thus contaminated sediments change very slowly over long time period, suggesting that "old" contamination could influence the sediment biocoenosis [3]. Ostracod mortalities at all sites are possibly due to elevated As concentrations at sediments.…”

“…In terms of reliability and cost-effectiveness, bioindiactors are very appropriate biomonitors for short-and long-term environmental monitoring of metals [1,2]. Including the microorganisms, the assemblage of macrophytes, microalgae, macroinvertebrates and fish has been used to monitor water quality in aquatic ecosystems for different purposes [3]. Diatoms have been recognised as good indicators of land use and water quality.…”

The impact of chemical contaminants on biocenosis (ecotoxycological studies)

“…The growth inhibition (57%) and mortality (35%) of H. incongruens when applying Ostracodtoxcit F suggesting the existing impact of accumulated previously used chemicals in sediments on water biocenosis, as PCC "Rokita" mainly dealt and still deals with the production of chlorine and chlorinated products, organic compounds. Although the chemical industry is constantly evolving, and takes its impact on the natural environment into consideration [3,11]. On the other hand, chemical industries, such as PCC "Rokita" annually produce thousands of substances with an effect unknown to the environment and humans.…”

Assessment of Freshwater Springs, Associated Diseases and Indigenous Perception in Ghizer, Gilgit-Baltistan, Pakistan

“…1 Environmental contaminants including physical, chemical and biological can enter the aquatic environment through naturally occurring events as well as anthropogenic activities, consequently can accumulate in the sediment and may be re-released into the overlying water through chemical, physical and biological processes. 2 …”