TITLE:
A Large-Scale Identification of Sediment-Associated Risks of Contamination with Heavy Metals and Organics: Indicators and Algorithms
AUTHORS:
Yovana Todorova, Ivaylo Yotinov, Stilyana Lincheva, Yana Topalova
KEYWORDS:
Risk Identification, Dehydrogenase Activity, Phosphatase Activity Index, Sediments, Co-Contamination
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.7 No.2,
January
30,
2015
ABSTRACT: As
mediators in key biotransformation processes, the complex enzyme activities
(measured as a total of extracellular and intracellular activity on sub-organism, organism and
supra-organism level) have a high potential to be used as reliable indicators
for risk identification in co-contaminated sediments with organics and heavy
metals. Two enzyme activities—dehydrogenase activity (TTC-DHA) and phosphatase
activity index (PAI) were measured by use of methods with tetrazolium chloride
and p-nitrophenyl phosphate in polluted sediments of Middle Iskar River part,
Bulgaria. The environmental state of river sector has been strongly influenced
by the organics, nutrients, xenobiotics pollutants and by the intensive
hydrotechnical activity for construction of 9 micro-hydro power
plants. The change of
hydrological regime was a factor for intensive sediment accumulation and
concentration of pollutants in the area of the cascade. Data for total
activities of dehydrogenases and phosphatases in sediments were compared with
total count of culturable sediment bacteria and pollutants concentrations. The
results showed that the enzyme activities correlated positively with bacterial
abundance in sediments and organics content in sediments and negatively with
concentrations of xenobiotic pollutants (heavy metals). This approves a high
potential of enzyme indicators for regulation of ecosystem self-purification
capacity and for early assessment of sediment-associated risks of
co-contamination. The correlative relations allow dividing the mathematical
algorithms for control and management of processes in technologically
influenced hydroecosystem.