Scholarly record

EVALUATION OF NUTRIENT POLLUTION IN RED, BATCA DOAMNEI AND IZVORU MUNTELUI LAKES IN NEAM? COUNTY, ROMANIA

Andana Mihai

Abstract

Nutrient pollution and harmful algal blooms cause major environmental damage as well as serious human and animal health problems. Moreover, they take a toll on the economy, hurting industries and sectors that depend on clean water. High levels of nitrogen and phosphorus in water induce algae to grow faster than the lake ecosystems can handle. The increase in algae content damages the quality of lake water, food resources, and reduces the amount of oxygen needed to survive aquatic life. So-called algal blooms can severely reduce oxygen in water, leading to fish diseases and fish death. Based on analytical data (average, minimum and maximum values) obtained in each monitoring section, the surface water quality assessment has been done. Sampling was done in March, June, August and October in the three lakes situated in Neam? County, Romania (Eastern Carpathians). The trend assessment of the nitrates concentrations in surface water was also considered. The investigated indicators were: physical - temperature, chemical - pH, dissolved oxygen, total nitrogen, total phosphorus and biological numerical density, biomass and chlorophyll a. Total nitrogen and phosphorus as well as chlorophyll a were spectrophotometrically determined. The dissolved oxygen was measured with a titrimetric method using sodium thiosulfate. The evolution of phytoplankton in Red lake over time revealed a quantitative maximum of both analyzed indicators (numerical density and biomass) in October (966,500 organisms/L and 1,209 mg/L, respectively). Besides, the chlorophyll indicator also showed a peak in October (2.91 mg/L). The lowest numerical densities and biomass were reported in March in the middle lake area, both for B?tca Doamnei and Izvoru Muntelui, as a result of increased values for total suspended matter, which was negatively correlated with the phytoplankton development. The number of algal organisms and phytoplankton biomass produced were directly proportional to temperature and phosphorus concentration, but inversely proportional to the dissolved oxygen and total mineral nitrogen. As for Izvoru Muntelui Lake, the maximum biomass of phytoplankton in August confirmed the intensification of lake eutrophication. All three lakes had stable and low total phosphorus levels. As expected, A close relationship was found between the level of dissolved oxygen and the temperature of water of the investigated lakes.

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