CHEMICAL NUTRIENTS IN STREAMS OF THE WESTERN ALLEGHENY PLATEAU ECOREGION WITH GOOD BIOLOGICAL INDEXES FOR AQUATIC LIFE

The Western Allegheny Plateau (WAP) ecoregion in Ohio has been studied to understand the chemical, hydrological, geomorphological and biological factors impacting stream health through an inter-disciplinary approach. The first phase of this research is the investigation of streams that have relatively good habitat according to previous investigations. The purpose is to identify the factors that have positive or negative impact on aquatic life. In this paper, we present the results of the main chemical field parameters and nutrients in fifty pristine or least impacted (reference) sites in the ecoregion. Water and sediment samples were collected from18th July to 30th August, 2005. pH, TDS and conductivity among others were measured in the field while alkalinity, acidity, nitrate, phosphate, chloride and sulfate were determined in the laboratory using titration for alkalinity, specific electrode for chloride, and spectrophotometric methods for the other ions.

pH ranged between 6.6 and 8.2, with most sites having values higher than 7.1. This was consistent with high values of alkalinity that ranged from 33 to 240 mg CaCO3/l. Lower alkalinity and pH values were observed to the SE of the WAP. Most of the measured parameters were high in the Northeastern part of the WAP. Nitrate, phosphate, and sulfate ranged from 0.03 to 1.59, below detection to 1.59, and 15 to 361 mg/l, respectively. With Washington, Monroe, and Noble counties to the East showing low values. These values are within the EPA water quality criteria for aquatic life for pH, alkalinity, and nitrate. However, sixteen sites present phosphate concentrations higher than 0. 1 mg/l and a four sites concentrations of sulfate higher than 250 mg/l. In terms of the nutrients, phosphate contamination seems to be happening even in the least impacted streams of the WAP. The high alkalinity of the WAP ecoregion can be explained by the geology of the area which consists mainly of limestone with some sandstones, shales and coal. The coal in the region is rich in sulfides.Waters with high sulfate are probably produced by oxidation of sulfides. These results for the nutrients in the relatively healthy streams of the WAP ecoregion show that phosphorous is probably the nutrient of major concern. However, the general low concentrations of the other nutrients explain why the studied streams show better biological indexes for aquatic life.