A Study of Periphyton, Sediment and Diatom Community Structure as Monitors of Heavy Metal Pollution in the Embarras River and Brushy Fork

The purpose of this study was to evaluate periphyton (diatom) and sediment heavy metal content and diatom community structure as potential monitors of heavy metal pollution in the upper reaches of the Embarras River system. The study was initiated due to recent industrialization in the area which could potentially contribute to the present heavy metal burden of Brushy Fork and the Embarras River. These streams are already subject to agricultural runoff, wastewater plant effluent, landfill leachate and other miscellaneous urban and highway runoff. The Embarras River system drains an area of approximately 2800 square miles in 11 east-central Illinois counties from the origin of the Embarras River, south of Champaign/Urbana, to the river\u27s confluence with the Wabash River near Vincennes, Indiana. Artificial substrates, consisting of modified Catherwood Diatometers with attached Plexiglas sheets, were deployed in the Embarras River, upstream (UPEMB) and downstream (DNEMB) of the mouth of Brushy Fork, and in Brushy Fork, upstream (UPBFK) and downstream (DNBFK) of the mouth of Newman Drain #2, for successive 2 week intervals from 30 May 1990 through 22 September 1990. A sediment sample was also collected during each sampling interval along with data on stream flow, depth, pH, conductivity, temperature and dissolved oxygen. Subsamples of dry material, which included diatoms, were scraped from the artificial substrates for use in determination of i) total cations, ii) dry mass and volatile mass and iii) community structure. Subsamples were analyzed by the Illinois Natural History Survey laboratory at Urbana, Illinois using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) to determine the concentration (ppm) of the following metals in periphyton and sediment: Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, CU, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se, Si, Sn, V and Zn. Several potentially toxic heavy metals (Al, Ba, Co, Cr, Fe, Mn, Ni, V and Zn) were detected in sediment and/or periphyton, some of which (Al and Fe) were alarmingly high. Comparison of water, sediment and periphyton data showed periphyton was the superior method for monitoring heavy metals in water. Community structure determinations showed Achnanthes lanceolate lanceolata, Cocconeis placentula euglypta, Cocconeis placentula placentula, Cyclotella meneghiniana, Navicula lanceolata lanceolata andNavicula viridula viridula were the most important of the 77 varieties observed at UPEMB, DNEMB, UPBFK and DNBFK during this study. A. lanceolata lanceolata, C. placentula euglypta and C. placentula placentula were the early dominants, while N. lanceolata lanceolata, N. viridula viridula and Cyclotella meneghiniana were generally late season replacements. Fluctuations observed in community structure are suspected to have resulted from some agent (e.g., buildup of toxins, nutrients, water temperature, dissolved oxygen) related to flow