A comparison of 15N in aquatic invertebrates upstream and downstream of a wastewater treatment plant in Michigan's Upper Peninsula

Rivers, Lakes, & WetlandsNutrient loading from waste water effluent has become a contributing factor to environmental degradation and eutrophication. Chironomids from the order Diptera and Lepidostomatids from the order Trichoptera were collected upstream and downstream from a point source of wastewater effluent discharge in Michigan’s Upper Peninsula. If the effluent there was a significant amount of nitrogen coming from the effluent, we expected to see higher δ15N values for invertebrates downstream vs. upstream. The invertebrates were dried and tested for the stable isotope 15N. δ15N values for both invertebrate families were compared and found not significantly different, so δ15N was pooled from both families and combined within each sampling site. The δ15N enrichment for each sample site was compared, and the two upstream sites were found to be significantly lower in δ15N than the two downstream sites. There was a significant increase in nitrogen downstream of the wastewater treatment plant.http://deepblue.lib.umich.edu/bitstream/2027.42/57502/1/Moore_Shannon_2007.pd