TEMPORAL AND SPATIAL VARIATIONS OF TRACE METAL LOADING TO UTAH LAKE (UT), U.S.A

Utah Lake is one of the largest natural freshwater lakes in the United States. The major inlets to Utah Lake are the American Fork River, Provo River, Hobble Creek, and Spanish Fork River, while Jordan River is the only outlet. Utah Lake has long been considered severely polluted and undesirable for water recreation largely due to the fact that Utah Lake has received heavy loadings of various pollutants related to anthropogenic activities. One of these water quality issues is elevated concentrations of trace metals. Mining activities beginning in the mid-1800s have accelerated metal cycling in the local aquatic systems. Therefore, a good understanding of spatial and temporal trace metal variability is critical for developing integrated approaches for water quality management.

In this project, we collected quarterly water and floc layer sediment samples from the American Fork River, Provo River, Hobble Creek, Spanish Fork River, Jordan River, and Utah Lake to investigate the fluctuations of trace metal concentrations. The objectives of this project were to 1) quantify seasonal fluctuations of trace metal levels in Utah Lake, its inlets, and its outlet; and 2) build a trace metal budget for Utah Lake. Preliminary data showed that there were large temporal and spatial variations of trace metal concentrations at the sampling sites, indicating that Utah Lake is not horizontally well mixed. Significantly elevated arsenic concentrations in the river water samples at the end of March and beginning of May could be caused by fertilizers used during agricultural activities in the surrounding areas. For water samples specifically, the concentrations of trace elements at the lake locations tend to be more concentrated than at the river locations. This indicates that the lake tends to act like a sink for these elements. Furthermore, arsenic might be originated from non-point pollution sources in addition to the input from the inlets.