The New Jersey Department of Environmental Protection (NJDEP) has identified Lake Hopatcong (NJ) as being impaired because of high phosphate concentrations. Examples of potential sources of phosphorus are surface runoff from the watershed and leakage from septic systems. When a nutrient like phosphorus (but also nitrogen) is present in excess, it causes eutrophication, algal blooms, and invasive plant species usually overgrow and lead to the loss of native species. The objective of this study was to assess sediment phosphorus storage at Lake Hopatcong in order to identify areas with high phosphorus storage or phosphorus hot spots. We sampled sediment at 157 pre-selected study sites, throughout the lake basin. The phosphorus in the samples was extracted by acid digestion in autoclave, and analyzed using a Flow Injection Analyzer (FIA).
Results/Conclusions
The average concentration of total phosphorus (TP) at selected study sites was 2.96 ± 1.95 g of phosphorus/Kg of dried sediment (g/Kg), ranging from 0.33 to 22.40 g/Kg. 11% of selected sampling sites (16 out of 157) were found to have TP concentration greater than 4 g/Kg. The sampling site with the highest concentration of TP coincided with the deepest point in the center of the lake. This lake-wide, intensive sedimentary phosphorus assessment allows us to gain a better understanding of phosphorus storage in the lake sediment and help prioritize areas for future remediation efforts.