Dr. Laura Lautz (National Science Foundation) will present:
Legacy effects of cemeteries on groundwater quality and nitrate loads to headwater streams
Residential development and land use change have increased nutrient loads to streams and groundwater through increased use of fertilizers and discharge of wastewater effluent. Stream degradation in urbanizing areas has simultaneously reduced natural attenuation of nutrients. In this context, cemeteries are an often-overlooked land use that may contribute to nutrient loading in urbanizing watersheds. Although cemeteries provide ecosystem services, such as infiltration of stormwater, micrometeorology control, and greenspace, they also pose a unique threat to groundwater quality due to degradation and leaching of organic material. To assess the potential legacy impact of cemeteries on water quality, we explored the impact of a large cemetery on groundwater nitrate concentrations and stream nitrate loads. We found nitrate concentrations were significantly higher in cemetery groundwater (median = 6.2 mg/L) than in residential groundwater (median = 0.05 mg/L). During summer months (June through September), stream nitrate concentrations increase by 1.4-1.9 mg/L between the upstream edge of the cemetery and the downstream edge. Stream nitrate loads are consistently 20-40 kg NO 3-/day higher downstream of the cemetery between June to September. Given that the cemetery handles about 400 to 500 burials per year, it is possible that 25-50% of the increase in nitrate load is attributable to groundwater discharge of burial decay products. Our observations of nitrate concentrations in cemetery groundwater, coupled with the increases in nitrate loads in a stream traversing the cemetery property, suggest cemeteries may be an overlooked source of nutrient loading in developed watersheds.