T245 Hydrology of Urban Groundwater, Streams, and Watersheds (Posters)

Wednesday, 7 November 2012
9:00 AM - 6:00 PM
Hall B

BACTERIA AND NUTRIENT CONCENTRATIONS IN PIERMONT MARSH

Paper number: T245-10
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

Piermont Marsh, on the Southwest bank of Haverstraw Bay in the Hudson River estuary, is exposed to both the salinity of the Hudson River and the fresh water that runs through the Adirondack Mountains, resulting in a brackish wetland system. We sampled for the presence of the Enterococcus bacteria and nutrient concentrations (phosphate, nitrate, nitrite, ammonia) in the waters surrounding the Marsh (Sparkill Creek, Tidal Creek, Crumkill Creek, and two locations on the Hudson River) daily during, high, low, and mid tides. The samples were analyzed under a UV light for fluorescence and the bacteria were counted; nutrients were analyzed at the Lamont-Doherty marine biology lab. The nutrient measurements complement an existing 3-year sampling dataset. The bacteria sampling is, as far as we are aware, the first systematic study of Piermont Marsh bacterial variability.

There is a water treatment plant near Sparkill Creek that normally delivers approximately 30 million gallons of treated sewage, but which overflows with raw sewage during heavy rainfall. Storm runoff additionally draws nutrients and untreated waste from residential land in the surrounding Rockland County directly to the Sparkill Creek and the Hudson River. In this contribution we explore nutrient and bacterial variability with tidal cycle, distance from urban runoff, vegetative setting and, in particular, rainfall. We quantify the geographic variations and the decay in values after storm events. We also estimate large-scale nutrient uptake and primary productivity in the Marsh from the nutrient loss by differencing nutrient concentrations on the flow and ebb tides. Initial results indicate that nutrient loading, which may be implicated in shifting Marsh plant ecology, is dominated by a small number of inundation events following storm events, and that bacterial counts spike after runoff events, declining to background levels over approximately 4 days, and declining from North to South, that is: away from Sparkill Creek. All samples were collected and processed by public high school students and teachers from the Lamont-Doherty Earth Observatory Secondary School Field Research Program.