. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ECOLOGY: BIOGEOCHEMISTRY AND NUTRIENT CYCLING 249 nutrients (1). We assessed the effect of forest area and number of houses on inorganic nutrient concentrations in groundwater leaving Waquoit Bay watersheds with different proportions of these land covers. Salt marshes grow between land and estuaries, and ground- water-borne nutrients usually have to pass through salt marshes to reach estuaries. Salt marshes are known to support substantial rates of denitrification (2). We hypothesized that only a fraction of the nutrients pa
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ECOLOGY: BIOGEOCHEMISTRY AND NUTRIENT CYCLING 249 nutrients (1). We assessed the effect of forest area and number of houses on inorganic nutrient concentrations in groundwater leaving Waquoit Bay watersheds with different proportions of these land covers. Salt marshes grow between land and estuaries, and ground- water-borne nutrients usually have to pass through salt marshes to reach estuaries. Salt marshes are known to support substantial rates of denitrification (2). We hypothesized that only a fraction of the nutrients passing from land through salt marshes make it into estuaries. To measure the nutrient content of groundwater delivered to Waquoit Bay, samples were collected at the back of the salt marsh fringe all along the periphery of Sage Lot Pond (3, 4). Quashnet River (3, 4), Hamblin Pond, Jehu Pond, and Childs River (3, 4). To find the nutrient content of water that passed through salt marsh, samples of water were taken from outflowing tidal creeks and springs in the salt marsh of Sage Lot Pond (Mar- tin, unpub. data), Hamblin Pond, and Jehu Pond. The Quashnet and Childs Rivers have very little fringing marsh. In all samples, nitrate (NO,") and ammonium (NH4f) were measured with a Lachat Autoanalyzer, and phosphate (PO43+) was measured by a method adapted from Strickland and Parsons (5). We first focused on the effect of the two principal land covers, forest and residential land (6). on groundwater nutrient content. To do this, we plotted (Fig. 1, top) mean DIN (NO, + NH4+) and PO43+ concentrations in groundwater about to leave the aquifer against the percentage of forested area, and against the number of houses per watershed (unpub. data). We found that the greater the proportion of forested land in a watershed, the lower the concentration of DIN and PO43+ in groundwater entering the salt marsh (Fig. 1, upper and lower left, black circles). This may be the result of uptake and use
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
