HR: 17:45h
AN: B32D-08    [PDF]
TI: Subterranean Groundwater Nutrient Input to Coastal Oceans and Coral Reef Sustainability
AU: * Paytan, A
EM: apaytan@pangea.stanford.edu
AF: Stanford University, Geological and Environmental Sciences, Stanford, CA 94305-2115 United States
AU: Street, J H
EM: jstreet@stanford.edu
AF: Stanford University, Geological and Environmental Sciences, Stanford, CA 94305-2115 United States
AB: Coral reefs are often referred to as the tropical rain forests of the oceans because of their high productivity and biodiversity. Recent observations in coral reefs worldwide have shown clear degradation in water quality and coral reef health and diversity. The implications of this are severe, including tremendous economic losses mostly though fishing and tourism. Nutrient loading has been implicated as one possible cause for the ecosystem decline. A previously unappreciated potential source of nutrient loading is submarine ground water discharge (SGW). Ground water in many cases has high nutrient content from sewage pollution and fertilizer application for agriculture and landscaping. To better understand the effect of this potential source of nutrient input and degrading water quality, we are exploring the contribution of SGW to the nutrient levels in coral reefs. A key to this approach is determining the amount and source of SGW that flows into the coast as well as its nutrient concentrations. The SGW flux and associated input of chemical dissolved load (nutrient, DOC, trace elements and other contaminants) is quantified using naturally occurring Ra isotopes. Radium isotopes have been shown to be excellent tracers for SGW inputs into estuaries and coastal areas (Moore, 1996; Hussain et al., 1999; Kerst et al., 2000). Measurements of Ra activity within the coral reef, the lagoons and the open waters adjacent to the reef provide valuable information regarding the input of Ra as well as nutrients and possibly pollutant from groundwater discharge. Through this analysis the effect of SGD on the delicate carbon and nutrient balance of the fragile coral reef ecosystem could be evaluated. In addition to quantifying the contribution of freshwater to the nutrient mass balance in the reef, information regarding the length of time a water parcel has remained in the near-shore region over the reef can be estimated using the Ra isotope quartet.
DE: 1803 Anthropogenic effects
DE: 4805 Biogeochemical cycles (1615)
DE: 4820 Gases
DE: 4845 Nutrients and nutrient cycling
DE: 4857 Pollution
SC: Biogeosciences [B]
MN: 2003 Fall Meeting