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[1] The relationships among coupled groundwater and nitrogen (N) fluxes, groundwater age, and denitrification were examined for a section of West Bear Creek, an agricultural stream in the coastal plain of North Carolina, United States. Simultaneous streambed measurements of hydraulic conductivity (K) and hydraulic head gradient (J) and the concentrations of

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Natural chemical tracers of groundwater discharge ( 222 Rn and CH 4 ) were surveyed to evaluate possible patterns of groundwater interactions with surface water in Florida Bay. Radon and methane concentrations in water samples collected from wells, solution holes, canals, and Florida Bay showed a significant correlation, despite the fact that these two trace gases have independent sources. Groundwater flux was also measured directly via seepage meters in several Florida Bay locations. Natural abundance of nitrogen isotopes measured on attached algae and seagrass showed the greatest 15 N enrichment near the Keys. Collectively, our results suggested greater groundwater flow along the bay side of the Florida Keys. Nutrient flux estimates, based on interstitial nutrient concentrations and groundwater flux measurements, suggested that groundwater in the eastern part of Florida Bay may provide as much nitrogen (110 Ϯ 60 mmol N m Ϫ2 yr Ϫ1) and phosphate (0.21 Ϯ 0.11 mmol PO 4 3Ϫ m Ϫ2 yr Ϫ1) as surface freshwater sources from the Everglades (i.e., Taylor Slough and C-111). However, the inputs are clearly not uniform, and areas near solution holes or tidal springs may have a substantially greater nutrient flux into surface waters then these estimates.Submarine groundwater discharge (SGD) is an often overlooked yet possibly significant process in the geochemical and nutrient budgets of marine near-shore waters. According to Johannes (1980), ''SGD should occur anywhere that an aquifer is hydraulically connected with the sea through permeable rocks or bottom sediments and where the head is above sea level.'' Such conditions are met in most coastal areas. A simple model of SGD from a homogeneous unconfined aquifer indicates that freshwater flows out along the coast through a narrow gap between the freshwater-seawater interface where the water table outcrops at the shoreline. Harr (1962) predicted theoretically that the seepage discharge rate should decrease rapidly from shore in such a setting. This phenomenon has been confirmed in several lake

18Relative sea-level changes during the last ~2500 years in New Jersey, USA were reconstructed to test if 19 late Holocene sea level was stable or included persistent and distinctive phases of variability. 20Foraminifera and bulk-sediment δ 13 C values were combined to reconstruct paleomarsh elevation with 21 decimeter precision from sequences of salt-marsh sediment at two sites using a multi-proxy approach. 22The history of sediment deposition was constrained by a composite chronology. An age-depth model 23 developed for each core enabled reconstruction of sea level with multi-decadal resolution. Following 24 correction for land-level change (1.4mm/yr), four successive and sustained (multi-centennial) sea-level 25 trends were objectively identified and quantified using error-in-variables change point analysis to account 26 for age and sea-level uncertainties. From at least 500BC to 250AD sea-level fell at 0.11mm/yr. The 27 second period saw sea-level rise at 0.62mm/yr from 250AD to 733AD. Between 733AD and 1850AD sea 28 level fell at 0.12mm/yr. The reconstructed rate of sea-level rise since ~1850AD was 3.1mm/yr and 29 represents the most rapid period of change for at least 2500 years. This trend began between 1830AD and 30 1873AD and its onset is synchronous with other locations on the U.S. Atlantic coast. Since this change 31 point, reconstructed sea-level rise is in agreement with regional tide-gauge records and exceeds the global 32 average estimate for the 20 th century. These positive and negative departures from background rates 33 demonstrate that the late Holocene sea level was not stable in New Jersey. 34 35