Spring recycling rates of ammonium in turbid continental shelf waters off the southeastern United States

Nitrogen recycling in coastal waters of southeastern U.S. during summer 1986

“…In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1). This imbalance was well within the range of 105 to 20:1 reported by others (Glibert et al, 1982;Laws, 1984;Kokkinakis andWheeRer, 1987, Hanson andRobertson, 1988). Many environmental and biological conditions have been identified for the 15N mass imbalance (cf.…”

“…Rate measurements for NH 4 + recycling. Estimates of NH 4 + assimilation and regeneration were made following 15NH4+ tracer procedures described earlier (Hanson and Robertson, 1988). Briefly, water samples were spiked with 0.05 /-Lmoles/L 15NH4+ (99% atom enrichment) in 21 acid-cleaned polycarbonate bottles.…”

“…However, even in nitraterich coastal bays and upwelling systems, several researchers have reported problems in obtaining 15N mass balance (Gilbert et al, 1982;Laws, 1984;Kokkinakis and Wheeler, 1987). Likewise, Hanson and Robertson (1988) found 1.5 times more 15NH4+ left the dissolved phase [uptake (U)l than was recovered in particulate components [assimilated (A)l in organic-rich waters off southeastern U.S. In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1).…”

Nitrogen recycling in coastal waters of southeastern U.S. during summer 1986

“…In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1). This imbalance was well within the range of 105 to 20:1 reported by others (Glibert et al, 1982;Laws, 1984;Kokkinakis andWheeRer, 1987, Hanson andRobertson, 1988). Many environmental and biological conditions have been identified for the 15N mass imbalance (cf.…”

“…Rate measurements for NH 4 + recycling. Estimates of NH 4 + assimilation and regeneration were made following 15NH4+ tracer procedures described earlier (Hanson and Robertson, 1988). Briefly, water samples were spiked with 0.05 /-Lmoles/L 15NH4+ (99% atom enrichment) in 21 acid-cleaned polycarbonate bottles.…”

“…However, even in nitraterich coastal bays and upwelling systems, several researchers have reported problems in obtaining 15N mass balance (Gilbert et al, 1982;Laws, 1984;Kokkinakis and Wheeler, 1987). Likewise, Hanson and Robertson (1988) found 1.5 times more 15NH4+ left the dissolved phase [uptake (U)l than was recovered in particulate components [assimilated (A)l in organic-rich waters off southeastern U.S. In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1).…”

Community metabolism and nutrient cycling at Gray's Reef, a hard bottom habitat in the Georgia Bight

“…The high level of production w e measured at Gray's Reef (2.15 g C m-2 d-l) may be indicative of hydrographic coupling with the nearshore region, since productivity is generally < 300 mg C m-2 d-' further offshore (Thomas 1970, Turner et al 1979. Planktonic respiration and pelagic ammonium regeneration were high relative to most coastal regions (Hanson & Robertson 1988) but less than was observed by Hopkinson (1985) in the estuarine plume region of the nearshore Georgia Bight. The overall high levels of production, respiration and nutrient recycling in the Gray's Reef water column, which are in contrast to the generally low levels found in the mid-shelf region, suggest the influence of coupling with the nearshore region.…”

Nitrogen regeneration and dissolved organic nitrogen release during spring in a NW Mediterranean coastal zone (Gulf of Lions):implications for the estimation of new production

“…GentiLhomme & Rairnbault (1994) observed higher rates in the Algerian Current frontal area (SW Mediterranean Sea), ranging from 25 nM h ' at the surface to 125 nM h-' in the DCM. Some measurements performed during spring in other coastal marine systems (Harrison 1978, Cochlan 1986, Hanson & Robertson 1988) gave higher rates (from 2 to 240 nM h-'), but comparisons between their hourly and our daily rates are difficult since regeneration has been shown to vary greatly with the time of the day (Glibert 1982). Furthermore, in the latter studies (particularly in those of Harrison and of Cochlan) rates correspond to potential rates due to the large excess NH,' enrichment compared to the initial in situ NH4' concentrations (Selmer 1988).…”

Nitrogen recycling in coastal waters of southeastern U.S. during summer 1986

“…In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1). This imbalance was well within the range of 105 to 20:1 reported by others (Glibert et al, 1982;Laws, 1984;Kokkinakis andWheeRer, 1987, Hanson andRobertson, 1988). Many environmental and biological conditions have been identified for the 15N mass imbalance (cf.…”

“…Rate measurements for NH 4 + recycling. Estimates of NH 4 + assimilation and regeneration were made following 15NH4+ tracer procedures described earlier (Hanson and Robertson, 1988). Briefly, water samples were spiked with 0.05 /-Lmoles/L 15NH4+ (99% atom enrichment) in 21 acid-cleaned polycarbonate bottles.…”

“…However, even in nitraterich coastal bays and upwelling systems, several researchers have reported problems in obtaining 15N mass balance (Gilbert et al, 1982;Laws, 1984;Kokkinakis and Wheeler, 1987). Likewise, Hanson and Robertson (1988) found 1.5 times more 15NH4+ left the dissolved phase [uptake (U)l than was recovered in particulate components [assimilated (A)l in organic-rich waters off southeastern U.S. In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1).…”

Community metabolism and nutrient cycling at Gray's Reef, a hard bottom habitat in the Georgia Bight

“…The high level of production w e measured at Gray's Reef (2.15 g C m-2 d-l) may be indicative of hydrographic coupling with the nearshore region, since productivity is generally < 300 mg C m-2 d-' further offshore (Thomas 1970, Turner et al 1979. Planktonic respiration and pelagic ammonium regeneration were high relative to most coastal regions (Hanson & Robertson 1988) but less than was observed by Hopkinson (1985) in the estuarine plume region of the nearshore Georgia Bight. The overall high levels of production, respiration and nutrient recycling in the Gray's Reef water column, which are in contrast to the generally low levels found in the mid-shelf region, suggest the influence of coupling with the nearshore region.…”

Nitrogen regeneration and dissolved organic nitrogen release during spring in a NW Mediterranean coastal zone (Gulf of Lions):implications for the estimation of new production

“…GentiLhomme & Rairnbault (1994) observed higher rates in the Algerian Current frontal area (SW Mediterranean Sea), ranging from 25 nM h ' at the surface to 125 nM h-' in the DCM. Some measurements performed during spring in other coastal marine systems (Harrison 1978, Cochlan 1986, Hanson & Robertson 1988) gave higher rates (from 2 to 240 nM h-'), but comparisons between their hourly and our daily rates are difficult since regeneration has been shown to vary greatly with the time of the day (Glibert 1982). Furthermore, in the latter studies (particularly in those of Harrison and of Cochlan) rates correspond to potential rates due to the large excess NH,' enrichment compared to the initial in situ NH4' concentrations (Selmer 1988).…”

Nitrogen recycling in coastal waters of southeastern U.S. during summer 1986

“…In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1). This imbalance was well within the range of 105 to 20:1 reported by others (Glibert et al, 1982;Laws, 1984;Kokkinakis andWheeRer, 1987, Hanson andRobertson, 1988). Many environmental and biological conditions have been identified for the 15N mass imbalance (cf.…”

“…Rate measurements for NH 4 + recycling. Estimates of NH 4 + assimilation and regeneration were made following 15NH4+ tracer procedures described earlier (Hanson and Robertson, 1988). Briefly, water samples were spiked with 0.05 /-Lmoles/L 15NH4+ (99% atom enrichment) in 21 acid-cleaned polycarbonate bottles.…”

“…However, even in nitraterich coastal bays and upwelling systems, several researchers have reported problems in obtaining 15N mass balance (Gilbert et al, 1982;Laws, 1984;Kokkinakis and Wheeler, 1987). Likewise, Hanson and Robertson (1988) found 1.5 times more 15NH4+ left the dissolved phase [uptake (U)l than was recovered in particulate components [assimilated (A)l in organic-rich waters off southeastern U.S. In this study 15N balanced well within the estuary (1.06:1), but in coastal waters a large imbalance occurred (4.05:1).…”

Community metabolism and nutrient cycling at Gray's Reef, a hard bottom habitat in the Georgia Bight

“…The high level of production w e measured at Gray's Reef (2.15 g C m-2 d-l) may be indicative of hydrographic coupling with the nearshore region, since productivity is generally < 300 mg C m-2 d-' further offshore (Thomas 1970, Turner et al 1979. Planktonic respiration and pelagic ammonium regeneration were high relative to most coastal regions (Hanson & Robertson 1988) but less than was observed by Hopkinson (1985) in the estuarine plume region of the nearshore Georgia Bight. The overall high levels of production, respiration and nutrient recycling in the Gray's Reef water column, which are in contrast to the generally low levels found in the mid-shelf region, suggest the influence of coupling with the nearshore region.…”

Nitrogen regeneration and dissolved organic nitrogen release during spring in a NW Mediterranean coastal zone (Gulf of Lions):implications for the estimation of new production

“…GentiLhomme & Rairnbault (1994) observed higher rates in the Algerian Current frontal area (SW Mediterranean Sea), ranging from 25 nM h ' at the surface to 125 nM h-' in the DCM. Some measurements performed during spring in other coastal marine systems (Harrison 1978, Cochlan 1986, Hanson & Robertson 1988) gave higher rates (from 2 to 240 nM h-'), but comparisons between their hourly and our daily rates are difficult since regeneration has been shown to vary greatly with the time of the day (Glibert 1982). Furthermore, in the latter studies (particularly in those of Harrison and of Cochlan) rates correspond to potential rates due to the large excess NH,' enrichment compared to the initial in situ NH4' concentrations (Selmer 1988).…”