scholarly journals Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

2012 ◽  
Vol 9 (7) ◽  
pp. 9571-9601 ◽  
Author(s):  
Y. Shen ◽  
C. G. Fichot ◽  
R. Benner
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Arctic Ocean ◽  
Surface Waters ◽  
Microbial Growth ◽  
Chukchi Sea ◽  
Ecosystem Productivity ◽  
Western Arctic Ocean ◽  
Western Arctic ◽  
High Yields

Abstract. Dissolved organic carbon (DOC) and total dissolved amino acids (TDAA) were measured in high (Chukchi Sea) and low (Beaufort Sea) productivity regions of the Western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM). Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05) in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p < 0.0001) in the Chukchi than in the Beaufort. Unlike bulk DOC, TDAA concentrations and yields reflect ecosystem productivity in the Western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the Central Arctic basins.

scholarly journals Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

2012 ◽  
Vol 9 (12) ◽  
pp. 4993-5005 ◽  
Author(s):  
Y. Shen ◽  
C. G. Fichot ◽  
R. Benner
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Arctic Ocean ◽  
Surface Waters ◽  
Microbial Growth ◽  
Chukchi Sea ◽  
Ecosystem Productivity ◽  
Western Arctic Ocean ◽  
Western Arctic ◽  
High Concentrations

Abstract. Dissolved organic carbon (DOC) and total dissolved amino acids (TDAA) were measured in high (Chukchi Sea) and low (Beaufort Sea) productivity regions of the western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM). Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High concentrations and yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Concentrations and yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05) in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p < 0.0001) in the Chukchi than in the Beaufort. Unlike bulk DOC, TDAA concentrations and yields reflect ecosystem productivity in the western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi Sea implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the central Arctic basins.

scholarly journals Concentration maxima of volatile organic iodine compounds in the bottom layer water and the cold, dense water over the Chukchi Sea in the western Arctic Ocean: a possibility of production related to the degradation of organic matter

2016 ◽  
Vol 13 (1) ◽  
pp. 133-145 ◽  
Author(s):  
A. Ooki ◽  
S. Kawasaki ◽  
K. Kuma ◽  
S. Nishino ◽  
T. Kikuchi
Keyword(s):  
Organic Matter ◽  
Arctic Ocean ◽  
Chukchi Sea ◽  
Bottom Layer ◽  
Western Arctic Ocean ◽  
Dense Water ◽  
Organic Iodine ◽  
Iodine Compounds ◽  
Volatile Organic ◽  
Western Arctic

Abstract. We conducted a shipboard observation over the Chukchi Sea and the Canada Basin in the western Arctic Ocean in September and October 2012 to obtain vertical distributions of four volatile organic iodine compounds (VOIs) in seawater. The VOIs observed in this study were iodomethane (CH3I), iodoethane (C2H5I), diiodomethane (CH2I2), and chloroiodomethane (CH2ClI). Maximum concentrations of the four VOIs were found in the bottom layer water over the Chukchi Sea shelf, in which layer the maximum concentration of ammonium (NH4+) also occurred. A significant correlation was observed between C2H5I and NH4+ (correlation coefficient R = 0.93, P < 0.01, n = 64) and between CH3I and NH4+ (R= 0.77, P < 0.01, n =  64), suggesting that the production of these VOIs increased with the degradation of organic matter. Over the northern Chukchi Sea shelf–slope area, concentration maxima of CHI2, CH2ClI, and CH3I were found in the subsurface cold, dense water (CDW). A large nitrogen deficit (N deficit  =  NH4++ NO3−+ NO2−−16PO43−) occurred simultaneously in this water, suggesting the production of the three VOIs in the sediment or the bottom layer water over the shelf, probably in association with the degradation of organic matter. We conclude that VOI production over the Chukchi Sea shelf can be largely attributed to the degradation of organic matter that is produced in the highly productive shelf water. High concentrations of CH2ClI were also found in the Alaskan Coastal Water (ACW) from the Bering Strait to the surface of the northern Chukchi slope. The VOIs that originated at the Chukchi Sea shelf are expected to be laterally transported to the Arctic Ocean basin through the CDW and the surface ACW.

scholarly journals Concentration maxima of volatile organic iodine compounds in the bottom layer water and the cold, dense water over the Chukchi Sea in the western Arctic Ocean: a possibility of production related to degradation of organic matter

2015 ◽  
Vol 12 (14) ◽  
pp. 11245-11278 ◽  
Author(s):  
A. Ooki ◽  
S. Kawasaki ◽  
K. Kuma ◽  
S. Nishino ◽  
T. Kikuchi
Keyword(s):  
Organic Matter ◽  
Arctic Ocean ◽  
Chukchi Sea ◽  
Bottom Layer ◽  
Western Arctic Ocean ◽  
Dense Water ◽  
Organic Iodine ◽  
Iodine Compounds ◽  
Volatile Organic ◽  
Western Arctic

Abstract. We conducted a shipboard observation over the Chukchi Sea and the Canada Basin in the western Arctic Ocean in September and October 2012 to obtain vertical distributions of four volatile organic iodine compounds (VOIs) in seawater. VOIs are believed to play a role in ozone destruction in the troposphere and lower stratosphere. The VOIs observed in this study were iodomethane (CH3I), iodoethane (C2H5I), diiodomethane (CH2I2) and chloroiodomethane (CH2ClI). Maximum concentrations of the four VOIs were found in the bottom layer water over the Chukchi Sea shelf, in which layer the maximum concentration of ammonium (NH4+) also occurred. A significant correlation was observed between C2H5I and NH4+ (correlate coefficient R = 0.93) and between CH3I and NH4+ (R = 0.77), suggesting production of these VOIs increased with degradation of organic matter. Over the northern Chukchi Sea shelf–slope area, concentration maxima of CH2I2, CH2ClI, and CH3I were found in the subsurface cold, dense water (CDW). A large nitrogen deficit (N-deficit = NH4+ + NO3− + NO2− − 16PO43−) simultaneously occurred in this water, suggesting production of the three VOIs in the sediment or the bottom layer water over the shelf, probably in association with degradation of organic matter. We conclude that VOI production over the Chukchi Sea shelf can be largely attributed to the degradation of organic matter that is produced in the highly productive shelf water. High concentrations of CH2ClI were also found in the Alaskan Coastal Water (ACW) from the Bering Strait to the surface of the northern Chukchi slope. The VOIs that originated at the Chukchi Sea shelf are expected to be laterally transported to the Arctic Ocean Basin though the subsurface CDW and the surface ACW.

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