Carbon Oxidation and Denitrification Rates in Sediments of the Chukchi Sea

通过白令海峡向北的水流将富含硝酸盐的太平洋沃茨输送到北极盆地。 这种流入支持了北极地区最丰富的生产力。 据推测，这种生产力的一部分出口可以为北极中部提供大量的有机物质。 部分生产力在楚科奇海内通过沉积碳氧化消耗，美国楚科奇海地区的速率相当高。 然而，对沉积硫酸盐还原率的新测量表明，过去的估计值低了好几倍。 此外，无机氮转化为N2的反硝化作用在这些沉积物中似乎是快速的。 因此，美国楚科奇河的沉积物可能比以前认为的氧化更多的生产力和去除更多的氮。此外，俄罗斯楚科奇海大部分地区的海底都有大量富含有机物的沉积物，这表明俄罗斯地区可能会出现更大面积的沉积物消耗，氧化和反硝化速率可能会更高。 1996年仲夏，将在整个无冰区对美国和俄罗斯楚科奇海的有机物丰富区进行取样。 在每个站点，O2，N2，N2 O，无机营养物，TCO 2和碱度的沉积物-水通量将在重复通量实验中测量。 硫酸盐还原率的垂直剖面将通过目前的35 SO 4示踪技术确定。 还将确定关键溶质的孔隙度、有机质含量和孔隙水分布。 这些数据将扩大我们的沉积碳氧化和反硝化速率及其在楚科奇海生产力循环中的作用的知识。 对这些沉积过程的更好估计将更好地估计该区域向北极盆地其他地区输出大量有机物质的潜力。

The northward flow through the Bering Strait transports nitrate-rich Pacific waters into the Arctic basin. This influx supports the richest productivity found in the Arctic. It has been hypothesized that export of part of this productivity could supply significant amounts of organic matter to the central Arctic. Part of the productivity is consumed within the Chukchi Sea via sedimentary carbon oxidation, and the rates in the U.S. region of the Chukchi are moderately high. However, new measurements of sedimentary sulfate reduction rates indicate that past estimates were several-fold low. Furthermore, conversion of inorganic nitrogen to N2 by denitrification in these sediments appears to be rapid. Thus, the sediments in the American Chukchi may oxidize more of the productivity and remove more of the nitrogen than previously thought. Furthermore, a large pool of organic rich sediments underlies much of the Russian Chukchi Sea, suggesting that even larger areas of sedimentary consumption, perhaps with even greater rates of oxidation and denitrification, may occur in the Russian areas. The organic rich areas of the U.S. and Russian Chukchi Sea will be sampled throughout the ice-free regions in mid summer of 1996. At each site, sediment-water fluxes of O2, N2, N2O, inorganic nutrients, TCO2, and alkalinity will be measured in replicate flux experiments. Vertical profiles of sulfate reduction rates will be determined by current 35SO4 tracer techniques. Porosity, organic matter content and pore water distributions of key solutes will also be determined. These data would expand our knowledge of sedimentary carbon oxidation and denitrification rates and their role in the productivity cycle in the Chukchi Sea. The improved estimates of these sedimentary processes will better estimate the potential for this region to export significant quantities of organic matter to the rest of the Arctic basin.