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水域输送到北极盆地。这种涌入支持了北极发现的最丰富的生产力。据推测，部分生产力的出口可以为北极中部地区提供大量的有机物质。部分生产力通过沉积碳氧化在楚科奇海内消耗，美国楚科奇地区的生产率中等偏高。然而，对沉积硫酸盐还原速率的新测量表明，过去的估计低了好几倍。此外，在这些沉积物中，通过反硝化作用将无机氮转化为氮气似乎很快。因此，美国楚科奇地区的沉积物可能会比之前认为的更多地氧化生产力和去除更多的氮。此外，俄罗斯楚科奇海的大部分地区都有大量富含有机物质的沉积物，这表明俄罗斯地区可能会出现更大面积的沉积消耗，可能会有更高的氧化和反硝化速率。美国和俄罗斯楚科奇海的有机富集区将于1996年仲夏在整个无冰区进行采样。在每个站点，将通过重复通量实验测量沉积物-水的O2、N2、N2O、无机营养物质、TCO2和碱度的通量。硫酸盐还原速率的垂直剖面将由目前的35SO4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对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了解。对这些沉积过程的改进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.