湖泊沉积物-水界面氧气交换速率的测定及影响因素

Spatial heterogeneity of oxygen exchange between sediment-water interface in lakes

水流启动-停止法可有效获取体积式氧气交换速率(O2(t)),且该速率与沉积物柱样培养法获得的总氧气交换速率(TOE)之间具显著相关性;与由一维溶解氧剖面计算获得的氧气在扩散界面层中的扩散速率和氧气在沉积物中的扩散速率相比,O2(t)与TOE不仅能代表氧气扩散速率,而且还包括沉积物中生物呼吸以及生物扰动引起的界面氧气交换速率信息.此外,通过比较太湖及南四湖多位点不同沉积物性质条件下界面氧气交换速率,结果表明界面氧气交换速率在空间尺度上的差异性,除与生物因素有关外,还与沉积物有机物质含量显著相关.

Volumetric oxygen exchange rate （O2（t））, based on measurement by a flow-on/flow-offcontrolling method, is significantly correlated with TOE （total oxygen exchange） obtained from laboratory-incubated sediment cores. The difference between TOE and DOE （diffusive oxygen exchange in diffusive boundary layers） suggested that there is a fauna-mediated O2 consumption in the two factors. Comparison of DOE with DOEs （diffusive oxygen exchange in sediments） from one-dimensional oxygen concentration profiles at a steady stationary condition, O2（t） as well as TOE, is an integrated measurement for the diffusion, advection and fauna-mediated O2 consumption. Furthermore, a comparative study of TOE values among sediments from Lake Taihu and Lake Nansihu revealed that the difference from the sites was due to the variation of organic matter concentration in the surface sediments, additionally effects of benthic faunas.