Kern J, Darwich A, Furch K, Junk WJ
Max-Planck-Institute of Limnology, D-24302 Plan, Germany
Microb Ecol. 1996 Jul;32(1):47-57. doi: 10.1007/BF00170106.
Denitrification processes were measured by the acetylene-blockage technique under changing flood conditions along the aquatic/terrestrial transition zone on the Amazon floodplain at Lago Camaleao, near Manaus, Brazil. In flooded sediments, denitrification was recorded after the amendment with NO3- (100 μmol liter-1) throughout the whole study period from August 1992 to February 1993. It ranged from 192.3 to 640.7 μmol N m-2 h-1 in the 0- to 5-cm sediment layer. Without substrate amendment, denitrification was detected only during low water in November and December 1992, when it occurred at a rate of up to 12.2 μmol N m-2 h-1. Higher rates of denitrification at an average rate of 73.3 μmol N m-2 h-1 were measured in sediments from the shallow lake basin that were exposed to air at low water. N2O evolution was never detected in flooded sediments, but in exposed sediments, it was detected at an average rate of 28.3 μmol N m-2 h-1 during the low-water period. The results indicate that under natural conditions there is denitrification and hence a loss in nitrogen from the Amazon floodplain to the atmosphere. Rates of denitrification in flooded sediments were one to two orders of magnitude smaller than in temperate regions. However, the nitrogen removal of exposed sediments exceeded that of undisturbed wetland soils of temperate regions, indicating a considerable impact of the flood pulse on the gaseous turnover of nitrogen in the Amazon floodplain.
在巴西马瑙斯附近的卡马莱奥湖（Lago Camaleao），沿着亚马逊河漫滩水生/陆生过渡带，在不断变化的洪水条件下，采用乙炔阻断技术测量了反硝化过程。在1992年8月至1993年2月的整个研究期间，在水淹沉积物中添加NO3-（100μmol·L-1）后记录到了反硝化作用。在0至5厘米的沉积层中，反硝化速率范围为192.3至640.7μmol N·m-2·h-1。在没有添加底物的情况下，仅在1992年11月和12月的低水位期间检测到反硝化作用，其速率高达12.2μmol N·m-2·h-1。在低水位时暴露于空气中的浅湖盆沉积物中，测量到更高的反硝化速率，平均为73.3μmol N·m-2·h-1。在水淹沉积物中从未检测到N2O的释放，但在暴露的沉积物中，在低水位期间检测到其平均释放速率为28.3μmol N·m-2·h-1。结果表明，在自然条件下存在反硝化作用，因此亚马逊河漫滩的氮会向大气中流失。水淹沉积物中的反硝化速率比温带地区小一到两个数量级。然而，暴露沉积物的氮去除量超过了温带地区未受干扰的湿地土壤，这表明洪水脉冲对亚马逊河漫滩氮的气态周转有相当大的影响。
