Parr Lynn B, Mason Christopher F
Department of Biological Sciences, University of Essex, Wivenhoe Park, Essex, Colchester CO4 3SQ, UK.
Sci Total Environ. 2004 Apr 5;321(1-3):273-86. doi: 10.1016/j.scitotenv.2003.09.004.
In the River Brett, Eastern England, over the period 1955-1998 there was a significant long-term decline in dissolved oxygen (DO), as well as increases in TON (total oxidised nitrogen) and SRP (soluble reactive phosphorus). Flow decreased from 1963 to 1998. Field studies in 1998-2000 showed increased pH and a gradient of DO beneath the filamentous alga Cladophora glomerata. DO decreased through the summer. Macrophytes accounted for 45% of community respiration at the study site, while sediment accounted for 36%. In container studies, muddy sediments had the highest maximum sediment oxygen demand (SOD), but canopies of C. glomerata and Lemna minor together increased the SOD by up to 90% over control samples. During periods of high temperature, abundant growths of C. glomerata and/or L. minor would increase the SOD of organic mud in river areas with shallow, ponded water, eventually leading to anoxic conditions and the release of nutrients from the sediment. If a river had large areas of mud, these processes could dramatically affect the river's oxygen budget, and hence its ecology.
在英格兰东部的布雷特河，1955年至1998年期间，溶解氧（DO）出现了显著的长期下降，同时总氧化氮（TON）和可溶性活性磷（SRP）有所增加。1963年至1998年流量减少。1998年至2000年的实地研究表明，丝状绿藻团集刚毛藻下方的pH值升高且溶解氧呈梯度变化。溶解氧在夏季减少。大型植物占研究地点群落呼吸的45%，而沉积物占36%。在容器研究中，泥质沉积物的最大沉积物需氧量（SOD）最高，但团集刚毛藻和浮萍的冠层共同使SOD比对照样本增加了90%。在高温时期，团集刚毛藻和/或浮萍的大量生长会增加浅水积水河域有机泥的SOD，最终导致缺氧状况并使沉积物中的养分释放。如果一条河流有大面积的泥质区域，这些过程可能会极大地影响河流的氧气平衡，进而影响其生态。
