Steinman Alan D, Ogdahl Mary
Annis Water Resources Inst., Grand Valley State University, 740 West Shoreline Drive, Muskegon, MI 49441, USA.
J Environ Qual. 2008 Jan 4;37(1):22-9. doi: 10.2134/jeq2007.0142. Print 2008 Jan-Feb.
A whole-lake alum treatment was applied to eutrophic Spring Lake during October and November 2005. Eight months later, an ecological assessment of the lake was performed and compared with data collected in 2003 and 2004. Field measurements showed reduced soluble reactive phosphorus (SRP) and total phosphorus (TP) concentrations in the water column the summer after the alum application, but chlorophyll levels and irradiance profiles were not significantly affected. Total macroinvertebrate density declined significantly in 2006 compared with 2004, with chaoborids and oligochaetes experiencing the greatest reductions. Internal phosphorus release rates, measured using sediment cores incubated in the laboratory, ranged from -0.052 to 0.877 mg TP m(-2) d(-1) under anaerobic conditions. These internal loading rates were significantly lower than those measured in 2003 at three out of four sites. Mean porewater SRP concentrations were lower in 2006 than in 2003, but this difference was statistically significant only under aerobic conditions. The NaOH-extractable SRP fraction in the sediment was also significantly lower in 2006 compared with 2003, whereas the HCl-extractable SRP sediment fraction showed the opposite pattern. Overall, these results indicate that the alum treatment effectively reduced internal P loading in Spring Lake. However, water column phosphorus concentrations remain high in this system, presumably due to high external loading levels, and may account for the high chlorophyll levels. An integrated watershed management approach that includes reducing internal and external inputs of P is necessary to address the cultural eutrophication of Spring Lake.
2005年10月和11月，对富营养化的春湖进行了全湖明矾处理。八个月后，对该湖进行了生态评估，并与2003年和2004年收集的数据进行了比较。实地测量表明，明矾处理后的夏季，水柱中的可溶性活性磷（SRP）和总磷（TP）浓度降低，但叶绿素水平和光照强度分布未受到显著影响。与2004年相比，2006年大型无脊椎动物的总密度显著下降，其中摇蚊幼虫和寡毛纲动物的减少最为明显。在实验室中使用沉积物柱测量的内部磷释放率，在厌氧条件下范围为-0.052至0.877 mg TP m(-2) d(-1)。在四个地点中的三个地点，这些内部负荷率显著低于2003年测量的值。2006年孔隙水中的平均SRP浓度低于2003年，但仅在有氧条件下，这种差异具有统计学意义。与2003年相比，2006年沉积物中NaOH可提取的SRP部分也显著降低，而HCl可提取的SRP沉积物部分则呈现相反的模式。总体而言，这些结果表明，明矾处理有效地降低了春湖的内部磷负荷。然而，该系统中水柱中的磷浓度仍然很高，可能是由于外部负荷水平较高，这可能是叶绿素水平较高的原因。需要一种综合的流域管理方法，包括减少磷的内部和外部输入，以解决春湖的富营养化问题。
