WasserCluster Lunz GmbH, 3293, Lunz am See, Austria.
Environ Sci Pollut Res Int. 2013 Mar;20(3):1781-93. doi: 10.1007/s11356-012-1135-2. Epub 2012 Sep 4.
Intensive agricultural land use imposes multiple pressures on streams. More specifically, the loading of streams with nutrient-enriched soil from surrounding crop fields may deteriorate the sediment quality. The current study aimed to find out whether stream restoration may be an effective tool to improve the sediment quality of agricultural headwater streams. We compared nine stream reaches representing different morphological types (forested meandering reaches vs. deforested channelized reaches) regarding sediment structure, sedimentary nutrient and organic matter concentrations, and benthic microbial respiration. Main differences among reach types were found in grain sizes. Meandering reaches featured larger mean grain sizes (50-70 μm) and a thicker oxygenated surface layer (8 cm) than channelized reaches (40 μm, 5 cm). Total phosphorous amounted for up to 1,500 μg g(-1) DW at retentive channelized reaches and 850-1,050 μg g(-1) DW at the others. While N-NH(4) accumulated in the sediments (60-180 μg g(-1) DW), N-NO(3) concentrations were generally low (2-5 μg g(-1) DW). Benthic respiration was high at all sites (10-20 g O(2) m(-2) day(-1)). Our study shows that both hydromorphology and bank vegetation may influence the sediment quality of agricultural streams, though effects are often small and spatially restricted. To increase the efficiency of stream restoration in agricultural landscapes, nutrient and sediment delivery to stream channels need to be minimized by mitigating soil erosion in the catchment.
集约化农业用地对溪流施加了多种压力。更具体地说，从周围农田中向溪流中输入富含养分的土壤可能会降低沉积物的质量。本研究旨在探讨溪流恢复是否可能是改善农业上游溪流沉积物质量的有效工具。我们比较了代表不同形态类型的 9 个溪流段（森林蜿蜒溪流段与无林渠道化溪流段），比较了它们的沉积物结构、沉积养分和有机质浓度以及底栖微生物呼吸作用。在粒径方面，发现各溪流段之间存在明显差异。蜿蜒溪流段的平均粒径较大（50-70 μm），且富氧表层较厚（8 cm），而渠道化溪流段的平均粒径较小（40 μm，5 cm）。在保留的渠道化溪流段中，总磷含量高达 1500μg/g DW，而在其他溪流段中为 850-1050μg/g DW。虽然 N-NH(4)在沉积物中积累（60-180 μg/g DW），但 N-NO(3)浓度通常较低（2-5 μg/g DW）。所有地点的底栖呼吸作用都很高（10-20 g O(2) m(-2) day(-1)）。我们的研究表明，水力学形态和河岸植被都可能影响农业溪流的沉积物质量，尽管影响通常较小且空间上受到限制。为了提高农业景观中溪流恢复的效率，需要通过减轻集水区的土壤侵蚀来减少养分和沉积物向溪流输送。
