排序方式: 共有2条查询结果,搜索用时 15 毫秒
1
1.
Mark D. Tomer Michael G. Dosskey Michael R. Burkart David E. James Matthew J. Helmers Dean E. Eisenhauer 《Agroforestry Systems》2009,75(1):17-25
Agroforestry buffers in riparian zones can improve stream water quality, provided they intercept and remove contaminants from
surface runoff and/or shallow groundwater. Soils, topography, surficial geology, and hydrology determine the capability of
forest buffers to intercept and treat these flows. This paper describes two landscape analysis techniques for identifying
and mapping locations where agroforestry buffers can effectively improve water quality. One technique employs soil survey
information to rank soil map units for how effectively a buffer, when sited on them, would trap sediment from adjacent cropped
fields. Results allow soil map units to be compared for relative effectiveness of buffers for improving water quality and,
thereby, to prioritize locations for buffer establishment. A second technique uses topographic and streamflow information
to help identify locations where buffers are most likely to intercept water moving towards streams. For example, the topographic
wetness index, an indicator of potential soil saturation on given terrain, identifies where buffers can readily intercept
surface runoff and/or shallow groundwater flows. Maps based on this index can be useful for site-specific buffer placement
at farm and small-watershed scales. A case study utilizing this technique shows that riparian forests likely have the greatest
potential to improve water quality along first-order streams, rather than larger streams. The two methods are complementary
and could be combined, pending the outcome of future research. Both approaches also use data that are publicly available in
the US. The information can guide projects and programs at scales ranging from farm-scale planning to regional policy implementation. 相似文献
2.
The degree to which floating aquatic plants concentrate Se in tissues was determined for four species grown in solutions containing various levels of Se. Results of this greenhouse study showed that all four plant species, Azolla caroliniana, Eichhornia crassipes, Salvinia rotundi folia, and Lemna minor absorbed Se quickly upon exposure to Se in water as concentrated as 2.5 g Se mL–1, and attained maximum tissue concentrations within 1 to 2 weeks. Azolla absorbed Se to the highest tissue concentration (about 1000 g Se g–1 dry matter) from the 2.5 g Se mL–1 solution, followed by Salvinia (700 g Se g–1), Lemna (500 g Se g–1),and Eichhornia (300 g Se g–1). Plant growth appeared unaffected by solution Se concentrations lower than about 1.25 g mL–1. These results indicate potential for rapid Se movement from water into aquatic food chains, and for use of aquatic plants for Se removal in wastewater treatment systems. 相似文献
1