US Geological Survey, Denver Federal Center, Denver, CO 80225, USA.
Environ Pollut. 2012 Jul;166:125-35. doi: 10.1016/j.envpol.2012.03.019. Epub 2012 Apr 11.
Spatially explicit estimates of critical loads of nitrogen (N) deposition (CL(Ndep)) for nutrient enrichment in aquatic ecosystems were developed for the Rocky Mountains, USA, using a geostatistical approach. The lowest CL(Ndep) estimates (<1.5 ± 1 kg N ha(-1) yr(-1)) occurred in high-elevation basins with steep slopes, sparse vegetation, and abundance of exposed bedrock and talus. These areas often correspond with areas of high N deposition (>3 kg N ha(-1) yr(-1)), resulting in CL(Ndep) exceedances ≥ 1.5 ± 1 kg N ha(-1) yr(-1). CL(Ndep) and CL(Ndep) exceedances exhibit substantial spatial variability related to basin characteristics and are highly sensitive to the NO(3)(-) threshold at which ecological effects are thought to occur. Based on an NO(3)(-) threshold of 0.5 μmol L(-1), N deposition exceeds CL(Ndep) in 21 ± 8% of the study area; thus, broad areas of the Rocky Mountains may be impacted by excess N deposition, with greatest impacts at high elevations.
采用地统计学方法，为美国落基山脉地区制定了富营养化的氮（N）沉积临界负荷（CL（Ndep））的空间明确估计值。最低的 CL（Ndep）估计值（<1.5 ± 1 kg N ha（-1）yr（-1））出现在高海拔、坡度陡峭、植被稀疏、基岩和碎石大量暴露的流域。这些地区通常与高 N 沉积区（>3 kg N ha（-1）yr（-1））相对应，导致 CL（Ndep）超过≥ 1.5 ± 1 kg N ha（-1）yr（-1）。CL（Ndep）和 CL（Ndep）超过值与流域特征相关，具有很大的空间变异性，并且对被认为会发生生态效应的 NO（3）（-）阈值非常敏感。基于 0.5 μmol L（-1）的 NO（3）（-）阈值，研究区有 21 ± 8%的区域的 N 沉积超过了 CL（Ndep）；因此，落基山脉的广大地区可能受到过量 N 沉积的影响，高海拔地区的影响最大。
