Baron Jill S
U.S. Geological Survey, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado 80523-1499, USA.
Ecol Appl. 2006 Apr;16(2):433-9. doi: 10.1890/1051-0761(2006)016[0433:hndtda]2.0.co;2.
Using an estimated background nitrogen (N) deposition value of 0.5 kg N x ha(-1) x yr(-1) in 1900, and a 19-year record of measured values from Loch Vale (Colorado, USA; NADP site CO98), I reconstructed an N-deposition history using exponential equations that correlated well with EPA-reported NO(x) emissions from Colorado and from the sum of emissions of 11 western states. The mean wet N-deposition values for the period 1950-1964 was approximately 1.5 kg N x ha(-1) x yr(-1), corresponding to the reported time of alteration of diatom assemblages attributed to N deposition in alpine lakes in Rocky Mountain National Park (USA). This value becomes the critical load defining the threshold for ecological change from eutrophication. Thus if an N-deposition threshold for ecological change can be identified, and the date at which that threshold was crossed is known, hindcasting can derive the amount of atmospheric deposition at the time of change, at least for alpine lakes. Independent support for the technique and the deposition amount comes from experimental studies, ecosystem modeling, and paleolimnological records from northern Wyoming (USA).
利用1900年估计的背景氮（N）沉降值0.5千克氮×公顷⁻¹×年⁻¹，以及来自美国科罗拉多州洛赫韦尔（NADP站点CO98）的19年测量值记录，我使用指数方程重建了氮沉降历史，这些方程与美国环境保护局报告的科罗拉多州以及11个西部州排放总和中的氮氧化物排放量具有良好的相关性。1950 - 1964年期间的平均湿氮沉降值约为1.5千克氮×公顷⁻¹×年⁻¹，这与美国落基山国家公园高山湖泊中归因于氮沉降的硅藻组合变化的报告时间相对应。该值成为定义富营养化导致生态变化阈值的临界负荷。因此，如果能够确定生态变化的氮沉降阈值，并且知道该阈值被突破的日期，那么至少对于高山湖泊，后推法可以得出变化时的大气沉降量。对该技术和沉降量的独立支持来自美国怀俄明州北部的实验研究、生态系统建模和古湖沼学记录。
