Granular measures of agricultural land use influence lake nitrogen and phosphorus differently at macroscales
Granular measures of agricultural land use influence lake nitrogen and phosphorus differently at macroscales
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农业土地利用的细化措施在宏观尺度上对湖泊氮和磷的影响不同
DOI：
10.1002/eap.2187
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发表时间：
2020
影响因子：
5
通讯作者：
Soranno, P. A.
中科院分区：
文献类型：
--
作者：
Stachelek, Jemma;Weng, W.;Carey, C. C.;Kemanian, A. R.;Cobourn, K. M.;Wagner, T.;Weathers, K. C.;Soranno, P. A.
农业土地利用通常与河流营养物质浓度高和湖泊营养物质负荷增加有关。对于湖泊，这些关联的证据大多来自对单个湖泊或流域的研究，这些研究将氮(N)或磷(P)的浓度与农业土地利用的综合衡量指标联系起来，例如湖泊流域农业用地的比例。然而，在宏观尺度上(即，在大空间范围内的数百到数千个湖泊中)，围绕这种关系存在着高度的变异性，目前尚不清楚考虑更细粒度(或更详细)的农业数据，如化肥施用量、特定作物的种植或近河流种植的程度，是否会改善预测，并有助于了解湖泊营养驱动因素。此外，还不清楚N湖和P湖与这些措施是否有不同的关系，以及这些关系是否会因区域而异，因为以前的研究使用农业综合措施观察到了区域差异。为了解决这些知识差距，我们使用贝叶斯分层建模方法，研究了美国东北部和中西部928个湖泊及其流域的农业活动颗粒指标与湖泊总磷(TP)和总氮(TN)浓度之间的关系。我们发现湖泊TN和TP浓度都与这些农业措施有关，尤其是近水农业。农业措施与湖泊TN浓度之间的关系比TP之间的关系更具地域性。相反，相对于总氮，总磷浓度与湖泊特有的措施，如深度和流域水文的相关性更强。我们发现湖泊TN和TP浓度与农业活动的颗粒测量具有不同的关系，这对于设计有效和高效的政策方法来维持和改善水质具有重要意义。
Agricultural land use is typically associated with high stream nutrient concentrations and increased nutrient loading to lakes. For lakes, evidence for these associations mostly comes from studies on individual lakes or watersheds that relate concentrations of nitrogen (N) or phosphorus (P) to aggregate measures of agricultural land use, such as the proportion of land used for agriculture in a lake’s watershed. However, at macroscales (i.e., in hundreds to thousands of lakes across large spatial extents), there is high variability around such relationships and it is unclear whether considering more granular (or detailed) agricultural data, such as fertilizer application, planting of specific crops, or the extent of near‐stream cropping, would improve prediction and inform understanding of lake nutrient drivers. Furthermore, it is unclear whether lake N and P would have different relationships to such measures and whether these relationships would vary by region, since regional variation has been observed in prior studies using aggregate measures of agriculture. To address these knowledge gaps, we examined relationships between granular measures of agricultural activity and lake total phosphorus (TP) and total nitrogen (TN) concentrations in 928 lakes and their watersheds in the Northeastern and Midwest U.S. using a Bayesian hierarchical modeling approach. We found that both lake TN and TP concentrations were related to these measures of agriculture, especially near‐stream agriculture. The relationships between measures of agriculture and lake TN concentrations were more regionally variable than those for TP. Conversely, TP concentrations were more strongly related to lake‐specific measures like depth and watershed hydrology relative to TN. Our finding that lake TN and TP concentrations have different relationships with granular measures of agricultural activity has implications for the design of effective and efficient policy approaches to maintain and improve water quality.