Nitrogen deposition and lake nitrogen concentrations: a regional analysis of terrestrial controls and aquatic linkages

Abstract

Abstract. Loading of nutrients from terrestrial ecosystems strongly influences the productivity and biogeochemistry of aquatic ecosystems. Human activities can supplement and even dominate nutrient loading to many lakes, particularly in agricultural and urbanized settings. For lakes in more remote regions such as the Adirondack Mountains of New York, N deposition represents the primary potential anthropogenic nutrient source. We combined a spatial model of N deposition with data on lake-N concentrations and spatial data on watershed configuration to identify the sources of watershed N loading for over 250 lakes in the Adirondacks. The analysis indicates that while wetlands are stronger sources of N loading per unit area than forests in the absence of inorganic N deposition, wetlands retain essentially all N deposition, while forests retained ;87% of N deposition. Since forests cover close to 90% of the watersheds, upland forests are, on average, the single largest source of N loading to Adirondack lakes. Direct deposition of N to the lake surface accounted for as large a fraction of loading as that from wetlands in the watersheds. We found no evidence that presence of wetlands along flowpaths to lakes reduced loading from upland forests. Moreover, there was no evidence that net loading to lakes declined with increasing distance of a source area to the lake. Lake N-concentrations thus primarily reflect N-loading from forests in concert with loss rates determined by water residence time and within-lake processes.

Cascading influences of grassland degradation on nutrient limitation in a high mountain lake and its inflow streams

“…More specifically, we suggest that, as grassland degradation increases, aboveground vegetation declines together with deterioration of soil physical, chemical, and biological properties, such as soil moisture, nitrogen content, and microbial activity (Abril and Bucher 1999, Viragh et al 2011, Dlamini et al 2014. Soil and vegetation as well as soil microbes are the key factors influencing nutrient accumulation and export (Canham et al 2012), which then influence nutrient availability and movement potential in a watershed (Fraterrigo and Downing 2008). It has been demonstrated that high grass productivity increases soil N stocks by N fixation and enhances N mineralization (Fornara and Tilman 2008, Oelmann et al 2011, Cong et al 2014.…”

“…Soil and vegetation as well as soil microbes are the key factors influencing nutrient accumulation and export (Canham et al. ), which then influence nutrient availability and movement potential in a watershed (Fraterrigo and Downing ). It has been demonstrated that high grass productivity increases soil N stocks by N fixation and enhances N mineralization (Fornara and Tilman , Oelmann et al.…”

“…As a result, lakes have an intimate relationship with catchment characteristics through materials transported by surface runoff (Canham et al. , Cronan , Sadro et al. ).…”

“…Streams and rivers receive nutrients (such as nitrogen and phosphorus) and organic matter exported from terrestrial ecosystems and are strongly influenced by the landscapes through which they flow (Bring andDestouni 2009, Holmes et al 2012). As a result, lakes have an intimate relationship with catchment characteristics through materials transported by surface runoff (Canham et al 2012, Cronan 2012, Sadro et al 2012). Thus, changes in catchment landcover can alter the export of carbon and nutrients from catchments to lake ecosystems (Abell et al 2011, Erol and Randhir 2013, Umbanhowar et al 2015 and can indirectly shift nutrient status and limitation of lake ecosystems , Hoffmann and Dodson 2005, Vanni et al 2011.…”

First Assessment of Inorganic Nitrogen Deposition Budget Following the Impoundment of a Subtropical Hydroelectric Reservoir (Nam Theun 2, Lao PDR)

“…Studies of N input to various water surfaces (coastal, lake, river, and ocean) indicate that atmospheric nitrogen deposition represents a significant amount of the total nitrogen input (Canham et al, ; Gao et al, ; Jung et al, ; Qi et al, ; Whitall et al, ). Recent N deposition‐monitoring studies also showed very high N deposition rates at several observation sites including agricultural catchments in different regions of East Asia (Pan et al, ; Shen et al, ; Sugimoto & Tsuboi, ).…”