The importance of the riparian zone and in-stream processes in nitrate attenuation in undisturbed and agricultural watersheds – A review of the scientific literature

Ranalli, Anthony J.; Macalady, Donald L.

doi:10.1016/j.jhydrol.2010.05.045

Cited by 205 publications

(150 citation statements)

References 84 publications

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“…Further, the inclusion of parameters to describe the relative saturation of soils (i.e., the topographic index) did not improve model fits. In theory nitrate moving into saturated soils should be lost to processes like denitrification as demonstrated by numerous studies (Hill 1996, Mayer et al 2007, Ranalli and Macalady 2010. However, this biogeochemical processing will have much less impact on total nitrogen if dissolved organic nitrogen is the principal agent of transport and downstream loading, particularly in these remote, largely undeveloped watersheds (Perakis and Hedin 2002).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2012

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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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2012

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“…Riparian zones are noted for their nutrient and sediment retention capacity (Ranalli and Macalady, 2010), and have the potential to sequester C in places where oxygen supply is limited by the stream water thus hampering aerobic decomposition of organic matter (Holden, 2005). Denitrification in riparian buffers is often found to be the major process responsible for NO − 3 removal from subsurface runoff and groundwater .…”

Section: Biogeochemistry In Riparian Zones and Delivery To Streamsmentioning

confidence: 99%

Nutrient dynamics, transfer and retention along the aquatic continuum from land to ocean: towards integration of ecological and biogeochemical models

et al. 2013

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Abstract. In river basins, soils, groundwater, riparian zones and floodplains, streams, rivers, lakes and reservoirs act as successive filters in which the hydrology, ecology and biogeochemical processing are strongly coupled and together act to retain a significant fraction of the nutrients transported. This paper compares existing river ecology concepts with current approaches to describe river biogeochemistry, and assesses the value of these concepts and approaches for understanding the impacts of interacting global change disturbances on river biogeochemistry. Through merging perspectives, concepts, and modeling techniques, we propose integrated model approaches that encompass both aquatic and terrestrial components in heterogeneous landscapes. In this model framework, existing ecological and biogeochemical concepts are extended with a balanced approach for assessing nutrient and sediment delivery, on the one hand, and nutrient in-stream retention on the other hand.

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“…The correlation between NO 3 and temperature independent of solar radiation, suggests a possible role for non-photosynthetic organisms, perhaps in the deeper part of the hyporheic zone where uptake is not light-dependent (see review by Ranalli and Macalady, 2010). Denitrification or other removal processes in the hyporheic zone are a possibility (see Trimmer, 2012), even though this is a well-oxygenated system, but further research is required to determine the significance of this process to the diurnal streamwater NO 3 dynamics.…”

Section: Upper Hafren Controlsmentioning

confidence: 99%

Upland streamwater nitrate dynamics across decadal to sub-daily timescales: a case study of Plynlimon, Wales

et al. 2013

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Abstract. Streamwater nitrate dynamics in the River Hafren, Plynlimon, mid-Wales were investigated over decadal to sub-daily timescales using a range of statistical techniques. Long-term data were derived from weekly grab samples and high-frequency data from 7-hourly samples (2007)(2008)(2009)) both measured at two sites: a headwater stream draining moorland and a downstream site below plantation forest. This study is one of the first to analyse upland streamwater nitrate dynamics across such a wide range of timescales and report on the principal mechanisms identified. The data analysis provided no clear evidence that the long-term decline in streamwater nitrate concentrations was related to a decline in atmospheric deposition alone, because nitrogen deposition first increased and then decreased during the study period. Increased streamwater temperature and denitrification may also have contributed to the decline in stream nitrate concentrations, the former through increased N uptake rates and the latter resultant from increased dissolved organic carbon concentrations. Strong seasonal cycles, with concentration minimums in the summer, were driven by seasonal flow minimums and seasonal biological activity enhancing nitrate uptake. Complex diurnal dynamics were observed, with seasonal changes in phase and amplitude of the cycling, and the diurnal dynamics were variable along the river. At the moorland site, a regular daily cycle, with minimum concentrations in the early afternoon, corresponding with peak air temperatures, indicated the importance of instream biological processing. At the downstream site, the diurnal dynamics were a composite signal, resultant from advection, dispersion and nitrate processing in the soils of the lower catchment. The diurnal streamwater nitrate dynamics were also affected by drought conditions. Enhanced diurnal cycling in Spring 2007 was attributed to increased nitrate availability in the post-drought period as well as low flow rates and high temperatures over this period. The combination of high-frequency short-term measurements and long-term monitoring provides a powerful tool for increasing understanding of the controls of element fluxes and concentrations in surface waters.

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The importance of the riparian zone and in-stream processes in nitrate attenuation in undisturbed and agricultural watersheds – A review of the scientific literature

Cited by 205 publications

References 84 publications

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

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

Nutrient dynamics, transfer and retention along the aquatic continuum from land to ocean: towards integration of ecological and biogeochemical models

Upland streamwater nitrate dynamics across decadal to sub-daily timescales: a case study of Plynlimon, Wales

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