Evaluating Stream Water Quality through Land Use Analysis in Two Grassland Catchments

Abstract

We evaluated the impacts of natural wetlands and various land uses on stream nitrogen concentration in two grassland-dominated catchments in eastern Hokkaido, Japan. Analyzing land use types in drainage basins, measuring denitrification potential of its soil, and water sampling in all seasons of 2003 were performed. Results showed a highly significant positive correlation between the concentration of stream NO3-N and the proportion of upland area in drainage basins in both catchments. The regression slope, which we assumed to reflect the impact on water quality, was 24% lower for the Akkeshi catchment (0.012 +/- 0.001) than for the Shibetsu catchment (0.016 +/- 0.001). In the Akkeshi catchment, there was a significant negative correlation between the proportion of wetlands in the drainage basins and stream NO3-N concentration. Stream dissolved organic nitrogen (DON) and carbon (DOC) concentrations were significantly higher in the Akkeshi catchment. Upland and urban land uses were strongly linked to increases in in-stream N concentrations in both catchments, whereas wetlands and forests tended to mitigate water quality degradation. The denitrification potential of the soils was highest in wetlands, medium in riparian forests, and lowest in grasslands; and was significant in wetlands and riparian forests in the Akkeshi catchment. The solubility of soil organic carbon (SOC) and soil moisture tended to determine the denitrification potential. These results indicate that the water environment within the catchments, which influences denitrification potential and soil organic matter content, could have caused the difference in stream water quality between the two catchments.

Dissolved organic carbon and nitrogen in urban and rural watersheds of south-central Texas: land use and land management influences

“…Fewer studies have investigated what affect urbanization may have on dissolved organic nitrogen (Pellerin et al 2004(Pellerin et al , 2006Hayakawa et al 2006). The Ipswich watershed and its sub-catchments in Massachusetts comprising 35% urban area showed a very low but nevertheless significant positive relationship (r 2 = 0.09, p \ 0.05) between DON and developed land but the authors suggested that percentage wetland within the watershed and its sub-catchments was a better predictor of DON (Pellerin et al 2004).…”

Contribution of livestock farming systems to the nitrogen cascade and consequences for farming regions

“…This is also the conclusion of the European Environment Agency as illustrated in Figures 5 and 6. Nitrate leakages are predominantly related to the proportion of farmland in the region, the types of cropping systems present and the soil-climatic context (Johnson et al, 2001;Hayakawa et al, 2006;Lam et al, 2010;Montreuil et al, 2010;Shimizu et al, 2010;Durand et al, 2011). Concentrations found in rivers and aquifers have confirmed that although the water quality in regions of intensive livestock farming systems is generally degraded, they are not the only ones as the intensive croplands are also major nitrogen emitters because of the use of great quantities of inorganic fertilisers.…”

Evaluación de la producción de sedimentos y calidad de las aguas en cuencas agrarias de Navarra

“…Estas diferencias están en relación con la elevada actividad ganadera (vertido de purines) y agrícola en Op. Además, los suelos bajo bosque -por su alto poder denitrificante-reducen el aporte de nitrógeno hacia las corrientes de agua (Hayakawa et al, 2006). Igualmente, en cuencas dominadas por pasturas suelen registrarse exportaciones de nitrógeno que duplican a las medidas en cuencas forestales (Álvarez-Cobelas et al, 2008).…”