The prediction and management of aquatic nitrogen pollution across Europe: an introduction to the Integrated Nitrogen in European Catchments project (INCA)

The distributions of nitrate, nitrite and ammonium at various monitoring sites across the Humber basin (area 24 000 km 2 ) were examined within a Geographical Information System (GIS) framework. This basin contains diverse characteristics, from areas of high population and industry to rural and arable regions. The Humber River is a major provider of nutrient fluxes to the North Sea from the UK. Within the GIS analysis, the distributions of mean and mean flow weighted concentrations, flux and flux per unit area, were investigated. Empirical relationships between land characteristics and water quality for the whole catchment draining to each water quality monitoring site were established. Thirty-eight catchments were chosen for this analysis, with areas ranging from 46 km 2 to 8225 km 2 . These catchments are distributed across the Humber, encompassing the different conditions across the basin, thus allowing relationships between water quality and catchment characteristics to be used to estimate the nitrogen concentrations and flux throughout the basin river network. The main water quality data source was the Land Ocean Interaction Study (LOIS) dataset. The Environment Agency of England and Wales water quality datasets were used to infill areas of sparse LOIS monitoring network density within the Humber. The work shows the feasibility of estimating nitrate and, to a lesser extent, nitrite and ammonium concentrations and fluxes across the river network based on land characteristics, using a GIS methodology. The estimations work particularly well for the main river channels. However, there are local anomalies which are more difficult to predict. Maps showing concentration variations at 500 m intervals along the Humber basin river networks are presented; these are of particular value for environmental managers and socio-economists.

Section: Introductionmentioning

confidence: 99%

GIS-based methodologies for assessing nitrate, nitrite and ammonium distributions across a major UK basin, the Humber

Davies

Neal

2004

“…Both Dalelva and Øygard (as part of the larger Bjerkreim river system) have recently been included in a joint European project intending to adapt the process-oriented INCA model (Integrated Nitrogen model for CAtchments) (Wade and Whitehead, 2002) to key ecosystem types throughout 8 countries. By linking hydrology with the microbial processes controlling N behaviour in soils and river reaches, the model simulates the contribution of multiple sources to catchment N pools and river nitrate (NO 3 -) and ammonium (NH 4 + ) concentrations.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen dynamics in runoff from two small heathland catchments representing opposite extremes with respect to climate and N deposition in Norway

Kaste

Skjelkvåle

2002

Effects of contrasting climatic conditions and nitrogen (N) deposition levels on streamwater N dynamics are assessed at two small heathland catchments; Dalelva in northern Norway (69 o N) and Øygard in southwestern Norway (58 o N). The study comprises 11 years of data on climate, hydrology and N inputs/outputs from Dalelva and 8 years of corresponding data from Øygard. Both sites are comparable in catchment size, geology and land cover characteristics, but have large differences in climate and N deposition. Dalelva is characterised by a cold, arctic climate and low N deposition (2-3 kg N ha -1 yr -1 ), whereas the Øygard site has a more mild, humid climate with much larger N deposition (13-19 kg N ha -1 yr -1 ). Streamwater nitrate (NO 3 -) concentrations at Dalelva generally were negligible during the growing season, but showed a steady increase during the dormant season until a maximum of 40-100 µg N L -1 was reached just before snowmelt. At onset of the snowmelt flood, NO 3 -concentrations decreased momentarily to very low levels, suggesting that N eluted from the seasonal snowpack to a great extent was infiltrated and immobilised in the soils. At Øygard, flood peaks occurred frequently during all seasons, and usually there was no distinct spring flood. A lack of clear dilution effects from floods on streamwater NO 3 -concentrations may indicate a relatively high NO 3 -leaching potential in this catchment. On average, the annual NO 3 -export was negligible at Dalelva (<0.1 kg N ha -1 yr -1 ), while at Øygard it amounted to 3.0±0.3 (±1 s.d.) kg ha -1 yr -1 , or nearly 20% of the annual N deposition. In addition to this relatively high annual N loss, elevated NO 3 -concentrations during the growing season further indicate that the N supply at Øygard is in excess of the combined plant and microbial demand.

“…To provide a generic tool for management of water quality across Europe, the model has been tested and modified through investigations in a wide range of ecosystem types within eight European countries (Wade et al, 2002b;Wade, 2004). During this work, it became evident that INCA underestimates N transformation processes in northern catchments of Finland and Norway to a large extent in winter and spring when the catchments are covered with snow.…”

Section: Introductionmentioning

confidence: 99%

Adaptation of the Integrated Nitrogen Model for Catchments (INCA) to seasonally snow-covered catchments

Ранкинен

Kaste

Butterfield

2004

Testing of the Integrated Nitrogen model for Catchments (INCA) in a wide range of ecosystem types across Europe has shown that the model underestimates N transformation processes to a large extent in northern catchments of Finland and Norway in winter and spring. It is found, and generally assumed, that microbial activity in soils proceeds at low rates at northern latitudes during winter, even at sub-zero temperatures. The INCA model was modified to improve the simulation of N transformation rates in northern catchments, characterised by cold climates and extensive snow accumulation and insulation in winter, by introducing an empirical function to simulate soil temperatures below the seasonal snow pack, and a degree-day model to calculate the depth of the snow pack. The proposed snow-correction factor improved the simulation of soil temperatures at Finnish and Norwegian field sites in winter, although soil temperature was still underestimated during periods with a thin snow cover. Finally, a comparison between the modified INCA version (v.1.7) and the former version (v.1.6) was made at the Simojoki river basin in northern Finland and at Dalelva Brook in northern Norway. The new modules did not imply any significant changes in simulated NO 3 concentration levels in the streams but improved the timing of simulated higher concentrations. The inclusion of a modified temperature response function and an empirical snow-correction factor improved the flexibility and applicability of the model for climate effect studies.