The composition of nutrient fluxes from contrasting UK river basins

Abstract

Abstract:Accurate estimates of N and P loads were obtained for four contrasting UK river basins over a complete annual cycle. The fractionation of these loads into dissolved and particulate, and inorganic and organic components allowed a detailed examination of the nutrient load composition and of the factors in¯uencing both the relative and absolute magnitude of these components. The particulate phosphorus (TPP) loads account for 26±75% of the annual total phosphorus (TP) transport and are predominantly inorganic. The inorganic (PIP) and organic (POP) fractions of the TPP loads represent 20±47% and 6±28% of the annual TP transport, respectively. In contrast, the particulate nitrogen loads (TPN) represent 8% or less of the annual total nitrogen (TN) loads and are predominately organic. For dissolved P transport, the dissolved inorganic fraction (DIP) is more important, representing 15±70% of the TP loads, whereas the dissolved organic fraction (DOP) represents only 3±9% of the TP loads. The TN loads are dominated by the dissolved component and more particularly the total oxidized fraction (TON), which is composed of nitrate and nitrite and represents 76±82% of the annual TN transport. The remaining dissolved N species, ammonium (NH 4 -N) and organic N (DON) account for 0 . 3±1 . 2% and 13±16% of the annual TN transport, respectively. The TPN and TPP¯uxes closely re¯ect the suspended sediment dynamics of the study basins, which are in turn controlled by basin size and morphology. The dissolved inorganic nutrient¯uxes are in¯uenced by point source inputs to the study basins, especially for P, although the TON¯ux is primarily in¯uenced by diuse source contributions and the hydrological connectivity between the river and its catchment area. The dissolved organic fractions are closely related to the dissolved organic carbon (DOC) dynamics, which are in turn in¯uenced by land use and basin size. The magnitude of the NH 4 -N fraction was dependent on the proximity of the monitoring station to point source discharges, because of rapid nitri®cation within the water column. However, during storm events, desorption from suspended sediment may be temporarily important. Both the magnitude and relative contribution of the dierent nutrient fractions exhibit signi®cant seasonal variability in response to the hydrological regime, sediment mobilization, the degree of dilution of point source inputs and biological processes. #

Spatial and temporal variability of stream phosphorus in a New Zealand high‐country agricultural catchment

“…It was also much lower than values for the similar-sized River Dart catchment in the UK (186 kg km" 2 yr" 1 ), which is almost all in permanent pasture (Russell et al 1998), and for other values reported by Goulding et al (1996) for heavily fertilised plots in the UK (up to 300^00 kg km" 2 yr 1 ). During the storm, discharge rose and receded very rapidly (Fig.…”

“…Boxplots were constructed for concentrations at each station. The proportion of DRP to TP can be used to evaluate the amount of P bound to solids and sources and effects of P (Dils & Heathwaite 1996;Haygarth et al 1998;Russell et al 1998). Thus, the proportion of DRP to TP was estimated for each station.…”

“…In some areas this can be a significant source of loadings to surface water (Hill 1981;Dils & Heathwaite 1996). P can be removed from NPS areas during erosion of soil and transported in surface runoff to receiving waters during storm events (Smith 1987;Cooke & Dons 1988;Ng et al 1993;Pionke et al 1996;Russell et al 1998). P can also be leached and transported from source areas in dissolved form (Dils & Heathwaite 1996;Haygarth et al 1998;Russell et al 1998).…”

Determining the relative importance of catchment- and site-scale factors in structuring fish assemblages in small coastal streams

“…Previous studies assessing the impact of catchment-scale factors on stream fish assemblages revealed that agriculture and deforestation influence the structure of fish habitat by providing sediments to streams (Russell et al, 1998;Huryn et al, 2002;Quinn and Stroud, 2002). In the present study, the amount of unforested area in a catchment was shown to influence fish species composition.…”

Nutrient water quality of the Wye catchment, UK: exploring patterns and fluxes using the Environment Agency data archives

“…However, area-weighted TP fluxes for the Wye are also lower than corresponding TP yields for other lowland UK rivers of similar catchment scale (e.g. 1.6 -2.1 kg-P ha -1 a -1 , Russell et al, 1998). For the Wye, TP loads may be underestimated as a result of the relative infrequency of water sampling (monthly intervals), which has poor coverage of high-flow periods, when peak TP is transported.…”