TY  - JOUR
N1  - Published Version restricted in accordance with copyright policy of publisher (CUP)
ID  - usqep326652
UR  - http://dx.doi.org/10.1017/S0021859614000021
A1  - Mellander, P. - E.
A1  - Melland, A. R.
A1  - Murphy, P. N. C.
A1  - Wall, D. P.
A1  - Shortle, G.
A1  - Jordan, P.
Y1  - 2014///
N2  - The current study investigated the coupling of groundwater and surface water nitrogen (N) dynamics over 3 years, and considered intensive agricultural land-management influences over this period where the risk of N loss to water was considered high. Groundwater N (as nitrate) was monitored monthly in different strata and zones in four hillslopes, two in each of two agricultural catchments of c. 10 km2, and stream water N flux was monitored sub-hourly in the catchment outlets. Field nutrient sources were connected to surface water via groundwater; the groundwater along hillslopes was seen to be influenced spatially and temporally by management, geology and weather as observed in the concentration variability of nitrate in groundwater. Based on spatio-temporal averages of nitrate-N concentration, groundwater status was considered good (at least below a maximum acceptable concentration (MAC) of 11·3 mg/l). However, zones coincident with land-use change (ploughing and reseeding, typical of a management event in intensive landscapes), showed high spatio-temporal variability in nitrate-N concentration, exceeding the MAC temporarily, before recovering. This spatio-temporal variability highlighted the need for insight into these differences when interpreting groundwater quality data from a limited number of basin-scale sampling points and occasions. In both catchments the 3-year mean nitrate-N concentration in stream water was similar to the spatio-temporal mean concentration in groundwater. The magnitude and variability of loads, however, were more related to changes in annual runoff rather than changes in annual groundwater nitrate-N status. In one wet year, nitrate-N loads exceeded 48 kg/ha from an Arable catchment and 45 kg/ha from a grassland catchment (close to double the loss in a dry year).
PB  - Cambridge University Press
JF  - The Journal of Agricultural Science
VL  - 152
KW  - groundwater; water composition; water quality; agricultural catchment; concentration (composition); intensive agriculture; land use change; nitrogen cycle; permeability; spatiotemporal analysis; water chemistry
SN  - 0021-8596
TI  - Coupling of surface water and groundwater nitrate-N dynamics in two permeable agricultural catchments
SP  - S107
AV  - restricted
EP  - S124
ER  -