AN ANALYSIS OF THE RELATION BETWEEN GROUNDWATER NITRATE CONCENTRATION AND LAND USE IN THE MIYAKONOJO BASIN

2018 ◽  
Vol 74 (5) ◽  
pp. I_87-I_94
Author(s):  
Toru HIRAOKA ◽  
Yukio TOYOMITSU ◽  
Kei NAKAGAWA ◽  
Hirofumi NONAKA ◽  
Masaharu HIROTA ◽  
...  
Keyword(s):  
Land Use ◽  
Nitrate Concentration

scholarly journals Effect on nitrate concentration in stream water of agricultural practices in small catchments in Brittany: I. Annual nitrogen budgets

2002 ◽  
Vol 6 (3) ◽  
pp. 497-506 ◽  
Author(s):  
L. Ruiz ◽  
S. Abiven ◽  
P. Durand ◽  
C. Martin ◽  
F. Vertès ◽  
...  
Keyword(s):  
Land Use ◽  
Nitrate Concentration ◽  
Stream Water ◽  
Agricultural Practices ◽  
Climatic Conditions ◽  
Nitrogen Budgets ◽  
Annual Variations ◽  
Nitrate Concentrations ◽  
The Mean ◽  
Small Catchments

Abstract. The hydrological and biogeochemical monitoring of catchments has become a common approach for studying the effect of the evolution of agricultural practices on water resources. In numerous studies, the catchment is used as a "mega-lysimeter" to calculate annual input-output budgets. However, the literature reflects two opposite interpretations of the trends of nitrate concentration in streamwater. For some authors, essentially in applied studies, the mean residence time of leached nitrate in shallow groundwater systems is much less than one year and river loads reflect annual land use while for others, nitrate is essentially transport limited, independent of soil nitrate supply in the short term and annual variations reflect changes in climatic conditions. This study tests the effect of agricultural land-use changes on inter-annual nitrate trends on stream water of six small adjacent catchments from 0.10 to 0.57 km2 in area, on granite bedrock, at Kerbernez, in Western Brittany (France). Nitrate concentrations and loads in streamwater have been monitored for nine years (1992 to 2000) at the outlet of the catchments. An extensive survey of agricultural practices from 1993 to 1999 allowed assessment of the nitrogen available for leaching through nitrogen budgets. For such small catchments, year-to-year variations of nitrate leaching can be very important, even when considering the 'memory effect' of soil, while nitrate concentrations in streamwater appear relatively steady. No correlation was found between the calculated mean nitrate concentration of drainage water and the mean annual concentration in streams, which can even exhibit opposite trends in inter-annual variations. The climatic conditions do not affect the mean concentration in streamwater significantly. These results suggest that groundwater plays an important role in the control of streamwater nitrate concentration. Keywords: nitrate, diffuse pollution, agricultural catchment, nitrogen budget, leaching, Kerbernez catchments

scholarly journals Effect on nitrate concentration in stream water of agricultural practices in small catchments in Brittany: II. Temporal variations and mixing processes

2002 ◽  
Vol 6 (3) ◽  
pp. 507-514 ◽  
Author(s):  
L. Ruiz ◽  
S. Abiven ◽  
C. Martin ◽  
P. Durand ◽  
V. Beaujouan ◽  
...  
Keyword(s):  
Land Use ◽  
Nitrate Concentration ◽  
Stream Water ◽  
Agricultural Practices ◽  
Temporal Variations ◽  
Base Flow ◽  
Seasonal Patterns ◽  
Annual Variations ◽  
Nitrogen Inputs ◽  
Nitrate Concentrations

Abstract. In catchments with impervious bedrock, the nitrate concentrations in streamwater often show marked seasonal and small inter-annual variations. The inter-annual trends are usually attributed to changes in nitrogen inputs, due to changes in land use or in nitrogen deposition whereas seasonal patterns are explained in terms of availability of soil nitrate for leaching and of seasonality of nitrogen biotransformations. The companion paper showed that inter-annual variations of nitrogen in streamwater are not directly related to the variations of land use. The aim of this study is to describe nitrate concentration variations in a set of very small adjacent catchments, and to discuss the origin of the inter-annual and seasonal trends. Data from four catchments at the Kerbernez site (South Western Brittany, France) were used in this study. Nitrate concentrations in streamwater were monitored for eight years (1992 to 1999) at the outlet of the catchments. They exhibit contrasting inter-annual and seasonal patterns. An extensive survey of agricultural practices during this period allowed assessment of the amount of nitrogen available for leaching. The discharges measured since 1997 show similar specific fluxes but very different seasonal dynamics between the catchments. A simple, lumped linear store model is proposed as an initial explanation of the differences in discharge and nitrate concentration patterns between the catchments. The base flow at the outlet of each catchment is considered as a mixture of water from two linear reservoirs with different time constants. Each reservoir comprises two water stores, one mobile contributing to discharge, the other, immobile, where nitrate moves only by diffusion. The storm flow, which accounts for less than 10% of the annual flux, is not considered here. Six parameters were adjusted for each catchment to fit the observed data: the proportion of deep losses of water, the proportion of the two reservoirs and the size and initial concentration of the two immobile stores. The model simulates the discharge and nitrate concentration dynamics well. It suggests that the groundwater store plays a very important role in the control of nitrate concentration in streamwater, and that the pattern of the seasonal variation of nitrate concentration may result from the long term evolution of nitrogen losses by leaching. Keywords: nitrate, diffuse pollution, groundwater, seasonal variations, agricultural catchment, simulation model

Agricultural land use and hydrology affect variability of shallow groundwater nitrate concentration in South Florida

2007 ◽  
Vol 21 (18) ◽  
pp. 2464-2473 ◽  
Author(s):  
A. Ritter ◽  
R. Muñoz-Carpena ◽  
D. D. Bosch ◽  
B. Schaffer ◽  
T. L. Potter
Keyword(s):  
Land Use ◽  
Agricultural Land ◽  
Nitrate Concentration ◽  
Shallow Groundwater ◽  
South Florida ◽  
Agricultural Land Use

scholarly journals Accurate and precise quantification of atmospheric nitrate in streams draining land of various uses by using triple oxygen isotopes as tracers

2016 ◽  
Vol 13 (11) ◽  
pp. 3441-3459 ◽  
Author(s):  
Urumu Tsunogai ◽  
Takanori Miyauchi ◽  
Takuya Ohyama ◽  
Daisuke D. Komatsu ◽  
Fumiko Nakagawa ◽  
...  
Keyword(s):  
Land Use ◽  
Population Density ◽  
Catchment Area ◽  
Nitrate Concentration ◽  
Anthropogenic Source ◽  
Annual Average ◽  
Isotopic Compositions ◽  
Stable Isotopic ◽  
Atmospheric Nitrate ◽  
Precise Quantification

Abstract. Land use in a catchment area has significant impacts on nitrate eluted from the catchment, including atmospheric nitrate deposited onto the catchment area and remineralised nitrate produced within the catchment area. Although the stable isotopic compositions of nitrate eluted from a catchment can be a useful tracer to quantify the land use influences on the sources and behaviour of the nitrate, it is best to determine these for the remineralised portion of the nitrate separately from the unprocessed atmospheric nitrate to obtain a more accurate and precise quantification of the land use influences. In this study, we determined the spatial distribution and seasonal variation of stable isotopic compositions of nitrate for more than 30 streams within the same watershed, the Lake Biwa watershed in Japan, in order to use 17O excess (Δ17O) of nitrate as an additional tracer to quantify the mole fraction of atmospheric nitrate accurately and precisely. The stable isotopic compositions, including Δ17O of nitrate, in precipitation (wet deposition; n =  196) sampled at the Sado-seki monitoring station were also determined for 3 years. The deposited nitrate showed large 17O excesses similar to those already reported for midlatitudes: Δ17O values ranged from +18.6 to +32.4 ‰ with a 3-year average of +26.3 ‰. However, nitrate in each inflow stream showed small annual average Δ17O values ranging from +0.5 to +3.1 ‰, which corresponds to mole fractions of unprocessed atmospheric nitrate to total nitrate from (1.8 ± 0.3) to (11.8 ± 1.8) % respectively, with an average for all inflow streams of (5.1 ± 0.5) %. Although the annual average Δ17O values tended to be smaller in accordance with the increase in annual average stream nitrate concentration from 12.7 to 106.2 µmol L−1, the absolute concentrations of unprocessed atmospheric nitrate were almost stable at (2.3 ± 1.1) µmol L−1 irrespective of the changes in population density and land use in each catchment area. We conclude that changes in population density and land use between each catchment area had little impact on the concentration of atmospheric nitrate and that the total nitrate concentration originated primarily from additional contributions of remineralised nitrate. By using the average stable isotopic compositions of atmospheric nitrate, we excluded the contribution of atmospheric nitrate from the determined δ15N and δ18O values of total nitrate and estimated the δ15N and δ18O values of the remineralised portion of nitrate in each stream to clarify the sources. We found that the remineralised portion of the nitrate in the streams could be explained by mixing between a natural source with values of (+4.4 ± 1.8) and (−2.3 ± 0.9) ‰ for δ15N and δ18O respectively and an anthropogenic source with values of (+9.2 ± 1.3) and (−2.2 ± 1.1) ‰ for δ15N and δ18O respectively. In addition, both the uniform absolute concentration of atmospheric nitrate and the low and uniform δ18O values of the remineralised portion of nitrate in the streams imply that in-stream removal of nitrate through assimilation or denitrification had little impact on the concentrations and stable isotopic compositions of nitrate in the streams, except for a few streams in summer with catchments of urban/suburban land uses.

Predicting ground water nitrate concentration from land use

Ground Water ◽  
2005 ◽  
Vol 43 (3) ◽  
pp. 343-352 ◽  
Author(s):  
Kristin K. Gardner ◽  
Richard M. Vogel
Keyword(s):  
Land Use ◽  
Ground Water ◽  
Nitrate Concentration
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