scholarly journals Scale issues for assessment of nutrient leaching from agricultural land in Latvia

2012 ◽  
Vol 43 (4) ◽  
pp. 383-399 ◽  
Author(s):  
Ainis Lagzdins ◽  
Viesturs Jansons ◽  
Ritvars Sudars ◽  
Kaspars Abramenko
Keyword(s):  
Water Quality ◽  
Classification System ◽  
Agricultural Land ◽  
Pollution Monitoring ◽  
Nutrient Concentrations ◽  
Total N ◽  
Small Catchment ◽  
Total P ◽  
Term Data

This paper deals with water quality assessment and recommendations for a classification system based on nitrogen (N) and phosphorus (P) concentrations. In order to evaluate the influence of agricultural intensity, climate and hydrology on water quality, the long-term data (from 1995 to 2009) collected in three Latvian diffuse pollution monitoring sites (Berze, Mellupite and Vienziemite) were analysed. Measurements were carried out within areas where agriculture was the main source of diffuse nutrient loading at four spatial scales, i.e. experimental plot, drainage field, small catchment and river. The available long-term data series shows large variations in nutrient concentrations, depending on the intensity of agricultural production system and the scale of measurements. The concentrations of total N are higher at the plot scale, decreasing when the spatial scale of measurements increase. The proposed simplified classification system (five classes) was based upon the assumption that good chemical status for rivers in agricultural areas represent concentrations of total N < 1.5 mg L−1 and total P < 0.075 mg L−1, while in small catchments total N < 2.5 mg L−1 and total P < 0.050 mg L−1 and in subsurface drainage water total N < 5.5 mg L−1 and total P < 0.020 mg L−1.

Eutrophication of agricultural streams: defining nutrient concentrations to protect ecological condition

2008 ◽  
Vol 58 (11) ◽  
pp. 2203-2210 ◽  
Author(s):  
Patricia A. Chambers ◽  
C. Vis ◽  
R. B. Brua ◽  
M. Guy ◽  
J. M. Culp ◽  
...  
Keyword(s):  
Management Practices ◽  
Ecological Condition ◽  
Agricultural Landscapes ◽  
Nutrient Concentrations ◽  
Total N ◽  
Beneficial Management Practices ◽  
Agricultural Streams ◽  
Abundance And Diversity ◽  
Total P

Inputs of nutrients (phosphorus, P, and nitrogen, N) to coastal and fresh waters can accelerate eutrophication, resulting in excessive aquatic plant growth, depletion of oxygen, and deleterious changes in abundance and diversity of organisms. Using long-term (∼1995–2005) monitoring data from agriculturally-dominated watersheds in southern Ontario and Quebec, Canada, we developed and tested several approaches for setting targets for N and P. Our research showed that it is possible to set scientifically-credible targets for total P and total N to protect ecological condition of streams in agricultural landscapes, and define achievable targets attainable following adoption of beneficial management practices.

scholarly journals Spatial distribution of soils determines export of nitrogen and dissolved organic carbon from an intensively managed agricultural landscape

2012 ◽  
Vol 9 (11) ◽  
pp. 4513-4525 ◽  
Author(s):  
T. Wohlfart ◽  
J.-F. Exbrayat ◽  
K. Schelde ◽  
B. Christen ◽  
T. Dalgaard ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Agricultural Landscape ◽  
Agricultural Land ◽  
Stream Water ◽  
Organic Soils ◽  
Total N ◽  
Small Catchment ◽  
Landscape Characteristics ◽  
Intensively Managed

Abstract. The surrounding landscape of a stream has crucial impacts on the aquatic environment. This study pictures the hydro-biogeochemical situation of the Tyrebækken creek catchment in central Jutland, Denmark. The intensively managed agricultural landscape is dominated by rotational croplands. The small catchment mainly consist of sandy soil types besides organic soils along the streams. The aim of the study was to characterise the relative influence of soil type and land use on stream water quality. Nine snapshot sampling campaigns were undertaken during the growing season of 2009. Total dissolved nitrogen (TDN), nitrate (NO3−), ammonium nitrogen and dissolved organic carbon (DOC) concentrations were measured, and dissolved organic nitrogen (DON) was calculated for each grabbed sample. Electrical conductivity, pH and flow velocity were measured during sampling. Statistical analyses showed significant differences between the northern, southern and converged stream parts, especially for NO3− concentrations with average values between 1.4 mg N l−1 and 9.6 mg N l−1. Furthermore, throughout the sampling period DON concentrations increased to 2.8 mg N l−1 in the northern stream contributing up to 81% to TDN. Multiple-linear regression analyses performed between chemical data and landscape characteristics showed a significant negative influence of organic soils on instream N concentrations and corresponding losses in spite of their overall minor share of the agricultural land (12.9%). On the other hand, organic soil frequency was positively correlated to the corresponding DOC concentrations. Croplands also had a significant influence but with weaker correlations. For our case study we conclude that the fractions of coarse textured and organic soils have a major influence on N and DOC export in this intensively used landscape. Meanwhile, the contribution of DON to the total N losses was substantial.

Predicting Cyanobacteria dominance in lakes

2001 ◽  
Vol 58 (10) ◽  
pp. 1905-1908 ◽  
Author(s):  
John A Downing ◽  
Susan B Watson ◽  
Edward McCauley
Keyword(s):  
Field Experiments ◽  
Nutrient Concentrations ◽  
Strongly Correlated ◽  
Total N ◽  
Algae Biomass ◽  
Cyanobacteria Blooms ◽  
Freshwater Resource ◽  
Toxic Blooms ◽  
Total P ◽  
Controversial Concept

A controversial precept of aquatic ecology asserts that low ratios of nitrogen to phosphorus (N:P) lead to noxious and sometimes toxic blooms of Cyanobacteria. Cyanobacteria dominance is a major risk to human and ecosystem health. The stoichiometric control of Cyanobacteria therefore has become central to freshwater resource management. This controversial concept is based on observed Cyanobacteria dominance in lakes with low N:P and the results of lab and field experiments. Here we analyze data from 99 of the temperate zone's most studied lakes and show that this model is flawed. We show that the risk of water quality degradation by Cyanobacteria blooms is more strongly correlated with variation in total P, total N, or standing algae biomass than the ratio of N:P. Risks associated with Cyanobacteria are therefore less associated with N:P ratios than a simple increase in nutrient concentrations and algal biomass.

scholarly journals Assessment of the Impact of Land Cover Type on the Water Quality in Lake Tondano Using a SWAT Model

2021 ◽  
Vol 56 (1) ◽  
Author(s):  
Moh Sholichin ◽  
Tri Budi Prayogo
Keyword(s):  
Water Quality ◽  
Land Cover ◽  
Agricultural Land ◽  
Assessment Tool ◽  
Swat Model ◽  
Coefficient Of Determination ◽  
Organic N ◽  
Lake Water Quality ◽  
Total N ◽  
The Impact

Lake Tondano is the largest natural lake in North Sulawesi, Indonesia, which functions as a provider of clean water, hydroelectric power, rice field irrigation, inland fisheries, and tourism. This research aims to determine the effect of land cover types from the Tondano watershed on the lake water quality. The Soil and Water Assessment Tool (SWAT) model was used to evaluate the rate of soil erosion and the pollutant load of various land types in the watershed during the last ten years. Rainfall data is obtained from two rainfall stations, namely Paleloan Station and Noonan Station. The model is calibrated and validated before being used for analysis. We use climatological data from 2014 to 2019. The process of the SWAT model calibration and validation was carried out with the statistical formulas of the coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE). The results show that the potential for pollution load from the Tondao watershed is organic N of 0.039 kg/ha and organic P of 0.006 kg/ha coming from the agricultural land. The results of this study conclude that the fertility conditions of Lake Tondano are at the eutrophic level, where the pollutant inflow is collected in the lake waters, especially for the parameters of total N (1503697.44kg/year) and total P (144831.36kg/year). The SWAT simulation results show deviation between the modeling and field data collected with the value of R2 = 0.9303, and the significant level ≤ 10.

scholarly journals SURFACE MELT WATER RUNOFF ON THE ARABLE LANDS OF THE LOWER DON

2021 ◽  
Author(s):  
D. P. Sidarenko ◽  
Keyword(s):  
Agricultural Land ◽  
Arable Land ◽  
Water Runoff ◽  
Erosion Processes ◽  
Rostov Region ◽  
Melt Water ◽  
Runoff Rate ◽  
The Impact ◽  
Term Data

Purpose: to study the indicators of melt water runoff from arable land of various compaction and to assess its quantitative and qualitative characteristics based on long-term data. Materials and methods. Studies of the intensity of melt water runoff were carried out in the Azov zone of Rostov region in the period 1964–2018 by a number of researchers, including the author of the article. Results. The runoff indicators for a 55-year period are characterized by significant fluctuations. Analysis of long-term data revealed that the indicator of melt water runoff rate from loose arable land for the period 1964–2018 averaged 9.0 mm/year and on compacted arable land averaged 17.5 mm/year. On loose arable land, the maximum runoff rate for a 55-year period is 25.3 mm, on compacted arable land it is 47.3 mm. As a result of the analysis of the data, it was revealed that the average water reserve in snow on the surface of the fall-plowed land is 43.7 mm, and 48.7 mm on the winter wheat sowing. In general, for two agrophonies, the runoff indicator for the period 1964–2018 was most often characterized as weak and very weak only on loose arable land. Calculations of statistical indicators of runoff data revealed that they are not uniform, for example, the coefficient of runoff variation from loose arable land was 115.4 %, and from compacted arable land 70.4 %, with a coefficient of variation above 33 %, the aggregate is considered heterogeneous. Rostov region, having a large agricultural potential, is experiencing significant problems from the impact of negative natural processes, among which one of the first places belongs to erosion processes. Conclusions. In the course of generalization of long-term data on melt water runoff from arable land of varying degrees of compaction, indicators that made it possible to plot the flow availability curves were obtained. The use of the results obtained makes it possible to predict the occurrence of runoff of various intensities and thereby prevent its negative impact on agricultural land with the minimal material costs.

Influence of climate,geology and humans on spatial and temporal nutrient geochemistry in the subtropical Richmond River catchment, Australia

2001 ◽  
Vol 52 (2) ◽  
pp. 235 ◽  
Author(s):  
Lester J. McKee ◽  
Bradley D. Eyre ◽  
Shahadat Hossain ◽  
Peter R. Pepperell
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Agricultural Land ◽  
Anthropogenic Impacts ◽  
Inorganic Nitrogen ◽  
Point Sources ◽  
Nutrient Concentrations ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
River Catchment

Water quality was monitored on a spatial and temporal basis in the subtropical Richmond River catchment over two years. Nutrient concentrations varied seasonally in a complex manner with highest concentrations (maximum =3110 µg N L – 1 and 572 µg P L –1 ) associated with floods. However, median (444 µg N L – 1 and 55 µg P L – 1 ) concentrations were relatively low compared with other parts of the world. The forms of nitrogen and phosphorus in streams varied seasonally, with greater proportions of inorganic nitrogen and phosphorus during the wet season. Minimum nutrient concentrations were found 2—3 months after flood discharge. With the onset of the dry season, concentration increases were attributed to point sources and low river discharge. There were statistically significant relationships between geology and water quality and nutrient concentrations increased downstream and were significantly related to population density and dairy farming. In spite of varying geology and naturally higher phosphorus in soils and rocks in parts of the catchment, anthropogenic impacts had the greatest effects on water quality in the Richmond River catchment. Rainfall quality also appeared to be related both spatially and seasonally to human activity. Although the responses of the subtropical Richmond River catchment to changes in land use are similar to those of temperate systems of North America and Europe, the seasonal patterns appear to be more complex and perhaps typical of subtropical catchments dominated by agricultural land use.

scholarly journals Land Use and Stream Nitrogen Concentrations in Agricultural Watersheds Along the Central Coast of California

2001 ◽  
Vol 1 ◽  
pp. 615-622 ◽  
Author(s):  
Marc Los Huertos ◽  
Lowell E. Gentry ◽  
Carol Shennan
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Agricultural Land ◽  
Shallow Groundwater ◽  
Surface Water Quality ◽  
Spatial And Temporal Patterns ◽  
Total N ◽  
Nitrogen Concentrations ◽  
High Concentrations ◽  
N Loading

In coastal California nitrogen (N) in runoff from urban and agricultural land is suspected to impair surface water quality of creeks and rivers that discharge into the Monterey Bay Sanctuary. However, quantitative data on the impacts of land use activities on water quality are largely limited to unpublished reports and do not estimate N loading. We report on spatial and temporal patterns of N concentrations for several coastal creeks and rivers in central California. During the 2001 water year, we estimated that the Pajaro River at Chittenden exported 302.4 Mg of total N. Nitrate-N concentrations were typically <1 mg N l–1in grazing lands, oak woodlands, and forests, but increased to a range of 1 to 20 mg N l–1as surface waters passed through agricultural lands. Very high concentrations of nitrate (in excess of 80 mg N l–1) were found in selected agricultural ditches that received drainage from tiles (buried perforated pipes). Nitrate concentrations in these ditches remained high throughout the winter and spring, indicating nitrate was not being flushed out of the soil profile. We believe unused N fertilizer has accumulated in the shallow groundwater through many cropping cycles. Results are being used to organize landowners, resource managers, and growers to develop voluntary monitoring and water quality protection plans.

Landscape metrics as indicators of river water quality at catchment scale

2007 ◽  
Vol 38 (2) ◽  
pp. 125-138 ◽  
Author(s):  
Evelyn Uuemaa ◽  
Jüri Roosaare ◽  
Ülo Mander
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Landscape Metrics ◽  
Urban Areas ◽  
Shape Index ◽  
Landscape Configuration ◽  
Edge Density ◽  
Total N ◽  
Mean Shape ◽  
Total P

We investigated the relationship between land use parameters and FRAGSTATS-based landscape metrics (Edge Density, Patch Density, Mean Shape Index, Mean Euclidean Nearest Neighbour Index, Contagion, Patch Richness Density and Shannon's Diversity Index) and nutrient/organic-matter-based water quality indicators (BOD7 and CODKMnO4 values, total-N and total-P concentrations in water) in 24 catchments with various land use patterns in Estonia, using the CORINE Land Cover Map (1:100 000). Multiple regression analysis showed that, for BOD7, total-N and total-P, the most important predictor was the proportion of urban areas, but landscape metrics also had a significant relationship with water quality. Mean Shape Index and Contagion were the most important predictors for CODKMnO4. The knowledge that land use and landscape configuration impact water quality can be used in establishing and implementing water management plans in Europe.

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