An Introduction to the First Assessment of Nitrogen Loads to US Estuaries with an Atmospheric Perspective

2013 ◽  
pp. 1-10 ◽  
Author(s):  
Richard A. Valigura
Keyword(s):  
Nitrogen Loads

Specific organic and nutrient loads in stabilized sludge from municipal treatment plants

1996 ◽  
Vol 33 (12) ◽  
pp. 243-250 ◽  
Author(s):  
O. Nowak ◽  
A. Franz ◽  
K. Svardal ◽  
V. Müller
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Single Stage ◽  
Nutrient Loads ◽  
Activated Sludge Process ◽  
Waste Sludge ◽  
Sludge Stabilization ◽  
Nitrogen Loads ◽  
Theoretical Considerations ◽  
P Removal

By means of theoretical considerations and of statistical evaluations, specific organic and nitrogen loads in separately stabilized sludge have been found to be in the range of 16 to 20g VSS/PE/d and of 1.1 to 1.5 g N/PE/d respectively. About 0.6g P/PE/d are removed from the wastewater in activated sludge plants without chemical or enhanced biological P removal. By using the single-stage activated sludge process without primary sedimentation and without separate sludge stabilization, almost complete nitrogen removal can be achieved, but specific organic and nitrogen loads in the waste sludge are up to two times higher than in separately stabilized sludge.

scholarly journals Macrophyte Abundance in Waquoit Bay: Effects of Land-Derived Nitrogen Loads on Seasonal and Multi-Year Biomass Patterns

2008 ◽  
Vol 31 (3) ◽  
pp. 532-541 ◽  
Author(s):  
Sophia E. Fox ◽  
Erica Stieve ◽  
Ivan Valiela ◽  
Jennifer Hauxwell ◽  
James McClelland
Keyword(s):  
Nitrogen Loads ◽  
Waquoit Bay

Evaluating the effect of climate variation on the cost efficiency of a crop permit policy in Southern Sweden

2013 ◽  
Vol 4 (2) ◽  
pp. 110-117
Author(s):  
Dennis Collentine ◽  
Holger Johnsson
Keyword(s):  
Cost Efficiency ◽  
Agricultural Sector ◽  
Policy Design ◽  
Correlation Coefficients ◽  
Nitrogen Loads ◽  
Weather Variation ◽  
The Baltic ◽  
The Individual ◽  
The Cost ◽  
The Impact

Current international agreements call for a significant reduction of nitrogen loads to the Baltic Sea. New measures to reduce nitrogen loads from the agricultural sector and an increased focus on cost efficiency will be needed to meet reduction targets. For policy design and evaluation it is important to understand the impact of weather on the efficiency of abatement measures. One new proposed policy is the use of crop permits based on weather normalized average leaching. This paper describes the use of the Spearman method to determine the efficiency of this policy with annual weather variation. The conclusion is that the values of the Spearman correlation coefficients in the study indicate that using average leaching for the individual crops on specific soil types for calculating crop permit requirements is an efficient policy. The Spearman method is demonstrated to be a simple useful tool for evaluating the impact of weather and is recommended for use in new studies.

scholarly journals The Use of Constructed Wetlands for Nitrogen Removal from Agricultural Drainage: a Review

2017 ◽  
Vol 48 (2) ◽  
pp. 82-91 ◽  
Author(s):  
Jan Vymazal
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Coastal Waters ◽  
Free Water ◽  
Literature Survey ◽  
Agricultural Drainage ◽  
Severe Problem ◽  
Nitrogen Loads ◽  
Predominant Form ◽  
Close Relationship

Abstract Diffuse pollution from agricultural drainage is a severe problem for water quality and it is a major reason for eutrophication of both freshwaters and coastal waters. Constructed wetlands were proposed as a suitable tool for removal of nitrogen from agricultural drainage in the early 1990s. Since then constructed wetlands with free water surface have been successfully used in Europe, North America, Asia, and Australia. The predominant form of nitrogen in agricultural drainage waters is nitrate and therefore denitrification is considered as the major removal process. The literature survey of 41 full-scale constructed wetlands revealed that removed nitrogen amount varied widely between 11 and 13 026 kg N ha-1 per year with the median removal of 426 kg N ha-1 per year. A very close relationship was found between inflow and removed nitrogen loads but the overall percentual efficiency decreases with increasing inflow nitrogen load. It has also been found that nitrogen removal depends on the size of constructed wetland (W) as compared to catchment (C) area. The survey indicated that the W/C greater than 1% does not result in any substantial increase of nitrogen removal. There are still some gaps in our knowledge that need to be evaluated, namely the optimum vegetation maintenance.

Modelling the point and non-point nitrogen loads to the Venice Lagoon (Italy): the application of water quality models to the Dese-Zero basin

Desalination ◽  
2008 ◽  
Vol 226 (1-3) ◽  
pp. 81-88 ◽  
Author(s):  
Roberta Salvetti ◽  
Marco Acutis ◽  
Arianna Azzellino ◽  
Marta Carpani ◽  
Carlo Giupponi ◽  
...  
Keyword(s):  
Water Quality ◽  
Venice Lagoon ◽  
Quality Models ◽  
Nitrogen Loads ◽  
Water Quality Models

Study on nitrogen load reduction efficiency of agricultural conservation management in a small agricultural watershed

2014 ◽  
Vol 69 (8) ◽  
pp. 1689-1696 ◽  
Author(s):  
Xiaoli Liu ◽  
Qiuwen Chen ◽  
Zhaoxia Zeng
Keyword(s):  
Assessment Tool ◽  
Conservation Management ◽  
Swat Model ◽  
Black Soil ◽  
Agricultural Watershed ◽  
Load Reduction ◽  
Agricultural Conservation ◽  
Nitrogen Loads ◽  
Reduction Efficiency ◽  
The Impact

Different crops can generate different non-point source (NPS) loads because of their spatial topography heterogeneity and variable fertilization application rates. The objective of this study was to assess nitrogen NPS load reduction efficiency by spatially adjusting crop plantings as an agricultural conservation management (ACM) measure in a typical small agricultural watershed in the black soil region in northeast China. The assessment was undertaken using the Soil and Water Assessment Tool (SWAT). Results showed that lowland crops produce higher nitrogen NPS loads than those in highlands. It was also found that corn gave a comparatively larger NPS load than soybeans due to its larger fertilization demand. The ACM assessed was the conversion of lowland corn crops into soybean crops and highland soybean crops into corn crops. The verified SWAT model was used to evaluate the impact of the ACM action on nitrogen loads. The results revealed that the ACM could reduce NO3-N and total nitrogen loads by 9.5 and 10.7%, respectively, without changing the area of crops. Spatially optimized regulation of crop planting according to fertilizer demand and geological landscapes can effectively decrease NPS nitrogen exports from agricultural watersheds.

Sign in / Sign up

Export Citation Format

Share Document