Application of phosphorus loading models to understand drivers of eutrophication in a complex rural lake-watershed system

Agriculture accounts for 9 per cent of the total surface area of Finland and generates the greatest single nutrient input to Finnish watercourses. Since agricultural activity is scattered throughout the whole country its effects in lakes are less pronounced than those of domestic and industrial effluents. On the other hand, point source phosphorus loading of lakes and rivers decreased significantly during the nineteen-seventies. Phosphorus is the nutrient which primarily limits production in most Finnish lakes. The availability of phosphorus in agricultural runoff waters is therefore a crucial question in the evaluation of the eutrophicating effects of agriculture. Our results indicated that in runoff waters available phosphorus can be 60-70 per cent of the total phosphorus. However, the concentrations of available P were so low that they could be achieved in Finnish lakes of low ionic concentration through simple chemical desorption without the assistance of the algal uptake. The utilization of the spring maximum of runoff phosphorus in lakes would thus not depend on the concurrence of the maxima of loading and algal growth.

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Long-Term (15 Years) Results of NPS Controls in an Agricultural Watershed upon a Receiving Lake's Water Quality

Water Science & Technology ◽

10.2166/wst.1993.0447 ◽

1993 ◽

Vol 28 (3-5) ◽

pp. 441-449 ◽

Cited By ~ 8

Author(s):

Paul J. Garrison ◽

Timothy R. Asplund

Keyword(s):

Water Quality ◽

Structural Changes ◽

Soil Phosphorus ◽

Water Clarity ◽

Management Control ◽

Agricultural Watershed ◽

Control Measures ◽

Phosphorus Loading ◽

Phosphorus Concentration ◽

White Clay

Nonpoint source controls were installed in a 1215 ha agricultural watershed in northeastern Wisconsin in the late 1970. Changes were made in handling of animal wastes and cropping practices to reduce runoff of sediment and nutrients. Modelling results predicted a reduction in phosphorus runoff of 30 percent. The water quality of White Clay Lake has worsened since the installation of NPS controls. The lake's phosphorus concentration has increased from a mean of 29 µg L−1 in the late 1970s to 44 µg L−1 in recent years. Water clarity has declined from 2.7 to 2.1 m and the mean summer chlorophyll levels have increased from 9 to 13 µg L−1 with peak values exceeding 40 µg L−1. Increased phosphorus loading is not the result of elevated precipitation but instead the failure of the control measures to sufficiently reduce P loading. Most of the effort was placed on structural changes while most of the P loading comes from cropland runoff. Further, soil phosphorus concentrations have increased because of artificial fertilizers and manure spreading. The White Clay Lake experience is discouraging since the majority of the polluters in this watershed utilized some NPS control practices, including 76 percent of the farms which installed waste management control facilities.

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Loading rates of nutrients discharging from a golf course and a neighboring forested basin

Water Science & Technology ◽

10.2166/wst.1999.0535 ◽

1999 ◽

Vol 39 (12) ◽

pp. 99-107 ◽

Cited By ~ 10

Author(s):

Takao Kunimatsu ◽

Miki Sudo ◽

Takeshi Kawachi

Keyword(s):

Nutrient Loading ◽

Chamaecyparis Obtusa ◽

Phosphorus Loading ◽

Golf Course ◽

Nutrient Concentrations ◽

Golf Courses ◽

Japanese Cypress ◽

Arithmetic Average ◽

Loading Rates ◽

Runoff Rate

In the last ten years, the number of golf courses has been increasing in some countries as the game gains popularity. This indicates, a need to estimate the nutrient loading from golf courses in order to prevent the eutrophication of water bodies. Nutrient concentrations and flow rates of a brook were measured once a week from 1989 to 1990 at two sites: Site A of a brook flowing out from D-golf course (53 ha) and Site B of the same brook discharging into the golf course from an upper forested basin (23 ha) covered mainly with planted Japanese cypress (Chamaecyparis obtusa SIEB. et ZUCC). The bedrock of the area was granite. The annual values of precipitation and mean temperature were 1947 mm and 13.5°C in 1989, respectively. The arithmetic average values of discharge from the forested basin and the golf course were 0.392 and 1.26 mg/l total nitrogen (TN), 0.0072 and 0.145 mg/l total phosphorus (TP), 0.82 and 3.53 mg/l potassium ion (K+, 5.92 and 8.24 mg/l sodium ion (Na+), 2.1 and 9.9 mg/l suspending solid (0.001–2.0 mm, SS), 0.087 and 0.147 mS/cm electric conductivity (EC), and 0.031 and 0.037 m3/km2•s specific discharge, respectively. The loading rates of the forested basin and the golf course were 5.42 and 13.5 TN, 0.133 and 3.04 TP, 8.84 and 33.9 K+, 55.0 and 73.0 Na+, and 54.3 and 118 SS in kg/ha•y. The leaching and runoff rate of nitrogen in the chemical fertilizers applied on the golf course was calculated as 32%. These results indicated the importance of controlling the phosphorus loading for the management of golf courses.

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Use of Steel Slag to Reduce Phosphorus Loading in Animal Waste Handling Systems

10.13031/2013.32704 ◽

2010 ◽

Cited By ~ 1

Author(s):

R L Miller ◽

B J Jensen ◽

B T Munns ◽

G E Cardon

Keyword(s):

Steel Slag ◽

Phosphorus Loading ◽

Animal Waste ◽

Waste Handling

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A Case Study of the Effects of Management Interventions on the Phosphorus Dynamics at a Coastal, Eutrophic, Caribbean lagoon (Laguna Cartagena, Puerto Rico)

Water ◽

10.3390/w13040449 ◽

2021 ◽

Vol 13 (4) ◽

pp. 449

Author(s):

Yashira Marie Sánchez Colón ◽

Fred Charles Schaffner

Keyword(s):

Puerto Rico ◽

Water Column ◽

Water Levels ◽

Wildlife Habitat ◽

Freshwater Wetland ◽

Water Level Fluctuations ◽

Phosphorus Loading ◽

Estuarine Wetlands ◽

Management Interventions ◽

Management Recommendations

Laguna Cartagena is a coastal, eutrophic, shallow lake and freshwater wetland in southwestern Puerto Rico, managed by the US Fish and Wildlife Service. This ecosystem has been impacted by phosphorus loading from adjacent agricultural areas since the 1950s, causing eutrophication and deteriorating wildlife habitats. Herein, we describe phosphorus input and export during September 2010–September 2011 (Phase One) and October 2013–November 2014 (Phase Two). These two phases bracket a period of intensified management interventions including excavation and removal of sediment and vegetation, draining, and burning during the summers of 2012 and 2013. Results indicate that Laguna Cartagena retains a phosphorus (sink) in its sediments, and exhibits nutrient-releasing events (source, mainly total phosphorus) to the lagoon water column, which are associated with rainfall and rising water levels. External factors including water level fluctuations and rainfall influenced phosphorus export during Phase One, but after management interventions (Phase Two), internal processes influenced sink/source dynamics, releasing elevated phosphorus concentrations to the water column. When exposed sediments were re-flooded, phosphorus concentrations to the water column increased, releasing elevated P concentrations downstream to an estuarine wetlands area and the Caribbean Sea. Herein we offer management recommendations to optimize wildlife habitat without elevating phosphorus concentrations.

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Assessment of Trophic Responses of a Reservoir to Seasonal and Annual Variations in Monsoon

Water ◽

10.3390/w13152117 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2117

Author(s):

Su-mi Kim ◽

Hyun-su Kim

Keyword(s):

Water Quality ◽

Trophic State ◽

Monsoon Season ◽

Phytoplankton Growth ◽

Phosphorus Loading ◽

Nutrient Concentrations ◽

Trophic State Index ◽

Post Monsoon ◽

Post Monsoon Season ◽

State Index

The variations in water quality parameters and trophic status of a multipurpose reservoir in response to changing intensity of monsoon rain was investigated by applying a trophic state index deviation (TSID) analysis and an empirical regression model to the data collected in two periods from 2014 to 2017. The reservoir in general maintained mesotrophic conditions, and Carlson’s trophic state index (TSIc) was affected most by TSITP. Nutrient concentrations, particularly phosphorus, did not show strong correlations with precipitation, particularly in the period with weak monsoon, and a significant increase in total phosphorus (TP) was observed in Spring 2015, indicating the possibility of internal phosphorus loading under decreased depth and stability of water body due to a lack of precipitation. TSIChl was higher than TSISD in most data in period 1 when a negligible increase in precipitation was observed in the monsoon season while a significant fraction in period 2 showed the opposite trend. Phytoplankton growth was not limited by nutrient limitation although nutrient ratios (N/P) of most samples were significantly higher than 20, indicating phosphorus-limited condition. TSID and regression analysis indicated that phytoplankton growth was limited by zooplankton grazing in the Spring, and that cell concentrations and community structure in the monsoon and post-monsoon season were controlled by the changing intensity of the monsoon, as evidenced by the positive and negative relationships between community size and cyanobacterial population with the amount of precipitation in the Summer, respectively. The possibility of contribution from internal loading and an increase in cyanobacterial population associated with weak monsoon, in addition to potential for nutrient enrichment in the post-monsoon season, implies a need for the application of more stringent water quality management in the reservoir that can handle all potential scenarios of eutrophication.

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