Trends in eutrophication research and control

Abstract

Eutrophication is the natural ageing process of lakes. It is characterized by a geologically slow shift from in-lake biological production driven by allochthonous (external to the water body) loading of nutrients, to production driven by autochthonous (in-lake) processes. This shift typically is accompanied by changes in species and biotic community composition, as an aquatic ecosystem is ultimately transformed into a terrestrial biome. However, this typically slow process can be greatly accelerated by human intervention in the natural biogeochemical cycling of nutrients within a watershed; the resulting cultural eutrophication can create conditions inimical to the continued use of the water body for humandriven economic purposes. Excessive algal and rooted plant growth, degraded water quality, extensive deoxygenation of the bottom water layers and increased fish biomass accompanied by decreased harvest quality, are some features of this process.Following the Second World War, concern with cultural eutrophication achieved an intensity that spurred a significant research effort, culminating in the identification of phosphorus as the single most significant, and controllable, element involved in driving the eutrophication process. During the late 1960s and throughout the 1970s, much effort was devoted to reducing phosphorus in wastewater effluents, primarily in the developed countries of the temperate zone. These efforts generally resulted in the control of eutrophication in these countries, albeit with varying degrees of success. The present effort in the temperate zone, comprising mostly developed nations, has now shifted to the control of diffuse sources of a broader spectrum of contaminants that impact human water use.In the developing countries of the inter-tropical zone, however, rapidly expanding populations, a growing industrial economy and extensive urbanization have only recently reached an intensity at which cultural eutrophication can no longer be ignored. Further, initial attempts at applying temperate zone control measures in this region have been largely unsuccessful. Modification of the temperate zone eutrophication paradigm will be needed, especially to address the differing climatic and hydrological conditions, if cultural eutrophication is to be contained in this region, where eutrophication-related diseases continue to be a primary cause of human distress.

Impact of discharge wastewater effluents on the physico-chemical qualities of a receiving watershed in a typical rural community

“…Other investigators have pointed out that eutrophication-related problems in temperate zones of aquatic systems begin to increase at ambient total P concentrations exceeding 0.035 mg/P. In warm-water systems, the values range between 0.34 and 0.70 mg/P (Rast and Thornton, 1996). These represent nutrient threshold levels beyond which there will be a corresponding increase in the risk and intensity of plant-related water quality problems (OECD, 1982).…”

Impact of discharge wastewater effluents on the physico-chemical qualities of a receiving watershed in a typical rural community

“…Other investigators have pointed out that eutrophication-related problems in temperate zones of aquatic systems begin to increase at ambient total P concentrations exceeding 0.035 mg/P. In warm-water systems, the values range between 0.34 and 0.70 mg/P (Rast and Thornton, 1996). These represent nutrient threshold levels beyond which there will be a corresponding increase in the risk and intensity of plant-related water quality problems (OECD, 1982).…”

Effects of Nutrient Limitations and Watershed Inputs on Community Respiration in a Deep, Tropical Lake: Comparison of Pelagic and Littoral Habitats

“…This finding is consistent with literature showing that high levels of organic nitrogen, phosphorus, and carbon found in untreated wastewater stimulated primary productivity and bacterial respiration (Edmondson & Lehman, ; Phillips et al, ; Theodorou, ). Among the many nutrient sources created by humans, untreated wastewater is the most significant point source of nutrient loads (Jarvie et al, ), especially in developing countries (Rast & Thornton, ). While efforts to control direct sewage inflows to the lake are nonexistent at this time, it will be increasingly important to quantify the role of sewage in both autochthonous and allochthonous processes in the system given the recent, intermittent increase of algal production in the middle to late 2000s (Corman et al, ; Rejmankova et al, ).…”

Situation analysis of water quality in the Umtata River catchment

“…Other workers have reported that eutrophication-related problems in temperate zones aquatic systems begin to increase at ambient total P concentrations exceeding 0.035 mg P/l. The value is higher for warm-water systems -of the order of 0.34 to 0.70 mg P/l (Rast and Thornton, 1996). The associated N concentration would be of the order of 0.34 to 0.…”

“…It is accepted that these represent nutrient threshold levels, beyond which there will be a corresponding increase in the risk and intensity of plant-related water quality problems (OECD, 1982). These threshold values for nutrients (Rast and Thornton, 1996) are exceeded in the river and eutrophication is well pronounced in the river. The incidence of eutrophication could adversely affect the use of the river for recreation as the covering of large areas by macrophytes could prevent access to waterways and could cause unsightly and malodorous scum which could make recreation unpleasant (Murray et al, 2000).…”

Impact of discharge wastewater effluents on the physico-chemical qualities of a receiving watershed in a typical rural community

“…Other investigators have pointed out that eutrophication-related problems in temperate zones of aquatic systems begin to increase at ambient total P concentrations exceeding 0.035 mg/P. In warm-water systems, the values range between 0.34 and 0.70 mg/P (Rast and Thornton, 1996). These represent nutrient threshold levels beyond which there will be a corresponding increase in the risk and intensity of plant-related water quality problems (OECD, 1982).…”

Effects of Nutrient Limitations and Watershed Inputs on Community Respiration in a Deep, Tropical Lake: Comparison of Pelagic and Littoral Habitats

“…This finding is consistent with literature showing that high levels of organic nitrogen, phosphorus, and carbon found in untreated wastewater stimulated primary productivity and bacterial respiration (Edmondson & Lehman, ; Phillips et al, ; Theodorou, ). Among the many nutrient sources created by humans, untreated wastewater is the most significant point source of nutrient loads (Jarvie et al, ), especially in developing countries (Rast & Thornton, ). While efforts to control direct sewage inflows to the lake are nonexistent at this time, it will be increasingly important to quantify the role of sewage in both autochthonous and allochthonous processes in the system given the recent, intermittent increase of algal production in the middle to late 2000s (Corman et al, ; Rejmankova et al, ).…”

Situation analysis of water quality in the Umtata River catchment

“…Other workers have reported that eutrophication-related problems in temperate zones aquatic systems begin to increase at ambient total P concentrations exceeding 0.035 mg P/l. The value is higher for warm-water systems -of the order of 0.34 to 0.70 mg P/l (Rast and Thornton, 1996). The associated N concentration would be of the order of 0.34 to 0.…”

“…It is accepted that these represent nutrient threshold levels, beyond which there will be a corresponding increase in the risk and intensity of plant-related water quality problems (OECD, 1982). These threshold values for nutrients (Rast and Thornton, 1996) are exceeded in the river and eutrophication is well pronounced in the river. The incidence of eutrophication could adversely affect the use of the river for recreation as the covering of large areas by macrophytes could prevent access to waterways and could cause unsightly and malodorous scum which could make recreation unpleasant (Murray et al, 2000).…”

Impact of discharge wastewater effluents on the physico-chemical qualities of a receiving watershed in a typical rural community

“…Other investigators have pointed out that eutrophication-related problems in temperate zones of aquatic systems begin to increase at ambient total P concentrations exceeding 0.035 mg/P. In warm-water systems, the values range between 0.34 and 0.70 mg/P (Rast and Thornton, 1996). These represent nutrient threshold levels beyond which there will be a corresponding increase in the risk and intensity of plant-related water quality problems (OECD, 1982).…”

Effects of Nutrient Limitations and Watershed Inputs on Community Respiration in a Deep, Tropical Lake: Comparison of Pelagic and Littoral Habitats

“…This finding is consistent with literature showing that high levels of organic nitrogen, phosphorus, and carbon found in untreated wastewater stimulated primary productivity and bacterial respiration (Edmondson & Lehman, ; Phillips et al, ; Theodorou, ). Among the many nutrient sources created by humans, untreated wastewater is the most significant point source of nutrient loads (Jarvie et al, ), especially in developing countries (Rast & Thornton, ). While efforts to control direct sewage inflows to the lake are nonexistent at this time, it will be increasingly important to quantify the role of sewage in both autochthonous and allochthonous processes in the system given the recent, intermittent increase of algal production in the middle to late 2000s (Corman et al, ; Rejmankova et al, ).…”

Situation analysis of water quality in the Umtata River catchment

“…Other workers have reported that eutrophication-related problems in temperate zones aquatic systems begin to increase at ambient total P concentrations exceeding 0.035 mg P/l. The value is higher for warm-water systems -of the order of 0.34 to 0.70 mg P/l (Rast and Thornton, 1996). The associated N concentration would be of the order of 0.34 to 0.…”

“…It is accepted that these represent nutrient threshold levels, beyond which there will be a corresponding increase in the risk and intensity of plant-related water quality problems (OECD, 1982). These threshold values for nutrients (Rast and Thornton, 1996) are exceeded in the river and eutrophication is well pronounced in the river. The incidence of eutrophication could adversely affect the use of the river for recreation as the covering of large areas by macrophytes could prevent access to waterways and could cause unsightly and malodorous scum which could make recreation unpleasant (Murray et al, 2000).…”