The Sunshine Lake/Sunrise Waterway System, located in Southwest Florida （USA） previously experienced extensive and persistent algal blooms, with noxious odors and deep organic-rich sediments. This algal bloom was ad...The Sunshine Lake/Sunrise Waterway System, located in Southwest Florida （USA） previously experienced extensive and persistent algal blooms, with noxious odors and deep organic-rich sediments. This algal bloom was addressed via a lake-wide dredging project to remove the material from the lake bottom. A contributing factor to the algal bloom is elevated phosphorus in stormwater runoff, likely due to naturally phosphorus-rich geology in the surrounding watershed. Due to the naturally elevated phosphorus supply, excessive nutrient loads will likely continue in the future. An ongoing monitoring program, initiated after the dredging of the lake, determined that a type of algae （Chara sp,） other than that which caused the initial bloom had established itself by October 2015. This plant biomass is considered an alternative destination for incoming nutrient loads, and as such should be managed, rather than eliminated via the use of herbicides. The abundance and nutrient content of the mass of Chara sp. in the lake and waterway was estimated, and the amount of external nutrient load that would be removed from the lake with physical harvesting of Chara sp. was quantified. The cost-effectiveness of nutrient removal via physical harvesting of Chara sp. was then compared against typical stormwater treatment ponds.展开更多
Huntsman Lake is located within the Middle Run of the Pohick Creek watershed, which is itself located within the much larger Chesapeake Bay watershed. Data collected from both the water column and the lake＇s sediment...Huntsman Lake is located within the Middle Run of the Pohick Creek watershed, which is itself located within the much larger Chesapeake Bay watershed. Data collected from both the water column and the lake＇s sediments indicate that phosphorus-rich bottom sediments are an important internal loading source, and these internal phosphorus loads would continue to adversely impact water quality until and unless sediments are removed or inactivated. The implementation of artificial circulation was anticipated to be able to increase the sequestration of phosphorus within better oxygenated bottom sediments, and was the first lake management strategy deployed in Huntsman Lake. In the first two years after the installation of a whole-lake circulation system, the lake＇s waters are no longer stratified, and the bottom waters are no longer hypoxic and/or anoxic. While there is no evidence of a subsequent reduction in concentrations of nitrogen or chlorophyll-a, average phosphorus concentrations have decreased. However, high variability in the phosphorus data decreases our confidence that this is a sustained improvement. These results are consistent with prior findings, including those from downstream systems, that the reversal of the symptoms of eutrophication can involve lag-periods up to several years, if they are successful at all.展开更多
文摘The Sunshine Lake/Sunrise Waterway System, located in Southwest Florida （USA） previously experienced extensive and persistent algal blooms, with noxious odors and deep organic-rich sediments. This algal bloom was addressed via a lake-wide dredging project to remove the material from the lake bottom. A contributing factor to the algal bloom is elevated phosphorus in stormwater runoff, likely due to naturally phosphorus-rich geology in the surrounding watershed. Due to the naturally elevated phosphorus supply, excessive nutrient loads will likely continue in the future. An ongoing monitoring program, initiated after the dredging of the lake, determined that a type of algae （Chara sp,） other than that which caused the initial bloom had established itself by October 2015. This plant biomass is considered an alternative destination for incoming nutrient loads, and as such should be managed, rather than eliminated via the use of herbicides. The abundance and nutrient content of the mass of Chara sp. in the lake and waterway was estimated, and the amount of external nutrient load that would be removed from the lake with physical harvesting of Chara sp. was quantified. The cost-effectiveness of nutrient removal via physical harvesting of Chara sp. was then compared against typical stormwater treatment ponds.
文摘Huntsman Lake is located within the Middle Run of the Pohick Creek watershed, which is itself located within the much larger Chesapeake Bay watershed. Data collected from both the water column and the lake＇s sediments indicate that phosphorus-rich bottom sediments are an important internal loading source, and these internal phosphorus loads would continue to adversely impact water quality until and unless sediments are removed or inactivated. The implementation of artificial circulation was anticipated to be able to increase the sequestration of phosphorus within better oxygenated bottom sediments, and was the first lake management strategy deployed in Huntsman Lake. In the first two years after the installation of a whole-lake circulation system, the lake＇s waters are no longer stratified, and the bottom waters are no longer hypoxic and/or anoxic. While there is no evidence of a subsequent reduction in concentrations of nitrogen or chlorophyll-a, average phosphorus concentrations have decreased. However, high variability in the phosphorus data decreases our confidence that this is a sustained improvement. These results are consistent with prior findings, including those from downstream systems, that the reversal of the symptoms of eutrophication can involve lag-periods up to several years, if they are successful at all.
