摘要:

Off-site damage from soil erosion in freshwater lakes and reservoirs is an environmental concern worldwide. Suspended sediments are the most visible indicators of off-site damage and a major factor affecting water quality and biological activity in water bodies. A technique is needed to monitor the landscape and locate water bodies with significant suspended sediment concentrations. This paper describes a technique using remote sensing data from environmental satellites to estimate suspended sediment concentrations in lakes and reservoirs. Comparisons of water bodies on multiple Landsat scenes indicate reflectance from surface water is related to suspended sediment concentrations. Using satellite remote sensing, large segments of the landscape could be monitored quickly and efficiently to locate water bodies with significant suspended sediment concentrations. Conservation practices to reduce soil erosion and thus off-site damage from suspended sediments could be planned for the watersheds of water bodies with significant suspended sediment problems.

ISSN:1040-2381    

DOI:10.1080/07438148909354685

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Since the 1970s, nutrient-enriched agricultural drainage water has been pumped into the Everglades Water Conservation Areas, markedly changing plant communities and oxygen regimes. The sawgrass plains and diverse aquatic sloughs that once dominated the area are gradually being replaced by more heterotrophic cattail stands. An oxygen budget study in Water Conservation Area-2A revealed diurnal oxygen levels, and variations were greatest in slough and sawgrass areas and minimal at the nutrient-enriched cattail site. Sediment oxygen demand was the major oxygen sink at all sites, while reaeration (sawgrass and cattail sites) and benthic algal production (slough site) were the major sources of oxygen. The slough algal mat areas represent important sites for marsh primary production and detrital processes. These areas function as feeding areas for fishes, invertebrates, and waterfowl, as well as important oxygen sources for adjacent sawgrass areas. Their elimination, therefore, could have serious ecological consequences.

ISSN:1040-2381    

DOI:10.1080/07438148909354686

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Tensas River National Wildlife Refuge, Madison Parish, Louisiana, consists of bottomland hardwood swamps interspersed with small lakes and bayous supporting a diverse assemblage of waterfowl, fish, and assorted species of game and nongame wildlife. Fish collected in the refuge in 1984–85 from areas receiving direct inflow from agricultural runoff contained from 5 to 10 μg/g total DDT (primarily DDE) and toxaphene (measured on a whole-body, wet-weight basis). These concentrations in fish, which were still high enough to pose a threat to fish-eating birds and wildlife, demonstrated that residues from past use of DDT and toxaphene in the area were still available for transport and uptake. In future water projects, the incorporation of structures to prevent contaminated runoff from entering the refuge should reduce waterborne contamination to the refuge.

ISSN:1040-2381    

DOI:10.1080/07438148909354687

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The performance of a modified hydraulic potentiomanometer termed a littoral interstitial porewater (LIP) sampler was evaluated in the field. Patterned after the hydraulic potentiomanometer designed by the U.S. Geological Survey, this tube sampler allowed rapid characterization of groundwater interaction with surface waters. The littoral interstitial porewater sampler facilitates characterizing groundwater quality variability along a lake shoreline, and is used to corroborate information obtained from watershed well sampling. Results were not significantly affected by various sampling protocols or analytical error. Significant changes in water quality parameters were caused by spatial factors, and these corresponded to different land use patterns on shorelines sampled. A significant correlation between the littoral porewater samples and adjacent well water samples was shown. Littoral interstitial porewater pumping rate did not empirically estimate seepage rates. Descriptive statistics of littoral porewater quality data from 15 Massachusetts lakes were given. The correspondence between land use, specifically residential development intensity, and porewater chemistry was documented.

ISSN:1040-2381    

DOI:10.1080/07438148909354688

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Lime, calcium carbonate and/or calcium hydroxide were added eight times to three stormwater retention lakes in Edmonton from June to August 1988. The goal was to evaluate short-term effects of lime on algal biomass and phosphorus concentrations in rapidly-flushed systems – those designed with a water retention period of 0.25 to 0.5 yr. Most of the water flow occurs from May to September and varies greatly depending on annual precipitation. These lakes also provided an opportunity to evaluate lime treatment effects on hardwater lakes with unusually high sulfate and calcium concentrations (average summer concentrations were 334 and 65 mg/L, respectively). Within one week of applying at least 50 mg/L calcium hydroxide with or without calcium carbonate, chlorophylla(used to estimate algal biomass) and total phosphorus concentrations decreased significantly (P < 0.05). In the lake treated solely with calcium carbonate (in doses of 50 and 100 mg/L), neither total phosphorous nor chlorophylladecreased significantly (P > 0.05). Test results for lime controlling phosphorus levels and algal biomass in rapidly-flushed lake systems are promising.

ISSN:1040-2381    

DOI:10.1080/07438148909354689

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor