Showing papers on "Water quality published in 1999"

Phosphorus Retention in Streams and Wetlands: A Review

Abstract: Wetlands and streams buffer the interactions among uplands and adjacent aquatic systems. Phosphorus (P) is often the key nutrient found to be limiting in both estuarine and freshwater ecosystems. As such, the ability of wetlands and streams to retain P is key to determining downstream water quality. This article reviews the processes and factors regulating P retention in streams and wetlands and evaluates selected methodologies used to estimate P retention in these systems. Phosphorus retention mechanisms reviewed include uptake and release by vegetation, periphyton and microorganisms; sorption and exchange reactions with soils and sediments; chemical precipitation in the water column; and sedimentation and entrainment. These mechanisms exemplify the combined biological, physical, and chemical nature of P retention in wetlands and streams. Methodologies used to estimate P retention include empirical input-output analysis and mass balances, and process kinetics applied at various scales, including micro- a...

Water quality and treatment : a handbook of community water supplies

Abstract: Chapter 1: DRINKING WATER QUALITY STANDARDS, REGULATIONS, AND GOALS. Early Development of Drinking Water Standards. Early History of U.S. Federal Drinking Water Standards. The Safe Drinking Water Act Safe Drinking Water Act Amendments. 1988 Lead Contamination Control Act. 1996 Safe Drinking Water Act Amendments. Development of National Primary Drinking Water Regulations. International Drinking Water Standards. Trends for the Future. Chapter 2: HEALTH AND AESTHETIC ASPECTS OF WATER QUALITY. Waterborne Disease Outbreaks. Pathogenic Organisms. Indicators and Indicator Organisms. The Health Effects of Chemicals. Inorganic Constituents. Organic Constituents. Disinfectants and Disinfection By-Products. Radionuclides. Chapter 3: GUIDE TO SELECTION OF WATER TREATMENT PROCESSES. Water Supply Approaches. Factors Influencing Process Selection. Evaluating Process Options. Examples of Treatment Process Selection. Chapter 4: SOURCE WATER QUALITY MANAGEMENT. GROUNDWATER. Groundwater Source Quality: Relationship with Surface Water and Regulation. General Overview of Groundwater Sources and Impacts on Their Quality. Patterns of Private and Public Groundwater Source Uses: Quality Management Issues. SURFACE WATER. Quality Management of Surface Water Sources. Chapter 5: AIR STRIPPING AND AERATION. Theory of Gas Transfer. Unit Operations. Diffused or Bubble Aeration. Surface Aeration. Spray Aerators. Chapter 6: COAGULATION AND FLOCCULATION. Definitions. Contaminants. Stability of Particle Suspensions. Coagulants. The Flocculation Process. Chapter 7: SEDIMENTATION AND FLOTATION. History of Sedimentation. Sedimentation Theory. Operational and Design Considerations for Sedimentation. Dissolved-Air Flotation. Theory of Dissolved-Air Flotation. Operational and Design Considerations for Flotation. Applications. Nomenclature. Chapter 8. GRANULAR BED AND PRECOAT FILTRATION. An Overview of Potable Water Filtration. Filter Media Hydraulics of Flow Through Porous Media Rapid Granular Bed Filtration. Theory of Rapid Filtration and Modeling. Rapid Filter Performance. Direct Filtration. Flow Control in Filtration. Backwashing of Rapid Filters. Problems in Rapid Filters. Pressure Granular Bed Filters. Slow Sand Filters. Precoat Filtration. Other Filters. Emerging Technology. Waste Disposal. Chapter 9: ION EXCHANGE AND INORGANIC ADSORPTION. Introduction and Theory of Ion Exchange. Ion Exchange Materials and Reactions. Ion Exchange Equilibrium. Ion Exchange and Adsorption Kinetics. Column Processes and Calculations. Design Considerations. Cocurrent Versus Countercurrent Regeneration. Applications of Ion Exchange and Adsorption. Barium Removal by Ion Exchange. Radium Removal by Ion Exchange. Nitrate Removal by Ion Exchange. Fluoride Removal by Activated Alumina. Arsenic Removal by Resins and Alumina. Chromate Removal by Anion Exchange. Color and Organics Removal by Resins. Uranium Removal by Anion Exchange. Perchlorate Removal by Anion Exchange. Waste Disposal. Chapter 10: CHEMICAL PRECIPITATION. Fundamentals of Chemical Precipitation. Water Softening by Chemical Precipitation. Removal of Nominal Organic Material. Removal of Other Contaminants by Precipitation. Chapter 11: MEMBRANES. Classifications and Configurations of Membrane Processes. Membrane Properties and Rejection Characteristics. Mass Transport and Separation. Process Design Criteria. Waste Disposal. Chapter 12. CHEMICAL OXIDATION. Principles of Oxidation. Oxidants Used in Water Treatment. Applications of Oxidation Processes. Formation of Disinfection (and Oxidation) By-Products. Chapter 13: ADSORPTION OF ORGANIC COMPOUNDS. Adsorption Theory. GAC Adsorption Systems. Performance of GAC Systems. GAC Performance Estimation. PAC Adsorption Systems. PAC Performance. Thermal Reactivation of GAC Adsorption of Organic Matter on Resins. Chapter 14: DISINFECTION. History of Disinfection. Disinfectants and Theory of Disinfection. Disinfectant Demand Reactions. Assessment of Microbial Quality (Indicators). Pathogens of Concern. Disinfection Kinetics. The CT Approach in Regulation. UV Processes. Mode of Action of Disinfectants. Disinfectant Residuals for Posttreatment Protection. Application of Technologies. Use of Multiple Disinfectants. Relative Comparisons. Diagnostics and Troubleshooting. Chapter 15: WATER FLUORIDATION. History. Recent Studies. Present Status of Fluoridation. Theory. Operational and Design Consideration. Application. Chapter 16: WATER TREATMENT PLANT RESIDUALS MANAGEMENT. Quantity of Solid/Liquid Residuals Generated. Physical and Chemical Characteristics of Solid/Liquid Residuals. Thickening Solid/Liquid Residuals. Nonmechanical Dewatering of Solid/Liquid Residuals. Mechanical Dewatering of Solid/Liquid Residuals. Recycle. Membrane and Ion Exchange Residuals. Ultimate Disposal and Utilization of Solids. Chapter 17: INTERNAL CORROSION AND DEPOSITION CONTROL. Corrosion, Passivation, and Immunity. Types of Corrosion. Physical Factors Affecting Corrosion and Metals Release. Chemical Factors Affecting Corrosion. Corrosion of Specific Materials. Direct Methods for the Assessment of Corrosion. Indirect Methods for the Assessment of Corrosion. Corrosion Control Alternatives. Acknowledgments. Chapter 18: MICROBIOLOGICAL QUALITY CONTROL IN DISTRIBUTION SYSTEMS. General Considerations for Contamination Prevention. Engineering Considerations for Contamination Prevention. Factors Contributing to Microbial Quality Deterioration. Microbial Quality of Distributed Water. Microbial Colonization Factors. Monitoring Factors.

Effects of agriculture, urbanization, and climate on water quality in the northern Great Plains

Abstract: The Qu'Appelle Valley drainage system provides water to a third of the population of the Canadian Great Plains, yet is plagued by poor water quality, excess plant growth, and periodic fish kills. Fossil algae (diatoms, pigments) and invertebrates (chironomids) in Pasqua Lake were analyzed by variance partitioning analysis (VPA) to determine the relative importance of climate, resource use, and urbanization as controls of aquatic community composition 1920-1994. From fossil analyses, we identified three distinct biological assemblages in Pasqua Lake. Prior to agriculture (ca. 1776-1890), the lake was naturally eutrophic with abundant cyanobacterial carotenoids (myxo-xanthophyll, aphanizophyll), eutrophic diatoms (Stephanodiscus niagarae, Aulacoseira granulata, Fragilaria capucina/bidens), and anoxia-tolerant chironomids (Chironomus). Principal components (PCA) and dissimilarity analyses demonstrated that diatom and chironomid communities did not vary significantly (P > 0.05) before European settlement. Communities changed rapidly during early land settlement (ca. 1890-1930) before forming a distinct assemblage ca. 1930–1960 characterized by elevated algal biomass (inferred as β-carotene), nuisance cyanobacteria, eutrophic Stephanodiscus hantzschii, and low abundance of deep-water zoobenthos. Recent fossil assemblages (1977–1994) were variable and indicated water quality had not improved despite 3-fold reduction in phosphorus from sewage. Comparison of fossil community change and continuous annual records of 83 environmental variables (1890–1994) using VPA captured 71–97% of variance in fossil composition using only 10-14 significant factors. Resource use (cropland area, livestock biomass) and urbanization (nitrogen in sewage) were stronger determinants of algal and chironomid community change than were climatic factors (temperature, evaporation, river discharge). Landscape analysis of inferred changes in past algal abundance (as β-carotene; ca. 1780-1994) indicated that urban impacts declined with distance from point sources and suggested that management strategies will vary with lake position within the catchment.

Determining sources of fecal pollution in a rural Virginia watershed with antibiotic resistance patterns in fecal streptococci.

Abstract: Nonpoint sources of pollution that contribute fecal bacteria to surface waters have proven difficult to identify. Knowledge of pollution sources could aid in restoration of the water quality, reduce the amounts of nutrients leaving watersheds, and reduce the danger of infectious disease resulting from exposure to contaminated waters. Patterns of antibiotic resistance in fecal streptococci were analyzed by discriminant and cluster analysis and used to identify sources of fecal pollution in a rural Virginia watershed. A database consisting of patterns from 7,058 fecal streptococcus isolates was first established from known human, livestock, and wildlife sources in Montgomery County, Va. Correct fecal streptococcus source identification averaged 87% for the entire database and ranged from 84% for deer isolates to 93% for human isolates. To field test the method and the database, a watershed improvement project (Page Brook) in Clarke County, Va., was initiated in 1996. Comparison of 892 known-source isolates from that watershed against the database resulted in an average correct classification rate of 88%. Combining all animal isolates increased correct classification rates to > or = 95% for separations between animal and human sources. Stream samples from three collection sites were highly contaminated, and fecal streptococci from these sites were classified as being predominantly from cattle (>78% of isolates), with small proportions from waterfowl, deer, and unidentified sources ( approximately 7% each). Based on these results, cattle access to the stream was restricted by installation of fencing and in-pasture watering stations. Fecal coliforms were reduced at the three sites by an average of 94%, from prefencing average populations of 15,900 per 100 ml to postfencing average populations of 960 per 100 ml. After fencing, <45% of fecal streptococcus isolates were classified as being from cattle. These results demonstrate that antibiotic resistance profiles in fecal streptococci can be used to reliably determine sources of fecal pollution, and water quality improvements can occur when efforts to address the identified sources are made.

Effects of agriculture, urbanization, and climate on water quality in the northern

Abstract: The Qu’Appelle Valley drainage system provides water to a third of the population of the Canadian Great Plains, yet is plagued by poor water quality, excess plant growth, and periodic fish kills. Fossil algae (diatoms, pigments) and invertebrates (chironomids) in Pasqua Lake were analyzed by variance partitioning analysis (VPA) to determine the relative importance of climate, resource use, and urbanization as controls of aquatic community composition 1920‐1994. From fossil analyses, we identified three distinct biological assemblages in Pasqua Lake. Prior to agriculture (ca. 1776‐1890), the lake was naturally eutrophic with abundant cyanobacterial carotenoids (myxoxanthophyll, aphanizophyll), eutrophic diatoms (Stephanodiscus niagarae, Aulacoseira granulata, Fragilaria capucina/bidens), and anoxia-tolerant chironomids (Chironomus). Principal components (PCA) and dissimilarity analyses demonstrated that diatom and chironomid communities did not vary significantly (P . 0.05) before European settlement. Communities changed rapidly during early land settlement (ca. 1890‐1930) before forming a distinct assemblage ca. 1930‐1960 characterized by elevated algal biomass (inferred as b-carotene), nuisance cyanobacteria, eutrophic Stephanodiscus hantzschii, and low abundance of deep-water zoobenthos. Recent fossil assemblages (1977‐1994) were variable and indicated water quality had not improved despite 3-fold reduction in phosphorus from sewage. Comparison of fossil community change and continuous annual records of 83 environmental variables (1890‐1994) using VPA captured 71‐97% of variance in fossil composition using only 10‐14 significant factors. Resource use (cropland area, livestock biomass) and urbanization (nitrogen in sewage) were stronger determinants of algal and chironomid community change than were climatic factors (temperature, evaporation, river discharge). Landscape analysis of inferred changes in past algal abundance (as b-carotene; ca. 1780‐1994) indicated that urban impacts declined with distance from point sources and suggested that management strategies will vary with lake position within the catchment.

Nitrogen pollution: an assessment of its threat to amphibian survival.

Abstract: The potential for nitrate to affect amphibian survival was evaluated by examining the areas in North America where concentrations of nitrate in water occur above amphibian toxicity thresholds. Nitrogen pollution from anthropogenic sources enters bodies of water through agricultural runoff or percolation associated with nitrogen fertilization, livestock, precipitation, and effluents from industrial and human wastes. Environmental concentrations of nitrate in watersheds throughout North America range from 100 mg/L. Of the 8,545 water quality samples collected from states and provinces bordering the Great Lakes, 19.8% contained nitrate concentrations exceeding those which can cause sublethal effects in amphibians. In the laboratory lethal and sublethal effects in amphibians are detected at nitrate concentrations between 2.5 and 100 mg/L. Furthermore, amphibian prey such as insects and predators of amphibians such as fish are also sensitive to these elevated levels of nitrate. From this we conclude that nitrate concentrations in some watersheds in North America are high enough to cause death and developmental anomalies in amphibians and impact other animals in aquatic ecosystems. In some situations, the use of vegetated buffer strips adjacent to water courses can reduce nitrogen contamination of surface waters. Ultimately, there is a need to reduce runoff, sewage effluent discharge, and the use of fertilizers, and to establish and enforce water quality guidelines for nitrate for the protection of aquatic organisms.

Seasonal and long-term trends in the water quality of Florida Bay (1989–1997)

Abstract: Analysis of 6 yr of monthly water quality data was performed on three distinct zones of Florida Bay: the eastern bay, central bay, and western bay. Each zone was analyzed for trends at hrtra-annual (seasonal), interammal (oscillation), and long-term (monotonic) scales. The variables TON, TOC, temperature, and TN : TF' ratio had seasonal maxhna in the summer rainy season; APA and Chl a, indicators of the size and activity of the microplankton tended to have maxima in the fall. In contrast, NO,-, NO,-, NH,+, turbidity, and DO,. were highest in the winter dry season. There were large changes in some of the water quality variables of Florida Bay over the study period. Salinity and TP concentrations declined baywide while turbidity increased dramatically. Salinity declined in the eastern, central, and western Florida Bay by 13.6%0, 11.6%0, and 5.6%0, respectively. Some of the decrease in the eastern bay could be accounted for by increased freshwater flows from the Everglades. In contrast to most other estuarine systems, increased runoff may have been partially responsible for the decrease in TP concentrations as input concentrations were 0.3-6.5 PM. Turbidity in the eastern bay increased twofold from 1991 to 1996, while in the central and western bays it increased by factors of 20 and 4, respectively. Chl a concentrations were particularly dynamic and spatially heterogeneous. In the eastern bay, which makes up roughly half of the surface area of Florida Bay, Chl a declined by 0.9 pg lit (63%). The hydrographically isolated central bay zone underwent a fivefold increase in phytoplankton biomass from 1989 to 1994, then rapidly declined to previous levels by 1996. In western Florida Bay there was a significant increase in Cbl a, yet median concentrations of Chl a in the water column remained modest (-2 pg 1-l) by most estuarine standards. Only in the central bay did the DIN pool increase substantially (threefold to sixfold). Notably, these changes in turbidity and phytoplankton biomass occurred after the poorly-understood seagrass die-off in 1987. It is lihely the death and decom- position of large amounts of seagrass biomass can at least partially explain some of the changes in water quality of Florida Bay, but the connections are temporally disjoint and the processes indirect and not well understood.

Relationships Between Landscape Characteristics and Nonpoint Source Pollution Inputs to Coastal Estuaries.

Abstract: / Land-use activities affect water quality by altering sediment, chemical loads, and watershed hydrology. Some land uses may contribute to the maintenance of water quality due to a biogeochemical transformation process. These land-use/land-cover types can serve as nutrient detention zones or as nutrient transformation zones as dissolved or suspended nutrients or sediments move downstream. Despite research on the effects of individual land-use/land-cover types, very little has been done to analyze the joint contributions of multiple land-use activities. This paper examines a methodology to assess the relationships between land-use complex and nitrate and sediment concentrations [nonpoint source (NPS) pollutants] in streams. In this process, selected basins of the Fish River, Alabama, USA, were delineated, land-use/land-cover types were classified, and contributing zones were identified using geographic information system (GIS) and remote sensing (RS) analysis tools. Water samples collected from these basins were analyzed for selected chemical and physical properties. Based on the contributions of the NPS pollutants, a linkage model was developed. This linkage model relates land use/land cover with the pollution levels in the stream. Linkage models were constructed and evaluated at three different scales: (1) the basin scale; (2) the contributing-zone scale; and (3) the stream-buffer/riparian-zone scale. The contributing-zones linkage model suggests that forests act as a transformation zone, and as the proportion of forest inside a contributing zone increases (or agricultural land decreases), nitrate levels downstream will decrease. Residential/urban/built-up areas were identified as the strongest contributors of nitrate in the contributing-zones model and active agriculture was identified as the second largest contributor. The regression results for the streambank land-use/land-cover model (stream-buffer/riparian-zone scale) suggest that water quality is highest when passive land uses, such as forests and grasslands, are located adjacent to streams. Nonpassive land uses (agricultural lands or urban/built-up areas) located adjacent to streams have negative impacts on water quality. The model can help in examining the relative sensitivity of water-quality variables to alterations in land use made at varying distances from the stream channel. The model also shows the importance of streamside management zones, which are key to maintenance of stream water quality. The linkage model can be considered a first step in the integration of GIS and ecological models. The model can then be used by local and regional land managers in the formulation of plans for watershed-level management. KEY WORDS: Water quality; Land-use complex; Geographic information system; Nonpoint source pollution; Forested buffers

Changes in agricultural intensity and river health along a river continuum

Abstract: SUMMARY 1. The impact of agricultural activities on waterways is a global issue, but the magnitude of the problem is often not clearly recognized by landowners, and land and water management agencies. 2. The Pomahaka River in southern New Zealand represents a typical lowland catchment with a long history of agricultural development. Fifteen sites were sampled along a 119-km stretch of the river. Headwater sites were surrounded by low-intensity sheep farming, with high-intensity pasture and dairying occurring in the mid-reach and lower reaches. 3. Water clarity decreased significantly from about 6 m in the headwaters to less than 2 m in the lower reaches. Benthic sediment levels increased significantly downriver, peaking at 35 mg mT 2 below several tributaries with high-intensity agriculture in their catchments. Periphyton levels were also significantly greater in the lower reaches than the headwaters, and coincided with increased nitrogen (DIN) and phosphorus (SRP) concentrations. 4. Macro-invertebrate species richness did not change significantly throughout the river, but species composition did with Ephemeroptera, and to a lesser extent, Plecoptera and Trichoptera dominating the headwater sites (where there was high water clarity, and low nutrient and periphyton levels). Downriver these assemblages were replaced by molluscs, oligochaetes and chironomids. 5. Canonical correspondence analysis indicated that agricultural intensity and physical conditions associated with agriculture activity (e.g. impacted waters, high turbidity and temperature) were strongly associated with the composition of benthic assemblages at differing reaches down the Pomahaka River. 6. The present results indicate that quantifying agricultural intensity within a catchment, particularly relative livestock densities, may provide a useful tool for identifying threshold levels above which river health declines.

Water Quality Analysis of a Freshwater Diversion at Caernarvon, Louisiana

Abstract: Since 1991, Mississippi River water has been diverted at Caernarvon, Louisiana, into Breton Sound estuary. Breton Sound estuary encompasses 1100 km2 of fresh and brackish, rapidly subsiding wetlands. Nitrite + nitrate, total Kjeldahl nitrogen, ammonium, total phosphorus, total suspended sediments, and salinity concentrations were monitored at seven locations in Breton Sound from 1988 to 1994. Statistical analysis of the data indicated decreased total Kjeldahl nitrogen with associated decrease in total nitrogen, and decreased salinity concentrations in the estuary due to the diversion. Spring and summer water quality transects indicated rapid reduction of nitrite + nitrate and total suspended sediment concentration as diverted Mississippi River water entered the estuary, suggesting near complete assimilation of these constituents by the ecosystem. Loading rates of nitrite + nitrate (5.6–13.4 g m−2 yr−1), total nitrogen (8.9–23.4 g m−2 yr−1), and total phosphorus (0.9–2.0 g m−2 yr−1) were calculated along with removal efficiencies for these constituents (nitrite + nitrate 88–97%; total nitrogen 32–57%; total phosphorus 0–46%). The low impact of the diversion on water quality in the Breton Sound estuary, along with assimilation of TSS over a very short distance, suggests that more water may be introduced into the estuary without detrimental affects. This would be necessary if freshwater diversions are to be used to distribute nitrients and sediments into the lower reaches of the estuary, in an effort to compensate for relative sea-level rise, and reverse the current trend of rapid loss of wetlands in coastal Louisiana.

Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms

Abstract: Diatom assemblages were selected as indicators of lake condition and to assess historical lake water quality changes in 257 lakes in the northeastern United States The "top" (surface sediments, pr

Water Quality in Walnut Creek Watershed: Nitrate-Nitrogen in Soils, Subsurface Drainage Water, and Shallow Groundwater

Abstract: Nonpoint source contamination of surface and groundwater resources with nitrate-N (NO 3 -N) has been linked to agriculture across the midwestern USA. A 4-yr study was conducted to assess the extent of NO 3 -N leaching in a central Iowa field. Water flow rate was monitored continuously and data were stored on an internal datalogger. Water samples for chemical analysis were collected weekly provided there was sufficient flow. Twelve soil cores were collected in spring, early summer, mid-summer, and after harvest for each of the 4 yr. Nitrate-N concentrations in shallow groundwater exhibited temporal trends and were higher under Clarion soil than under Okoboji or Canisteo soil. Denitrification rates were two times higher in Okoboji surface soil than in Clarion surface soil and the highest denitrification potential among subsurface sediments was observed for deep unoxidized loess. Soil profile NO 3 -N concentrations decreased with depth and were the same below 30 cm for fertilized corn (Zea mays L.) and soybean (Glycine max L. Merr.). Nitrate-N concentrations in subsurface drainage water exceeded 10 mg L -1 for 12 mo and were between 6 and 9 mg L -1 for 32 mo during the 4-yr study. The temporal pattern of NO 3 -N concentrations in subsurface drainage water was not related to the timing of fertilizer N application or the amount of fertilizer N applied. Total NO 3 -N losses to subsurface drains were greatest in 1993 (51.3 kg ha 1 ) and least in 1994 (4.9 kg ha -1 ). Most of the subsurface drainage water NO 3 -N was lost when crop plants were not present (November-May), except in 1993. Our results indicate that NO 3 -N losses to subsurface drainage water occur primarily as a result of asynchronous production and uptake of NO 3 -N in the soil and the presence of large quantities of potentially mineralizable N in the soil organic matter.

Water quality prediction and probability network models

Abstract: It is a common strategy in surface water quality modeling to attempt to remedy predictive inadequacies by incorporating additional mechanistic detail into the model. This approach reflects the reas...

Aluminium in drinking water: An overview

Abstract: Aluminium (Al) is one of the trace inorganic metals present in drinking water. In addition to the naturally occurring Al in raw waters, use of Al-based coagulants especially Al 2(SO4)3 (alum) often leads to an increase in treated water Al concentrations. A high (3.6 to 6 mg/l) concentration of Al may precipitate as aluminium hydroxide giving rise to consumer complaints. Al is also a suspected causative agent of neurological disorders such as Alzheimer’s disease and presenile dementia. During conventional water treatment processes, Al undergoes various transformations (also called ‘speciation’ of Al) which are influenced by factor s such as pH, turbidity, temperature of water source, and the organic and inorganic ligands present in water. Chemical precipitat ion, reverse osmosis, electrodialysis and cation exchange methods are efficient in Al removal from water. This paper gives an overvi ew of the presence of Al in drinking water with reference to its speciation, removal (treatment methods), water supply and health problems, and the regulation of its levels in drinking water.

Field Evaluation of Permeable Pavement Systems for Improved Stormwater Management

Abstract: The contribution of impervious surfaces to the disrupted runoff processes in an urban watershed is overwhelming. Nearly all the problems ultimately result from the loss of the water-retaining function of the soil in the urban landscape. Traditional solutions for storm water management have not been widely successful; in contrast, permeable pavements can be one element of a more promising alternative approach to reduce the downstream consequences of urban development. We report on a constructed experimental facility for measuring water quantity and water quality from four different permeable parking surfaces. Preliminary results demonstrate similar runoff performances of the surfaces relative to each other, and significant attenuation of runoff relative to traditional asphalt.

Relative regional vulnerability of water resources to climate change.

Abstract: Changes in global climate may alter hydrologic conditions and have a variety of effects on human settlements and ecological systems. The effects include changes in water supply and quality for domestic, irrigation, recreational, commercial, and industrial uses; in instream flows that support aquatic ecosystems, recreation uses, hydropower, navigation, and wastewater assimilation; in wetland extent and productivity that support fish, wildlife, and wastewater assimilation; and in the frequency and severity of floods. Watersheds where water resources are stressed under current climate are most likely to be vulnerable to changes in mean climate and extreme events. This study identified key aspects of water supply and use that could be adversely affected by climate change, developed measures and criteria useful for assessing the vulnerability of regional water resources and water dependent resources to climate change, developed a regional database of water sensitive variables consistent with the vulnerability measures, and applied the criteria in a regional study of the vulnerability of U.S. water resources. Key findings highlight the vulnerability of consumptive uses in the western and, in particular, the southwestern United States. However, southern United States watersheds are relatively more vulnerable to changes in water quality, flooding, and other instream uses.

Percentage land use in the watershed determines the water and sediment quality of 22 marshes in the Great Lakes basin

Abstract: Data from 22 Ontario marshes were used to test the hypothesis that distribution of forested, agricultural, and urban land in the watershed determines the water and sediment quality of Great Lakes w...

Environmental geochemistry of the Pichavaram mangrove ecosystem (tropical), southeast coast of India

Abstract: Spatial and temporal geochemical variations of various parameters in the water and sediment of a relatively small mangrove situated on the southeast coast of India were examined in detail for the first time. The water quality generally reflects the impact of seawater and the Vellar estuary (mixing effect) aided by evaporation and in situ biological productivity. The depletion and fluctuation of dissolved silica are controlled by biological processes. Nitrate and phosphate are contributed by fertilizer input from adjoining agriculture fields. Total suspended matter (TSM) shows an erratic range and trend due to deforestation and resuspension processes. Sand and silt constitute 70–90% of the sediments. Statistical analysis of the sediments shows the prevalence of a moderately high-energy environment with very effective winnowing activity. Organic matter content is higher in the mangrove sediments in comparison to adjacent estuaries. Water and sediment show fluctuations in their chemical concentration, but no specific trends could be identified. Heavy metals are also enriched in the mangrove sediments, indicating their unique chemical behavior and the existence of trapping mechanisms. Factor analysis and correlation analysis of water and sediments show the complexity of the system and the multitude of contributing sources. The core sediment chemistry suggests the depletion of metal input due to the damming of the detrital inputs. The Pichavaram mangrove seems to be relatively unpolluted, since the anthropogenic signal observed is small and acts as a sink for heavy metals contributed from a multitude of sources without an adverse effect.

Impacts of the Reduction of Nutrient Levels on Bacterial Water Quality in Distribution Systems

Abstract: This study evaluated the impacts of reducing nutrient levels on bacterial water quality in drinking water. Two American Water System facilities (sites NJ102a and IN610) with histories of coliform problems were involved, and each water utility received two pilot distribution systems (annular reactors). One reactor simulated the conventional treatment conditions (control), while the other reactor was used to assess the effect of biological filtration and subsequent reduced biodegradable organic matter levels on suspended (water column) and biofilm bacterial concentrations in the distribution systems. Biodegradable organic matter levels were reduced approximately by half after biological treatment. For site NJ102a, the geometric mean of the assimilable organic carbon concentrations was 217 μg/liter in the plant effluent and 91 μg/liter after biological filtration. For both sites, plant effluent biodegradable dissolved organic carbon levels averaged 0.45 mg/liter, versus 0.19 to 0.22 mg/liter following biological treatment. Biological treatment improved the stability of free chlorine residuals, while it had little effect on chloramine consumption patterns. High bacterial levels from the biological filters resulted in higher bacterial concentrations entering the test reactors than entering the control reactors. On average, biofilms in the model systems were reduced by 1 log unit (from 1.4 × 105 to 1.4 × 104 CFU/cm2) and 0.5-log unit (from 2.7 × 105 to 7.8 × 104 CFU/cm2) by biological treatment at sites NJ102a and IN610, respectively. Interestingly, it required several months of biological treatment before there was an observable impact on bacterial water quality in the system, suggesting that the effect of the treatment change was influenced by other factors (i.e., pipe conditions or disinfection, etc.).

Water Quality in Walnut Creek Watershed: Setting and Farming Practices

Abstract: Nonpoint-source pollution has been linked to agricultural practices; however, there is a need for quantitative information describing the effect of specific farming practices on ground and surface water quality. Lack of information at the watershed scale limits our ability to make decisions about the effect of potential changes in either farming practices or landscape management that would enhance water quality. A multidisciplinary study was designed to evaluate the effect of farming practices on subsurface drainage, surface runoff, stream discharge, groundwater, volatilization, and soil processes that influence water quality. Walnut Creek watershed is a 5130-ha intensively cropped area in central Iowa on the Des Moines Lobe landform region. Soils within the watershed are in the Clarion-Nicollet-Webster (Typic Hapludoll-Aquic Hapludoll-Typic Haplaquoll) soil association, and the underlying surficial material is glacial till. Land use is predominantly corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. Fertilizer use, herbicide application, tillage practices, and crop selection were obtained through surveys of each field operator. Atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], cyanazine [2-[ 4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl amino]-2-methylpropanenitrile], EPTC [S-ethyl dipropyl carbamothioate], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] are the primary herbicides used within the watershed at rates similar to those for the state. Nitrogen fertilizer was applied as anhydrous ammonia on 60% of the corn fields at an average rate of 153 kg ha -1 for the 1991-1994 period, but the frequency of corn fields receiving <112 kg ha -1 has increased.