Showing papers on "Water quality published in 1984"

WHO guidelines for drinking-water quality.

Abstract: In soil, fertilizers containing inorganic nitrogen and wastes containing organic nitrogen are first decomposed to give ammonia, which is then oxidized to nitrite and nitrate. The nitrate is taken up by plants during their growth and used in the synthesis of organic nitrogenous compounds. Surplus nitrate readily moves with groundwater (2, 3). Under aerobic conditions, it percolates in large quantities into the aquifer because of the small extent to which degradation or denitrification occurs. Under anaerobic conditions, nitrate may be denitrified or degraded almost completely to nitrogen. The presence of high or low water tables, the amount of rainwater, the presence of other organic material, and other physicochemical properties are also important in determining the fate of nitrate in soil ( 4). In surface water, nitrification and denitrification may also occur, depending on the temperature and pH. The uptake of nitrate by plants, however, is responsible for most of the nitrate reduction in surface water. Nitrogen compounds are formed in the air by lightning or discharged into it from industrial processes, motor vehicles, and intensive agriculture. Nitrate is present in air primarily as nitric acid and inorganic aerosols, as well as nitrate radicals and organic gases or aerosols. These are removed by wet and dry deposition.

The Groundwater Supply Survey

Abstract: Resultats de mesure de 29 composes organiques volatils, de 5 trihalomethanes, et du carbone organique total de 945 reseaux d'alimentation d'eau

Isolation of Aeromonas hydrophila from a metropolitan water supply: seasonal correlation with clinical isolates.

Abstract: The occurrence of Aeromonas spp. in the metropolitan water supply of Perth, Western Australia, Australia, was monitored at several sampling points during a period of 1 year. Water within the distribution system conformed to international standards for drinking water but contained Aeromonas spp. in numbers comparable to those in raw surface water, although this water was free of Escherichia coli. Coliforms and E. coli were found in raw surface waters, and Aeromonas spp. were found in raw water from surface and underground sources. Chemical treatment, followed by chlorination at service reservoirs, resulted in water free of E. coli and a decrease in the number of Aeromonas spp. Aeromonas spp. were found in the greatest numbers in summer. Multiple regression analysis showed that growth of Aeromonas spp. in chlorinated water was related to water temperature, residual chlorine, and interaction between these variables. The incidence of Aeromonas-associated gastroenteritis, determined from isolates referred to us for enterotoxin testing, paralleled the pattern of isolation of Aeromonas spp. in water within the distribution systems. We suggest that the presence of Aeromonas spp. in drinking water needs public health appraisal and that further work should be undertaken to permit reevaluation of standards for the quality of drinking water.

A primer on trace metal-sediment chemistry

Abstract: In most aquatic systems, concentrations of trace metals in suspended sediment and the top few centimeters of bottom sediment are far greater than concentrations of trace metals dissolved in the water column. Consequently, the distribution, transport, and availability of these constituents can not be intelligently evaluated, nor can their environmental impact be determined or predicted solely through the sampling and analysis of dissolved phases. This Primer is designed to acquaint the reader with the basic principles that govern the concentration and distribution of trace metals associated with bottom and suspended sediments. The sampling and analysis of suspended and bottom sediments are very important for monitoring studies, not only because trace metal concentrations associated with them are orders of magnitude higher than in the dissolved phase, but also because of several other factors. Riverine transport of trace metals is dominated by sediment. In addition, bottom sediments serve as a source for suspended sediment and can provide a historical record of chemical conditions. This record will help establish area baseline metal levels against which existing conditions can be compared. Many physical and chemical factors affect a sediment's capacity to collect and concentrate trace metals. The physical factors include grain size, surface area, surface charge, cation exchange capacity, composition, and so forth. Increases in metal concentrations are strongly correlated with decreasing grain size and increasing surface area, surface charge, cation exchange capacity, and increasing concentrations of iron and manganese oxides, organic matter, and clay minerals. Chemical factors are equally important, especially for differentiating between samples having similar bulk chemistries and for inferring or predicting environmental availability. Chemical factors entail phase associations (with such sedimentary components as interstitial water, sulfides, carbonates, and organic matter) and ways in which the metals are entrained by the sediments (such as adsorption, complexation, and within mineral lattices). INTRODUCTION The basic goal of most chemically oriented water-quality studies is to describe or evaluate existing environmental conditions and to attempt to identify the source or sources of the constituents under investigation. An equally important goal is to attempt to predict or determine potential impacts. This heading could accommodate such subjects as bioavailability, amount of constituent transport, location of chemical sinks, ultimate fate, and potential toxic effects. Historically, the U.S. Geological Survey has attempted to assess trace metals in aquatic systems by analyzing water samples. This assessment has entailed determining concentrations of total and dissolved elements and compounds through the collection and analysis, respectively, of unfiltered and filtered water. Concentrations associated with suspended sediment (particulates, seston) are determined indirectly by the difference between total and dissolved concentrations. It is recognized that this approach casts doubt on the reliability of reported suspended-sediment chemical analyses. As a result, water quality tends to be evaluated on the kinds and concentration of various constituents found in solution (Feltz, 1980). However, in most aquatic systems, the concentration of trace metals in suspended sediment and the top few centimeters of bottom sediment is far greater than the concentration of trace metals dissolved in the water column. The strong association of numerous trace metals (for example, As, Cd, Hg, Pb, Zn) with seston and bottom sediments means that the distribution, transport, and availability of these constituents can not be intelligently evaluated solely through the sampling and analysis of the dissolved phase. Additionally, because bottom sediments can act as a reservoir for many trace metals, they must, for several reasons, be given serious consideration in the planning and design of any water-quality study. First, an undisturbed sediment sink contains a historical record of chemical conditions. If a sufficiently large and stable sink can be found and studied, it will allow the investigator to study changes over time and, possibly, to establish area baseline levels against which existing conditions can be compared and contrasted. Second, under changing environmental or physicochemical conditions (like pH, Eh, dissolved oxygen, bacterial action), sediment-bound trace metals can dissolve into the water column, possibly enter the food chain, and have a significant environmental impact. Third, several relatively inert or otherwise environmentally harmless inorganic constituents can degrade, or react with others, to form soluble and potentially toxic forms (for example, the conversion of elemental mercury to methyl-mercury). Finally, bottom sediments should be regarded as a major, if not the major, source of suspended sediment. Therefore, they must be investigated to determine transport potential. Under changing hydrologic conditions (such as a heavy storm or spring runoff), a localized pollution problem can suddenly become widespread and result in significant environmental impact. The foregoing discussion indicates that data on suspended and bottom sediments, as well as on the dissolved phase, are a requisite for the development of a comprehensive understanding of the impact of trace metals on water quality. Through the use of such additional data, it may be possible to begin to identify sources and sinks and the fate and potential effects of toxic or environmentally necessary metals. Similarly, sediment-chemical data are a requisite for transport modeling, for estimating geochemical cycles, and for inferring the availability of various trace metals in an ecological system.

Nutrient Cycling in an Agricultural Watershed: I. Phreatic Movement

Abstract: Much of the runoff from agricultural fields in the southeastern Coastal Plain is carried to a stream channel system in a shallow phreatic aquifer. This subsurface runoff often passes through a band of riparian forest before becoming streamflow. It is hypothesized that the riparian ecosystem acts as a nutrient sink and reduces the concentrations and loads of nutrients in the shallow aquifer before the nutrients reach the stream channel. Concentrations and loads (kg/m²) of NO₃-N, NH₄-N, organic N, dissolved molybdate-reactive P₁ total P, Ca, Mg, K, Cl, and SO₄-S were measured in shallow phreatic wells at 37 locations on an agricultural watershed near Tifton, Ga. Total water volume moving off the watershed in subsurface flow was < 1% of streamflow with corresponding small amounts of nutrients. Nitrate-N, Ca, and Mg had significantly higher concentrations in field wells than in forest or streamside wells. Concentrations of Cl were not reduced as water moved from field to forest. Processes within the riparian zone apparently converted primarily inorganic N from fields (76% NO₃-N, 6% NH₄-N, 18% organic N) into primarily organic N in streamside wells (10% NO₃-N, 14% NH₄-N, and 76% organic N). Concentration differences between field and forest wells indicated the riparian forest's ability to act as a sink for NO₃-N, Ca, Mg, K, and SO₄-S. Due to their role as nutrient sinks, riparian forests are important in maintaining stream water quality on agricultural watersheds.

Agriculture and stream water quality: A biological evaluation of erosion control practices

Abstract: Agricultural runoff affects many streams in North Carolina. However, there is is little information about either its effect on stream biota or any potential mitigation by erosion control practices. In this study, benthic macroinvertebrates were sampled in three different geographic areas of North Carolina, comparing control watersheds with well-managed and poorly managed watersheds. Agricultural streams were characterized by lower taxa richness (especially for intolerant groups) and low stability. These effects were most evident at the poorly managed sites. Sedimentation was the apparent major problem, but some changes at agricultural sites implied water quality problems. The groups most intolerant of agricultural runoff were Ephemeroptera, Plecoptera and Trichoptera. Tolerant species were usually filter-feeders or algal grazers, suggesting a modification of the food web by addition of particulate organic matter and nutrients. This study clearly indicates that agricultural runoff can severely impact stream biota. However, this impact can be greatly mitigated by currently recommended erosion control practices.

Detection of enteric viruses in treated drinking water.

Abstract: The occurrence of viruses in conventionally treated drinking water derived from a heavily polluted source was evaluated by collecting and analyzing 38 large-volume (65- to 756-liter) samples of water from a 9 m3/s (205 X 10(6) gallons [776 X 10(6) liters] per day) water treatment plant. Samples of raw, clarified, filtered, and chlorinated finished water were concentrated by using the filter adsorption-elution technique. Of 23 samples of finished water, 19 (83%) contained viruses. None of the nine finished water samples collected during the dry season contained detectable total coliform bacteria. Seven of nine finished water samples collected during the dry season met turbidity, total coliform bacteria, and total residual chlorine standards. Of these, four contained virus. During the dry season the percent removals were 25 to 93% for enteric viruses, 89 to 100% for bacteria, and 81% for turbidity. During the rainy season the percent removals were 0 to 43% for enteric viruses, 80 to 96% for bacteria, and 63% for turbidity. None of the 14 finished water samples collected during the rainy season met turbidity standards, and all contained rotaviruses or enteroviruses.

Complexation of heavy metals by extracellular polymers in the activated sludge process

Abstract: Raw industrial and domestic wastewaters are likely to contain persistent anthropogenic pollutants, one group of which, the heavy metals, is particularly hazardous. Therefore, these ma terials must be removed prior to effluent discharge to reduce the potentially harmful effects to both the ecosystem of the receiving watercourse and the public health.1 Englande and Reimers2 have stressed that adequate dilution capacity of receiving waters is important to minimize the adverse effects of effluents, especially in areas where water reuse is practiced. In the U.K., during the low flow period of 1976, 40% of the River Derwent consisted of effluent, mainly from industry3; in other areas with extensive water reuse, almost 90% of surface flow could be from wastewater effluents.4 Because of the nature of wastewater treatment processes, accumulation of mineral content is inherent in water reuse2; thus, considerable environ mental concern has focused on these nonbiodegradable and toxic heavy metals.5 By whatever method water quality control standards are used, the movement to reduce and ultimately eradicate aquatic pollution is likely to require increased restrictions on the discharge of metal-laden and other effluents.6 To comply with the standards, industrial effluents could be diverted from direct discharge to sewers, which could cause treatment plant perfor mance to deteriorate but which would improve the condition of receiving water. Thus, as standards are raised, wastewater treatment will contribute significantly to the maintenance of surface water quality. Particulate and precipitated material is removed by primary sedimentation, which generally accounts for up to 40% of the initial metal load.7'8 Forms of metal entering the biological treatment stage are predominantly soluble.9 Biological removal of soluble metals is critical because their overall retention depends on absorption by the activated sludge biomass.

Epilithic and epipelic diatoms in the Sandusky River, with emphasis on species diversity and water pollution

Abstract: Benthic diatom communities were collected seasonally from silty and rocky substrates to survey the water quality of the Sandusky River. Even though species composition was highly variable along the river, recurrent changes in relative abundance of specific diatom taxa and changes in overall community composition delineated areas where discharge of treated sewage affected water quality of the river. Changes in species diversity (Shannon formula), not decreases in diversity, marked the site where greatest pollution had occurred. Problems with using species diversity indices to indicate pollution tend to be related to predicting decreases in diversity in response to decreases in water quality. Evidence in the Sandusky River and the theories of diatom community dynamics suggest that species diversity can be greater in polluted areas than less polluted areas.

Trophic Response of Fishes to Habitat Variability in Coastal Seagrass Systems

Abstract: Shallow coastal areas of the northeast Gulf of Mexico are physically unstable in terms of short-term, seasonal, and year-to-year changes in temperature, salinity, nutrient concentration, and other water quality features. A 9-yr comparison was made of two estuaries, one polluted and one in the natural state, to determine the response of fish assemblages to habitat alteration in space and time. During the study period, extreme natural habitat changes due to storm water runoff and low winter temperatures were superimposed over water quality changes (increased color, turbidity, nutrients; reduced dissolved oxygen) associated with release of pulp mill effluents. Various grassbed fishes followed regular seasonal, age-specific feeding patterns, which did not change substantially in terms of qualitative food composition in the unpolluted estuary over a 7-yr period of observation. Such feeding behavior helped to explain temporally conservative cycles of relative abundance despite ex- treme (natural) habitat change. Anthropogenous habitat alterations, though seemingly slight, were associated with reductions in benthic macrophyte distribution, enhanced phytoplankton productivity, and changes in the relative dominance and numerical abundance of associated fish assemblages. Grassbed species were replaced by plankton-feeding fishes, and disruption of feeding habits of various species was apparent in the affected area relative to the unpolluted estuary. Those fishes dependent on specific benthic food organisms altered their feeding habits during the years of pollution in the affected estuary. Subsequent water quality improvement over time was associated with shifts in the age-specific dietary patterns of various species toward those observed in the unaffected estuary, although such recovery varied from species to species according to habitat utilization and trophic needs. From these results, it is clear that a relatively complex coastal seagrass system exposed to periodic, extreme natural disturbance is relatively resilient to such changes in terms of relative dominance and food web structure. However, apparently slight water quality changes due to pollution, which are outside the evolutionary experience of the biotic components, can cause serious disruptions of the basic habitat structure, energy flow, and community composition of the grassbed assemblages at various levels of biological organization.

Use of artificial wetlands to remove nitrogen from wastewater

Abstract: As demands for water continue to increase and new water sources become scarcer and more expensive to develop, water resource planners look for alternative methods, such as waste water reclamation, to increase supplies. The Clean Water Act of 1977 (PL95-217) encourages the use of alternative and in novative technologies for water reuse. The concept of using wetlands for cost-effective and energy efficient treatment of municipal wastewaters has been dem onstrated both in Europe,1,2 and in the United States,3-6 with some degree of success; however, to date there has been little literature published on the operational parameters and associated treatment efficiency of wetlands (either natural or artificial) spe cifically designed for the removal of certain problem constituents, such as nitrogen. The deleterious effects of nitrogen on the aquatic environment include the increased eutrophication of receiving waters, and the increased risk of methemoglobinemia in human infants where elevated levels of nitrate (N03) or nitrite (N02) nitrogen are present in drinking supplies.7 With regard to the latter case, the Committee on Water Quality Criteria of the National Acad emy of Science has recommended that N03-nitrogen (NO3-N) concentration not exceed 10 mg/L in public water supplies.8 Therefore, it is essential that whenever reclaimed wastewater is injected or percolated into a domestic groundwater supply for recharge, a treatment process be selected that is capable of meet ing drinking water standards (<10 mg/L NO3-N). The most successful procedure for the removal of nitrogen from wastewater is sequential nitrification-denitrification, whereby ammonia (NH3) is first oxidized to NO3 by chemoau totrophic nitrifying bacteria, and then reduced to the gaseous end products (nitrogen gas, N2 or nitrous oxide, N20) by denitrifying bacteria, which utilize N03 or N02 as respiratory electron acceptors to carry out the oxidation of carbonaceous organic substrates. Denitrifying systems for NO3 removal from secondary wastewaters, agricultural drainage waters, or contam inated groundwater supplies, all of which contain very low levels of biochemical oxygen demand (BOD)?and often require sup plemental organic carbon (methanol) to increase the carbon pool and stimulate denitrification. Ehreth and Basifico9 pointed out the importance of low-cost alternatives to methanol, the use of which can account for nearly 50% of the operation and maintenance costs of treatment.10 Gersberg et al.,11 described the use of pilot-scale (66-m2) ar tificial wetlands as biological systems for the removal of N03 from secondary wastewater effluents. This report describes stud ies with larger, demonstration-scale (820-m2) artificial wetlands, which removed nitrogen from secondary wastewater effluents. Methanol, or lower-cost alternatives such as mulched plant bio mass or blended primary effluent, were used as the carbon sources to drive the denitrification process.

Ground-Water Quality at a Creosote Waste Site

Abstract: An abandoned creosote facility in Conroe, Texas, has become a field site for the National Center for Ground Water Research (NCGWR) at Rice University. Ground-water contamination in the shallow aquifer beneath the site was characterized by sampling soils and water quality at 14 monitoring wells and 35 boreholes. Results from six sampling trips over two years for inorganic and organic chemical concentrations in the ground water show wells around the site were contaminated to levels above 800 μg/l for naphthalene, 400 μg/1 for methyl naphthalene, and 150 μg/1 for dibenzofuran. Conservative constituents, traced by chloride concentrations up to 75 mg/l, have migrated 300 ft (90 m) downgradient of the site. Organic contaminants have been adsorbed and microbially degraded in their migration from the waste source as evidenced by their attenuated concentrations. Detailed field pump tests have been performed to evaluate hydraulic conductivity at several of the shallow wells. The U.S. Geological Survey (USGS) Solute Transport Model (Konikow and Bredehoeft, 1978) has been used to predict chloride plume patterns and evaluate parameters which govern transport processes at the Conroe waste site.

Water Quality Index for Chao Phraya River

Abstract: Statsistical approaches to water quality evaluation and parameter estimation are investigated Water quality indices for the Chao Phraya River in Thailand are developed using the techniques of cluster type analysis, factor analysis, and multiple regression Results of factor analysis are also used to assess the possible reduction in the number of variables measured, adequacy of sampling locations, and the underlying causes of pollution

Subsurface Drainage Water Quality from Land Application of Swine Lagoon Effluent

Abstract: WATER quality was monitored for subsurface drainage from small plots receiving 325, 650 and 1300 kg N/ha/yr from sprinkler-irrigated swine-lagoon effluent. Subsurface flow volumes and nutrient concentrations are reported for 20 months at the end of a 6-yr treatment period. Nutrient mass balances for nitrogen and phosphorus which include uptake by Coastal bermudagrass, soil accumulation, surface runoff, subsurface drainage and an estimate of nutrients leaching below the root zone are reported.

Derivation of site-specific water quality criteria for cadmium and the St. Louis River Basin, Duluth, Minnesota

Abstract: Several freshwater aquatic species were exposed to cadmium in site and laboratory water to evaluate a protocol recommended by the U.S. Environmental Protection Agency for deriving site-specific water quality criteria. The recalculation, indicator species and resident species procedures of this protocol were used to modify the national cadmium criteria. These procedures were used to account for differences in species sensitivity and in the biological availability and/or toxicity of cadmium due to physical and/or chemical characteristics of the site water. The site-specific maximum concentration derived from the recalculation procedure was slightly lower (1.3 as compared with 2.2 μg/L) than the national criterion. The maximum concentration derived from the indicator species procedure was 7.0 μg/L and was calculated by using a water effect ratio from tests conducted in both site and laboratory water. Acute tests with several species demonstrated that cadmium was less toxic in site water than in laboratory water. The site-specific maximum concentration derived from the resident species procedure (from eight species exposed to cadmium in site water) was 1.9 μg/L. The 30-d average concentrations were the same as the maximum concentrations in the procedures in which the national acute/chronic ratio was used in the calculation. These concentrations were much lower when the site-specific acute/chronic ratio was applied. Acute tests conducted monthly in site water showed that cadmium toxicity varied by more than a factor of 3 over the year. This indicates the need for considering seasonal changes in physical and chemical characteristics of the site water when deriving criteria to protect aquatic life.

Trends in lake Rotorua water quality

Abstract: Fourteen determinands relating to the water quality of Lake Rotorua were examined for trend over the period 1966–1983. A linear regression package was used, but additional manipulations were performed to eliminate markedly non‐normal distributions, remove seasonality, compute monthly averages, fill gaps, and correct for serial correlation. Since lake data came from 3 different organisations, with possibly different analytical techniques, trends were calculated over 3 periods separately. Lake quality deteriorated during 1967–1970 largely because meteorological conditions favoured lake stratification. During 1978–1983, despite favourable meteorological conditions, quality again deteriorated at the same time as, and probably as a result of, an increase of available nutrient input from sewage effluent. Improved sewage nutrient removal could halt this deterioration.

Major ion and carbonate system chemistry of a navigable freshwater canal

Abstract: SUMMARY. 1. An examination has been made of the water quality of a 50 km (Wigan to Litherland) length of the Leeds-Liverpool canal. Regular in situ measurements accompanied by sampling for laboratory analysis were made at seventeen stations over a 15-month period. 2. Three principal contributory water types have been recognized, and the observations have allowed estimates to be made of their relative contributions to the total water flux in the lower reaches of the system. Linear flow rates (c. 0.6 km day−1 near Litherland) are consistent with previous reports. 3. The combined field and laboratory measurements have been used to obtain estimates of the partial pressure of CO2 in the water (P co2), the degree of saturation of the water with respect to calcite (Ω) and the major ion speciation in the water. Because of the variable ionic compositions of the waters examined, these estimates were made using a program (WATEQ) which took account of ion-pairing. 4. Diurnal and annual cycles with respect to pH, P co2 and ω occur, these being most marked in the lower parts of the study length when, for a large proportion of the spring and summer, P co2 was below the atmospheric level and noticeable supersaturation with respect to calcite occurred. In contrast, two of the contributory water types, the River Douglas input and the Creek, showed low pH and Ω values and high P co2 values throughout the year.

Comparison of different methods of water quality evaluation by means of oligochaetes

Abstract: Using as examples water bodies in different geographical zones (Lake Ladoga, the River Sukhona, shallow-water ponds of the North Caucasus) the known methods of water quality evaluation by means of oligochaetes are considered. There is no unique universal method of pollution bioindication in this way. In water bodies of all types the mass development of oligochaetes and the reduction of their species diversity are indications of: (1) large quantities of organic matter; (2) favourable oxygen regime; (3) absence or insignificant quantity of heavy metal solids, petroleum substances and agricultural chemicals; (4) intensive self-purification of the water body.