AN ECONOMIC AND ENVIRONMENTAL EVALUATION OF ALTERNATIVE LAND DEVELOPMENT AROUND LAKES1

ABSTRACT: The objective of the study was to evaluate alternative land developments around New Hampshire lakes. Alternative development patterns, evaluated by their impacts on the lake area environment and area economy, included residential patterns, commercial patterns, and combinations of these two types. Phosphorus loading of the lake water was used as a proxy variable for changes in the lake water quality. Commercial developments yielded the highest revenues to the town and the local area. It also attracted the most lake users to the area as well as contributing the largest phosphorus loading in the lake waters. Residential developments, although contributing high revenues to the businessmen in the area, yielded less net income to the town. Phosphorus loading levels from residential developments were much lower than lake phosphorus loading by commercial developments.     

Nutrient fluxes in a eutrophic coastal Louisiana freshwater lake

Nitrogen and phosphorus cycling in a eutrophic Louisiana freshwater lake system (Lac des Allemands) was studied. Nutrients from runoff entering the lake, as well as sediment-interstitial and lake water nitrogen and phosphorus fractions, were measured seasonally. Sedimentation rates in the lake were determined using¹³⁷Cs dating.Phosphorus levels in the lake were found to be largely dependent on concentrations in the incoming bayou water from upland drainage. Lake water concentrations appear to respond to fluctuations in incoming waters. Laboratory equilibrium studies showed bottom sediments in the lake are a major sink for the incoming dissolved orthophosphate phosphorus. Total nitrogen concentrations in the lake water generally exceeded incoming runoff concentrations, suggesting fixation by the large blue-green algae population in the lake as being the major source of nitrogen to the system.Sedimentation ranged from 0.44 cm/year to 0.81 cm/year, depending on the proximity to the inlet bayous. Even though the lake is eutrophic the sediment served as a buffer by removing large amounts of carbon, nitrogen, and phosphorus through sedimentation processes. Carbon, nitrogen, and phosphorus were accumulating in the sediment at rates of 60, 7.1, and 1.1 g/m²/year, respectively.The water quality of the lake is likely to continue to decline unless measures are taken to reduce municipal, industrial, and agricultural inputs of phosphorus into the lake.     

Eutrophication of Lake Waters in China: Cost, Causes, and Control

Lake water eutrophication has become one of the most important factors impeding sustainable economic development in China. Knowledge of the current status of lake water eutrophicatoin and determination of its mechanism are prerequisites to devising a sound solution to the problem. Based on reviewing the literature, this paper elaborates on the evolutional process and current state of shallow inland lake water eutrophication in China. The mechanism of lake water eutrophication is explored from nutrient sources. In light of the identified mechanism strategies are proposed to control and tackle lake water eutrophication. This review reveals that water eutrophication in most lakes was initiated in the 1980s when the national economy underwent rapid development. At present, the problem of water eutrophication is still serious, with frequent occurrence of damaging algal blooms, which have disrupted the normal supply of drinking water in shore cities. Each destructive bloom caused a direct economic loss valued at billions of yuan. Nonpoint pollution sources, namely, waste discharge from agricultural fields and nutrients released from floor deposits, are identified as the two major sources of nitrogen and phosphorus. Therefore, all control and rehabilitation measures of lake water eutrophication should target these nutrient sources. Biological measures are recommended to rehabilitate eutrophied lake waters and restore the lake ecosystem in order to bring the problem under control.     

GOLD-MINING EFFECTS ON STREAM HYDROLOGY AND WATER QUALITY,CIRCLE QUADRANGLE,ALASKA1

Effects of placer mining on the hydrology and water quality of several interior Alaska streams were studied as part of a project on the impacts of placer mining on stream ecosystems. Surface and subsurface waters were analyzed in the field for conductivity, pH, temperature, alkalinity, total and calcium hardnesses, iron, copper, manganese, ammonia-N, nitrate-N, nitrite-N, settleable solids, and turbidity. Total, nonfiltrable, and filtrable residues were determined in the laboratory. In the streams placer mining increased turbidity, settleable solids, nonfiltrable and filtrable residues and total iron. Surface and subsurface water levels, as measured in wells driven in the stream beds, were correlated with stream flow. Fine sediment deposited on stream beds in mined drainages reduced the hydraulic contact between the surface and subsurface waters of the stream and caused the piezometric water level to be below the surface water level of the mined streams. This resulted in higher specific conductance and significantly lower dissolved oxygen concentrations in the subsurface waters of mined streams compared to their surface waters. No significant differences were found for any water quality characteristics comparing surface to subsurface waters for the unmined streams.     

Limnological effects of wood ash application to the subcatchments of boreal,humic lakes

To assess environmental risks of wood ash, limnological effects of ash application to the drainage basins of two small, humic lakes and one reference lake in southern Finland were examined in this three-year study. Treated areas corresponded to 12 and 19% of the total catchment and the amount of wood ash added was 6400 kg ha(-1). Immediate effects of wood ash on lake water were investigated in three tank experiments each lasting 1.5 wk. In tank experiments, addition of wood ash increased pH, alkalinity, conductivity, and Ca and P concentrations of humic lake water, while growth of phytoplankton decreased. After wood ash application to the subcatchments, pH, alkalinity, conductivity, and concentrations of K+, SO4(2-), and Cl- slightly increased, both in inflowing waters and in the lakes, but no increased leaching of Ca, N, or P from the treated subcatchments occurred. Phytoplankton biomass increased in both experimental lakes in comparison with the reference lake. In the lake with 19% application rate to the catchment, zooplankton biomass also increased. The results indicate that, over the short term, a small-scale ash treatment to a forested drainage basin will not necessarily cause significant changes in the water quality of boreal humic lakes, but at higher application rates, changes in water chemistry and biology are more evident.     

FACTORS AFFECTING SALINITY REDUCTION IN LAKE TARPON,PINELLAS COUNTY,FLORIDA1

ABSTRACT: Following an enclosure of a sink-hole connecting Lake Tarpon to the Gulf of Mexico, the chloride concentration of lake waters decreased. Water and chloride budgets for the lake in 1975 were prepared, and predictions using the model of Lerman and Brunskill (1971) were made as to the time required for the lake to achieve fresh water status. Model verification indicated good agreement with predictions in 1976; however, data on [C1^-] for 1977 and 1978 are not as supportive of the model used. The information concerning the Lake Tarpon watershed provided by this latter fact is discussed.     

RESPONSE OF PHYSICAL AND CHEMICAL PARAMETERS TO ELIMINATING THERMAL STRATIFICATION IN A RESERVOIR1

ABSTRACT The effects of maintaining a 19 ha Colorado montane reservoir in a thermally destratified condition for one year were evaluated. Water temperatures were kept nearly vertically agd horizontally isothermal throughout the year. The weighted mean temperature of the lake was 1-4°C colder in winter and 1-2°C warmer in summer than normal. Deep water in summer was up to 6°C warmer than typical hypolimnion temperatures, but summer surface temperature was unaltered. Without destratification dissolved oxygen depletion develops in summer and winter, but by eliminating stratification, oxygen was kept near saturation throughout the year. Alkalinity, pH, conductivity, and total residue were not significantly affected. Seston decreased which was probably due to declines in planktonic diatom populations. Increases in iron and manganese did not occur in deep water during destratification. Calcium concentrations increased slightly. Magnesium and most anions (chloride, nitrate-N, and silica) were not greatly altered, but sulfate concentration was reduced. Artificial destratification, as a reservoir management tool, will be very useful in altering chemical problems; particularly increasing oxygen and decreasing iron and manganese concentrations.     

EFFECTS OF SELECTED HERBICIDES ON BACTERIAL POPULATIONS IN NONTREATED AND TREATED WATER1

ABSTRACT: Bacterial populations in nontreated and herbicide-treated waters were subjected to three different herbicides. Diuron, dichlobenil, and diquat were added (100 mg/l) to water samples from two fresh water lakes and two herbicide-treated ponds. Total numbers of bacteria were monitored. Bacterial populations in fresh lake water decreased after herbicide additions; however, final populations were significantly greater than the controls. Similar observations were recorded for bacteria in dichlobenil- and diuron-treated waters. Selective enrichment is probably expressed in these experiments.     

PHOSPHATE IN WATERS: I. REDUCTION USING NORTHERN LIGNITE FLY ASH1

Fly ashes fiom lignite coal fixed steam electric plants contain appreciable amounts of materials that can, in principle, decrease the phosphorus concentration in surface waters. Typical samples of un-weathered fly ash were used to test efficacies of removal of phosphorus from standard phosphate solutions and actual lake water samples. The effects of changing parameters such as contact time, pH, fly ash/water ratios, and solution temperature are presented. Water soluble and insoluble factors in the ash both appear to be reactive constituents. Trials with municipal waste waters showed near quantitative removal of ortho-phosphate.     

不同pH条件下沉积磷释放到水体中化学行为的模拟研究

通过室内模拟湖泊沉积物在不同pH条件下，研究释放到水体中各种磷形态的迁移转化行为，结果表明：碱性条件和酸性条件下，水体磷的时空变化由于其释放机制的不同，其迁移转化行为各不相同，同时，pH值的变化对水体中各种磷的相互转化没有明显的作用，各种磷形态的浓度变化，在很大程度上取决于水体中总磷的浓度。研究结果对认识沉积磷在环境条件变化时，磷在沉积物和水体体系中的迁移转化有重要的意义。     

Photodegradation of selected herbicides in various natural waters and soils under environmental conditions

The photochemical degradation of herbicides belonging to different chemical groups has been investigated in different types of natural waters (ground, river, lake, marine) and distilled water as well as in soils with different texture and composition. Studied herbicides and chemical groups included atrazine, propazine, and prometryne (s-triazines); propachlor and propanil (acetanilides); and molinate (thiocarbamate). The degradation kinetics were monitored under natural conditions of sunlight and temperature. Photodegradation experiments were performed in May through July 1998 at low concentrations in water samples (2-10 mg/L) and soil samples (5-20 mg/kg), which are close to usual field dosage. The photodegradation rates of all studied herbicides in different natural waters followed a pseudo-first order kinetics. The half-lives of the selected herbicides varied from 26 to 73 calendar days in waters and from 12 to 40 d in soil surfaces, showing that the degradation process depends on the constitution of the irradiated media. The presence of humic substances in the lake, river, and marine water samples reduces degradation rates in comparison with the distilled and ground water. On the contrary, the degradation in soil is accelerated as the percentage of organic matter increases. Generally, the photodegradation process in soil is faster than in water. The major photodegradation products identified by using gas chromatography-mass spectrometry (GC-MS) techniques were the hydroxy and dealkylated derivatives for s-triazines, the dechlorinated and hydroxy derivative for the anilides, and the keto-derivative for the thiocarbamate, indicating a similar mode of degradation for each chemical category.     

A MANGANESE OXIDATION MODEL FOR RIVERS1

ABSTRACT: The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the low pH conditions, or their combinations.     

Organochlorine pollutants in remote mountain lake waters

Hexachlorocyclohexanes (HCHs; alpha- and gamma-isomers), endosulfans (alpha- and beta-isomers and the sulfate residue), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDTs), and polychlorobiphenyls (PCBs) were measured in waters from three European remote mountain lakes situated in the Alps, Pyrenees, and Caledonian mountains. Sampling encompassed both ice-free and ice-covered periods at different water column depths. High HCH concentrations were found in all lakes, those in the Alps and Pyrenees (990-2,900 pg/L) being among the highest recorded in continental waters. Endosulfans and endosulfan sulfate (120-1,150 pg/L) were the second major group of organochlorine contaminants, showing a remarkable stability upon atmospheric long-range transport. The concentrations of HCB, DDTs, and PCB (4-8, 0.6-16, and 26-110 pg/L, respectively) were low in comparison with other continental waters. Hexachlorocyclohexanes, endosulfans, and HCB were essentially found in the dissolved phase. Phase partitioning of the more hydrophobic compounds exhibited a dependence on temperature and water-suspended particles. Comparison between different sampling seasons and water depths indicated a remarkable concentration uniformity within lake, but major interlake differences. Normalization to turnover rates showed higher interlake similarity. Preferential accumulation of the less volatile compounds in the Alp lake and significant increase of baseline contributions of organochlorine compounds and residues in the Caledonian lake are also evidenced from these turnover rates.     

THE EFFECTS OF ARTIFICIAL CIRCULATION ON A HYPEREUTROPHIC LAKE1

ABSTRACT: Crystal Lake, a small urban lake in Robbinsdale, MN, had been artificially circulated for 12 years before a detailed water quality evaluation was undertaken. In 1986, the circulation system was shut off for a two-year assessment. Although the lake remained hypereutrophic, the use of the lake, which included shoreline fishing and feeding ducks and geese, did not appear to be seriously impaired by the absence of artificial circulation. The circulation system was returned to service in October 1987 (there are 16 diffusers in this 0.31 km^?2 lake). Continuous limnological data from October 1987 through October 1988, plus several sampling dates in 1989, compares to the two non-circulation years (1986 and 1987) as follows: there was a two- to three-fold increase in the lake's concentration of total phosphorus, total Kjeldahl nitrogen, and chlorophyll and a similar decrease in Secchi disk transparency. The surface oxygen concentration was reduced and the deep waters were nearly anoxic. In fact, following a wind storm in 1988, the entire lake became anoxic due to the mixing of high BOD throughout the water column, and a summertime fish-kill resulted. All of these occurrences are related to the artificial circulation of the lake.     

东湖磷酸酶活力及其生态学意义研究

本文对东湖磷酸酶活力(PA)的来源,不同湖区活力水平的比较,及其与主要环境因子的关系作了初步研究。结果表明,东湖水柱中磷酸酶活力主要来自藻类,底泥中则主要来自细菌;在东湖磷浓度波动范围内,磷对碱性磷酸酶活力(ALPA)无明显抑制,实验室条件下相当于环境水平的磷浓度不能抑制PA;光照促进藻类PA的增加;溶解氧有利于藻类PA提高,对细菌PA则相反。     

MANGANESE OXIDATION RELATED TO THE RELEASES FROM RESERVOIRS1

ABSTRACT: Stratified reservoir waters frequently contain objectionable quantities of dissolved manganese. The oxidation and removal of dissolved manganese during transport below Normandy Dam, Tennessee, was shown to be much more rapid than expected from chemical oxidation. Oxidation took place in only a day of travel time rather than months or years. Laboratory studies showed that removal was associated with a slime found on rock surfaces below the dam and led to the development of column technology as a possible method of treating natural waters containing manganese. Hydraulic loadings on the columns in the range of 390–780 m³/hr.ha accomplished a 90 percent removal rate of soluble manganese over an influent concentration range of 2 to 15 mg/l.     

重庆市应用湖库水水源热泵系统条件分析

通过对重庆市气候条件、湖库水水资源状况以及湖库水水温和水质分析,结果显示:重庆地区采用传统空气源热泵系统已不适宜,而采用水源热泵系统具有较高的节能优势。丰富的湖库水水资源量以及重庆市建筑沿湖库水而建特点,为在重庆市开展湖库水水源热泵系统创造便利条件;湖库水水温和水质基本能满足地表水水源热泵系统的水源要求;湖库水藻类易爆发,因此发展湖库水水源热泵主要解决的水质问题是藻类的堵塞问题。     

Use of sequential sampling of amphipod abundance to classify the biotic integrity of acid-sensitive lakes

A sequential sampling program using previously published zoobenthos data is described for ubiquitous, cost-effective biomonitoring of the effects of lake acidification. Spring densities of the littoral amphipodHyalella azteca are quantitatively sorted into five abundance catagories. An essential step in the a priori definition of decision criteria is the stratification of proportional densities per unit macrophyte biomass in relation to aqueous total phosphorus concentrations. Density rankings were related to lake acidity and to detailed lake-specific information on patterns ofHyalella life history and acid tolerance. Incorporation ofHyalella abundance as a potential metric for the assessment of the biological integrity of acid-sensitive waters is recommended. The temporal integration of transient changes in spring meltwater chemistry is an important rationale for the development of such biomonitoring procedures.     

Selenium stable isotope ratios in California agricultural drainage water management systems

Selenium stable isotope ratios are known to shift in predictable ways during various microbial, chemical, and biological processes, and can be used to better understand Se cycling in contaminated environments. In this study we used Se stable isotopes to discern the mechanisms controlling the transformation of oxidized, aqueous forms of Se to reduced, insoluble forms in sediments of Se-affected environments. We measured 80Se/76Se in surface waters, shallow ground waters, evaporites, digested plants and sediments, and sequential extracts from several sites where agricultural drainage water is processed in the San Joaquin Valley of California. Selenium isotope analyses of samples obtained from the Tulare Lake Drainage District flow-through wetland reveal small isotopic contrasts (mean difference 0.7%) between surface water and reduced Se species in the underlying sediments. Selenium in aquatic macrophytes was very similar isotopically to the NaOH and Na2SO3 sediment extracts designed to recover soluble organic Se and Se(0), respectively. For the integrated on-farm drainage management sites, evaporite salts were slightly (approximately 0.6%) enriched in the heavier isotope relative to the inferred parent waters, whereas surface soils were slightly (approximately 1.4%) depleted. Bacterial or chemical reduction of Se(VI) or Se(IV) may be occurring at these sites, but the small isotopic contrasts suggest that other, less isotopically fractionating mechanisms are responsible for accumulation of reduced forms in the sediments. These findings provide evidence that Se assimilation by plants and algae followed by deposition and mineralization is the dominant transformation pathway responsible for accumulation of reduced forms of Se in the wetland sediments.     

Biota Connect Aquatic Habitats throughout Freshwater Ecosystem Mosaics

Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.