CHANGE IN LAKE TROPHIC STATE AND INTERNAL PHOSPHORUS RELEASE AFTER ALUMINUM SULFATE APPLICATION1

ABSTRACT: Recovery of eutrophic lakes after nutrient diversion may be delayed if the lake experiences significant internal phosphorus (p) loading to the water column. A maximum dose of aluminum sulfate, defined herein, was applied to the anaerobic sediments of the hypolimnia of two dimictic Ohio lakes following septic tank diversion, with the objective of attaining long term control of the release of phosphorus to the water column from these sediments. The results were compared to a similar, downstream, untreated lake. Total phosphorus concentration declined sharply after treatment and has remained so through 1980 for both lakes, a period of 5 and 6 years of control, respectively. Internal P loading from anaerobic, hypolimnetic sediments was partially controlled by the treatment but there are other important sources, perhaps in the littoral zone, in these lakes. Algal biomass is Smaller and water transparency has increased. Both lakes became mesotrophic after treatment, as described by the Carlson (1977) trophic state index, and remain in that improved condition to date. No deleterious side effects were observed, although one lake experienced a significant decrease in diversity of planktonic microcrustacea and a lakeward extension of the macrophyte community. This method appears to be an effective and lasting means of accelerating the recovery of a eutrophic lake following nutrient diversion.     

SIDE EFFECTS OF 58 YEARS OF COPPER SULFATE TREATMENT OF THE FAIRMONT LAKES,MINNESOTA1

The shallow Fairmont Lakes in southern Minnesota have been treated with copper sulfate for 58 years to reduce excessive algal growth. Copper sulfate was applied to five lakes at cumulative rates upo to 1647 kg/ha (1470 1b/acre), totaling 1.5 million kilograms. Data collected since treatment of the Fairmont Lakes began in 1921 provide alarming insights into lake responses to sustained chemical treatment with copper sulfate. Short-term and long-term effects have occurred. Short-term effects include: a) the intended temporary killing of algae, b) dissolved oxygen depletion by decomposition of dead algae, c) accelerated phosphorus recycling from the lake bed and recovery of the algal population within 7 to 21 days, and d) occasional fish kills due to oxygen depletion or copper toxicity or both. Long-term effects are shown to include: a) copper accumulation in the sediments, b) tolerance adjustments of certain species of algae to higher copper sulfate dosages, c) shift of species from green to blue-green algae and from game fish to rough fish, d) disappearance of macrophytes, and e) reductions in benthic macroinvertebrates. The conclusion is that while copper sulfate treatments enjoy great popularity because they kill and remove algae almost instantaneously, other immediate or cumulative side effects can be harmful to many other aquatic organisms.     

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.     

DO WETLANDS BEHAVE LIKE SHALLOW LAKES IN TERMS OF PHOSPHORUS DYNAMICS?1

ABSTRACT: The applicability of empirical relationships governing phosphorus (P) retention and nutrient assimilation in lakes and reservoirs was extended to include free surface water wetland treatment systems. Mixed reactor models have been used in lakes to predict steady state P concentration, characterize trophic state, compare P‐dynamics, and predict permissible P‐loading rates. Applying lake models to free surface water wetlands treatment systems, it was found that: sedimentation rates, loading rates, and settling velocity in these wetlands, and their typology are comparable to their lake counterparts. The analyses also suggest that phosphorus removal efficiency in a free surface water wetland treatment system is independent of trophic status, and similar to lakes, these wetlands can be classified according to their trophic state. Oligo‐and eutrophic wetland treatment systems can be defined by low and high TP inflow concentrations, respectively. In this study, olig‐otrophic status is defined as systems receiving inflow P‐loading less than 0.10 g m^‐2 year‐¹, and their P inputs are mainly derived from agricultural and stormwater runoff. Eutrophic treatment systems, on the other hand, are defined as those receiving inflow P‐loading higher than 0.20 g m² year‐¹, and their inputs are mainly derived from industrial and municipal wastewater. The comparability found between lakes and free surface water wetlands treatment systems raises the question: should we consider these wetlands “shallow lakes?”     

LAKE RESTORATION BY SEDIMENT REMOVAL1

ABSTRACT: Fresh water lake sediment removal is usually undertaken to deepen a lake and increase its volume to enhance fish production, to remove nutrient rich sediment, to remove toxic or hazardous material, or to reduce the abundance of rooted aquatic plants. Review of more than 60 projects and five case histories reveals that the first three objectives are usually met through sediment removal. Dredging to control aquatic plants has not been well documented. Disadvantages of dredging include cost, temporary phosphorus release from sediment, increased phytoplankton productivity, noise, lake drawdown, temporary reduction in benthic fish food organisms, the potential for toxic material release to the overlying water and potential for environmental degradation at the dredged material disposal site. The technique is recommended for deepening and for long range reduction of phosphorus release from sediment. Sediment removal to control toxic materials is possible with minimal environmental impact when proper equipment is used, but it may more than double the cost. Lack of definitive information about rooted plant regrowth rates in dredged areas prohibits explicit recommendations on sediment removal to control plant growth.     

A Comparison of Alternative Strategies for Cost-Effective Water Quality Management in Lakes

Roughly 45% of the assessed lakes in the United States are impaired for one or more reasons. Eutrophication due to excess phosphorus loading is common in many impaired lakes. Various strategies are available to lake residents for addressing declining lake water quality, including septic system upgrades and establishing riparian buffers. This study examines 25 lakes to determine whether septic upgrades or riparian buffers are a more cost-effective strategy to meet a phosphorus reduction target. We find that riparian buffers are the more cost-effective strategy in every case but one. Large transaction costs associated with the negotiation and monitoring of riparian buffers, however, may be prohibiting lake residents from implementing the most cost-effective strategy. An erratum to this article is available at .     

Natural alkalinity generation in neutral lakes affected by acid mine drainage

Lakes in surface mining areas are often subject to continuous loads of acid mine drainage. The knowledge of internal alkalinity generation in a lake is necessary to predict if the lake will stay circumneutral or may acidify. The most important processes of alkalinity production in lakes are sulfate reduction, denitrification, and the burial of N in the sediment. By summarizing data from the literature, we present probable rates of these different processes in circumneutral mining lakes. The critical acidity load that can probably be compensated for by internal processes, is 5.09 mmol(-) m(-2) d(-1) in productive lakes and 0.50 mmol(-) m(-2) d(-1) in less productive lakes. Under the assumption that methanogenesis is inhibited by high sulfate concentrations, the highest probable acidity loads in such lakes are 6.85 mmol(-) m(-2) d(-1) and 1.06 mmol(-) m(-2) d(-1), respectively. Denitrification, sulfate reduction, and N burial contributed significantly to total alkalinity production. Sulfate reduction had the largest potential. However, existing models cannot predict alkalinity generation from sulfate concentrations alone because the long-term stability of reduced S compounds in the sediment is crucial for a sustainable biological alkalinity generation. The larger acid-neutralizing potential of higher trophic lakes is caused both by higher rates of microbial activity and by a greater stability of reduced reaction products in the sediment. The largest uncertainties in our knowledge with respect to the total alkalinity budget are related to microbial processes in sulfate-rich freshwater lakes and the long-term stability of reduced reaction products in the sediment.     

THE DILUTION/FLUSHING TECHNIQUE IN LAKE RESTORATION1

ABSTRACT: Dilution/flushing has been documented as an effective restoration technique to restore eutrophic Moses and Green Lakes in Washington State. The dilution water added to both lakes was low in nitrogen and phosphorus content relative to the lake or normal input water. Consequently, lake nutrient content dropped predictably. Dilution or flushing rates were about ten times normal during the spring-summer periods in Moses Lake and three times normal on an annual basis in Green Lake. Improvement in quality (nutrients, algae, and transparency) was on the order of 50 percent in Moses Lake and even greater in Green Lake. The facilities for supplying dilution water were largely in place for the cited lakes; thus, costs for water transport were minimal. Available facilities, and therefore, costs, for water transport would usually vary greatly, however. Achieving maximum benefit from the technique may be more limited by availability of low nutrient water rather than facilities costs. Quality improvement may occur from physical effects of algal cell washout and water column instability if only high nutrient water is available.     

CHEMICAL COMPOSITION OF SOFTWATER FLORIDA LAKES AND THEIR SENSITIVITY TO ACID PRECIPITATION1

ABSTRACT: Based on alkalinity data for 596 lakes, 31 percent of Florida's 7300 lakes have < 100 μeq/l alkalinity and are sensitive to acid depostion. More than two-thirds of the lakes in 12 northern Florida counties fit this criterion. Increasing aluminum and decreasing nutrient and chlorophyll a concentrations were observed with decressing pH in a survery of 20 softwater lakes. Maximum measured aluminum values (100-150 μg/L) are below levels asociated with fish toxicity. Factor analysis showed that lake chemistry was related to three principal factors, representing three major processes: watershed weathering, acidification, and nutrient inputs. An acidification index defined as the difference between excess SO₄^2- and excess (Ca²⁺+Mg²⁺) accounted for 74 percent of the variance in lake pH. Comparison of historical (late 1950a) and present data for pH, alkalinity, and excess SO₄^2- indicated loss of alkalinity (>25 μeq/L) and increase in excess SO₄^2- (16-34 μeq/L) in several softwater lakes.     

湖泊蓝藻水华数字化预警系统构建探讨

构造湖泊蓝藻水华数字化预警系统是我国湖泊水环境管理的一个重要方向。本文探讨了构建湖泊蓝藻水华数字化预警系统的若干技术问题，包括：（1）数字化预警数学模式。提出需重视流域尺度的氮磷营养物和沉积动态输入以及营养物、沉积物对水生态结构动力过程的影响，建立非点源模型和湖泊生态结构动力学模型相耦合的预警数学模型模式；在此基础上提出了各种数学模型的可借鉴模式。（2）湖泊蓝藻水华预警监测技术。总结了常规水质监测的数据筛选方法，探讨了遥感技术和实时传输监测技术在水质监测中的应用模式，提出了实时监测和遥感监测需解决的技术难题和实现方法。（3）湖泊蓝藻数字化预警系统的设计。提出了数学模型系统、水质监控系统的网络化集成设计模式，提出了基于网络化地理信息系统的计算机应用软件实现模式。     

NEBRASKA'S SANDHILLS LAKES: A HYDROGEOLOGIC OVERVIEW1

ABSTRACT: Lakes, marshes and wet meadows occur in the broad, flat, interdune valleys of the Nebraska Sandhills, a vegetation-stabilized dune field underlain by sediments containing an enormous supply of groundwater. Hydrologic, geologic and possibly climatologic factors influence the chemical quality of lake water. Central and eastern lakes generally are in connection with the groundwater reservoir. The hydrologic nature of western lakes and the cause of their high alkalinity is not fully understood. Lakes in close proximity may vary in both their chemical characteristics and in the degree to which they change in size and depth over time. Climatic, hydrogeologic and natural lake-aging processes of accumulation of organics appear to be primarily responsible for lake-size variations.     

PREDICTIVE MODELS FOR THE BIOMASS OF BLUE-GREEN ALGAE IN LAKES1

In lakes which experience water quality problems due to the nuisance growth of blue-green algae, summer concentrations of chlorophyll a may not always be a meaningful measure of water quality for making management decisions. Models for the prediction of summer mean blue-green algal biomass were thus developed from data collected from five systems located in North America and Sweden. It is suggested that the model of choice is log BG =?0.142 + 0.596 log TP – 0.963 log Z, where BG is the biomass of blue-green algae (g m^?3), TP is the concentration of total phosphorus (mg m^?3), and Z is the mean depth of the lake (m). When coupled to current loading models, this model can potentially be used to assess the impacts of phosphorus loading reductions on threshold odor in water supplies.     

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.     

Comparing Hydrogeomorphic Approaches to Lake Classification

A classification system is often used to reduce the number of different ecosystem types that governmental agencies are charged with monitoring and managing. We compare the ability of several different hydrogeomorphic (HGM)—based classifications to group lakes for water chemistry/clarity. We ask: (1) Which approach to lake classification is most successful at classifying lakes for similar water chemistry/clarity? (2) Which HGM features are most strongly related to the lake classes? and, (3) Can a single classification successfully classify lakes for all of the water chemistry/clarity variables examined? We use univariate and multivariate classification and regression tree (CART and MvCART) analysis of HGM features to classify alkalinity, water color, Secchi, total nitrogen, total phosphorus, and chlorophyll a from 151 minimally disturbed lakes in Michigan USA. We developed two MvCART models overall and two CART models for each water chemistry/clarity variable, in each case comparing: local HGM characteristics alone and local HGM characteristics combined with regionalizations and landscape position. The combined CART models had the highest strength of evidence (ω_i range 0.92–1.00) and maximized within class homogeneity (ICC range 36–66%) for all water chemistry/clarity variables except water color and chlorophyll a. Because the most successful single classification was on average 20% less successful in classifying other water chemistry/clarity variables, we found that no single classification captures variability for all lake responses tested. Therefore, we suggest that the most successful classification (1) is specific to individual response variables, and (2) incorporates information from multiple spatial scales (regionalization and local HGM variables).     

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。     

Effects of organic matter on phosphorus release kinetics in different trophic lake sediments and application of transition state theory

Sediments have a significant influence on the overlying water, and phosphorus (P) release from sediments is an important source for the lake eutrophication, particularly in shallow ones. In this study, effects of organic matter on P release from sediments in different trophic lakes from the middle and lower reaches of Yangtze River, China, were investigated, and the release kinetics of different P fractions at different temperature were studied. The results show that the release kinetics of soluble reactive phosphorus (SRP), dissolved organic phosphorus (DOP) and dissolved total phosphorus (DTP) were similar for the studied sediments, the release rate increased rapidly in the initial hours, and it increased gradually after 10h. The release kinetics of SRP, DOP and DTP followed the Power Function model. SRP was the major fraction among the released DTP, while DOP was an important fraction in the heavily polluted sediments. Organic matter restricted the SRP and DTP release while it promoted the DOP release. Both DOP and SRP release processes were endothermic. The thermodynamic properties in the P release kinetics were calculated and discussed.     

Reducing sediment and phosphorus in tributary waters with alum and polyacrylamide

The Salton Sea is the largest inland water body in California, covering an area of 980 km(2). Inflow to the Salton Sea (1.6 km(3) yr(-1)) is predominately nutrient-rich agricultural wastewater, which has led to eutrophication. Because internal phosphorus release from the bottom sediments is comparatively low and external phosphorus loading to the Salton Sea is high, reduction of tributary phosphorus is expected to reduce algal blooms, increase dissolved oxygen, and reduce odors. Removing both dissolved phosphorus and phosphorus-laden sediment from agricultural drainage water (ADW) should decrease eutrophication. Both alum and polyacrylamide (PAM) are commonly used in wastewater treatment to remove phosphorus and sediment and were tested for use in tributary waters. Laboratory jar tests determined PAM effectiveness (2 mg L(-1)) for turbidity reduction as cationic > anionic = nonionic. Although cationic PAM was the most effective at reducing turbidity at higher speeds, there was no observed difference between the neutral and anionic PAMs at velocity gradients of 18 to 45 s(-1). Alum (4 mg L(-1) Al) reduced turbidity in low energy systems (velocity gradients < 10 s(-1)) by 95% and was necessary to reduce soluble phosphorus, which comprises 47 to 100% of the total P concentration in the tributaries. When PAM was added with alum, the anionic PAM became ineffective in aiding flocculation. The nonionic PAM (2 mg L(-1)) + alum (4 mg L(-1) Al) is recommended to reduce suspended solids in higher energy systems and reduce soluble P by 93%.     

RELATIONS BETWEEN COLOR AND SOME LIMNOLOGICAL CHARACTERISTICS OF FLORIDA LAKES1

Data obtained from a limnological survey of 165 Florida lakes were analyzed to determine regional differences in lake color (Pt-Co units) and relations between color and various physical, chemical, and biological parameters. Average color measurements for the different lakes ranged from 0 to 416 Pt-Co units with individual measurements being as high as 600 Pt-Co units. With the exception of extreme south Florida, lake color concentrations were found to increase from north to south and from inland highlands to lowlands. Central Florida had the greatest heterogeneity in lake color because of an extremely diverse geology and physiography. Color was inversely related to Secchi disc transparency and positively related to total iron concentrations. Color was not strongly related to pH, total alkalinity, nutrients, chlorophyll a, and many other limnological parameters. Although lakes having color concentrations greater than 20 Pt-Co units can often be visually identified as colored lakes, the limnological processes in these are not necessarily different from those of lakes having clear water.     

ON THE USE OF SEEPAGE METERS TO ESTIMATE GROUNDWATER NUTRIENT LOADING TO LAKES1

Data from a study on East Lake Tohopekaliga, Florida, indicate that the seepage meter measurement method may often overestimate nutrient contributions to lakes. Nutrient loading data from this method and a method employing lakeside piezometer nutrient data and seepage meter flows were not comparable. Seepage nutrient loading from the meter and piezometer methods comprised 39 and 18 percent of the nitrogen budget and 38 and 9 percent of the phosphorus budget, respectively, for East Lake Tohopekaliga. In terms of water, groundwater seepage accounted for only 14 percent of the total input to the lake. It is felt that some of the past studies using the seepage meter method to estimate nutrient loading may be in error due to reasons related to the enclosure of lake sediments by the meter and the accompanying anaerobic conditions which quickly result.     

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。