PHYTOPLANKTON PRODUCTIVITY AND BIOMASS IN THE CHARLOTTE HARBOR ESTUARINE SYSTEM,FLORIDA1

ABSTRACT: Phytoplankton carbon-14 productivity at a depth of 50 percent of surface light and chlorophyll-α concentrations were measured every other month from November 1985 through September 1986 at 12 stations in the Charlotte Harbor estuarine system. Maximum productivity and chlorophyll-α concentrations occurred during summer or early autumn near the mouths of tidal rivers. Most of the variability in light-normalized productivity and chlorophyll-α could be attributed to two factors derived from Principal Component Analysis of ambient water-quality characteristics. One factor related to seasonal variability and the other to spatial variability. The seasonal factor incorporated the interaction of temperature and nutrients. The spatial factor incorporated the interaction of salinity, nutrients, and water color that resulted from the mixing of freshwater inflow and seawater. Although freshwater inflow increased the availability of nutrients in low salinity (less than 10‰) waters, the highly colored freshwater restricted light penetration and phytoplankton productivity. Maximum productivity and biomass occurred where color associated with the freshwater inflow had been diluted by seawater so that light and nutrients were both available. Concentrations of inorganic nitrogen were often at or below detection limit throughout most of the high salinity (greater than 20‰) waters of the estuary and was probably the most critical nutrient in limiting phytoplankton productivity.     

REVIEW OF LAKE RESTORATION PROCEDURES1

ABSTRACT Relevant information on the restoration of lakes is presented. The restoration procedures considered are applicable to the water, the bottom sediments, and aquatic plant improvement. A summary of thirteen (13) suggested methods of restoration are reviewed.     

INFLUENCE OF WELL WATER QUALITY VARIABILITY ON SAMPLING DECISIONS AND MONITORING1

ABSTRACT: Local governmental agencies responsible for decisions in ground water quality management need not only data on ground water quality but they also must understand the relationship of accuracies and risks associated with this data as related to the number of wells to sample. In this report we address this problem by using the philosophical doctrines of probabilism and relativism with simple statistical procedures. This requires a reasonable estimate of the population variance in a quality parameter for a given management-unit area, and requires that the decisionmaker formulate constraints with an acceptable standard error of the sample mean and be willing to accept some level of probability of being Wrong. This technique is illustrated using a 21-year data base of well water chemical data in a 653 km² ground water quality study area in the San Joaquin Valley of California.     

A BASKET SAMPLING TECHNIQUE FOR QUANTIFYING RIVERINE MACROBENTHOS1

ABSTRACT: A colonization basket sampling technique for quantifying macroinvertebrates in rubble bottom rivers is described. Basket samplers were compared to collections made using the Surber square foot sampler. Procedure for processing samples is described. Macrobenthos were more accurately quantified by basket samplers because both surface and subsurface habitats were sampled, no organisms were lost when samplers were removed from the river, substrata and associated fauna were retained for analysis, and the samplers were used efficiently in both pool and riffle areas. At the end of the colonization period the basket samplers contained one-half cubic foot of river bottom and macroinvertebrates spatially arranged within.     

EFFLUENT IRRIGATION OF PARA GRASS: WATER,NITROGEN, AND BIOMASS BUDGETS1

Para grass, irrigated with secondary domestic sewage effluent, showed excellent response for disposal of large amounts of water, effective nitrogen removal, and high production of excellent fodder. This grass is found throughout the tropics and parts of the subtropics. It endures flooding and forms dense, easily maintained stands. This is the first time its use has been reported for effluent irrigation. Water, nitrogen, and biomass budgets over a 17-month period were measured in eight percolate style lysimeters. Under irrigation rates as great as 98 mm/day, five days/week, evapo-transpiration averaged 4.6 mm/day. With nitrogen applications of 130 to 2,600 kg/ha/yr, ≥ 79 percent of applied nitrogen was harvested in the grass; 3 percent percolated; and ≤ 28 percent was denitrified. With the highest effluent irrigation rates, nitrate-nitrogen levels remained below the 10 mg/L maximum recommended for potable water. Crop productivity for full effluent treatments averaged 110 t/ha/yr, dry weight. Maximum calculated crude protein content was 13 percent. No nitrate-nitrogen level in the forage exceeded 0.1 percent.     

LAKE LEVEL DRAWDOWN AS A MACROPHYTE CONTROL TECHNIQUE1

ABSTRACT: Lake drawdown as a management or restoration technique for controlling macrophytes in eutrophic lakes is reviewed for effectiveness, longevity, and positive and negative impacts. Drawdown can be effective but is species specific, and some nuisance plants are resistant or stimulated. The responses of 63 nuisance plants are reviewed. Advantages of the technique include low cost, absence of toxic chemicals, enhancement of fisheries, and the opportunity to carry out other lake improvements. Drawbacks include nutrient release, algal blooms, low dissolved oxygen, lake user dissatisfaction during the process, and failure to refill. The technique is recommended for situations where susceptible species are the major nuisance and where prolonged (1–2 months) dewatering of sediments under rigorous conditions of heat or cold is possible.     

THE USE OF OVERWINTER DRAW DOWN FOR AQUATIC VEGETATION MANAGEMENT1

ABSTRACT: Overwinter draw down can be a useful technique for aquatic plant management. Its effectiveness depends largely on the susceptibility of nuisance species to draw down. A single overwinter draw down provided good control of aquatic plants in a flowage dominated by Potamogeton robbinsii Little additional control was gained by a second draw down the following winter. Rapid reinvasion of plants after draw down ceased dictates continued management. To avoid fish kills caused by low dissolved oxygen levels caution is advised when using overwinter draw down. The growth of Zizania aquatica was not negatively influenced by draw down. The influence on water quality of nutrient release from decaying vegetation and exposed bottom sediments was uncertain.     

THERMAL AND DISSOLVED OXYGEN CHARACTERISTICS OF A SOUTH CAROLINA COOLING RESERVOIR1

ABSTRACT: Temperature and dissolved oxygen concentrations were measured monthly from January 1971 to December 1982 at 1-m depth intervals at 13 stations in Keowee Reservoir in order to characterize spatial and temporal changes associated with operation of the Oconee Nuclear Station. The reservoir water column was i to 4°C warmer in operational than in non-operational years. The thermo-dine was at depths of 5 to 15 m before the operation of Oconee Nuclear Station, but was always below the upper level of the intake (20 m) after the station was in full operation; this suggests that pumping by the Oconee Nuclear Station had depleted all available cool hypolimnetic water to this depth. As a result summer water temperatures at depths greater than 10 m were usually 10°C higher after plant operation began than before. By fall the reservoir was nearly homothemious to a depth of 27 m, where a thermocine developed. Seasonal temperature profiles varied with distance from the plant; a cool water plume was evident in spring and a warm water plume was present in the summer, fall, and winter. A cold water plume also developed in the northern section of the reservoir due to the operation of Jocassee Pumped Storage Station. Increases in the mean water temperature of the reservoir during operational periods were correlated with the generating output of the power plant. The annual heat load to the reservoir increased by one-third after plant operations began. The alteration of the thermal stratification of the receiving water during the summer also caused the dissolved oxygen to mix to greater depths.     

EFFECTIVENESS OF DUPONT TYPAR SHEETING IN CONTROLLING MACROPHYTE REGROWTH AFTER OVERWINTER DRAWDOWN1

ABSTRACT: A new polypropylene sheeting compound, DuPont Typar 3201 and 3301, was applied to the sediments of Country Lake (Portage Co., Ohio) in March 1978 after an overwinter drawdown, and regrowth of rooted macrophytes was compared to an adjacent control area in summer 1978. Regrowth was slight, and macrophyte biomass was at least 100X less than in controls. The sheeting material was permeable to gases and did not “balloon.” This material is recommended for use around docks, swimming areas, and boat mooring sites. Cost in 1978 was about $0.24/m².     

EFFECT OF pH ON PHOSPHORUS RELEASE DURING MACROPHYTE (ELEOCHARIS sp.) DECOMPOSITION1

ABSTRACT: Laboratory microcosms were used to evaluate the effect of pH on release of soluble reactive phosphorus (SRP) during aerobic decomposition of the aquatic macrophyte Eleocharis sp., which is common in oligotrophic Florida lakes. The total amount of SRP released during a 227-day incubation in the dark was independent of pH over the range 3.7 to 5.5, but initial rates of release were faster at the lowest pH. The results indicate that the low total phosphorus concentrations observed in many acidic lakes are not necessarily attributable to reduced rates of decomposition and nutrient mineralization at low pH, as some researchers have suggested.     

CHARACTERISTICS OF EXTREME PRECIPITATION1

ABSTRACT: Records of extreme precipitation were investigated using the Discrete Autoregressive Moving Average (DABMA) process, which can explain long persistences of wet and dry spells that exist in daily precipitation data. The results show that the daily precipitation with strong autocorrelation is inclined to be better fit by a Discrete Autoregressive (DAB) model. On the other hand, those data with weak autocorrelations tend to be best fit by a Discrete Moving Average (DMA) model. It can also be concluded that based on the records from extremely wet and dry regions there is no geographic preference regarding the selection of the best model.     

HARVESTING AS A CONTROL FOR AQUATIC PLANTS1

Studies of the effects of harvesting on hydrophytes in Lake Mendota, Wisconsin indicate that one harvest reduced growth by at least 50%, two harvests reduced it by 75% and three harvests virtually eliminated plant material for the year. The studies also indicated that harvesting one year reduced the biomass the following year, especially in deep water. Three harvests during the previous year were most effective in controlling biomass the second year.     

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.     

SEDIMENTATION CHARACTERISTICS OF GORGE-TYPE RESERVOIRS1

ABSTRACT. An investigation of the hydraulics of gorge-type reservoirs was conducted with scale models. Reservoir shapes were moulded within a large basin. Water was circulated using a centrifugal pump-motor unit and uniform sediment (specific gravity 2.65) with mean diameters of 0.20 mm and 0.60 mm were utilized. Observations were made to study sedimentation patterns from the commencement of sediment inflow until the final stage of a fully silted reservoir. In particular, the mode of deposition of the sediment beds, the mechanics of transportation and sediment bed slopes were investigated. These aspects of reservoir siltation were examined in relation to the factors which influence it, which included sediment characteristics and flow parameters. Bed slopes and flow depths were analyzed by various methods; the Kalinske equation in conjunction with the Manning and Einstein-Barbarossa relations as proposed by Doland-Chow produced the best results.     

DISSIPATION OF 2,4-D DMA AND BEE FROM WATER,MUD, AND FISH AT LAKE SEMINOLE,GEORGIA1

ABSTRACT: Four 10-ha plots in dense watermilfoil beds of Lake Seminole, Georgia, were each treated with either 2,4-D DMA or 2,4-D BEE at rates of 22.5 and 45 kg a.e./ha. Both formulations were shown to be rapidly converted to the 2,4-D acid form, with no detection of 2,4-D DMA or 2,4-D BEE in the water within less than 24 hours after treatment. The maximum detected 2,4-D concentrations in the high rate 2,4-D DMA and 2,4-D BEE plots were 3.6 and 0.68 mg/, respectively. However, all but seven samples at a 2,4-D BEE plot showed nondetectable herbicide levels by day 7, with all water samples showing nondetectable levels by day 13. Dimethylnitrosamine and 2,4-dichlorophenol, potentially toxic transformation products of the herbicide formulations, were at nondetectable levels in all water samples. Sediment samples showed no significant net accumulation of 2,4-D, 2,4-D BEE, or 2,4-dichlorophenol during the summer monitoring; dimethylnitrosamine remained at nondetectable levels. There was no accumulation of 2,4-D in fish collected from the two plots treated with 2,4-D DMA. Four of 24 game fish from the 2,4-D BEE treatment plots contained low levels of 2,4-D in muscle tissue, with a maximum value of 0.29 μg/g. In contrast, 18 of 20 gizzard shad collected from these plots through day 13 contained detectable 2,4-D in the muscle, with a maximum concentration of 6.9 μg/g. All fish collected after day 13 contained nondetectable levels of 2,4-D. Small decreases in dissolved oxygen and pH, associated with the complete watermilfoil control in all plots, had returned to normal summer values by day 28.     

EFFECT OF SERIAL CORRECTION ON GROUND WATER QUALITY SAMPLING FREQUENCY1

ABSTRACT: Methods of calculating uncertainty in estimates of serial correlation coefficients, and correcting for bias in short and medium length (less than 50 data point) records, are presented. Uncertainty and bias in the estimation of serial correlation coefficients for ground water quality data is shown to be considerable and to result in inaccurate calculation of the sampling frequencies for monitoring purposes. The methods are applied to a ground water data set consisting of 87 monthly measurements of nitrate concentrations. The variation in serial correlation coefficients with variation of record length is examined. The optimum sampling frequencies for detection of changes in ground water nitrate concentrations are estimated.     

PRESERVATION OF SAMPLES FOR DISSOLVED MERCURY1

ABSTRACT: Water samples for dissolved mercury require special treatment because of the high chemical mobility and volatility of this element. Widespread use of mercury and its compounds has provided many avenues for contamination of water. Two laboratory tests were done to determine the relative permeabilities of glass and plastic sample bottles to mercury vapor. Plastic containers were confirmed to be quite permeable to airborne mercury, glass containers were virtually impermeable. Methods of preservation include the use of various combinations of acids, oxidants, and complexing agents. The combination of nitric acid and potassium dichromate successfully preserved mercury in a large variety of concentrations and dissolved forms. Because this acid-oxidant preservative acts as a sink for airborne mercury and plastic containers are permeable to mercury vapor, glass bottles are preferred for sample collection. To maintain a healthy work environment and minimize the potential for contamination of water samples, mercury and its compounds are isolated from the atmosphere while in storage. Concurrently, a program to monitor environmental levels of mercury vapor in areas of potential contamination is needed to define the extent of mercury contamination and to assess the effectiveness of mercury clean-up procedures.     

STORM CHARACTERISTICS OF CONVECTIVE-SCALE PRECIPITATION1

A classification scheme for convective precipitation, having applications in both analysis and modeling of meteorological and hydrological events, is presented. The method is based upon observations of rainfall at the ground, radar scans of storm events, and visible and infrared satellite imagery of larger storm systems. Empirical and theoretical frequency distributions are derived for total storm rainfall, rainfall duration and time between storms for each of the convective categories. This stratification is directly applicable to the experimental design and evaluation of weather modification projects and may be useful for the development and interpretation of meteorological and hydrological models. When atmospheric conditions limit storm development to cells, rainfall was seldom observed. Small clusters also produce small amounts of rainfall but have a longer lifetime than cells and are likely candidates for cloud seeding attempts to encourage their growth to large clusters. Large and nested clusters usually produce large amounts of natural precipitation. A few large storms account for most of a season's rainfall.     

EVALUATION OF WATER QUALITY SAMPLING LOCATIONS ON THE YUKON RIVER1

ABSTRACT: This paper presents an approach to the evaluation of water quality sampling locations for their potential use for long term monitoring. This approach was applied to four sites on the Yukon River near the Canada-United States boundary. At three of these sites it was difficult to obtain representative samples due to the presence of extensive lateral heterogeneities. These heterogeneities occur because of a lack of mixing between the Yukon River and the major tributaries upstream from Dawson. Only one of the sampling locations is spatially homogeneous enough to provide representative samples. Concentration variations over the annual cycle are very large, often as much as two orders of magnitude. Estimates are made of the frequency and density with which samples must be collected to be able to detect a 10 percent different between annual mean concentrations. The estimated frequencies are so large that such an undertaking would be impractical. More importantly, the assumptions of this analysis are invalid, and time series analysis of fixed frequency samples is proposed as an alternative that is statistically rigorous and requires fewer samples.