The St. Johns River Water Management District is one of five Florida water management districts that is responsible for managing groundwater and surface water resources in Florida. SJRWMD covers an 18-county region in northeast and east-central Florida. The Florida Department of Environmental Protection has general supervisory authority over the water management districts.It employs approximately 600 people at offices in Palatka, Jacksonville, Maitland and Palm Bay. The district's headquarters is located in Palatka.The budget for 2013-14 is $135.5 million. Wikipedia.
Ouyang Y.,St. Johns River Water Management District |
Luo S.M.,Ecological Agriculture Key Laboratory of the Ministry of Agriculture |
Luo S.M.,South China Agricultural University |
Cui L.H.,South China Agricultural University
Ecological Engineering | Year: 2011
The vertical-flow constructed wetland (VFCW) is a promising engineering technique for removal of excess nutrients and certain pollutants from wastewater and stormwater. The aim of this study was to develop a model using the STELLA software for estimating nitrogen (N) dynamics in an artificial VFCW (i.e., a substrate column with six zones) associated with a growing Cyperus alternifolius species under a wetting (wastewater) -to-drying ratio of 1:3. The model was calibrated by our experimental data with a reasonable agreement prior to its applications. Simulations showed that rates of NH4 +-N and NO3 --N leaching decreased with increasing zone number (or column depth), although such a decrease was much more profound for NH4 +-N. Our simulations further revealed that rate of NH4 +-N leaching decreased with time within each zone, whereas rate of NO3 --N leaching increased with time within each zone. Additionally, both the rates of NH4 +-N and NO3 --N leaching through zones followed the water flow pattern: breakthrough during wetting period and cessation during drying period. In general, the cumulative amounts of total nitrogen (TN) were in the following order: leaching>denitrification>uptake>settlement. About 54% of the TN from the wastewater flowed out of the VFCW system, 18% of TN lost due to denitrification, 6% of TN was taken up by roots of a single plant (one hill), and the rest of 22% TN from the wastewater was removed from other mechanisms, such as volatilization, adsorption, and deposition. This study suggested that to improve the overall performance of a VFCW for N removal, prevention of N leaching loss was one of the major issues. © 2010 Elsevier B.V.
Dix N.,Harbor Branch Oceanographic Institute |
Phlips E.,University of Florida |
Suscy P.,St. Johns River Water Management District
Estuaries and Coasts | Year: 2013
Patterns in phytoplankton biomass are essential to understanding estuarine ecosystem structure and function and are the net result of various gain and loss processes. In this study, patterns in phytoplankton biomass were explored in relation to a suite of potentially regulating factors in a well-flushed, subtropical lagoon, the Matanzas River Estuary (MRE) in northeast Florida. We examined temporal variability in water temperature, light availability, nutrient concentrations, phytoplankton productivity, and phytoplankton standing stock over 8 years (2003-2010) and explored relationships among variables through correlation analysis. Laboratory experiments in the spring and summer of 2009 quantified phytoplankton growth rates, nutrient limitation potential, and zooplankton grazing rates. The potential influence of oyster grazing was also examined by scaling up population metrics and filtration rate estimates. Results indicated that phytoplankton biomass in the study area was relatively low mainly due to a combination of low temperature and light availability in the winter and consistent tidal water exchange and bivalve grazing throughout the year. Relatively low levels of phytoplankton standing stock and small inter-annual variability within the MRE reflect a balance between gain and loss processes which provide a degree of resilience of the system to natural and anthropogenic influences. © 2013 Coastal and Estuarine Research Federation.
Ling D.-J.,Guangdong Ocean University |
Huang Q.-C.,Guangdong Ocean University |
Ouyang Y.,St. Johns River Water Management District
Ecotoxicology and Environmental Safety | Year: 2010
Acid rain pollution is a serious environmental problem in the world. This study investigated impacts of simulated acid rain (SAR) upon four types of soil enzymes, namely the catalase, acid phosphatase, urease, and amylase, in a latosol. Latosol is an acidic red soil and forms in the tropical rainforest biome. Laboratory experiments were performed by spraying the soil columns with the SAR at pH levels of 2.5, 3.0, 3.5., 4.0, 4.5, 5.0, and 7.0 (control) over a 20-day period. Mixed results were obtained in enzyme activities for different kinds of enzymes under the influences of the SAR. The catalase activities increased rapidly from day 0 to 5, then decreased slightly from day 5 to 15, and finally decreased sharply to the end of the experiments, whereas the acid phosphatase activities decreased rapidly from day 0 to 5, then increased slightly from day 5 to 15, and finally decreased dramatically to the end of the experiments. A decrease in urease activities was observed at all of the SAR pH levels for the entire experimental period, while an increase from day 0 to 5 and then a decrease from day 5 to 20 in amylase activities were observed at all of the SAR pH levels. In general, the catalase, acid phosphatase, and urease activities increased with the SAR pH levels. However, the maximum amylase activity was found at pH 4.0 and decreased as the SAR pH increased from 4.0 to 5.0 or decreased from 4.0 to 2.5. It is apparent that acid rain had adverse environmental impacts on soil enzyme activities in the latosol. Our study further revealed that impacts of the SAR upon soil enzyme activities were in the following order: amylase>catalase>acid phosphatase>urease. These findings provide useful information on better understanding and managing soil biological processes in the nature under the influence of acid rains. © 2010 Elsevier Inc.
Phlips E.J.,University of Florida |
Badylak S.,University of Florida |
Christman M.C.,University of Florida |
Lasi M.A.,St. Johns River Water Management District
Estuaries and Coasts | Year: 2010
This paper describes the results of 10 years of water quality monitoring in the Indian River Lagoon Florida, with special emphasis on the relationships between trends in climatic conditions and the distribution, composition, and abundance of the phytoplankton community. The Indian River Lagoon, which spans 220 km of Florida's east coast, is a region of particular concern because of the rapid rate of human development throughout the region and the hydrologically restricted character of the lagoon, which heightens the potential for algal bloom. Water sampling was carried out on a monthly to twice-monthly basis at six sites located in the northern and central lagoon. The 10-year study included both extended periods of below and above average rainfall. A number of ecologically distinct regions exist within the lagoon, which differ considerably in water exchange properties and watershed inputs. The northern lagoon is characterized by longer water residence times, lower phosphorus concentrations, higher nitrogen concentrations, and more stable salinity conditions than the central lagoon. Mean phytoplankton biovolumes were substantially higher at the sites in the northern lagoon than at the sites in the central lagoon, and algal blooms were more common and intense in the former region. Inter-annual patterns of phytoplankton biovolume were also different in the northern and central lagoon. In the northern lagoon, phytoplankton biovolumes were lowest during the drought period, from the autumn of 1998 to the spring of 2001. By contrast, algal bloom events in the central lagoon were not only less frequent but were not tied to periods of high rainfall. The most widespread and common bloom formers were the potentially toxic dinoflagellate Pyrodinium bahamense var. bahamense and two centric diatoms, Dactyliosolen fragilissimus and Cerataulina pelagica. Many of the biovolume peaks observed over the study period were attributable to these three species. The results of time series modeling of phytoplankton dynamics further highlighted the disparities between the two regions of the lagoon in terms of the suite of parameters that best predict the observed trends in the biomass of phytoplankton. Overall, the outcome of this initial modeling effort in the Indian River Lagoon suggests that time series approaches can help define the factors that influence phytoplankton dynamics. © 2009 Coastal and Estuarine Research Federation.
Rey J.R.,University of Florida |
Carlson D.B.,Indian River Mosquito Control District |
Brockmeyer Jr. R.E.,St. Johns River Water Management District
Wetlands Ecology and Management | Year: 2012
High mosquito populations have always been a part of Florida's environment. While mosquito-transmitted diseases have played a major role in Florida's history, saltmarsh mosquitoes have not been implicated in these disease outbreaks. However, the impact of high saltmarsh mosquito numbers on the well-being of residents and visitors cannot be underestimated. Coastal wetland management efforts in Florida, which date back to the 1920s, have included ditching, dredging and filling, and impounding, all having mosquito control and environmental benefits and liabilities. In the early 1980s, efforts to encourage coastal wetlands management for both mosquito control and environmental interests came to the forefront. This resulted in the Florida Legislature creating the Florida Coordinating Council on Mosquito Control and its Subcommittee on Managed Marshes. Through the efforts of these committees, a heavy investment in research, interagency cooperation, and public acquisition of coastal wetlands property, tremendous progress has been made in management of coastal wetlands. This has occurred largely by implementing management and restoration techniques that minimize environmental impacts, allow for mosquito control, and minimize the need for pesticide use. Continued efforts are needed to place into public ownership remaining privately owned coastal wetland property to allow implementation of best management practices on these important habitats. © 2011 Springer Science+Business Media B.V.
Gu B.,South Florida Water Management District |
Schelske C.L.,University of Florida |
Coveney M.F.,St. Johns River Water Management District
Aquatic Sciences | Year: 2011
The purposes of this study were to assess if Lake Apopka (FL, USA) was autotrophic or heterotrophic based on the partial pressure of dissolved carbon dioxide (pCO2) in the surface water and to evaluate factors that influence the long-term changes in pCO2. Monthly average pH, alkalinity and other limnological variables collected between 1987 and 2006 were used to estimate dissolved inorganic carbon (DIC), pCO2 and CO2 flux between surface water and atmosphere. Results indicated that average pCO2 in the surface water was 196 μatm, well below the atmospheric pCO2. Direct measurements of DIC concentration on three sampling dates in 2009 also supported pCO2 undersaturation in Lake Apopka. Supersaturation in CO2 occurred in this lake in only 13% of the samples from the 20-year record. The surface-water pCO2 was inversely related to Chl a concentrations. Average annual CO2 flux was 28. 2 g C m-2 year-1 from the atmosphere to the lake water and correlated significantly with Chl a concentration, indicating that biological carbon sequestration led to the low dissolved CO2 concentration. Low pCO2 and high invasion rates of atmospheric CO2 in Lake Apopka indicated persistent autotrophy. High rates of nutrient loading and primary production, a high buffering capacity, a lack of allochthonous loading of organic matter, and the dominance of a planktivorous-benthivorous fish food web have supported long-term net autotrophy in this shallow subtropical eutrophic lake. Our results also showed that lake restoration by the means of nutrient reduction resulted in significantly lower total phosphorus (TP) and Chl a concentrations, and higher pCO2. © 2010 Springer Basel AG.
Cheesman A.W.,University of Florida |
Dunne E.J.,St. Johns River Water Management District |
Turner B.L.,Smithsonian Tropical Research Institute |
Reddy K.R.,University of Florida
Journal of Environmental Quality | Year: 2010
Newly created and restored wetlands play an important role in sequestering excess nutrients at the landscape scale. In evaluating the long-term efficacy of nutrient management strategies to increase wetland capacity for sequestering P, information is needed on the forms of P found across the upland - wetland transition. To assess this, we studied soils (0-10 cm) from four wetlands within cow - calf pastures north of Lake Okeechobee, FL. Wetlands contained significantly (P < 0.05) greater concentrations of organic matter (219 g C kg-1), total P (371 mg P kg-1), and metals (Al, Fe) relative to surrounding pasture. When calculated on an aerial basis, wetland surface soils contained significantly greater amounts of total P (236 kg ha -1) compared with upland soils (114 kg ha-1), which was linked to the concomitant increase in organic matter with increasing hydroperiod. The concentration of P forms, determined by extraction with anion exchange membranes, 1 mol L-1 HCl, and an alkaline extract (0.25 mol L-1 NaOH and 50 mmol L-1 ethylenediaminetetraacetic acid [EDTA]) showed significant differences between uplands and wetlands but did not alter as a proportion of total P. Speciation of NaOH - EDTA extracts by solution 31P nuclear magnetic resonance spectroscopy revealed that organic P was dominated by phosphomonoesters in both wetland and pasture soils but that myo-inositol hexakisphosphate was not detected in any sample. The tight coupling of total C and P in the sandy soils of the region suggests that the successful management of historically isolated wetlands for P sequestration depends on the long-term accumulation and stabilization of soil organic matter. Copyright © 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.
Knowles Jr. L.,U.S. Geological Survey |
Katz B.G.,U.S. Geological Survey |
Toth D.J.,St. Johns River Water Management District
Hydrogeology Journal | Year: 2010
The Silver Springs Group, Florida (USA), forms the headwaters of the Silver River and supports a diverse ecosystem. The 30 headwater springs divide into five subgroups based on chemistry. Five selected spring vents were sampled in 2007 to better understand the contaminant sources and groundwater flow system. Elevated nitrate-N concentrations (>0.8mg/L) in the five spring vents likely originate from inorganic (fertilizers) and organic sources, based on nitrogen and oxygen isotope ratios of nitrate. Evidence for denitrification in the Lost River Boil spring includes enriched δ15N and δ18O, excess N2 gas, and low dissolved O2 concentrations (<0.5mg/L). Multiple age-tracer data (SF6, 3H, tritiogenic 3He) for the two uppermost springs (Mammoth East and Mammoth West) indicate a binary mixture dominated by recent recharge water (mean age 6-7 years, and 87-97% young water). Tracer data for the three downstream spring vents (Lost River Boil, Catfish Hotel-1, and Catfish Conventional Hall-1) indicate exponential mixtures with mean ages of 26-35 years. Contamination from non-atmospheric sources of CFCs and SF5CF3 precluded their use as age tracers here. Variations in chemistry were consistent with mean groundwater age, as nitrate-N and dissolved O2 concentrations were higher in younger waters, and the Ca/Mg ratio decreased with increasing mean age. © 2010 Springer-Verlag (outside the USA).
Zhu W.-L.,South China Agricultural University |
Cui L.-H.,South China Agricultural University |
Ouyang Y.,St. Johns River Water Management District |
Long C.-F.,South China Agricultural University |
Tang X.-D.,South China Agricultural University
Pedosphere | Year: 2011
Constructed wetlands (CWs) are engineered systems that utilize natural systems including wetland vegetations, soils, and their associated microbial assemblages to assist in treating wastewater. The kinetic adsorption of ammonium nitrogen (NH+4-N) by CW substrate materials such as blast furnace slag (BFS), zeolite, ceramsite, vermiculite, gravel, paddy soil, red soil, and turf, was investigated using batch experiments and kinetic adsorption isotherms. Both Freundlich and Lang-muir isotherms could adequately predict the NH+4-N adsorption process. The maximum adsorption capacities of NH+4-N, estimated from the Langmuir isotherm, ranked as: zeolite (33 333.33 mg kg-1) > turf (29 274.01 mg kg-1) > BFS (5 000 mg kg-1) > vermiculite (3 333.33 mg kg-1) > gravel (769.23 mg kg-1) > paddy soil (588.24 mg kg-1) > red soil (555.56 mg kg-1) > ceramsite (107.53 mg kg-1). Some properties of the substrate materials, including bulk density, specific gravity, hydraulic conductivity, uniformity coefficient (K60), curvature coefficient (Cc), organic matter, pH, exchangeable (or active) Cu, Fe, Zn and Mn, total Cu, and Fe, Mn, Zn, Cd, Pb and Ca, had negative correlations with NH+4-N adsorption. Other properties of the substrate materials like particle diameter values of D10, D30 and D60 (the diameters of particle sizes of a substrate material at which 10%, 30% and 60%, respectively, of the particles pass through the sieve based on the accumulative frequency), cation exchange capacity (CEC), exchangeable (or active) Ca and Mg, and total K and Mg had positive correlations with NH+4-N adsorption. In addition, active K and Na as well as the total Na had significant positive correlations with NH+4-N adsorption. This information would be useful for selection of suitable substrate materials for CWs. © 2011 Soil Science Society of China.
Steward J.S.,St. Johns River Water Management District |
Lowe E.F.,St. Johns River Water Management District
Limnology and Oceanography | Year: 2010
We developed empirical models that can predict maximum allowable, nutrient loading rates or load limits (LM) for maintenance of mesotrophy in Florida's fresh and estuarine waters. Water residence time (τW) explains most of the variation in LM previously set by the U.S. Environmental Protection Agency and Florida's environmental agencies for total phosphorus (TP) and for total nitrogen (TN). We found that a single model for TP and for TN fit data from both estuarine and freshwater systems. Further, we show that the models are consistent with or analogous to the critical loading model of the Organization of Economic Cooperation and Development (OECD 1982): Lc = [TP or TN]C X Z/τW(1 + τw0.5)The LM - τw model for TP is sufficiently similar to the OECD model as to indicate that either model could provide a reasonable fit to mesotrophy in both temperate and subtropical systems. The models can facilitate the development of total maximum daily loads for estuaries and inland waters of Florida and may have broader regional utility. They may also aid the development of nutrient concentration criteria. © 2010, by the American Society of Limnology and Oceanography, Inc.