Search

The South Florida landscape is highly engineered featuring ∼3380 km of canals, ∼1225 water control structures, >70 pumping stations, managed wetlands, densely populated coastal watersheds, and impacted estuaries. Landscape scale agricultural and urban modifications require flood control which sometimes results in the release of excess freshwater that potentially damages estuarine ecology. The Central Everglades Planning Project (CEPP) is a partnership between the U.S. Army Corps of Engineers and the South Florida Water Management District focused on restoring natural patterns of freshwater flow to the Everglades and associated estuaries. One of the primary project goals is to reduce deleterious inflows eastward to the St. Lucie Estuary (SLE) and westward to the Caloosahatchee River Estuary (CRE) by diverting freshwater south from Lake Okeechobee. Performance evaluation of the CEPP relies upon integrated modeling which links the watershed engineering projects to estuarine salinities and biotic responses. The objective of this study was to utilize seagrass and oyster models to evaluate the effectiveness of alternative inflow scenarios. There are three different scenarios: the existing condition base (ECB), the future without proposed CEPP projects (FWO) but with other landscape features that could alter freshwater inflows, and alternative 4R (ALT4R) that incorporates a suite of restoration projects including those associated with the CEPP. Each of these inflow scenarios was used to generate daily salinity time series from 1965 to 2005 at multiple locations in the SLE and CRE which were used to run site-specific seagrass and oyster models. The hydrodynamic and ecological effects of freshwater inflow were greater in the SLE compared to the much larger CRE. Predicted densities of oysters (individuals m −2 ) and seagrass (shoots m −2 ) were greater in the wet season (May–Oct) vs. the dry season (Nov–Apr) in both estuaries. Oyster and seagrass densities increased under the ALT4R inflow scenario that mitigated high inflows to the estuaries in the wet season. This result improved environmental conditions while increasing freshwater availability for other parts of the Greater Everglades and the southern estuaries such as Florida Bay and Biscayne Bay. [ABSTRACT FROM AUTHOR]

Planning and implementation of unprecedented projects for restoring the greater Everglades ecosystem are underway and the hydrologic and hydrodynamic modeling of restoration alternatives has become essential for success of restoration efforts. In view of the complex nature of the South Florida water resources system, regional-scale (system-wide) hydrologic models have been developed and used extensively for the development of the Comprehensive Everglades Restoration Plan. In addition, numerous subregional-scale hydrologic and hydrodynamic models have been developed and are being used for evaluating project-scale water management plans associated with urban, agricultural, and inland costal ecosystems. The authors provide a comprehensive summary of models of all scales, as well as the next generation models under development to meet the future needs of ecosystem restoration efforts in South Florida. The multiagency efforts to develop and apply models have allowed the agencies to understand the complex hydrologic interactions, quantify appropriate performance measures, and use new technologies in simulation algorithms, software development, and GIS/database techniques to meet the future modeling needs of the ecosystem restoration programs. [ABSTRACT FROM AUTHOR]

Abstract: Comparing with the studies on large estuarine systems, such as the Chesapeake Bay and the San Francisco Bay, the processes of stratification and transport in small and shallow estuaries are relatively less studied. The St. Lucie Estuary (SLE) is a riverine estuary located on the east coast of south Florida. It is small and shallow, with mean depth of 2.4m. To study the estuarine processes in the SLE, a hydrodynamic model was developed based on the Environmental Fluid Dynamics Code (EFDC) [Hamrick, J.M., 1992. A three-dimensional environmental fluid dynamics computer code: theoretical and computational aspects. The College of William and Mary, Virginia Institute of Marine Science, Special Report 317, 63 pp.]. The model was calibrated and verified using observational data obtained in 1999 and 2000, respectively. The model variables used for model data-comparisons are water elevation, velocity, temperature, and salinity. The model is then applied to study the hydrodynamic processes in the SLE. It is found that freshwater inflow plays a major role in the stratification and net flushing of the SLE. Stratification generally increases with freshwater inflow. But when the inflow is persistently large for a relatively long period, the estuary can suddenly change from very stratified to well mixed within a few tidal cycles and the stratification collapses. This finding suggests that large and persistent freshwater inflows do not always increase estuarine stratification. Instead, it may cause the stratification to collapse within a short period of time. In addition to gauged tributaries, ungauged lateral inflows can also be important to small and shallow estuaries like the SLE. Although small individually, the ungauged streams and surface runoffs can be a significant portion of the total inflow and affect salinity distribution significantly. Flushing time affects a wide range of hydrodynamic and water quality processes in the estuary. The model results indicate that commonly used formulas, such as the tidal prism formula and the Knudsen formula, may significantly underestimate the flushing time. [Copyright &y& Elsevier]

Abstract: The distributions of dissolved organic carbon (DOC), Ba, U, and a suite of naturally occurring radionuclides in the U/Th decay series (222Rn, 223,224,226,228Ra) were studied during high- and low-discharge conditions in the Loxahatchee River estuary, Florida to examine the role of submarine groundwater discharge in estuarine transport. The fresh water endmember of this still relatively pristine estuary may reflect not only river-borne constituents, but also those advected during active groundwater/surface water (hyporheic) exchange. During both discharge conditions, Ba concentrations indicated slight non-conservative mixing. Such Ba excesses could be attributed either to submarine groundwater discharge or particle desorption processes. Estuarine dissolved organic carbon concentrations were highest at salinities closest to zero. Uranium distributions were lowest in the fresh water sites and mixed mostly conservatively with an increase in salinity. Suspended particulate matter (SPM) concentrations were generally lowest (<5 mg L−1) close to zero salinity and increased several-fold (∼18 mg L−1; low discharge) toward the seaward endmember, which may be attributed to dynamic resuspension of bottom sediments within Jupiter Inlet. Surface water-column 222Rn activities were most elevated (>28 dpm L−1) at the freshwater endmember of the estuary and appear to identify regions of the river most influenced by the discharge of fresh groundwater. Activities of four naturally occurring isotopes of Ra (223,224,226,228Ra) in this estuary and select adjacent shallow groundwater wells yield mean estuarine water-mass transit times of less than 1 day; these values are in close agreement to those calculated by tidal prism and tidal frequency. Submarine groundwater discharge rates to the Loxahatchee River estuary were calculated using a tidal prism approach, an excess 226Ra mass balance, and an electromagnetic seepage meter. Average SGD rates ranged from 1.0 to 3.8×105 m3 d−1 (20–74 L m−2 d−1), depending on river-discharge stage. Such calculated SGD estimates, which must include both a recirculated as well as fresh water component, are in close agreement with results obtained from a first-order watershed mass balance. Average submarine groundwater discharge rates yield NH4 + and PO4 −3 flux estimates to the Loxahatchee River estuary that range from 62.7 to 1063.1 and 69.2 to 378.5 μmol m−2 d−1, respectively, depending on river stage. SGD-derived nutrient flux rates are compared to yearly computed riverine total N and total P load estimates. [Copyright &y& Elsevier]

GPAT, the rate-limiting enzyme in triacylglycerol (TAG) synthesis, plays an important role in seed oil accumulation. In this study, two AhGPAT9 genes were individually cloned from the A- and B- genomes of peanut, which shared a similarity of 95.65%, with 165 site differences. The overexpression of AhGPAT9 or the knock-down of its gene expression increased or decreased the seed oil content, respectively. Allelic polymorphism analysis was conducted in 171 peanut germplasm, and 118 polymorphic sites in AhGPAT9A formed 64 haplotypes (a1 to a64), while 94 polymorphic sites in AhGPAT9B formed 75 haplotypes (b1 to b75). The haplotype analysis showed that a5, b57, b30 and b35 were elite haplotypes related to high oil content, whereas a7, a14, a48, b51 and b54 were low oil content types. Additionally, haplotype combinations a62/b10, a38/b31 and a43/b36 were associated with high oil content, but a9/b42 was a low oil content haplotype combination. The results will provide valuable clues for breeding new lines with higher seed oil content using hybrid polymerization of high-oil alleles of AhGPAT9A and AhGPAT9B genes. [ABSTRACT FROM AUTHOR]

• Long-term application of blend controlled-release potassium chloride (BBF). • Applying BBF increased maize yield and net profit over 5-year period. • BBF was more productive due to superior lodging resistance and bleeding-sap. • BBF may be a promising alternative to other traditional potassium fertilizer. Controlled-release potassium chloride (CRK) has been shown to improve potassium (K) use efficiency (KUE) and crop yields. However, its widespread use has limited by its high manufacturing costs. To help address this problem and to find the best techniques for using CRK, we mixed it with traditional potassium chloride (KCl) in 1:1 ratios in a five-year field test to find the resulting KUE, bleeding sap, yields, and economic returns of maize (Zea mays L.). There were six treatments subjected to varying K fertilization: full-dose, traditional KCl; full-dose, CRK; reduced-dose, CRK; full-dose, mixed CRK and traditional KCl; reduced-dose, mixed CRK and traditional KCl; and the control, which had no added K fertilizer. Applying high dose, mixed CRK and traditional KCl and high dose, CRK to maize significantly increased grain yields 14.0% and 7.2%, respectively, compared with the traditional KCl treatment during 2014–2018. When the K was provided at the low rate (reduced by one-third), the low dose, mixed CRK and traditional KCl and low dose, CRK treatments led to the same yields as the traditional KCl treatment. However, crude starch contents of the mixed CRK and traditional KCl and CRK treatments each were significantly increased compared with the traditional KCl treatment in 2018. Mean KUE increased 30.5%–56.5% for mixed CRK and traditional KCl treatments, compared with traditional KCl during 2016–2018. Mean net profits from the high dose, mixed CRK and traditional KCl treatment significantly increased 18.9%, when K was provided by the lower rate of mixed CRK and traditional KCl led to the same net profit, compared with traditional KCl treatment from the 2016–2018 years. During the milky maturity stage of maize plants, bleeding sap in the high dose, mixed CRK and traditional KCl treatment were 47.5% and 23.4% lower than from the traditional KCl and high dose, CRK treatments, respectively. Meanwhile, the high dose, mixed CRK and traditional KCl and high dose, CRK treatments significantly increased soil available K levels compared with the traditional KCl treatment, hence, meeting the nutrient demands of maize plants during their later growth stages. The exchangeable Ca2+ levels within the soil near the surface was also maximized by the long-term application of mixed CRK and traditional KCl treatments. Hence, applying mixed CRK and traditional KCl fertilizers were recommended for maintaining continued nutrient absorption soil fertility, sustainable increases in crops yields and for maximizing net profits. [ABSTRACT FROM AUTHOR]

The pulp black liquor accounts for about 90 percent of pollution of the whole paper and pulp industry. The clean production technology of extracting useful bio-based substances from pulp black liquor can increase wastewater utilization and benefit the environment. This paper examines chemical characteristics and biological activities of fulvic acid-like substance extracted from leonardite (FA1), which serves as the benchmark, and from pulp black liquor (FA2). Instrumental analyses with Fourier transform infrared (FT-IR) spectroscopy, 13C-nuclear magnetic resonance (13C-NMR) spectroscopy and 1H-nuclear magnetic resonance (1H-NMR) spectroscopy indicated that FA1 and FA2 shared common functional groups existed in typical fulvic acid. A series of rice seed germination bioassays proved that FA2 had the same growth promotion function as FA1. The optimal concentration for water absorption and seed germination was 5 mg/L for FA1 and 60 mg/L for FA2. FA1 and FA2 treatments also increased the activity of α-amylase under the action of hydrolytic enzymes and promoted root development by increasing cell size and cell division. The study implied that pulp black liquor can be used for bio-renewable and eco-friendly production of fulvic acid for wide applications in agriculture. Image 108448 • Eco-friendly and bio-renewable FA-like substance was extracted from black liquor. • FA-like substance from black liquor had similar functional groups with typical FA. • Fulvic acid from black liquor enhanced rice seed germination and roots development. • Fulvic acid from black liquor can be used as a functional fertilizer synergist. • A potential strategy will be opened for wastewater reutilization in pulp industries. [ABSTRACT FROM AUTHOR]

• Catalytic oxidation (H 2 O 2) is used to activate fulvic acid-like in paper mill effluent. • Activated fulvic acid-like features lower molecular weight and richer functional groups than un-activated fulvic acid-like. • Activated fulvic acid-like enhances rice seed germination and seedling growth under salt stress. • Activated fulvic acid-like improve salt tolerance by alleviating salt-induced oxidative damage at the cellular level. Increasing environmental concerns about organic waste in paper mill effluents demand alternative wastewater management technology. We reported novel activation of fulvic acid-like in paper mill effluents using hydrogen peroxide (H 2 O 2) as oxidizer and titanium oxide (TiO 2) as catalyst. Spectroscopic characteristics of fulvic acid-like in paper mill effluents before and after activation (PFA and PFA-Os, respectively) were compared with a benchmark fulvic acid extracted from leonardite (LFA). Results indicated that PFA-Os exhibited less lignin structures, more functional groups and lower molecular weight than PFA, sharing much similarity with LFA. Among PFA-Os with varying degrees of oxidation, PFA-O-3 activated with 1:2 vol ratio of paper mill effluent and 30% H 2 O 2 for 20 min digestion at 90 °C stands out to be the optimal for further examination of its biological activity. Bioassays with rice seed/seedling indicated that applications of LFA at 2–5 mg-C/L and PFA-O-3 at 60–100 mg-C/L significantly increased rice seed germination rate and seedling growth under salt stress imposed with 100 mM NaCl. The mechanism was mainly through reduced oxidative damage via activation of antioxidative enzymes and lipid peroxidation. This study provides the needed technical basis of safer and cleaner technologies for innovative management of paper mill effluents. [ABSTRACT FROM AUTHOR]