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Rationally designing highly active oxygen evolution reaction (OER) electrocatalysts with robust stability is critical for industrial electrochemical water splitting. Hierarchical iron–nickel oxyhydroxide nanosheets directly grown on porous TiFe2-based intermetallics are designed and prepared as OER catalysts. The best-performing nanosheets only need 295 mV to achieve 100 mA cm−2, along with exceptional durability at a high current density of 1000 mA cm−2. This work introduces a scalable strategy for producing robust OER catalysts that have potential for industrial applications. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting offers an appealing method to produce hydrogen as we attempt to achieve global carbon neutrality. However, the lack of earth-abundant, low-cost, active, and stable catalysts at large current densities severely hinders its industrial applications. TiNi3-based intermetallics as porous monolith catalysts (PMCs) exhibit an efficient hydrogen evolution reaction (HER) performance (an overpotential of 244 mV to afford 200 mA cm−2) and excellent stability in 1 M KOH. Theoretical calculations demonstrate that the synergetic effect between Ni and Mo can enhance HER activity. PMCs provide a new strategy to design catalysts with efficient and stable performance for industrial applications. [ABSTRACT FROM AUTHOR]

The rational design and synthesis of cost-effective and efficient bifunctional electrocatalysts are crucial for developing hydrogen energy yet challenging. Here we report porous monolith electrocatalysts (PMECs) comprising transition metal silicide (e.g., nickel silicide) with high activity and durability. These PMECs offer strong synergetic effects and high exposure of active sites, resulting in excellent kinetics in catalyzing both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), which surpass the benchmark catalysts RuO 2 and Pt/C. The doping strategy is demonstrated to further enhance electrocatalytic performance by constructing Mo-doped Ni 2 Si PMEC, which requires only a cell voltage of 1.60 V at 100 mA cm−2. Density functional theory calculations display that the synergistic effect of Ni and Si can reduce the energy barriers of intermediate adsorption, and the introduction of Mo into Ni 2 Si can further decrease the energy barrier of determining step and optimize the H* adsorption energy, thus enhancing the electrochemical kinetics for OER and HER. Our work paves the way for designing high-efficiency and low-cost porous monolith catalysts through a facile and scalable method, showing great prospects for industrialization. [Display omitted] • The porous monolith Ni 2 Si electrocatalyst has superior OER/HER performances. • The electrocatalyst has an ultralow cell voltage of 1.60 V at 100 mA cm−2. • The synergistic effect can decrease the energy barriers of intermediate adsorption. • This work provides a new strategy for designing porous monolith electrocatalysts. [ABSTRACT FROM AUTHOR]

Industrial applications for filtration and separation require the design of a porous material with low cost and strong corrosion resistance. Herein, porous TiFe intermetallic was fabricated by the reactive synthesis of elemental powders. The pore formation and phase transformation of porous TiFe intermetallic were investigated, and the corrosion behavior of porous TiFe intermetallic in 0.5 mol/L H 2 SO 4 , 3.5 wt% NaCl, and 1 mol/L KOH solutions was studied by electrochemical tests. The synthesized porous TiFe intermetallic formed by the diffusion reaction of Ti and Fe has a highly porous structure with open porosity of 57.6%, which is the result of a combination of the gap between powder particles and the Kirkendall effect. The porous TiFe intermetallic exhibits good corrosion resistance in H 2 SO 4 solution, furthermore, it shows better corrosion resistance than 316L stainless steel in both KOH and NaCl solutions, which is related to its larger resistance, more positive corrosion potential, lower corrosion current density, and wider passivation regions. The synthesized porous Fe-based intermetallic exhibits an excellent corrosion resistance and structure stability in acid, salt and alkaline environments, and thus exhibiting its potential in the field of filtration and separation. • Porous TiFe intermetallic was fabricated by the reactive synthesis of elemental powders. • The formation of pore structure and phase transformation of porous TiFe were clarified. • Porous TiFe exhibited good corrosion resistance in acid, salt, alkali environments. [ABSTRACT FROM AUTHOR]

Porous TiNi intermetallic compounds have a promising future as biomaterials, with some challenges for their corrosion resistance. In this work, TiNi intermetallic compound was prepared by reactive synthesis of elemental powders. The evolution of the microstructure and phase composition of TiNi at different temperatures was studied. And the electrochemical corrosion behavior of TiNi intermetallic compound in NaCl solution was investigated by electrochemical tests. The results show the formation of a core-shell structure during the sintering process, where Ni is the core and Ti 2 Ni, TiNi and TiNi 3 are the shells. With uniform diffusion, a large pore replaces the Ni core due to the Kirkendall effect. TiNi intermetallic compound has a well-developed open pore structure with an open pore ratio of 50.98%. TiNi intermetallic compound exhibits better corrosion resistance compared to Ni and Ti, which can be attributed to the generation of passivation film on the surface. • A porous TiNi intermetallic was prepared by reactive synthesis of elemental powders. • A core-shell structure was formed during the sintering process. • TiNi intermetallic exhibits better corrosion resistance compared to Ni. [ABSTRACT FROM AUTHOR]

The semiconductors based on simple oxide have unique features with controllable electrical property by element doping. Y3+ doped NiO (Ni1−xYxO, x ≤ 0.01) and Mg2+ substituted Ni0.995Y0.005O (Ni0.995−yY0.005MgyO, y ≤ 0.5) powders were synthesized by a wet chemical method. The related ceramics were obtained by conventional ceramic processing. Phase component, microstructure, electrical property and temperature sensitivity of the prepared ceramics were investigated. All ceramics have a rock‐salt type crystalline structure. The room‐temperature resistivity of the ceramics can be widely adjusted from 254 to 12 322 Ω·cm by changing the concentrations of Y3+ and Mg2+ ions. The samples show typical characteristics of negative temperature coefficient of resistivity and have high temperature sensitivity with material constants higher than 4745 K. The analysis of impedance spectra indicates that the electrical properties resulted from both grain effect and grain boundary effect. Both band conduction and small polaron hopping were proposed as possible conduction mechanisms in the studied ceramics. Y3+‐ion concentration dependence of B25/85 and ?25 in Y‐doped NiO (Ni1‐xYxO) ceramics, and the inset is the plots of Mg2+ concentration dependence of B25/85 and ?25 in Ni0.995‐yY0.005MgyO ceramics [ABSTRACT FROM AUTHOR]

Highlights • Urea and amino acids accounted for ∼20% of DON in surface water. • The composition of DCAA and DFAA varied between water and sediment. • Sediment NH 4 -N concentration was associated with 14 water DFAA concentrations. • A model was developed to predict the variations of DON in surface water. Abstract Sediment and nutrient fluxes from agricultural areas to rivers have led to high dissolved organic nitrogen (DON) concentrations that promote algal blooms. Few studies have been conducted to evaluate the effect of sediments on aquatic nitrogen, especially DON, on such blooms. Here, concentrations of dissolved inorganic nitrogen, DON, urea, free amino acids (DFAA), combined amino acids (DCAA), excitation-emission matrices (EEMs) were simultaneously determined in both sediments and the overlying waters from three different waterways and their interactions were analyzed, together with sediment enzyme activities, in the agriculture dominant St. Lucie Watershed. Concentrations of DCAA were generally higher, as compared to DFAA regardless of medium. The sum of urea and amino acids accounted for ∼20% of water DON. The composition of DCAA and DFAA varied between water and sediment. Degradation index of both DFAA and DCAA was similar between sediment and water, suggesting strong exchange activities between water and sediment. Sediment NH 4 -N concentration was associated closely with 14 water DFAA. A model, comprised of sediment DON, NH 4 -N, activities of acid phosphatase (AP) and leucine aminopeptidase (LAP), and two fluorescence compounds, can predict the variations of water NH 4 -N (55%), NO 3 -N (77%), DOC (83%), DON (64%), DFAA (>88%), DCAA (62–96%), and fluorescence indexes (98%). While this model provided an accurate prediction of water nutrient status in the St. Lucie Watershed, it still needs to be verified in situ across larger environmental gradients to incorporate real-world complexity and increase generality. [ABSTRACT FROM AUTHOR]

Decaying experiments of four major aquatic macrophyte detritus, namely cattail ( Typha orientalis ), water lettuce ( Pistia stratiotes ), hydrilla ( Hydrilla verticillata ) and maidencane ( Panicum hemitomon ), were conducted using the litterbag technique in the stormwater detention pond of South Florida, USA. Dry weight and chemical composition of remaining biomass were dynamically determined during the 185-day decay experiment. The results showed that decomposition rates ( k ), and the derived turnover ( t 50% and t 95% ) were species specific. The k values decreased in the order of hydrilla (0.0123 g day −1 ) > water lettuce (0.0082 g day −1 ) > maidencane (0.0049 g day −1 ) > cattail (0.0031 g day −1 ), whereas t 50% and t 95% varied in the reverse way. Biomass properties including concentrations of C, N, P, lignin, cellulose, hemicellulose, and the ratios of C/N, C/P, N/P and lignin/N affected decaying rate of the studied aquatic plants. The dry mass loss and concentrations of C, N, P, lead (Pb), chromium (Cr), copper (Cu), manganese (Mn), zinc (Zn), lignin, cellulose, hemicellulose and ratios C/N, C/P, N/P and Lignin/N of plant detritus were significantly affected by species, decaying time, and their interactions. However, the influence of species differences was greater than that of decaying time on those indexes. The estimated amounts (kg) of nutrients and metals released based on k values for the waterways of the IRL basin (water surface area 15.6 km 2 ) were N 126.85 × 10 3 , P 8.89 × 10 3 , Zn 408.20, Pb 97.95, Cr 128.99, Mn 313.03, and Cu 82.40. Water lettuce contributed most, accounting for 52.13% N, 56.81% P, 74.95% Zn, 59.58% Pb, and 74.65% Mn, followed by hydrilla, cattail and maidencane. For Cr and Cu, cattail had the greatest contribution of 65.77% and 54.15%, respectively, followed by water lettuce, hydrilla and maidencane. [ABSTRACT FROM AUTHOR]

Leaching of dissolved organic nitrogen (DON) has been reported as a pathway of N loss from agriculture, but the molecular composition of DON in agricultural water is poorly understood. Runoff water samples were collected from citrus grove furrows (CGF), ditches (CGD) and pasture ditches (PD) in four seasons. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to investigate molecular composition of DON. Chemodiversity index of DON had spatiotemporal variations, while the molecular composition of total DON showed minimal variations, except for PD in November. Lignin derivatives constituted 61% of the total DON compounds. Relative abundance of aliphatic compounds, char and condensed aromatics of unique DON compounds varied spatiotemporally and had a significant correlation with DON concentration. Aromaticity index decreased from CGF to connected CGD, implying that photodegradation is possibly the dominant process that alters molecular composition of aquatic DON during the transport. Significant differences in unique DON composition between CGD and PD indicates that fertilization and land use affect DON composition. The information on molecular characterization of DON should be useful for tracking DON source and developing technologies to remove DON in the agricultural runoff water. [ABSTRACT FROM AUTHOR]

Aquatic macrophytes have an important role in cleaning eutrophic runoff water from agriculture and urban areas. However, minimal information is available regarding the quantity of nutrients and/or pollutant they can remove each year from the water and sediments in waterways. This study investigated the biomass productivity of eight dominating aquatic plant species, the concentrations of nutrients in plant tissues and their capacity to absorb and store nutrients. Samples of plant, water, and sediment were collected from October 30 to November 19, 2014 at 22 representative sites in the waterways of the Indian River Lagoon basin, South Florida, USA. The biomass yield of the plant species decreased in the order: cattail ( Typha orientalis )> pickerelweed ( Pontederia cordata )> water lettuce ( Pistia stratiotes )> hydrilla ( Hydrilla verticillata )> maidencane ( Panicum hemitomon )> spatterdock ( Nuphar advena )> pondweed ( Potamogeton spp . )> salvinia ( Salvinia spp.). Cattail had the highest biomass productivity, but only a small part (35.8%) of the total biomass productivity was harvestable, whereas, water lettuce and hydrilla were mostly harvestable and could contribute almost 100% to harvestable biomass. Concentration of nutrients in plant varied significantly among the eight plant species and with the sampling sites, suggesting that in addition to genetic differences, physicochemical parameters of overlying water and surface sediment influenced uptake of nutrients by the plants. Among the eight plant species, cattail had the highest total nitrogen (N) (23.4 g N m −2 ) and phosphorus (P) (1.59 g P m −2 ) storage but water lettuce and hydrilla exhibited the highest total N (14.6 g N m −2 ) and P (1.04 g P m −2 ) net storage capacity in this survey. In addition, the highest N and P uptake per year occurred with water lettuce and hydrilla, with the peak of 146 kg N ha −1 y −1 and 10.4 kg P ha −1 y −1 , respectively. The results also indicate that multiple harvests of biomass are necessary to realize the removal potential of nutrients/pollutant by the aquatic plants, as the harvesting (cutting) practice can enhance plant growth and prevent release of nutrients/pollutant back into water from plant residue decomposition, which are estimated at 1.87 × 10 3 to 72.4 × 10 3 kg N and 0.07 × 10 3 to 4.80 × 10 3 kg P per year in the IRL basin. [ABSTRACT FROM AUTHOR]

Phosphorous (P) concentration in stormwater runoff varies at different spatial and temporal scales. Excessive P loading from agriculture system into the St. Lucie Estuary (SLE) contributed to water quality deterioration in southern Indian River Lagoon. This study examines the spatial and temporal shifts of different P forms in runoff and storm water under different land use, water management, and rainfall conditions. Storm water samplings were conducted monthly between April 2013 and December 2014 in typical farmland and along the waterway (Canal C-24) that connects lands to the SLE. Concentrations of different P forms and related water quality variables were measured. Approximately 89% of the collected water samples contained total P (TP) concentrations exceeding the total maximum daily load (TMDL) level (0.081 mg L −1 ). Concentrations of different P forms declined from agricultural field furrows to the canal and then increased from the upstream to the downstream in the canal where urban activities dominated land use. Total dissolved P (TDP) was the predominant form of TP, followed by PO 4 -P. Speciation and concentrations of P varied with sites and sampling times, but were significantly higher in the summer months (from June to September) than in the winter. Water pH explained ∼20% of TP variation. Spatiotemporal variations of P concentrations and compositions provide a data-based guide for development of best management practices (BMPs) to minimize P export from the SLE watershed. [ABSTRACT FROM AUTHOR]

The effects of growth-promoting hormone gibberellic acid 3 (GA3) on physiology, Pb phytoextraction, and metal detoxification mechanisms inLolium perennewere studied. Results showed that addition of GA3alone at lower doses (1 or 10 μM) facilitated antioxidant defense ofL. perenneunder Pb stress, decreased the toxicity of Pb in plant shoot by increasing the proportion of Pb in cell wall, hence significantly enhanced photosynthesis and plant growth, as well as Pb uptake and accumulation in L. perenne (P < 0.05). However, these indicators showed the opposite changes when treated with GA3at a higher dose (100 μM). Of the total Pb in plant shoot, 36–51% was associated with cell wall, and 31–40% was soluble fraction, while 41.4–49.7% was NaCl extractable, 24.6–35.4% HAc extractable followed by other fractions. These findings suggest that Pb fixation by pectates and proteins in cell wall and sequestration in vacuole are responsible for Pb detoxification in plant, and the GA3at 1 μM appears to be optimal for enhancing Pb phytoextraction byL. perennefrom Pb polluted soils. [ABSTRACT FROM PUBLISHER]

In the last decade, extensive studies have been conducted to understand the chemical and biological processes of nanoparticles and their effects on ecological functions and human health. This review focuses on the nature and properties of natural nanoparticles (NNPs) and their influence on the physical, chemical, and biological processes in plant–soil–water systems. The NNPs are involved directly or indirectly in numerous soil processes such as aggregate formation, nutrient retention, microbial activities, and water purification and pollution mitigation and thus affect soil/environment quality and human health. This paper is intended to provide a brief review of recent progress in related fields. [ABSTRACT FROM AUTHOR]

Abstract: Eutrophication of Lake Okeechobee in southern Florida has been a great concern for decades. Previous studies in the Lake Okeechobee Watershed indicate that net phosphorus (P) import was primarily in the form of pasture fertilizers and dairy feeds, whereas total P export was primarily in the form of milk, cows, and crops. This study is an update of P import and export analyses in the Lake Okeechobee Watershed. The net import P coefficient obtained from the budget analysis was applied to the appropriate land use area for calculating a basin-wide P budget using a Geographic Information System (GIS). The runoff P was estimated with the Watershed Assessment Model (WAM). The P loads to the lake were simulated at discharge structures from each basin. On-site P storage and wetland assimilation values were estimated using a mass balance approach for each basin. Overall, there was a 25% decrease in net P imports and a 29% decrease in onsite P storage, as compared to the previous analyses. The differences in the net P coefficients relative to previous P budgets may be partially the result of better available information. The net P imports for improved pasture increased by 15%, primarily due to the land application of residuals, which had not been included in the previous P budgets. The increase in P import for citrus production may have resulted from changed coefficients in the Lake Istokpoga and Upper Kissimmee regions where citrus was previously found to be a net P exporter. These results indicate that nutrient management practices may have played a role in reducing P loads to the Lake. [Copyright &y& Elsevier]

Abstract: A decision support system (DSS) is an interactive software-based system used to help decision-makers compile useful information from a combination of raw data, documents, and personal knowledge; to identify and solve problems; and to make an optimized decision. The DSS architecture consists of the database (or knowledge base), the model (i.e., the decision context and user criteria), and the user interface. The main advantages of using a DSS include examination of multiple alternatives, better understanding of the processes, identification of unpredicted situations, enhanced communication, cost effectiveness, and better use of data and resources. The application DSS in agriculture and environment has been rapidly increased in the past decade, which allows rapid assessment of agricultural production systems around the world and decision-making at both farm and district levels, though constraints exist for successful adoption of this technology in agriculture. One of the important applications of DSS in agriculture is water management at both field and district levels. Agriculture is facing more severe and growing competition with other sectors for freshwater. The water resources are becoming increasingly insufficient to meet the demand in developing countries and their quality is declining due to pollution and inadequate management. Irrigation is an effective means to enhance crop productions, but water needs to be supplied accurately, taking into account its availability, crop requirement and land size, irrigation systems, and crop productivity and feasibility. This chapter attempts to present the state-of-art principles, design, and application of DSS in agriculture, particularly irrigation practices, and to identify emerging approaches and future direction of research in this field. [Copyright &y& Elsevier]

Properties and distribution dynamics of nanoparticles are pertinent to ecological and human health. Wide variation in particle density confounds their accurate separation for study. The objective of this study was to develop a fine-particle separation protocol requiring no constant density assumption. Six soils with contrasting properties were chosen for study. Size distributions of suspended particles following centrifugation were assessed using dynamic light scattering. Mineralogy was determined by X-ray diffraction. Particle characteristics were examined using transmission electron microscopy. A significant pooled logarithmic relationship was found between centrifugation speed and particle-size distribution. Nanoparticles (<100 nm) became dominant by fractional volume at widely differing separation energies among the six soils. However, relations were strong between separation energies and fractional volume for individual soils. Bi- and tri-modal-size distributions within suspensions were related to density differences of soil components. Re-aggregation at high separation energy was apparent for the tropical soils. Light-scattering, UV-Visible absorbance, and chemical analyses distinguished samples of high hematite content from those without hematite. These results indicate that dynamic light scattering in conjunction with a standard centrifuge regimen provides a practical means of collecting colloidal particles within a targeted size range, compensating for natural variations among the soil samples. [ABSTRACT FROM AUTHOR]

Background and aims: Long-term use of copper (Cu) based fungicides has accelerated Cu contamination in soils and subsequently its export to the environment. Field trials were conducted in representative commercial citrus groves in the Indian River area, South Florida to evaluate the effectiveness of calcium water treatment residue (Ca-WTR) for stabilizing Cu in soil and its subsequent influence on Cu loading in surface runoff and citrus growth. Methods: Soil and surface runoff samples were monitored over a 3-year period on two field sites under navel orange and Ruby Red grapefruit production. Results: Soil amendment with Ca-WTR generally raised soil pH and soil available Ca, but decreased available Cu. The mean concentrations of Cu in surface runoff water were reduced by 36 % and 28 % for the navel orange and grapefruit site, respectively. The results of species distribution of Cu in the runoff water using MINTEQ indicated that the application of Ca-WTR decreased the concentrations of free Cu by 61 % and 39 % for the two sites. Fruit quality and yields were improved, because of the improved nutrient availability and other soil conditions. Conclusions: The results indicate that in situ application of Ca-WTR may provide a cost-effective remediation method for the Cu-contaminated soils without affecting citrus production. [ABSTRACT FROM AUTHOR]

Abstract: Surface runoff water is an important non-point source of fecal pollution to downstream water; however, there is a lack of systematic studies on the microbial quality of surface runoff water from watersheds with mixed land uses. In this study water samples from 12 surface runoff holding water bodies (SRW), which collected runoff from various patterns of land use within the St. Lucie watershed along the southeastern coastline of Florida, were collected monthly for 22months. The concentration of fecal indicator bacteria (FIB) and frequency of detection of Salmonella and host specific markers (HF183, CF128, CF193, and HS-esp) were determined, and their associations with land use, rainfall, and water physico-chemical parameters were investigated. Higher FIB concentrations were observed from urban land and cattle ranch sites. Within the same primary land use pattern, different sub-patterns did not have the same level of FIB: golf communities contributed less to fecal pollution than residential areas, and plant nursery sites contained relative higher FIB concentrations than other agricultural sites. Salmonella, CF128, and CF193 markers were more frequently detected from the cattle ranch sites. In contrast the frequency of detecting human specific markers (HF183 and HS-esp) was much higher in residential sites. Rainfall positively affected the concentration of FIB and occurrence of Salmonella, possibly by providing more inputs or mobilizing the sources from sediments. Water temperature, dissolved organic carbon (DOC), and nutrient levels were positively correlated with FIB concentrations and occurrence in SRW, possibly by promoting their growth and survival. This study indicated the need for site specific mitigation strategies to improve SRW and downstream water quality. [Copyright &y& Elsevier]

Abstract: Transport of dissolved organic matter in runoff water plays a critical role in the increased inputs of nutrients (N and P) and metals (Fe, Cu and Zn) in water, and the deposition of muck sediments in the Saint Lucie Estuary and Indian River Lagoon, Florida. The objectives of this study were to investigate the variation of dissolved organic carbon (DOC) and dissolved nitrogen (DN) in surface runoff water with varying land uses, and to explore their possible relations with the leaching losses of nutrients N and P, and metals Fe, Cu, and Zn from different land uses. For this, surface runoff water from two major agricultural production systems (citrus grove and vegetable farm) in south Florida was collected weekly using pre-installed autosamplers during Jan. 2008–Mar. 2010. Meanwhile, runoff water from twelve field sites with varying land uses (such as ranch, golf course, and forest) was collected monthly using a grab sampler from Aug. 2008 to April, 2010, and soils were collected at the depth of 0–15cm and 15–30cm twice a year from autosampler-installed locations and on Nov. 25th, 2008 from grab sampling locations as well. In the field, water samples were measured for electrical conductivity, dissolved oxygen, and temperature; in the laboratory, water samples were analyzed for pH, total solids, turbidity, DOC, DN, total P (TP), and metals Cu, Fe and Zn with or without passing a 0.45μm filter membrane. After passing a 2mm sieve, fresh soil samples were analyzed for moisture, pH, electrical conductivity, 0.5M K2SO4 solution extractable DOC/DN, and Mehlich 3 extractable P, Fe, Cu, and Zn. Spatial and temporal variations in the concentrations of DOC and DN in runoff water were observed, with the greatest average concentrations of DOC and DN from ranch (∼28 and ∼2.3mgL−1) and the lowest from golf course (∼16mgL−1) for DOC and from forest and nursery for DN (∼1.5–1.6mgL−1), respectively. Temporal fluctuations of DOC and DN in runoff water from varying land uses were in good accord with rainfall intensity and frequency of rainfall. Temporal variations of TP and metals Fe, Cu, and Zn were influenced by climatic condition as well. Citrus grove exported greater amounts of DOC and DN in runoff water (27.6 and 3.51mgL−1 of median value) than vegetable farms (13.8 and 2.26mgL−1 of median value). Annual cumulative loads of DOC and total N in 2008, 2009 or 2010 were >20kgha−1, greater than those of TP (<13.5kgha−1) and metals Fe, Cu, and Zn (<1.5kgha−1). Ranch soil had the highest extractable DOC concentration (>100mgkg−1), accounting for 1% of its total organic carbon. Soil extractable DN had significant correlations with extractable P and Cu/Zn in soils. In conclusion, soil total organic carbon pool and its availability had an important effect on DOC and DN in runoff water. Land use type and rainfall event were the two influential factors affecting concentrations of DOC and DN, and the export of nutrients N and P, and metals in runoff water. [Copyright &y& Elsevier]

Abstract: Soil contamination by heavy metals like Ni was originally restricted to metalliferous soils but in modern time it has become a general problem due to increasing anthropogenic activities. Because of the characteristics of cost-effectiveness, environmental friendliness, and fewer side-effects, the development of plant based remediation technologies for the cleanup of Ni-contaminated soils has attracted much attention. Nickel is an essential micronutrient, but is toxic to plants at excessive levels. Some plant species can accumulate Ni in the shoots at a high concentration, these plants are called hyperaccumulators. In the past two decades, researchers have endeavored to understand the physiological and molecular mechanisms of Ni uptake, transport, and detoxification in the Ni-hyperaccumulator plants. This is the basis of creating ideal plants for phytoremediation through cell and genetic engineering technologies, which may subsequently improve phytoremediation efficiency for decontaminating Ni-contaminated soils. Both rhizosphere microorganisms and endophytes can play a role in phytoremediation. Optimizing plant and soil management practices, particularly the correction of soil pH and additions of amendments of exogenous chelates and fertilizers, can also enhance phytoremediation of Ni-contaminated soils. The primary objective of this review is to discuss the recent progresses in basic and applied research relevant to phytoremediation of Ni-contaminated soils. [Copyright &y& Elsevier]

Most soils in Florida are very sandy, and water-soluble fertilizers (WSF) are subjected to leaching loss. Alternate fertilization is a promising practice to reduce such loss. Dolomite phosphate rock (DPR), which contains calcium, magnesium, and phosphorus, is potentially useful for agricultural production and landscaping plants. In this study, DPR fertilizers were developed from mixing of DPR material and N-viro soil. A typical agricultural soil (Alfisol) in Florida was used for greenhouse studies, and ryegrass and citrus seedlings were tested. The DPR fertilizers appeared superior to WSF for the growth of ryegrass based on dry-matter yield and nutrient concentrations in plant; however, it was not evident in citrus seedlings. DPR fertilizers were effective in raising pH (by 3 units) and electrical conductivity of acidic sandy soils and increasing soil organic matter, total nutrients, and available nutrients. The concentrations of copper, lead, and zinc in the plant tissues were less than toxicity limits. [ABSTRACT FROM AUTHOR]

Abstract: Calcium water treatment residue (Ca-WTR), an industrial by-product, was found to be effective in decreasing Cu availability in contaminated soils and transport to the environment. In this study, a greenhouse study was conducted to test the ability of Ca-WTR to reduce the toxicity and uptake of Cu by ryegrass (Lolium perenne L.) and lettuce (Lactuca sativa L.) as indicator crop plants in Cu-contaminated sandy soils. Eight weeks growing period was observed in Alfisol and Spodosol amended with different levels of Ca-WTR (5–100gkg−1 soil). Plant biomass yields increased with WTR application rates at the low levels (5–20gkg−1 for Alfisol, pH 5.45 and 5–50gkg−1 for Spodosol, pH 4.66), and decreased at the high levels (>20gkg−1 for Alfisol and >50gkg−1 for Spodosol). The maximum growth of ryegrass with Ca-WTR was 133% and 149% of the control (without Ca-WTR) for the original Alfisol and Spodosol (without spiked Cu), respectively, while the corresponding values for lettuce was 145% and 206%. Copper concentrations in ryegrass shoots decreased significantly with increasing Ca-WTR application rates. For lettuce, Cu concentration decreased only at high Ca-WTR rates (>50gkg−1). In addition, ryegrass had a greater potential for Cu uptake and translocation than lettuce in both soils. [Copyright &y& Elsevier]

Abstract: Bacteroidales markers are promising indicators of fecal pollution and are now widely used in microbial source tracking (MST) studies. However, a thorough understanding of the persistence of Bacteroidales population after being released into environmental waters is lacking. We investigated the persistence of two host specific markers (HF183 and CF193) and temporal change of Bacteroidales population over 14 days in freshwater microcosms seeded with human or bovine feces. The concentrations of HF183/CF193 and Escherichia coli were determined using quantitative polymerase chain reaction (qPCR) and standard cultivation method, respectively. Shifts in the Bacteroidales population structure were fingerprinted using PCR-denaturing gradient gel electrophoresis (DGGE) and subsequent sequencing analysis targeting both 16S rDNA and rRNA-transcribed cDNA. Both HF183 and CF193 decayed significantly faster than E. coli but the decay curves fit poorly with first-order model. High diversity of Bacteroidales population was observed for both microcosms, and persistence of different species in the population varied. Sequence analysis indicated that most of the bovine Bacteroidales populations in our study are unexplored. DGGE and decay curve indicated that RNA decayed faster than DNA, further supporting the use of rRNA as indicator of metabolically active Bacteroidales population. Evaluations with more realistic scenarios are warranted prior to extending the results of this study to real field settings. [Copyright &y& Elsevier]

Abstract: Understanding the survival and persistence of Escherichia coli in soil with different microbial composition is essential for the accuracy of water quality assessment and microbial source tracking. This microcosm experiment was conducted to investigate the survival pattern of three E. coli strains (originated from soil, dog feces and human feces, separately) in soil with modified microbial community composition. Bile salt No. 3 (BS3) of progressively increased density (0.05%, 0.15%, 0.30% and 0.50%) was added into sandy loam soils and incubated for 90 days. Laboratory cultured E. coli were then inoculated into soil and incubated for another 150 days to monitor their survival pattern. Change of bacterial community diversity by BS3 was detected by both cultivation based and cultivation independent (PCR-Denaturing Gradient Gel Electrophoresis) methods. In general, progressively increased BS3 concentration resulted in decreased CFU counts both at 10 days and 90 days incubation. DGGE analysis indicated only a slight change in bacterial community composition at 10 days but a significant change at 90 days. Cluster analysis suggested that BS3 treatment grouped separately from controls. Survival of E. coli in soil was significantly influenced by the complexity of the microbial community, as die-off rate of E. coli progressively declined with the reduction of microbial community diversity. Differential survival of E. coli under different soil microbial stress highlights the importance of incorporating biotic factors in predictive models for water quality management and microbial source tracking study. [Copyright &y& Elsevier]

Abstract: Chemical remediation has attracted increasing attention for heavy metal contaminated soils because of its relatively low cost and high efficiency. In this study laboratory incubation and column leaching experiments were conducted to understand the mechanisms of copper (Cu) immobilization by calcium water treatment residue (Ca-WTR) and to estimate the optimal rate for remediating Cu-contaminated soils. The results showed that Ca-WTR amendment significantly raised soil pH and decreased water soluble and exchangeable Cu by 62–90% in the contaminated soils. Most of the bioavailable Cu was converted into more stable Cu fractions, i.e. oxides-bound and residual Cu. The cumulative amount of Cu in the leachate after 10 leaching events was reduced by 80% and 73%, respectively for the two tested soils at the Ca-WTR rate of 20gkg−1 for Alfisol and 100gkg−1 for Spodosol. These results indicate that Ca-WTR is effective in raising soil pH and converting labile Cu to more stable forms in the contaminated soils. A pH value of 6.5 was found to be critical for lowering Cu availability in the soils. Based on this criterion and pH response curve to Ca-WTR application, the optimal rates of Ca-WTR can be estimated for different Cu-contaminated soils. [Copyright &y& Elsevier]

A new nylon membrane bag (NMB) assay was developed for studies to determine the effect of chemicals added to soil on survival of soilborne plant pathogens. The rapid and effective assay can be used to study organisms for which there are no selective media or for which a selective medium is expensive or difficult to prepare. This assay consists of placing pathogens inside a bag made of small-pore (0.22-μm) nylon filtration membrane, which is placed in soil and later retrieved to determine survival of the pathogens on nonselective media. Chemicals but not other microorganisms can enter the bag from the soil. Using this assay, Streptomyces scabies, Fusarium oxysporum f. sp. lycopersici race 3, and Ralstonia solanacearum were successfully recovered from soil after 72 h as demonstrated by growth on a semiselective Streptomyces medium (S. scabies) or nonselective potato dextrose agar medium (F oxysporum f. sp. lycopersici race 3 and R. solanacearum) with minimal microbial contamination. Addition of acetic acid (200 mM) to soil killed 100% of S. scabies. SPK (a mixture of organic chemicals) at a concentration of 1,500 mg kg-1 of soil killed 83.3% of F oxysporum f. sp. lycopersici race 3 culture plugs, 100% of F oxysporum f. sp. lycopersici race 3 spores, and 97.2% of R. solanacearum cells. SPK at 1,000 mg kg-1 of soil killed 50% of F oxysporum f. sp. lycopersici race 3 culture plugs, 68.2% of F oxysporum f. sp. lycopersici race 3 spores, and 12% of R. solanacea rum. Benlate (500 to 1,500 mg kg-1 of soil) did not kill the culture plugs of F oxysporum f. sp. lycopersici race 3 but reduced the growth rate of F oxysporum f. sp. lycopersici race 3. Benlate (500, 1,000, and 1,500 mg kg-1 of soil) reduced F oxysporum f. sp. lycopersici race 3 spore germination by 39.4, 49.3, and 50.4%, respectively. Streptomycin sulfate (1,500, 800, 400, and 200 mg kg' of soil) caused 75.3, 21, 11.9, and 0.9% mortality, respectively, of R. solanacea rum. [ABSTRACT FROM AUTHOR]

Abstract: The effect of probiotics on alkaline phosphatase activity (APA) and nutrient concentrations (total phosphorus, (TP); total inorganic phosphorus, (TIP); total organic phosphorus, (TOP); total organic carbon (TOC) and total nitrogen (TN)) in sediment of shrimp, Penaeus vannamei, cultural pond was investigated. Three ponds were treated with commercial probiotics and three were used as the control (without any probiotics). TP was significantly lower (P <0.05) in the treatment group compared with the control group at 20, 40 and 60 days post treatment. However, the difference of TP content was reduced to less significant after 80 days. The TIP concentrations of the treatment in sediment was lower (P <0.05) than that of the control on day 20, 40 and 80. No significant difference (P >0.05) was found in TOP content. The amount of total N and TOC contents at day 0 of the experiment were not significantly between treatment and control ponds (P >0.05). However, the probiotic supplementation remarkably decreased TN and TOC (P <0.05) in the treatment group after day 20. APA was no significant difference (P >0.05) between treatment and the control groups. The seasonal APA followed a similar trend for all the ponds, low at the beginning, peaked on day 20, and then showed a second peak on day 100. The data showed that the application of probiotics would mitigate the nitrogen and phosphate pollution in ponds sediments. [Copyright &y& Elsevier]

Addition of organic amendments can alleviate the level of aluminum (Al) phytotoxicity in acid soils by affecting the nature and quantity of Al species. This study evaluated the transformation of Al in an acidic sandy Alaquod soil amended with composts (10 and 50 g kg-1 soil of yard waste, yard + municipal waste, GreenEdge®, and synthetic humic acid) based on soil Al fractionation by single and sequential extractions. Though the organic compost amendments increased total Al in soil, they alleviated Al potential toxicity in acidic soil by increasing soil pH and converting exchangeable Al to organically bound and other noncrystalline fractions, stressing the benefits of amending composts to improve acid soil fertility. The single-extraction method appears to be more reliable for exchangeable Al than sequential extraction because of the use of nonbuffered pH extract solution. [ABSTRACT FROM AUTHOR]

Ten Mile Creek (TMC) is a major tributary of the Indian River Lagoon (IRL), one of the largest and most ecologically diverse estuaries of the east coast of Florida. Recent algal blooms within the IRL have focused attention on the role of different watersheds playing in the supply of growth-limiting nutrients. The goal of this study was to determine the nutrient-limiting status of the TMC outflow, which is influenced by both agricultural input and urban development. Four laboratory experiments were conducted with water samples from TMC, adding different concentrations of phosphorus (P) and nitrogen (N) under controlled conditions. The results showed that turbidity and phytoplankton biomass (in terms of chlorophyll a concentration) in TMC water samples were responsive to N additions. Turbidity and phytoplankton biomass increased with addition of available N, but were not affected by addition of reactive P. The results indicate that available N is the limiting nutrient for the growth of phytoplankton in the TMC. [ABSTRACT FROM AUTHOR]

Abstract: Steel slag with magnetic separation was used to remove phosphate from aqueous solutions. The influence of adsorbent dose, pH, and temperature on phosphate removal was investigated in a series of batch experiments. Phosphate removal increased with the increasing temperature, adsorbent dose and decreased with increasing initial phosphate concentrations, while it was at its peak at pH of 5.5. The phosphate removal predominantly occurred through ion exchange. The specific surface area of the steel slag was 2.09m2/g. The adsorption of phosphate followed both Langmuir and Freundlich isotherms. The maximum adsorption capacity of the steel slag was 5.3mgP/g. The removal rates of total phosphorus (TP) and dissolved phosphorus (DP) from secondary effluents were 62–79% and 71–82%, respectively. Due to their low cost and high capability, it was concluded that the steel slag may be an efficient adsorbent to remove phosphate both from solution and wastewater. [Copyright &y& Elsevier]

This study was the first attempt to examine the possible role of the naturally occurring rhizospheric bacteria in heavy metal removal by Sedum alfredii Hance, a terrestrial Zn/Cd hyperaccumuluator, from Zn, Cd, Cu and Pb contaminated water using antibiotic ampicillin. Moreover, the toxicity symptom in plants under heavy metal stress expressed as total chlorophyll, chlorophyll a and b content, growth inhibition, root length, and N, P contents were studied, and the possible relationship among them were also discussed. These results indicate that rhizospheric bacteria may play an important role in the uptake of N and P by S. alfredii, and consequently result in the increase of Chlorophyll content in the leaves and plant biomass due to improved photosynthesis. At the same time, root length significantly decreased under the treatment with ampicillin, which suggested that rhizospheric bacteria appeared to protect the roots against heavy metal toxicity. The Pb, Zn, Cu and Cd concentrations in the roots, stems and leaves of S. alfredii were much higher than those exposed to ampicillin. Accordingly, metal concentrations in the contaminated water without ampicillin treatment were lower than those treated with ampicillin. These results suggest that the rhizospheric bacteria may be useful in plant tolerance to heavy metal toxicity, and also accelerate the metal removal from contaminated water. [Copyright &y& Elsevier]

Water quality is influenced by agricultural development and varies with surrounding land management. Seasonal and spatial patterns in the concentrations of nitrogen (NH4-N and NO3-N), phosphorus (P), and heavy metals were investigated at six drainage ditches distributed in commercial vegetable farms and citrus groves in St. Lucie County, Florida. The concentrations ranged from nondetectable to 9.13 mg l−1 for NH4-N, to 283 mg l−1 for NO3-N, and to 4.86 mg l−1 for total P. The concentrations of Cu and Zn ranged from nondetectable to 63.7 and 121.7 μg l−1, respectively. Spatial and temporal variations of water quality were noted among the different drainage ditches. Since fertilizer rates were higher on the vegetable farms than in the citrus groves, the concentrations of N, P and K were generally higher in the ditches on the vegetable farms than in the citrus groves. Seasonally, the higher concentrations of N, P, K, Cu, and Zn occurred in the wet season than in the dry season, which might result from higher nutrient input from the adjacent field. Mean N, P, Zn, and Cu concentrations in the ditch water were significantly correlated with soil test N, P, Zn, and Cu levels and annual amounts of N and P applied in the adjacent fields. However, the concentrations of Cd, Co, Cr, Ni, Pb, Mo, and As were generally low, with small seasonal variations, probably due to limited water-soluble Cd, Co, Cr, Ni, Pb, Mo, and As in the soil of adjacent fields. The results indicate that nutrients and heavy metals accumulated in the soils and fertilization practices have significant influences on water quality in adjacent drainage ditches, and water quality of drainage ditch can vary with season. [Copyright &y& Elsevier]

It is well known that the availability of nutrients in red soils (equivalent to Ultisols and some of the Alfisols and Oxisols in the soil taxonomy of USA) changes after conversion of upland to irrigated rice (Oryza sativa L.) production, but long-term changes in carbon (C) and nutrients are not well documented. To characterize changes in C and nutrients in paddy fields on a Quaternary red clay (clayey, kaolinitic thermic typic plinthudults) during long-term rice cropping, we measured total C, nitrogen (N), phosphorus (P) and potassium (K), particulate organic matter (POM), N in the POM, potential mineralized N, available P, as well as other properties (pH, exchangeable cations, effective cation exchange capacity (ECEC), aggregate stability) in the plow layer (0–15 cm) of 66 rice fields with rice-cultivation time ranging from 2 to 100 years. Total C, N, and P distributions were also determined in six soil profiles with rice-cultivation times of 2, 5, 19, 48, 68, and 100 years, respectively. Significant increases in organic C, total N, and P concentrations in plow layer were found in the first 30–40 years of rice cropping, accompanied by increases in available P and potential mineralized N, exchangeable Ca, Mg, Na, base saturation, and water-stable aggregates, and decreases in total K and clay content. The C/N ratio of organic matter tended to decrease in the first 20 years of rice cropping, and remained constant at approximately 10, whereas the ratio of humic acid to fulvic acid (H/F ratio) increased gradually to about 1 after 50 years of rice cropping. Long-term rice cropping elevated C, N, and P in the plow layer and increased accumulation of C, N, and P in the subsurface soils. The results indicate: (i) long-term rice cropping improved soil fertility as evidenced by neutralization of soil acidity, and increases in ECEC, organic C content, and H/F ratio; (ii) imbalance of fertilization by high N and low K, as revealed by decreased soil K and increased soil N; (iii) long-term rice cropping caused downward movement of organic C, N, and P, which may result in environmental impacts. [Copyright &y& Elsevier]

Red soils belong to Oxisols, Ultisols, and some of the Alfisols in the soil order of the United States soil taxonomy. These soils had and continue to play an important role in the economic development of China. Non-judicious use of red soil resources, particularly deforestation, has caused severe soil erosion, resulting in the degradation of the environment and reduced agricultural production in the red soil regions. Various approaches have been developed to restore the fertility of degraded red soils. These include: 1) reclamation of the surface and subsurface soil by a mixture of lime, manures, and chemical fertilizers; 2) improvement of the entire rooting depth of citrus and other deeply-rooting crops using trench-planting and soil chiseling techniques; 3) increased input of organic materials applied alone or together with chemical fertilizers or lime; 4) integrated utilization of red soil resources to minimize soil erosion and water losses; and 5) diversified crop production systems to increase economic return. These efforts have proved to be effective in sustaining agricultural production and further improving nutrient utilization efficiency and environmental quality in the red soil regions of China. [ABSTRACT FROM AUTHOR]

Sandy soils in Florida are vulnerable to toxic metal pollution, and it is necessary to identify desirable amendments for the remediation of metal contaminated soils. Sorption and incubation experiments were conducted to compare the effectiveness of dolomite phosphate rock (DPR), humic acid activated dolomite phosphate rock (ADPR) and biochar (BC) in immobilizing Cd2+ and Pb2+ in two representative agricultural soils in south Florida (Alfisol-Riviera and Spodosol -Ankona series). The results showed that the soils had a low sorption capacity for metals with maximum sorption of 0.767–3.30 mg/g. Application of amendments increased the maximum sorption by 4.2–4.8 times for Pb2+ and 1.5–2.2 times for Cd2+ in Alfisol soil, and 7.1–7.9 times for Pb2+ and 1.7–3.1 times for Cd2+ in Spodosol soil. ADPR was the most effective amendment for increasing the soil's sorption capacity for Cd2+ and Pb2+. 0.01 M CaCl 2 extractable metals in the contaminated soils were significantly decreased by all the amendments, especially ADPR, which reduced extractable Cd2+ and Pb2+by 87.2 and 76.0% in Alfisol and 91.3 and 76.3% in Spodosol soil as compared to control. The amounts of extractable Cd2+ and Pb2+ were negatively correlated with soil pH and available P, indicating that the change of soil characteristics by amendments was the dominant mechanism for enhanced immobilization of metals in the contaminated soils. These results indicate that ADPR has great potential for remediating toxic levels of Cd2+ and Pb2+ in contaminated soils. Image 1 • Activated DPR (ADPR) and biochar were compared for immobilizing metals in two soils. • The immobilizing effectiveness of amendments varied with metal and soil type. • Activation with humic acid increased the immobilizing power of DPR for Cd2+ and Pb2+. • The immobilization of metals by ADPR is related to increased soil pH and available P. [ABSTRACT FROM AUTHOR]

• Organic-C chemical quality regulates microbial N immobilization in soil. • C/N ratio cannot accurately predict microbial N immobilization. • Organic-C mainly in the form of labile compounds may favor microbial N immobilization. • Nitrate immobilization was found to occur even when NH 4 + was present. Microbial nitrogen (N) immobilization in soil can be enhanced by increasing carbon (C) bioavailability, yet the response of microbial N immobilization to the addition of organic matter is uncertain. In the present study, we investigated the effect of organic matter quality on microbial N immobilization. The response ratio (ln R), i.e., the ratio of microbial N immobilization in organic-C amended soil to that in control treatments, was calculated using data from 51 published studies. Overall, the addition of organic-C increased significantly microbial N immobilization by 105% relative to unamended soil. The type of organic-C affected the response of microbial N immobilization to organic-C addition. Glucose (classified as a labile compound) was more effective in stimulating microbial N immobilization than cellobiose and cellulose (classified as intermediately decomposable compounds). Tannin and oxalic acid (classified as recalcitrant compounds) did not significantly affect microbial N immobilization. The C/N ratio of organic materials did not affect the response of microbial N immobilization in the short-term (≤280 d); differences in the effect size (ln R +) were not significant among different C/N ratio groups. The effect of the form of inorganic-N (ammonium [NH 4 + or nitrate [NO 3 −) on the response of microbial N immobilization to organic-C addition was not significant, with a mean ln R + of 0.838 (confidence interval [CI]: 0.590–1.099) for NH 4 + and 1.642 (CI: 0.951–2.452) for NO 3 −. Moreover, the ln R of microbial NH 4 + immobilization showed a significant positive relationship (P < 0.01) with that of microbial NO 3 − immobilization. The ln R + for the experimental period decreased in the order of <30 d, 60–120 d, ≥120 d, and 30–60 d. The chemical quality of organic-C defined by three C pools (i.e., labile, intermediate, and recalcitrant) rather than the C/N ratio is a critical factor regulating the response of microbial N immobilization to organic-C addition. [ABSTRACT FROM AUTHOR]

As the power density of modern CPUs is gradually increasing, thermal management has become one of the primary concerns for multicore systems, where task scheduling and dynamic voltage/frequency scaling (DVFS) play a pivotal role in effectively managing the system temperature. In this article, we propose CARTAD, a new reinforcement learning (RL)-based task scheduling and DVFS method for temperature minimization and latency guarantee on multicore systems. The novelty of CARTAD framework is that we exploit the machine learning technique to analyze the applications’ intermediate representations (IRs) generated by a compiler and identify an important feature which is critical for predicting the application’s performance. With the newly explored feature, we construct an RL-based scheduler with the more effective state representation and reward function such that the system temperature can be minimized while guaranteeing applications’ latency. We implement and evaluate CARTAD on real platforms in comparison with the state-of-the-art approaches. Experimental results show CARTAD can reduce the maximum temperature by up to 16 °C and the average temperature by up to 10 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] Here, we show that a reactive synthesis method of mixed elemental powders can be used to synthesize a porous electrode consisting of an intermetallic Fe 5 Si 3 that exhibits catalytic activity towards oxygen evolution reaction (OER) in acidic solutions, which is capable of delivering 10 mA cm−2 at an overpotential of 0.73 V and a small Tafel slope of ~ 381.8 mV dec-1. The amorphous silica formed in the anode surface during the electrochemical process is multifunctional, as it protects the electrode substrate from corrosion and acts as electrocatalysts for OER. Remarkably, the Si-based intermetallics can be generalized to include other OER catalytic elements (Mn, Fe, Co), including Mn-Si and Co-Si intermetallics. [ABSTRACT FROM AUTHOR]

• Alternate wetting and drying irrigation increased inorganic N in soil, but not plant N accumulation of rice. • Alternate wetting and drying irrigation reduced water usage with similar or reduced rice grain yield. • Zeolite amendment increased inorganic N in soil and plant N accumulation of rice. • Zeolite amendment enhanced plant growth and subsequent grain yield of rice. Zeolite (Z) has been widely used for improving rice production, but there is a lack of information on how nitrogen (N) accumulation and translocation affect yield performance of paddy field in the alternate wetting and drying irrigation (AWD) amended with zeolite. In this study, a 2-year field experiment with installed lysimeters was carried out to determine the influence of Z application (0, 5 and 10 t Z ha−1) on rice yield, tiller number, leaf area index (LAI), dry matter accumulation and translocation (DMA and DMT), N accumulation and translocation (NA and NT), inorganic N content in soil under two irrigation regimes (CF: continuously flooded irrigation, AWD). The results showed that AWD didn't affect rice grain yield in 2016, but reduced it in 2017 without Z application; and rice yield was not affected by AWD with the application of 10 t Z ha−1 in two years, relative to CF. AWD reduced highest and ineffective tiller number in 2016, and highest and final tiller number in 2017; as well as LAI after joint-booting stage, relative to CF. Z amendment significantly increased highest and final tiller number, but didn't affect ineffective tiller number; and increased LAI after joint-booting stage. The principal components analysis showed that grain yield was more significantly correlated with the panicles per m2, NT, and aboveground DMA and NA after panicle-initiation stage. As compared to CF, AWD significantly reduced aboveground DMA after panicle-initiation stage; aboveground NA after joint-booting stage in both years; and NT in 2016, but not in 2017. Z amendment significantly improved aboveground DMA and NA after tillering stage, as well as NT and panicles per m2. In addition, AWD with Z amendment significantly improved inorganic N content in soil. [ABSTRACT FROM AUTHOR]

The foliar application of zinc (Zn) has been regarded as a practical and economical way to reduce grain cadmium (Cd) accumulation and enhance grain quality in crops. Herein, a two-year field experiment was carried out to examine the efficacy of different application rates of the foliar Zn fertilizer in Cd reduction and microelement biofortification in wheat (Triticum aestivum L.) grains. The results show that the T4 and T5 treatments, 500 and 250-fold dilution of the foliar Zn fertilizer, respectively, increased the grain yield to varying degrees in the two years. When compared with controls and based on the average of the two years' results, spraying with the foliar Zn fertilizer remarkably decreased grain Cd concentrations (44.5%), Cd translocation from stem to grain (TFStem/Grain) (4.92%), the H R I values of Cd (45.5%), PA/Ca (27.8%), PA/Fe (21.4%) and PA/Mn (5.81%) under the T2 treatment (1000-fold dilution). Furthermore, the T2 treatment significantly increased the Zn (37.8%), Ca (48.9%), Fe (37.6%), Mn (14.8%) and total protein (7.92%) contents and the estimated Zn bioavailability (28.9%) in wheat grains after two years. All these findings suggest that the foliar Zn fertilizer holds considerable promise as a safe crop production technique and a means of mitigating "hidden hunger" in developing countries. [ABSTRACT FROM AUTHOR]

Zinc-oxide nanoparticles (ZnO-NP) effect on crop physiology and zinc recovery remains poorly studied for acidic-sandy soils. To address this, greenhouse pot (plastic-pots, 6 kg soil, maize) experiments with ZnO-NP (50, 100, 150, 200 mg kg−1) applied via different methods (soil-drench, seed-coating and foliar-spray) was conducted in a 60 days study. Results revealed that ZnO-NP via seed-coating (100 mg kg−1) and soil-drench (150 mg kg−1) enhanced shoot and total P uptake, while ZnO-NPs (foliar) (50 mg kg−1) enhanced maize growth (6–11%), with agronomic and physiological improvements ultimately resulted in greater biomass (16–20%), Zn agronomic efficiency and uptake. Compared to ZnSO4 treatment and the control, seed-coating with 100 mg kg−1 ZnO-NP increased leaf chlorophyll and pigment content by 12–127%. Principal component analysis revealed a close association among growth traits, plant pigments, fluorescence parameters, total Zn and P concentration, and uptake with total biomass as influenced by ZnO-NPs. Thus, compared to conventional ZnSO4 and higher dosages of ZnO-NPs, foliar-spray of ZnO-NP at 50 mg kg−1, seed-coating at 100 mg kg−1, or soil-drench at 150 mg kg−1 increased maize biochemical characteristics, growth, biomass, and Zn agronomic efficiency. These elucidate important implications of ZnO-NP application for increasing plant development and Zn biofortification in acidic-sandy soils. [ABSTRACT FROM AUTHOR]

Sugarcane yield in China is low because of the shallow A-horizon soil layer, or as it is commonly called by farmers, the "plow soil layer", as well as low soil organic matter and fertilizer utilization efficiency. Fenlong-ridging deep tillage (FT), also called vertical rotary tillage, and amendment with biochar have been shown to improve soil quality and crop yield. In this study, field trials were conducted with newly planted and ratoon sugarcane to evaluate the effectiveness of FT, together with amendment with biochar and nitrogen fertilization, to improve sugarcane yield. The treatments were conventional tillage with chemical fertilizer without biochar (CT-CF, which was the control of this experiment), FT with chemical fertilizer without biochar (FT-CF), conventional tillage with chemical fertilizer mixed with biochar (CT-CFB), and FT with chemical fertilizer mixed with biochar (FT-CFB). FT-CFB treatment presented higher soil porosity, as well as higher contents of available N, P, K, total N, and organic matter, and lower soil bulk density. Similarly, results showed that FT-CFB presented higher sugarcane root fresh and dry weights, higher germination percentage, higher tiller number, and higher yield with statistically significant differences among treatments for both newly planted and ratoon sugarcane plants. Significant interactions between biochar and FT were observed for these crop traits. The interactions of FT and amendment with biochar improved the soil's physical and chemical properties and increased the available nutrients, resulting in improved root growth and sugarcane yield. The statistical results of the present study imply that Fenlong-ridging deep tillage combined with chemical fertilizer mixed with biochar (FT-CFB) application is a new promising farm management practice for improving the soil's physical and chemical properties and root growth, increasing total yield in China's sugarcane belt area. [ABSTRACT FROM AUTHOR]

Highlights • Alternate wetting and drying irrigation slightly reduced NH 3 volatilization but increased N leaching. • Alternate wetting and drying irrigation improved water productivity. • Zeolite amendment reduced NH 3 volatilization and N leaching. • Zeolite amendment improved grain yield, water productivity and economic benefit. Abstract Clinoptilolite zeolite (Z) has been increasingly recognized as a valuable soil conditioner, which is beneficial to nitrogen (N) loss reduction and crop yield improvement. However, limited information is available for a rice production system, especially under alternate wetting and drying irrigation (AWD). Therefore, a 2-year field experiment with lysimeter was carried out in a split plot design with two irrigation regimes (CF: continuously flooded irrigation, AWD: alternate wetting and drying irrigation) as main plots and three Z amendment rates (0, 5 and 10 t Z ha−1) as sub-plots. The impact of Z amendment on ammonia (NH 3) volatilization, N leaching, rice grain yield, water productivity (WP) and economic benefit were analyzed under both irrigation regimes. The results showed that AWD slightly reduced NH 3 volatilization without Z application, but significantly increased residual mineral N (RMN) in soil at the depths of 0 − 30 and 30 − 60 cm, and NH 4 +-N and NO 3 −-N leaching, relative to CF. AWD-grown rice significantly improved WP without affecting grain yield in 2016, but reduced yield in 2017 without Z amendment. Compared with control (without Z amendment), addition of 5 and 10 t Z ha-1 increased RMN by 12 and 21%, respectively in the 0 − 30 cm soil depth, but reduced it by 18 and 32%, respectively in the 30 − 60 cm soil depth. Total NH 3 volatilization and NH 4 +-N and NO 3 −-N leaching loss decreased with increasing rates of Z amendment. Z amendment significantly increased N uptake, rice grain yield, economic benefit and WP, especially under AWD. In the two years, integration of 10 t Z ha-1 with either AWD or CF management reduced NH 3 volatilization without increasing N leaching and increased rice grain yield and WP, with an increased economic benefit of $126 − 195 ha-1, as compared to conventional management (CF without Z). The use of zeolite merits further investigation for application in the rice production systems. [ABSTRACT FROM AUTHOR]

Activation of low-grade phosphate rocks such as dolomite phosphate rock (DPR) with organic molecules of humic acid (HA) and sodium lignosulfonate (SLS) holds promise for developing slow release P fertilizers. Consequently, activated DPR fertilizers also contains multiple essential plant elements, including P, Ca, Mg, Zn, and Fe, while minimizing leaching losses of nutrients and heavy metals. Greenhouse experiments were conducted to examine the availability of Ca, Mg, and trace metals in soils applied with activated DPR fertilizers and subsequent response of lettuce (Lactuca Sativa L.) as compared with original DPR and water-soluble P fertilizers including superphosphates (SP) and diammonium phosphates (DAP). Application of activated DPR fertilizers stimulated the uptake of Ca, Mg, Zn, Fe, B by lettuce plants relative to original DPR and DAP. Potential toxic elements such as Cr, Cd, Ni, Pb, and Cu were mostly immobilized in soil without uptake by lettuce when applied with activated DPRs primarily due to increased soil pH, as compared with water soluble fertilizers such as DAP and SPs. Apparently, the activated DPR fertilizers offer advantages over original DPR materials and water-soluble P fertilizers in providing multiple nutrients with minimal adverse effects on soil and environmental quality. [ABSTRACT FROM AUTHOR]

• Cd bioavailability in HT rhizospheres was higher than those of LT. • Soil type is the strongest determinant of root-associated community. • HT rhizosphere could recruit taxa involved in Cd activation. Cadmium (Cd) bioavailability in the rhizosphere makes an important difference in grain Cd accumulation in wheat. Here, pot experiments combined with 16S rRNA gene sequencing were conducted to compare the Cd bioavailability and bacterial community in the rhizosphere of two wheat (Triticum aestivum L.) genotypes, a low-Cd-accumulating genotype in grains (LT) and a high-Cd-accumulating genotype in grains (HT), grown on four different soils with Cd contamination. Results showed that there was non-significant difference in total Cd concentration among four soils. However, except for black soil, DTPA-Cd concentrations in HT rhizospheres were higher than those of LT in fluvisol, paddy soil and purple soil. Results of 16S rRNA gene sequencing showed that soil type (52.7%) was the strongest determinant of root-associated community, while there were still some differences in rhizosphere bacterial community composition between two wheat genotypes. Taxa specifically colonized in HT rhizosphere (Acidobacteria, Gemmatimonadetes, Bacteroidetes and Deltaproteobacteria) could participate in metal activation, whereas LT rhizosphere was highly enriched by plant growth-promoting taxa. In addition, PICRUSt2 analysis also predicted high relative abundances of imputed functional profiles related to membrane transport and amino acid metabolism in HT rhizosphere. These results revealed that the rhizosphere bacterial community may be an important factor regulating Cd uptake and accumulation in wheat and indicated that the high Cd-accumulating cultivar might improve Cd bioavailability in the rhizosphere by recruiting taxa related to Cd activation, thus promoting Cd uptake and accumulation. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: Improving crop yields by increasing fertilizer-use-efficiency is essential to minimizing agriculture's environmental impact. Water-dispersible carbon nanomaterials (CNM) have emerged as an innovative material to improve crop yields by increasing nutrient utilization and enhancing crop physiological processes. However, the optimum dose of CNM, performance on crop growth, and impact on soil biochemical properties remain poorly understood. Methods: A greenhouse pot experiment (55 days) was conducted to evaluate the effect of three CNM rates, applied basally as a soil drench amendment, on the growth of two lettuce varieties and soil biochemical properties. We compared three CNM rates (200, 400 & 800 mg kg−1; C200F, C400F & C800F) along with a negative control (C0F0; no fertilizer or CNM) and a positive control (C0F; fertilizer at recommended doses like CNM treatments, no CNM applied). Results: We found that nitrogen (N), phosphorus and potassium (K) accumulation by lettuce and availability in soil were enhanced with CNM application, with 31% (C200F) and 34% (C400F) increases in shoot N accumulation compared to C0F, and K accumulation peaking at C800F (230% increase over C0F). Compared to C0F, soil microbial biomass carbon was 67–180% (C200F) or 42–150% (CF400) higher, phosphatase enzyme activity was 29–32% higher with C200F, and urease enzyme activity was 37–38% higher at C400F, indicating greater soil biological activity at lower application rates. Conclusion: Overall, CNM (200–400 mgkg−1 soil) promoted lettuce growth, enhanced soil fertility and soil biological activity, elucidating that water-dispersible CNM can be an alternative soil amendment to improve crop growth and soil biochemical quality. [ABSTRACT FROM AUTHOR]

Cacao ( Theobroma cacao ) trees are grown in tropical regions worldwide for chocolate production. We studied the effects of agroforestry management systems and cover cropping on soil microbial communities under cacao in two different replicated field experiments in Peru. In the first experiment, two agroforestry systems, Improved Traditional Agroforestry System (ITAS) and Improved Natural Agroforestry System (INAS), were compared. ITAS was a ‘slash and burn’ system in which all native vegetation was removed prior to replanting with cacao and other trees while INAS used selective removal of uneconomical trees followed by cacao planting. Soil microbial communities were analyzed by phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Soils in the ITAS system had altered microbial community structure and a lower Gram-negative to Gram-positive ratio when compared to soils in the INAS system. However, soil microbial community structure was also affected by a large soil pH gradient (three pH units) across this experiment. In the cover crop experiment, five cover crops, Arachis pintoi (perennial peanut), Calopogonium mucunoides (calopo), Canavalia ensiformis (jackbean), Centrosema macrocarpum (centro), and Callisia repens (callisia), and two controls (one with and one without nitrogen fertilization), were compared. Cover cropping with centro or perennial peanut increased the Gram-negative to Gram-positive ratio, while centro reduced the fungal biomass. Microbial community structure was significantly affected by cover cropping. Our results indicate that management systems and cover cropping can affect soil microbial community structure in tropical agroforestry systems, but the effects of soil edaphic properties must be considered as well. [ABSTRACT FROM AUTHOR]

Brachiariaare tolerant to low phosphorus (P) soils and may enhance P soil availability. The identification of mechanisms driving this effect is important. Our objective was to determine responses of palisade grass and ruzigrass to mineral oxide-bound P. Palisade grass (Brachiaria brizantha) and ruzigrass (Brachiaria ruziziensis) were grown in nutrient solution (NS), where P was supplied as goethite and amorphous aluminum-oxide (Al-oxide). Only half of each pot received P. Dry matter yields ofBrachiariaspecies having oxide-P as the sole P source were similar to those grown with water-soluble P. Inorganic P was found in the NS after 7 days, and organic P at 14 days after plant emergence. The presence of dissolved organic carbon (DOC) indicates an intense and quick response of the root system to the treatments. Results indicate enzyme and/or organic acids (OAs) root exudation as a strategy of these plants to access soil sparingly soluble P forms. [ABSTRACT FROM AUTHOR]

Management of biomass waste is crucial to the efficiency and sustainable operation of constructed wetlands. In this study, biochars were prepared using the biomass of 22 plant species from constructed wetlands and characterized by BET-N 2 surface area analysis, FTIR, TGA, SEM, EDS, and elemental compositions analysis. Biochar yields ranged from 32.78 to 49.02%, with mesopores dominating the pore structure of most biochars. The biochars had a R 50 recalcitrance index of class C and the carbon sequestration potential of 19.4–28%. The aquatic plant biomass from all the Chinese constructed wetlands if made into biochars has the potential to sequester 11.48 Mt carbon yr −1 in soils over long time periods, which could offset 0.4% of annual CO 2 emissions from fossil fuel combustion in China. In terms of adsorption capacity for selected pollutants, biochar derived from Canna indica plant had the greatest adsorption capacity for Cd 2+ (98.55 mg g −1 ) and NH 4 + (7.71 mg g −1 ). Whereas for PO 4 3− , Hydrocotyle verticillata derived biochar showed the greatest adsorption capacities (2.91 mg g −1 ). The results from this present study demonstrated that wetland plants are valuable feedstocks for producing biochars with potential application for carbon sequestration and contaminant removal in water remediation. [ABSTRACT FROM AUTHOR]

Forest soils play a critical role in the sequestration of atmospheric CO2 and subsequent attenuation of global warming. The nature and properties of organic matter in soils have an influence on the sequestration of carbon. In this study, soils were collected from representative forestlands, including a subtropical evergreen broad-leaved forest (EBF), a coniferous forest (CF), a subalpine dwarf forest (DF), and alpine meadow (AM) along an elevation gradient on Wuyi Mountain, which is located in a subtropical area of southeastern China. These soil samples were analyzed in the laboratory to examine the distribution and speciation of organic carbon (OC) within different size fractions of water-stable soil aggregates, and subsequently to determine effects on carbon sequestration. Soil aggregation rate increased with increasing elevation. Soil aggregation rate, rather than soil temperature, moisture or clay content, showed the strongest correlation with OC in bulk soil, indicating soil structure was the critical factor in carbon sequestration of Wuyi Mountain. The content of coarse particulate organic matter fraction, rather than the silt and clay particles, represented OC stock in bulk soil and different soil aggregate fractions. With increasing soil aggregation rate, more carbon was accumulated within the macroaggregates, particularly within the coarse particulate organic matter fraction (250–2000 μm), rather than within the microaggregates (53–250μm) or silt and clay particles (< 53μm). In consideration of the high instability of macroaggregates and the liability of SOC within them, further research is needed to verify whether highly-aggregated soils at higher altitudes are more likely to lose SOC under warmer conditions. [ABSTRACT FROM AUTHOR]