苏北滩涂海水灌溉与施氮对籽粒苋生长的影响

为创建海涂海水种、养复合清洁生产模式,首先要探索海水灌溉经济植物的种植条件,为此,在苏北滩涂布置田间小区试验,研究海水灌溉下氮肥与海水对籽粒苋生长的耦合效应。结果表明:1)20%海水灌溉下,施纯氮量120kg.hm-2,植株鲜草和籽粒产量均显著高于施纯氮量60kg.hm-2下的产量,且与施纯氮量180kg.hm-2处理下的产量差异不显著;40%海水灌溉下,施氮120kg.hm-2时籽粒产量最高,但其产量显著低于20%海水灌溉、施纯氮量120kg.hm-2下的产量。2)鲜草产量在淡水灌溉、施纯氮60kg.hm-2下达到最高值,籽粒产量在淡水灌溉,施纯氮180kg.hm-2下达到最高值。但20%海水灌溉、施纯氮120kg.hm-2组合下,籽粒产量和鲜草产量均未与最高产量达显著差异。3)随施氮量的增加,茎、叶中K+含量增加,而根、茎、叶中Na+含量和Cl-含量均先减少后增加。在施氮量为120kg.hm-2范围内,茎K+/Na+随施氮量的增加而升高,施氮量进一步增加,K+/Na+又随之下降。4)20%海水灌溉下,叶片氮素含量在120kg.hm-2处理下达到最高值,在40%海水处理下,氮肥施用对叶片氮素含量影响不显著。...     

A culture-dependent bacterial community structure analysis based on liquid cultivation and its application to a marine environment

A method for analyzing culture-dependent bacterial community structure by liquid cultivation was established using 96-well microplates. Using 96-well microplates, this method can easily provide accurate enumeration of viable microorganisms and simultaneous separation of bacteria, which allowed us to analyze the bacterial community. Bacteria in diluted surface seawater were separated using 96-well microplates and cultivated with 1/5 ZoBell 2216E liquid medium. The 98 cultures obtained were subsequently applied to phylogenetic analysis based on 16S rRNA gene sequences. The bacterial diversity, evaluated by the Shannon–Weaver index, was relatively small but comparable to previously reported bacterial communities of several environments. The most abundant group was the family Rhodobacteraceae , which has been frequently detected in marine environments. Most bacteria were phylogenetically related to bacteria or uncultured clones detected in marine environments, but distant from published species. The analysis of bacterial community structure by liquid cultivation would be useful as an alternative culture-dependent approach.     

Too hot to handle: Unprecedented seagrass death driven by marine heatwave in a World Heritage Area

The increased occurrence of extreme climate events, such as marine heatwaves (MHWs), has resulted in substantial ecological impacts worldwide. To date, metrics of thermal stress within marine systems have focussed on coral communities, and less is known about measuring stress relevant to other primary producers, such as seagrasses. An extreme MHW occurred across the Western Australian coastline in the austral summer of 2010–2011, exposing marine communities to summer seawater temperatures 2–5°C warmer than average. Using a combination of satellite imagery and in situ assessments, we provide detailed maps of seagrass coverage across the entire Shark Bay World Heritage Area (ca. 13,000 km²) before (2002 and 2010) and after the MHW (2014 and 2016). Our temporal analysis of these maps documents the single largest loss in dense seagrass extent globally (1,310 km²) following an acute disturbance. Total change in seagrass extent was spatially heterogeneous, with the most extensive declines occurring in the Western Gulf, Wooramel Bank and Faure Sill. Spatial variation in seagrass loss was best explained by a model that included an interaction between two heat stress metrics, the most substantial loss occurring when degree heating weeks (DHWm) was ≥10 and the number of days exposed to extreme sea surface temperature during the MHW (DaysOver) was ≥94. Ground truthing at 622 points indicated that change in seagrass cover was predominantly due to loss of Amphibolis antarctica rather than Posidonia australis, the other prominent seagrass at Shark Bay. As seawater temperatures continue to rise and the incidence of MHWs increase globally, this work will provide a basis for identifying areas of meadow degradation, or stability and recovery, and potential areas of resilience.     

Regulating the Hidden Solvation‐Ion‐Exchange in Concentrated Electrolytes for Stable and Safe Lithium Metal Batteries

Lithium–sulfur batteries are attractive for automobile and grid applications due to their high theoretical energy density and the abundance of sulfur. Despite the significant progress in cathode development, lithium metal degradation and the polysulfide shuttle remain two critical challenges in the practical application of Li–S batteries. Development of advanced electrolytes has become a promising strategy to simultaneously suppress lithium dendrite formation and prevent polysulfide dissolution. Here, a new class of concentrated siloxane‐based electrolytes, demonstrating significantly improved performance over the widely investigated ether‐based electrolytes are reported in terms of stabilizing the sulfur cathode and Li metal anode as well as minimizing flammability. Through a combination of experimental and computational investigation, it is found that siloxane solvents can effectively regulate a hidden solvation‐ion‐exchange process in the concentrated electrolytes that results from the interactions between cations/anions (e.g., Li⁺, TFSI^?, and S^2?) and solvents. As a result, it could invoke a quasi‐solid‐solid lithiation and enable reversible Li plating/stripping and robust solid‐electrolyte interphase chemistries. The solvation‐ion‐exchange process in the concentrated electrolytes is a key factor in understanding and designing electrolytes for other high‐energy lithium metal batteries.     

Cathodic behaviour of stainless steel in coastal Indian seawater: calcareous deposits overwhelm biofilms

Type-316 stainless steel (SS) was investigated as the cathode in galvanic couples in full-strength seawater from the Gulf of Mannar on the southeast coast of India. Tests were devised to examine the impact of SS cathodes on anode materials with or without the accrual of marine biofilms. Biofilmed SS cathodes significantly enhanced the rate of corrosion of nickel, causing noble shifts in the couple potentials. With mild steel and zinc as the anodes, calcareous deposits developed quite rapidly on the SS cathodes and led to a significant reduction of bacterial numbers. The calcareous deposits also caused substantial reduction of galvanic corrosion rates for mild steel, whereas there was no difference for zinc. The deposits were identified by XRD as essentially carbonates, oxides and hydroxides of calcium and magnesium. Potentiodynamic polarization performed on the actual couples after disconnection and equilibration provided reasonable interpretations of the galvanic corrosion trends. Data from this work suggest that a potential of about ?0.70 V vs. saturated calomel electrode (SCE) should provide optimum protection of SS in warmer, full-strength seawater that supports the precipitation of calcareous deposits. The criterion commonly recommended for temperate conditions of lower water temperature and estuarine waters of lower alkalinity is ?1.0 V (SCE).     

Sulphide production and corrosion in seawaters during exposure to FAME diesel

Experiments were designed to evaluate the corrosion-related consequences of storing/transporting fatty acid methyl ester (FAME) alternative diesel fuel in contact with natural seawater. Coastal Key West, FL (KW), and Persian Gulf (PG) seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used in 60 day incubations with unprotected carbon steel. The original microflora of the two seawaters were similar with respect to major taxonomic groups but with markedly different species. After exposure to FAME diesel, the microflora of the waters changed substantially, with Clostridiales (Firmicutes) becoming dominant in both. Despite low numbers of sulphate-reducing bacteria in the original waters and after FAME diesel exposure, sulphide levels and corrosion increased markedly due to microbial sulphide production. Corrosion morphology was in the form of isolated pits surrounded by an intact, passive surface with the deepest pits associated with the fuel/seawater interface in the KW exposure. In the presence of FAME diesel, the highest corrosion rates measured by linear polarization occurred in the KW exposure correlating with significantly higher concentrations of sulphur and chlorine (presumed sulphide and chloride, respectively) in the corrosion products.     

Inorganic speciation of organotin(IV) cations in natural waters with particular reference to seawater

Abstract

This paper examines the inorganic complexing capacity of seawater, where chloride and sulfate ions are present in high concentration, towards mono- di- and tri-organotin(IV) cations which show a different trend of acidity, depending on cation charges, and a corresponding tendency to hydrolysis. By considering hydrolytic species and chloride and sulphate complex formation, a basic inorganic speciation model of organotins in synthetic seawater (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^?, SO₄^2?) has been built up. The model has been extended to also consider interactions of organotins with carbonate and fluoride ions, which are other important components of seawater. Because of the strength of hydrolysis processes, the main complexes formed are in general mixed hydroxo-species. No species are formed by organotin cations and/or their hydroxo-species with fluoride owing to their very low concentration in fluoride, in comparison to the other components of seawater. In order to simplify calculations and to establish a cumulative inorganic binding capacity for seawater, we applied a chemical complexation model, according to which the major inorganic components of seawater are considered as a single salt BA.     

Calcification, growth and mortality of juvenile clams Ruditapes decussatus under increased pCO2 and reduced pH: Variable responses to ocean acidification at local scales?

We investigated the effects of ocean acidification on juvenile clams Ruditapes decussatus (average shell length 10.24 mm) in a controlled CO₂ perturbation experiment. The carbonate chemistry of seawater was manipulated by diffusing pure CO₂, to attain two reduced pH levels (by −0.4 and −0.7 pH units), which were compared to unmanipulated seawater. After 75 days we found no differences among pH treatments in terms of net calcification, size or weight of the clams. The naturally elevated total alkalinity of local seawater probably contributed to buffer the effects of increased pCO₂ and reduced pH. Marine organisms may, therefore, show diverse responses to ocean acidification at local scales, particularly in coastal, estuarine and transitional waters, where the physical-chemical characteristics of seawater are most variable. Mortality was significantly reduced in the acidified treatments. This trend was probably related to the occurrence of spontaneous spawning events in the control and intermediate acidification treatments. Spawning, which was unexpected due to the small size of the clams, was not observed for the pH −0.7 treatment, suggesting that the increased survival under acidified conditions may have been associated with a delay in the reproductive cycle of the clams. Future research about the impacts of ocean acidification on marine biodiversity should be extended to other types of biological and ecological processes, apart from biological calcification.     

Genetic diversity among Norwegian Vibrio parahaemolyticus

Aims: To examine the variability among environmental Vibrio parahaemolyticus (including trh+ isolates) from Norway, and to compare these to clinical isolates and isolates from imported foods. Methods and Results: A total of 246 V. parahaemolyticus were successfully digested with NotI, and the fragments were separated by pulsed field gel electrophoresis (PFGE). The isolates could be divided into 72 clusters and 103 pulsotypes. Eleven clusters contained 4–31 environmental isolates, and the isolates within these clusters greatly varied with respect to origin. None of the trh+ and /or tdh+ isolates clustered with trh?/tdh? isolates. The trh+ environmental isolates included in the study belonged to two separate clusters. A subset of isolates was serotyped, and great serotype diversity was observed among the environmental V. parahaemolyticus. The clinical isolates included O3:K6 and O3:KUT, and these were identical or related to a pandemic reference strain by PFGE. Conclusions: Environmental V. parahaemolyticus (including trh+) were genetically diverse, but certain variants occurred throughout the coastal environment, and some were persistent over time. Significance and Impact of the Study: Although trh+ V. parahaemolyticus persisted in the Norwegian environment, no evidence indicated that indigenous isolates have caused disease.     

海水及海产品中溶藻弧菌的分离与鉴定

从上海东海海域随机采集海水样品50份及各市场购买海产品95份,参照国标中副溶血性弧菌的检验方法,对采集样品进行了分离与鉴定。样品增菌后选用TCBS及科玛嘉弧菌显色培养对其进行初步分离,挑取可疑单菌落进行生理生化验证和分子生物学方法鉴定,其中从9份海水、24份海产品中分离出溶藻弧菌菌株,分离率分别为18.0%与25.3%。