The influence of cadmium contamination and salinity on the survival,growth and phytoremediation capacity of the saltmarsh plant Salicornia ramosissima

The major aim of this study was to evaluate the capacity of Salicornia ramosissima on Cadmium phytoremediation under distinct salinities and, consequently, the toxic effects on the plant's development. A greenhouse experiment was performed, using two Cd concentrations (50 and 100 μg l⁻¹) in different salinities (0, 5 and 10). Mortality and weight variation, observed at the end of the experiment, showed significant differences between some treatments, meaning that these variables were affected by the salinity and Cd concentrations. The highest Cd accumulation was detected in the roots, and decreased with the increase of salinity and Cd concentration. S. ramosissima is a potential candidate for Cd phytoremediation at salinities close to 0 and its capabilities in Cd phytoaccumulation and phytoestabilization proved to be quite interesting. The optimization of phytoremediation processes by S. ramosissima could turn possible the use of this plant in the recovery of contaminated ecosystems.     

Application of Superabsorbent Polymers for Improving the Ecological Chemistry of Degraded or Polluted Lands

About 3.5 billion ha of land, which amounts to almost 30% of the total solid land of the world, has been degraded by human activities. The ecological restoration of these lands is a major challenge for mankind since they are the only option left for increasing the amount of arable land and producing food for the ever growing worldwide population. One common feature of these degraded lands is the fact that their organic soil matter is degraded also. Rainfall therefore, changes from a blessing to a menace since it is not kept in the soil and therefore causes erosion. A solution for the restoration of these lands could be the application of superabsorbent polymers (SAPs) to these soils. These substances are like ‘artificial humus’ as they are hydrophilic and contain carboxylic groups. This enables them to bind cations and water. They have the following advantages for the restoration of degraded lands. They increase the plant available water in the soil which enables the plants to survive longer under water stress. SAP amendment to soils reduces the evapotranspiration rate of the plants. They induce a significantly higher growth rate in plants growing on SAP amended soil. They bind heavy metals and mitigate their action on plants. They mitigate the effects of salinity. The benefits of SAP amendment to soils substantially outweigh their costs.     

Seismic reflection along the path of the Mediterranean Undercurrent

Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately two orders of magnitude higher than CTD casting. The seismic data are compared with co-located historical oceanographic data. Three seismic reflectivity zones are identified: North Atlantic Central Water, Mediterranean Water and North Atlantic Deep Water. Seismic evidence for the path of the Mediterranean Undercurrent is found in the near-slope reflectivity patterns, with rising reflectors between about 500 and 1500 m. However, the core of the undercurrent is largely transparent. Seismic images show that central and, particularly, intermediate Mediterranean Waters have fine structure coherent over horizontal distances of several tens of kilometers. However, the intensity of the reflectors, and their horizontal coherence, decreases downstream. This change in seismic reflectivity is probably the result of diminished vertical thermohaline contrasts between adjacent water masses, so that double-diffusion processes become unable to sustain temperature and salinity staircases. Comparison of root-mean-square seismic amplitudes with temperature and salinity differences between the Mediterranean Undercurrent and the overlying central waters suggests a causal relationship between observed thermohaline fine structure and true seismic amplitudes. We estimate that, within this intermediate water stratum, impedance contrasts are mainly controlled by sound speed contrasts (a factor between 3.5 and 10 times larger than density contrasts), which are mainly controlled by temperature contrasts (a factor between 1.5 and 5 times larger than salinity contrasts).     

Correlations between microbial indicators, pathogens, and environmental factors in a subtropical Estuary

The objective of this study was to evaluate whether indicator microbes and physical–chemical parameters were correlated with pathogens within a tidally influenced Estuary. Measurements included the analysis of physical–chemical parameters (pH, salinity, temperature, and turbidity), measurements of bacterial indicators (enterococci, fecal coliform, Escherichia coli, and total coliform), viral indicators (somatic and MS2 coliphage), viral pathogens (enterovirus by culture), and protozoan pathogens (Cryptosporidium and Giardia). All pathogen results were negative with the exception of one sample which tested positive for culturable reovirus (8.5 MPN/100 L). Notable physical–chemical parameters for this sample included low salinity (<1 ppt) and high water temperature (31 °C). Indicator bacteria and indicator virus levels for this sample were within average values typically measured within the study site and were low in comparison with levels observed in other freshwater environments. Overall results suggest that high levels of bacterial and viral indicators were associated with low salinity sites.     

海水痕量元素——有机配体的配分特征与影响因素研究进展

在痕量元素的海洋生物地球化学循环过程中,有机配体直接控制痕量元素在不同形态及粒径范围内的分配,进而影响痕量元素的迁移转化过程和生物可利用性。深入研究海水中痕量元素-有机配体的配分特征及影响因素,明确有机配体分子量组分及其对痕量元素的配合作用差异,对于了解痕量元素的生物地球化学行为,评估痕量元素的生物可利用性和毒性效应均具有十分重要的意义。对海水中痕量元素-有机配体的分布规律、配分特征及盐度、pH、氧化还原条件和生物活动对配体的影响进行了系统总结。海水中的有机配体一般以低分子量部分为主体,配合能力因元素性质差异存在随分子量增加而提高或降低的不同趋势。除此之外,有机配体的结构、配合能力及分子量分布随水体各物理化学参数的变化而改变。盐度的增加会降低有机配体相邻官能团的静电排斥力从而降低配体的配合能力,还会导致高分子量金属有机配合物发生絮凝和降解而去除。pH的增加不仅可以促使有机配体离子化,还能促进部分痕量元素水解为与有机配体亲和力更高的形式,提高有机配体配合率。氧化还原环境同时影响了痕量元素的价态和有机配体的浓度,间接影响痕量元素-有机配体的配合率。浮游植物利用及微生物分解可以增加低分子量有机配体的比例,从而提高其配合能力,但当生物遭受过量金属离子的毒性胁迫时,其细胞内会释放胞内配体,将致毒元素转化为配合物并排出体外,从而增加水体中痕量元素高分子量有机配体的浓度。未来应结合有机物结构分析技术及痕量元素分离检测技术,系统研究海洋环境中不同分子量有机配体的结构及与痕量元素配合强度的相互关系,进一步揭示痕量元素的迁移转化过程与生态学意义。     

The Distribution of Trace Elements-Organic Ligands in Seawater and Factors Influencing Their Complexation

Organic metal-binding ligands represent an essential role in the bioavailability of trace elements since they govern the species and sizes of those elements in seawater. The distribution and properties of organic ligands in seawater as well as the factors influencing their complexation abilities were summarized in this paper. Most organic ligands exist in the low molecular weight fraction, and their concentration nearshore is often higher than that of open ocean while the vertical distribution varies in different areas. The complexation of trace elements and organic ligands is influenced by several factors such as molecular weight of organic ligands, salinity, pH, biological activities and redox conditions. Ligand with a lower molecular weight usually represents stronger complexation ability, whereas the opposite seems to be true sometimes due to the specific affinity between some elements and ligands. Increasing salinity lowers the electrostatic repulsion among adjacent functional groups of ligands and thus decreases their complexing rate, yet increasing pH promotes the ionization of organic ligands and results in the formation of more complexes. The utilization of phytoplankton and degradation of microorganism release more low molecular weight organic ligands while more high molecular weight ligands are released from marine organisms under heavy metal stress. Therefore, sufficient significance should be attached to characterizing the structure and molecular weight of organic ligands and exploring the interaction between trace elements and organic ligands and the influence of related marine factors on their behaviors, which will certainly help us to understand the global biogeochemical cycles and ecological significance of trace elements.     

Research and Application Progress of DRAINMOD Model

Establishing an effective hydrological model is important for guiding the design of small-scale drainage systems. The simulation principle and the sensitivity of key parameters of DRAINMOD model were summarized from four aspects:Hydrological characteristics, nitrogen transport, salt transport and model cooperation. The research application progresses of DRAINMOD model and its coupled model at home and abroad were systematically reviewed, and the limitations and development trends of the model were discussed. It is pointed out that DRAINMOD model has good simulation performance in the fields of agricultural drainage, nitrogen removal and stain reduction. In the simulation of cold area or urban stormwater regulation, domestic research needs to reference from foreign research results. The research suggests that the key research directions of DRAINMOD model could be summarized as the following aspects:\mathrm{①}Simulating the migration of phosphorus, organic micro-pollutants and heavy metal elements and their impacts on soil and crops; \mathrm{②}Mechanism research on the freezing-thawing of snow and application in cold regions; \mathrm{③}Application in the construction of urban stormwater regulation facilities.     

Evaluation of boron isotopes in halite as an indicator of the salinity of Qarhan paleolake water in the eastern Qaidam Basin,western China

In this study, nineteen brine samples from the Qarhan Salt Lake (QSL) in western China were collected and analyzed for boron (B) and chlorine (Cl) concentrations, total dissolved solids (TDS), pH values and stable B isotopic compositions. The B concentrations and δ¹¹B values of brines in the QSL range from 51.6 mg/L to 138.4 mg/L, and from +9.32‰ to +13.08‰, respectively. By comparison of B concentrations and TDS of brines in QSL with evaporation paths of brackish water, we found that B enrichment of brines primarily results from strong evaporation and concentration of Qarhan lake water. Combining with comparisons of B concentrations, TDS, pH values and δ¹¹B values of brines, previously elemental ratios (K/Cl, Mg/Cl, Ca/Cl, B/Cl) and δ¹¹B values of halite from a sediment core (ISL1A), we observe good correlations between B concentrations and TDS, TDS and pH values, pH and δ¹¹B values of brines, which demonstrate that higher B concentrations and more positive δ¹¹B values of halite indicate higher salinity of the Qarhan paleolake water as well as drier paleoclimatic conditions. Based on this interpretation of the δ¹¹B values of halite in core ISL1A, higher salinity of the Qarhan paleolake occurred during two intervals, around 46–34 ka and 26–9 ka, which are almost coincident with the upper and lower halite-dominated salt layers in core ISL1A, drier climate phases documented from the δ¹⁸O record of carbonate in core ISL1A and the paleomoisture record in monsoonal central Asia, and a higher solar insolation at 30°N. These results demonstrate that the δ¹¹B values of halite in the arid Qaidam Basin could be regarded as a new proxy for reconstructing the salinity record of paleolake water as well as paleoclimate conditions.