Cadmium (Cd) pollution in soil, rivers and lakes isa serious problem due to the current industrialization and urbani-zation in China. Duckweeds are recognized as promising species for Cd phytoremediation. However, intraspecific var-iations in Cd accumulation in duckweeds remain largely unknown. In this study, 16 accessions selected from 39 geographically isolated duckweed strains were chosen to investigate their Cd remediation abilities. The optimal acces-sion Landoltia punctata named 07SGZP01 (L. punctata 0701) was identified and shown to accumulate maximal Cd in the body while maintaining the highest biomass. The dominant variety treated with different Cd concentrations showed that the biomass of L. punctata 0701 was significantly lower than that of the control group (CK). Cd contents in L. punctata 0701 were substantially increased from 2511.1 to 30,641.01 mg kg(-1) with an increase in Cd treatment levels from 0.3 to 20 mg L-1. The transport coefficient (TF) increased as Cd levels increased from 0.3 to 2 mg L-1. In addition, the Cd content in leaves was greater than that in roots (TF > 1) within this Cd concentration range, whereas the Cd content in roots was greater than that in leaves (TF < 1) when the concentration of the Cd treatment was greater than 5 mg L-1. The bioaccumulation factor (BCF) decreased significantly with increasing Cd levels (P < 0.05). The rate of Cd removal in the solution gradually decreased with increasing Cd concentrations, and the removal rate achieved the highest value (75%) when the Cd concentration was 0.5 mg L-1. In addition, Cd treatment (2 mg L-1) not only damaged the ultrastructure of L. punctata 0701, as characterized by chloroplast deformation and cell vacuolation but also caused most of the stomata to close, and the leaf epidermal cells were damaged and ruptured.

To assess the impacts of increasing human disturbance, wetland degradation, and biodiversity loss, and to determine the main environmental factors affecting the spatial distribution of phytoliths in Nanjishan Nature Reserve, phytoliths from 17 topsoil samples and a sediment core sample were analyzed. Yellow-brown, silty, and gray-black clays were the main sedimentary constituents, and the total organic carbon content decreased with increasing depth. Lakes Zhanbei, Chang, and Sanniwan were located in an alluvial delta and characterized by intensive human activity and grass communities of Triarrhena lutarioriparia and Zizania latifolia, whereas Lakes Shangbeijia, Beishen, Nanshen and Baisha were characterized by a lower degree of disturbance and grass communities of T. lutarioriparia and Phragmites australis. A total of 11,942 phytoliths (4248 in topsoil and 7694 in core sediment) were isolated from 46 samples and 19 distinct morphological types were identified. Vesicular cells constituted 42%-51% of all samples, short cells 24%-32%, and elongate types 15%-26%. The phytolith assemblages at Lakes Zhanbei, Chang, and Sanniwan were mainly composed of fans, rectangles, points and elongates. While Lake Shangbeijia, Beishen, Nanshen and Baisha were dominated by fans, saddles and elongates. Based on phytolith analysis, we found that the typical communities in the study area were significantly degraded from 1986 to 2003. Sediment cores dated by 210Pb showed that the main plant communities were transformed from Carex and T. lutarioriparia to Z. latifolia, T. lutarioriparia and P. australis.

为了分析梯级溢流堰对袁河新泉乡段河道行洪及河床抗冲的影响,优化河道治理工程中溢流堰布置,建立了将拦河溢流堰作为闭边界条件的二维水动力数值模型,采用非结构化网格的有限体积法,对比分析了十年一遇洪水情况下梯级溢流堰建设前后河道水动力、河道水位、流场沿程变化特征,讨论了溢流堰布置对河道防洪及冲刷的影响。结果表明,在十年一遇洪水情况下溢流堰会抬升河道水位,平均增加0.49 m,满足河道行洪要求;梯级溢流堰使河道整体形成人工"阶梯-深潭"体系,河道流速在空间上发生明显的异质性,堰上流速下降幅度较堰下流速大;水流发生急流与缓流之间交替,水流紊动强烈,加剧了水流能量损失,有效降低流速,减轻了河道冲刷,有利于稳定河岸结构。

Duckweed (Landoltia punctata) is an ideal species to restore cadmium (Cd)-polluted waters due to its fast growth and easy harvesting. To understand its tolerance and detoxification mechanism, the Cd stress responses, sub -cellular Cd distribution and chemically bound Cd forms (especially protein-bound Cd) were surveyed in this study. L. punctata, a potential Cd bioremediation plant, was cultured hydroponically with Cd concentrations of 0.0, 0.5, 2.0, and 5.0 mg L-1 for 5 days. The results showed that the Cd content in L. punctata increased significantly as the Cd content increased. The majority of Cd was localized in the soluble fraction (23-55%) and the cell wall fraction (21-54%), and only 14-23% of Cd was located in cell organelles. Analysis of the Cd chemical forms demonstrated that the largest portion of Cd was found in 1 M NaCl extracts, followed by d-H2O and 2% HAc extracts, indicating that Cd was mainly bound to different proteins. Albuminand globulin-bound Cd forms were predominant, together accounting for over 80% of the total protein-bound Cd in L. punctata. These results indicate that cell wall immobilization and vacuolar dissociation of Cd are possible primary strategies for Cd biosorption and detoxification in L. punctata, which occur mainly through chemical forms changes, especially the binding of Cd to proteins.

为全面了解鄱阳湖流域浮萍种属资源分布及其生长水环境,对流域内浮萍资源开展调查并测定生长水体的水质.结果显示,鄱阳湖流域采集到的浮萍共4属5种,分别为青萍（Lemna minor）、稀脉浮萍（Lemna perpusilla）、紫背浮萍（Spirodela polyrrhiza）、少根紫萍（Landoltia punctata）、芜萍（Wolffia arrhiza）、青萍和紫背浮萍为该地区的优势种.青萍生长水体的p H范围最广（5.5-9.43）,其他浮萍生长水体呈弱酸性.青萍生长水体中的氨氮（NH3-N）、硝态氮（NO3-N）、总氮（TN）、化学需氧量（COD）浓度范围较其他4种浮萍更为广泛,分别为0.18-4.25 mg/L、0.027-3.27mg/L、0.38-13.28 mg/L、16.16-614.72 mg/L,少根紫萍生长水体的总磷（TP）浓度范围最广,为0.06-2.68 mg/L.从重金属含量来看,青萍生长水体Cu、Pb、Zn、Co含量范围最广,少根紫萍对Cd、紫背浮萍对Mn的适应能力表现出优势.从自然状态下富集效果来看,青萍对Zn、紫背浮萍对Cr、少根紫萍对Mn的富集能力强.青萍和紫背浮萍对Pb富集效果好于少根紫萍.RDA分析表明,少根紫萍的分布主要受TN、TP、NH3-N的影响,紫背浮萍主要受Mn的影响,青萍主要受NO3-N的影响.稀脉浮萍和芜萍分别受Cd、Cr的影响.不同浮萍种属的水环境差异较大,在修复富营养化水体时,可利用当地优势品种组合以达到最佳的去除效果.根据浮萍对重金属耐受能力、富集效果的不同可筛选出对特定重金属耐性好且富集能力强的品种.本研究对利用浮萍品种修复不同污染的水体具有一定的指导意义.（图4表5参40）

研究降水在年内的集中程度,对干旱、洪涝及水资源管理具有重要意义。本文基于1957—2012年鄱阳湖流域的月降水资料,并利用两种降水集中度（PCI和PCD）指标、一种降水集中期（PCP）指标,研究了降水集中指标在鄱阳湖流域的适用性及其时空变化特征。结果表明采用的这些降水集中指标在鄱阳湖流域有较好的适用性。两种降水集中度指标均呈现出由西南向东北逐渐增加的趋势,其时空分布特征十分相似。降水集中期变化范围为4月上旬至6月中旬,呈由西向东逐渐减少的趋势。通过对月降水集中几种指标的变化进行MMK趋势检验,发现流域内大部分站点的降水集中度指标呈不显著的减小趋势,降水集中期呈不显著的延后趋势。

Combined with sediment pollutant analysis, the gastropod Cipangopaludina cahayensis was chosen as an indicator organism to evaluate the environmental behavior of trace metals and the aquatic ecological risk that they present in a backwater area of Xian'nv Lake. Based on hydrological characteristics, 24 sampling sites representing the main stream (MS), tributaries (TR), lake area (LA) and lake tributaries (LT) were collected. The results revealed that cadmium (Cd) was the main pollutant and that it significantly accumulated in sediments of the research area. Based on the pollutant concentrations, the degree of Cd pollution was ranked in the following order: LA > MS > TR > LT. Several intersections between the rivers and Xian'nv Lake, including LA1, LA7 and LA 10, were observed to have higher Cd deposition. There was a significant difference in the spatial distribution of pollutants, which resulted in a higher accumulation of trace metals in the backwater area and its tributary. The Cd content in the visceral sac of C. cahayensis was positively correlated with the concentration of heavy metals in the sediment. The response of multiple antioxidant biomarkers, including superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), as well as the glutathione (GSH) content and the level of by-products of lipid peroxidation (TBARS), in C. cahayensis revealed a potential relationship to the environmental behavior of the pollutants. By combining the different biomarkers responses, the integrated biomarker response index (IBR) corresponded well with the pollution distribution characteristics in different areas.

Benthic diatom indices developed in the Europe Union have been widely accepted as indicators of the trophic state and water quality in freshwater ecosystems. In China, most of the benthic diatom-based indices have not been widely tested or evaluated before. For this purpose, the water quality parameters and benthic diatoms community structures at 20 sample sites in the dish lake of Nanjishan Nature Reserve in Poyang Lake were investigated in this study and 18 widely-applied diatom indices were established. The statistical results indicated that most water quality parameters including Total Nitrogen (TN), Total Phosphorus (TP), ammonia nitrogen (NH4+), Chemical Oxygen Demand (COD) and Chlorophyll (Chl) were highly correlated with each other at a confidence level of 0.05. Water quality sampling sites from 8 lakes could be classified into 4 groups based on the integrated comprehensive scores using principal components analysis (PCA). Monitoring sites could also be divided into 4 groups based on clustering analysis with hierarchical methods for diatom dominant species in 20 sampling sites. According to the status of water ecological health recognition and box plot analysis in different water quality groups and diatom dominant species groups, only 3 diatom indices including the Biological Diatom Index (IBD), Specific Pollution Sensitivity Index (IPS) and Louis Leclercq Diatom Index (IDSE) demonstrated good evaluation suitability and good correlation within different water quality grades at the final stage. The above results revealed that IBD, IPS and IDSE were the most suitable diatom indices for the water quality evaluation of the dish lake in the Nanjishan Nature Reserve, Lake Poyang. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Eco-friendly and cost-effective designs of adsorbents are highly desirable to realize highly efficient removal of heavy metals and organic pollutants from wastewater. Herein, the biomimetic co-deposition from polyphenol-substance tannic acid induced the grafting of renewable cardanol-derived siloxane on a cellulose nanofiber (CNF) framework to form an eco-friendly and low-cost microporous aerogel to capture Cu(II) and organic contamination. Owing to the three-dimensional cellulosic porous structure and easily accessible active sites, the as-prepared aerogel manifested a low density and favorable hydrophobicity, which were vital for highly efficient absorption toward Cu(II) and oil droplets. The saturated adsorption capacity of modified aerogels for Cu(II) was found to be 45.6 mg/L, which is higher than the majority of reported biobased adsorbents. Based on thermodynamic and kinetic studies, the Cu(II) adsorption closely approximated that of a spontaneous and endothermic chemisorption process. In addition, the modified aerogel effectively collected various oils and organic solvents from water, with maximum absorption capacities up to 108 g/g (chloroform); it also exhibited good stability in a Cu(II)/chloroform binary system. The multiple separation efficiency indicated that the obtained aerogel is very suitable for application in practical water purification. It is particularly important that the whole synthesis process of modified aerogels is green and economical without additional toxic agents; this allows them to significantly reduce secondary pollution to the environment after use, contamination emissions to the environment. These results demonstrated that the novel nanostructured composites with a naturally functional polymer layer have unexpected potential as an ideal candidate for practical water purification. © 2020 Elsevier Ltd