Species richness in a riparian plant community along the banks of the Xiangxi River,the Three Gorges region

The distribution of vascular plant species richness along an altitudinal gradient and their relationships with environmental variables, including slope, aspect, bank (flooding) height, and river width of the Xiangxi River, Hubei Province, were examined. Total vascular plant species richness changed with elevation: it increased at lower elevations, reached a maximum in the midreaches and decreased thereafter. In particular, tree and herbaceous species richness were related to altitude. Correlation analysis (Kendall's τ) between species richness and environmental variables indicated that the change in species richness in the riparian zone was determined by riparian environmental factors and characteristics of regional vegetation distribution along the altitudinal gradient. The low species richness at lower elevations resulted from seasonal flooding and human activities – agriculture and fuel collection – and the higher species richness in the midreaches reflected transitional zones in natural vegetation types that had had little disturbance. These results on species distribution in the riparian community could be utilized as a reference for restoration efforts to improve water quality of the emerging reservoir resulting from the Three Gorges Hydroelectric Dam project.     

全氟化合物对水生植物的生态效应研究Ⅱ——金鱼藻对水中PFOS的生物富集及生理响应

为探究全氟化合物对水生植物的生态效应,选择金鱼藻(Ceratophyllum demersum L.)为受试生物,设定5、100、1 000、10 000、50 000、100 000μg·L-1以及对照共7个PFOS浓度梯度进行水培,分析包括超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)在内的抗氧化系统酶和细胞色素含量等生理响应特征,并研究金鱼藻对PFOS的生物有效性及富集能力。结果表明:金鱼藻对PFOS的富集量最高可达3 180 mg·kg-1dw,最大富集系数高达40.7倍,可作为PFOS污染水体植物修复的遴选物种。随PFOS浓度升高,SOD活力总体上没有明显变化,但POD活力表现为双重效用,即低浓度促进酶活力积累,而高浓度抑制酶活力积累。CAT活力在低浓度组(0、5、100、1 000μg·L-1),未表现出明显异常,在高浓度组(10 000、50 000、100 000μg·L-1),出现先升高后降低的趋势。色素含量也反应较为敏感,低浓度处理后色素含量升高,高浓度处理则导致色素含量先升高后降低,最高浓度处理下一直处于较低水平,可作为评价PFOS污染水体的生理敏感性指标。     

全氟化合物对水生植物的生态效应研究Ⅰ——典型城市河道全氟化合物的暴露水平及植物富集特征

全氟化合物(perfluorinated compounds,PFCs)近年来得到国内外广泛关注,针对工业源排放区域的环境暴露、来源解析以及动物层面的生态效应有较多研究,但对于普遍存在于非工业源(生活源)的城市河道PFCs暴露及水生植物富集等研究较为缺乏。本研究选择位于北京北部东西贯通的城市河道——清河水体为对象,分析结果表明,清河水体中12种目标PFCs均有检出(总量最高为65.45 ng·L-1),并以全氟丁烷磺酸盐(perfluorobutane sulfonate,PFBS)为主(最高达45.63 ng·L-1);6种水生植物(篦齿眼子菜、黑藻、金鱼藻、芦苇、菖蒲及水葱)的富集物质均以全氟辛烷磺酸盐(perfluorooctane sulfonate,PFOS)和全氟辛酸(perfluorooctanoic acid,PFOA)为主,沉水植物中金鱼藻对于PFOS的蓄积效果优于黑藻及篦齿眼子菜,挺水植物中根部PFCs含量高于茎叶,根部PFOA及PFOS含量高于茎叶,但全氟丁酸(perfluorobutanoic acid,PFBA)含量茎叶则高于根部。整体来看,尽管芦苇、菖蒲和水葱3种挺水植物尚不能作为PFCs的超富集植物,但其根部对PFCs均有显著的吸收效果,具有一定的生态修复潜质;沉水植物中金鱼藻是北方自然河道的优势物种,且对PFOS具有显著的富集效应,因此有必要进一步探索其PFCs生物指示和生态修复功能。     

Photo-polymerization of triclosan in aqueous solution induced by ultraviolet radiation

The formation of 2,8-dichlorodibenzo-p-dioxin and other harmful degradation products in the photo-degradation process of triclosan is of increasing concern. Here we worked on the identification of polymerized products at high triclosan concentration and on the mechanism of photoreaction. Five dimmers and two trimers of triclosan were detected by liquid chromatography-mass spectrum analysis. 2,8-dichlorodibenzo-p-dioxin was also identified by comparing with an authentic standard. Relatively low pH and high concentration favored the polymerization of triclosan. Three main routes of photoreaction were postulated, namely dechlorination, ring closure and polymerization.     

Effects of an iron-silicon material,a synthetic zeolite and an alkaline clay on vegetable uptake of As and Cd from a polluted agricultural soil and proposed remediation mechanisms

Economic and highly effective methods of in situ remediation of Cd and As polluted farmland in mining areas are urgently needed. Pot experiments with Brassica chinensis L. were carried out to determine the effects of three soil amendments [a novel iron-silicon material (ISM), a synthetic zeolite (SZ) and an alkaline clay (AC)] on vegetable uptake of As and Cd. SEM–EDS and XRD analyses were used to investigate the remediation mechanisms involved. Amendment with ISM significantly reduced the concentrations of As and Cd in edible parts of B. chinensis (by 84–94 % and 38–87 %, respectively), to levels that met food safety regulations and was much lower than those achieved by SZ and AC. ISM also significantly increased fresh biomass by 169–1412 % and 436–731 % in two consecutive growing seasons, while SZ and AC did not significantly affect vegetable growth. Correlation analysis suggested that it was the mitigating effects of ISM on soil acidity and on As and Cd toxicity, rather than nutrient amelioration, that contributed to the improvement in plant growth. SEM–EDS analysis showed that ISM contained far more Ca, Fe and Mn than did SZ or AC, and XRD analysis showed that in the ISM these elements were primarily in the form of silicates, oxides and phosphates that had high capacities for chemisorption of metal(loid)s. After incubation with solutions containing 800 mg L^?1 AsO₄ ^2? or Cd²⁺, ISM bound distinctly higher levels of As (6.18 % in relative mass percent by EDS analysis) and Cd (7.21 % in relative mass percent by EDS analysis) compared to SZ and AC. XRD analysis also showed that ISM facilitated the precipitation of Cd²⁺ as silicates, phosphates and hydroxides, and that arsenate combined with Fe, Al, Ca and Mg to form insoluble arsenate compounds. These precipitation mechanisms were much more active in ISM than in SZ or AC. Due to the greater pH elevation caused by the abundant calcium silicate, chemisorption and precipitation mechanisms in ISM treatments could be further enhanced. That heavy metal(loid)s fixation mechanisms of ISM ensure the remediation more irreversible and more resilient to environmental changes. With appropriate application rate and proper nutrients supplement, the readily available and economic ISM is a very promising amendment for safe crop production on multi-metal(loids) polluted soils.     

Control concept and countermeasures for shallow lakes’ eutrophication in China

Research on lake eutrophication in China began in the early 1970s, and many lakes in China are now known to be in meso-eutrophic status. Lake eutrophication has been showing a rapidly increasing trend since 2000. Investigations show that the main reasons for lake eutrophication include a fragile lake background environment, excessive nutrient loading into lakes, excessive human activities, ecological degeneration, weak environmental protection awareness, and lax lake management. Major mechanisms resulting from lake eutrophication include nutrient recycling imbalance, major changes in water chemistry (pH, oxygen, and carbon), lake ecosystem imbalance, and algal prevalence in lakes. Some concepts for controlling eutrophication should be persistently proposed, including lake catchment control, combination of pollutant source control with ecological restoration, protection of three important aspects (terrestrial ecology, lake coast zone, and submerged plant), and combination of lake management with regulation. Measures to control lake eutrophication should include pollution source control (i.e., optimize industrial structural adjustments in the lake catchment, reduce nitrogen and phosphorus emission amounts, and control endogenous pollution) and lake ecological restoration (i.e. establish a zone-lake buffer region and lakeside zone, protect regional vegetation, utilize hydrophytes in renovation technology); countermeasures for lake management should include implementing water quality management, identifying environmental and lake water goals, legislating and formulating laws and regulations to protect lakes, strengthening publicity and the education of people, increasing public awareness through participation in systems and mechanic innovations, establishing lake region management institutions, and ensuring implementation of governance and management measures.     

毒理学领域的新思维：功能基因组学在毒理学中的应用

功能医学要求应用国际上最先进的检查技术定量检查反应器官功能的各种分子,从而评估器官功能。将功能医学应用到毒理学研究中,必将更早发现环境中有害因素对人体的早期损害,因此它能够将毒理学研究推向一个新高度。     

Abundance,distribution and prey composition of scyphomedusae in the southern North Sea

The annual cycle of abundance and distribution of the scyphozoan medusae Aurelia aurita, Cyanea lamarckii, C. capillata and Chrysaora hysoscella were studied in the southern North Sea in 2004 and 2005. Three different patterns of seasonal occurrence of medusae were distinguished: (1) the early occurring C. lamarckii (February–August), (2) C. capillata and A. aurita (April–August) and (3) the late appearing C. hysoscella (July/August–September). Cyanea lamarckii was the most frequently encountered species in this study; its highest mean abundance was 1.8 ± 2.7 ind. 100 m⁻³. The prey spectra of C. lamarckii, C. capillata and C. hysoscella contained several copepod and other crustacean species and thus make them potential competitors with fish larvae. Medusae in this study also consumed fish eggs and larvae, including clupeids, in all months analysed. Although peak spawning of sprat (Sprattus sprattus) coincides with the maximum abundance of medusae (May–June) the relative low abundance of all medusae species in this study makes jellyfish predation unlikely to be a factor controlling sprat recruitment in the time frame investigated.     

Formation of disinfection byproducts from accumulated soluble products of oleaginous microalga after chlorination

When microalgae are simultaneously applied for wastewater treatment and lipid production, soluble algal products (SAP) should be paid much attention, as they are important precursors for formation of disinfection byproducts (DBPs), which have potential risks for human health. Chlorella sp. HQ is an oleaginous microalga that can generate SAP during growth, especially in the exponential phase. This study investigated the contribution of SAP from Chlorella sp. HQ to DBP formation after chlorination. The predominant DBP precursors from SAP were identified with the 3D excitation-emission matrix fluorescence. After chlorination, a significant reduction was observed in the fluorescence intensity of five specific fluorescence regions, particularly aromatic proteins and soluble microbial by-product-like regions, accompanied with slight shifting of the peak. The produced DBPs were demonstrated to include trihalomethanes and haloacetic acids. As the algal cultivation time was extended in wastewater, the accumulated SAP strengthened the formation of DBPs. The trend for DBP formation was as follows: chloroform>dichloroacetic acid>trichloroacetic acid.

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Understanding the patterns and mechanisms of urban water ecosystem degradation: phytoplankton community structure and water quality in the Qinhuai River, Nanjing City, China

The temporal and spatial distribution characteristics of environmental parameters and the phytoplankton community were investigated in October 2010 and January 2011 in the Qinhuai River, Nanjing, China. Results showed that the water quality in the study area was generally poor, and the main parameters exceeding standards (level V) were nitrogen and phosphorus. The observed average concentrations of the total nitrogen (TN) were 4.90 mg?L^?1 in autumn and 9.29 mg?L^?1 in winter, and those of the total phosphorus (TP) were 0.24 mg?L^?1 in autumn and 0.88 mg?L^?1 in winter, respectively. Thirty-seven species, 30 genera, and four phyla of phytoplankton were detected in the river. Cyanophyta and Bacillariophyta were the dominant phyla in autumn, with average abundance and biomass of 221.5?×?10⁴?cells?L^?1 and 4.41 mg?L^?1, respectively. The dominant population in winter was Bacillariophyta, and the average abundance and biomass were 153.4?×?10⁴?cells?L^?1 and 6.58 mg?L^?1, respectively. The results of canonical correspondence analysis (CCA) between environmental parameters and phytoplankton communities showed that Chlorophyta could tolerate the higher concentrations of the permanganate index, nitrogen, and phosphorus in eutrophic water; Bacillariophyta could adapt well to changing water environments; and the TN/TP ratio had obvious impacts on the distributions of Cyanophyta, Euglenophyta, and some species of Chlorophyta. CCA analyses for autumn and winter data revealed that the main environmental parameters influencing phytoplankton distribution were water temperature, conductivity, and total nitrogen, and the secondary factors were dissolved oxygen, NH₄ ⁺–N, NO₃–N, TN, COD_Mn, TN/TP ratio, and oxidation-reduction potential.