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a b s t r a c tIn this study, the source and risk associated with heavy metals in the estuarine sediments of Chaohu Lake Valley in East China were studied. The results demonstrated that most metal contents (Cd, Pb and Zn) increased continuously from 0.21, 8.05 and 73.76 mg/kg in the substrate to 0.33, 17.20 and 100.22 mg/kg in the surface sediments on average, respectively, in all ten estuaries evaluated. In addition, the high proportion of chemically reactive forms of Cd (18.10-33.60%) implied a moderately high risk, while the risk associated with Pb and Zn was moderate in most estuaries. Enrichment factor (EF) and cluster analysis (CA) were conducted to assess the metal sources. The EF values of Cd, Pb and Zn (4.96, 3.68 and 2.25, respectively) indicated that they had accumulated in the estuarine sediments. Additionally, CA suggested that their primary sources were anthropogenic, namely the extensive use of fertilizers. Therefore, heavy metal pollution due to agricultural intensification in Chaohu Lake Valley should be taken into account during the formation of valley management strategies for the water environment.

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The release of anthropogenic pollution into freshwater ecosystems has largely transformed biodiversity and its geographical distribution patterns globally. However, for many communities including ecologically crucial ones such as zooplankton, it is largely unknown how different communities respond to environmental pollution. Collectively, dispersal and species sorting are two competing processes in determining the structure and geographical distribution of zooplankton communities in running water ecosystems such as rivers. At fine geographical scales, dispersal is usually considered as the dominant factor; however, the relative role of species sorting has not been evaluated well, mainly because significant environmental gradients rarely exist along continuously flowing rivers. The Chaobai River in northern China represents a rare system, where a significant environmental gradient exists at fine scales. Here, we employed high-throughput sequencing to characterize complex zooplankton communities collected from the Chaobai River, and tested the relative roles of dispersal and species sorting in determining zooplankton community structure along the pollution gradient. Our results showed distinct patterns of zooplankton communities along the environmental gradient, and chemical pollutant-related factors such as total phosphorus and chlorophyll-a were identified as the major drivers for the observed patterns. Further partial redundancy analyses showed that species sorting overrode the effect of dispersal to shape local zooplankton community structure. Thus, our results reject the dispersal hypothesis and support the concept that species sorting caused by local pollution can largely determine the zooplankton community structure when significant environmental gradients exist at fine geographical scales in highly polluted running water ecosystems.

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The writers are conducting a comprehensive research program, with the goal to develop modern bamboo structures for buildings and bridges. This paper reports the design, construction, and testing of modern bamboo bridges. Laminated bamboo girders or glubam were developed and verified for satisfactory mechanical performance through full-scale testing. It was demonstrated that the laminated bamboo girders have satisfactory stiffness and load carrying capacity. The use of carbon fiber-reinforced plastics can further enhance the stiffness and capacity of the bamboo girders. Based on the test results and analysis, a 10-m long single lane roadway bridge was designed and constructed, which was the first of its kind in the world. The field tests were carried out using an over loaded two-axel truck with a total weight of 8.6 t which exceeded the given design truckload of 8.0 t. The bridge performed satisfactorily with the midspan deflection corresponding to the critical service loading condition being much smaller than the code required limit. Computer simulation of the field tests shows that the trend of the measured midspan deflection can be reasonably well captured. Examples of other bridge applications are also reported in this paper.

River ecosystems are among the most affected habitats globally by human activities, such as the release of chemical pollutants. However, it remains largely unknown how and to what extent many communities such as zooplankton are affected by these environmental stressors in river ecosystems. Here, we aim to determine major factors responsible for shaping community structure of zooplankton in heavily polluted river ecosystems. Specially, we use rotifers in the Haihe River Basin (HRB) in North China as a case study to test the hypothesis that species sorting (i.e. species are “filtered” by environmental factors and occur at environmental suitable sites) plays a key role in determining community structure at the basin level. Based on an analysis of 94 sites across the plain region of HRB, we found evidence that both local and regional factors could affect rotifer community structure. Interestingly, further analyses indicated that local factors played a more important role in determining community structure. Thus, our results support the species sorting hypothesis in highly polluted rivers, suggesting that local environmental constraints, such as environmental pollution caused by human activities, can be stronger than dispersal limitation caused by regional factors to shape local community structure of zooplankton at the basin level.

Based on water quality surveys over 2years (July to December, in 2014 and 2015) in a typical arid river in northern China the Xingtai segment of the Fuyang River basin - the variation of nitrogen (N) and phosphorus (P) was analyzed. The extent of water eutrophication of this segment was also assessed using a universal index formula for eutrophic evaluation and a logarithmic power function. The results showed that the average concentration of total N (TN) was 27.2mg/L (NH-N, 63.5%), total P (TP) was 2.0mg/L (solution reactive phosphorus, 68.8%). Temporal and spatial variations of N and P in this segment were observed. Concentrations of N and P in the arid season were higher than those in the rainy season. Spatially, the N and P concentrations followed the same trend; i.e., higher in the city segment than in the suburbs, and decreasing along the river. The water eutrophication in the studied segment reached extremely high levels at all times (eutrophication index ≥76.3). Spatially, its trend was clearly linked with N and P. Water shortage, pollution accumulation and a weak self-purification function are the main reasons for the prominent eutrophication in this segment.