Advanced Materials Research Vols. 356-360

Abstract: Flow characteristics of horizontal two-phase gas-liquid stratified flows in condensate natural gas pipeline are studied through both air-water and air- natural gas condensate experiments on the large-scale multiphase experimental loop. Based on measurement and observation of flow pattern, “apparent rough surface” (ARS) model is selected to calculate frictional pressure gradient with gas-liquid momentum balance equations. The predictions of the models are compared with the data measured in the experiment. Some results of pressure gradient are obtained, so ARS interfacial shape is recommended in horizontal two-phase gas-liquid flows with low liquid loading.

Abstract: Nitrogen and phosphorous pollution is common in China and worldwide. The pollution deteriorates water quality and even causes significant change of the freshwater ecosystem. Management must be strengthened in order to reduce the pollution to secure water supply safety and to maintain healthy ecosystems. This paper investigated the yield of total nitrogen (TN) for different land use types, exemplified in the Xitiaoxi catchment of Lake Taihu basin, where catchment-generated nitrogen pollution is severe. Extensive water quality sampling was performed for different river levels and various land use types. A distributed hydrological model was also employed to simulate the river discharges at locations where flow observation is not available, and the simulated river discharges were used for the calculation of nitrogen yield. It is found that generally the catchment’s nitrogen export is still as high as 2.6 t/km²/year. The yield for forest is 0.8-1.0 t/km²/year, while the yields for arable land and for the river sections immediately downstream of urban area are higher than the average ranging 2.8-3.3 t/km²/year. It is also concluded that the hydrological modelling using a spatially distributed model is helpful and essential in obtaining flows at any locations, which can subsequently be used jointly with the water quality data to identify the critical source areas with high nitrogen yields.

Abstract: In the research, HNO₃-HClO ₄ method and Tessier method were chose to extract the total content and chemical form of Pb、Zn in the total suspended particles (TSP) in both heating period and non-heating period. The pollution characteristics of Pb、Zn in TSP of Xi’an was analysed by discussing their total content、chemical form and the distribution characteristics of bioavailability. The result indicated that in the heating period, total content of Pb in January was bigger then it in February and residual was the advantage state. Total content of Zn changed greatly and the highest level appeared in January and the advantage state was exchangeable. However, in the non-heating period, the highest level of Pb、Zn appeared in June and April respectively, and the lowest level appeared in April and May. In this period, the advantage state of Pb、Zn was bound to carbonates and its distribution characteristics of bioavailability was contrary to it in heating period.

Abstract: The total contents and chemical phase partitioning of Cd, Ni, Cu, Zn and Pb from long-time sewage- irrigated soil were analyzed in this paper. The results showed that the contents of Ni, Cu, Zn, and Pb did not exceed the the second-level limit of Standard of Soil Environment (GB15618-1995), but the average content of Cd was 1.81 mg•kg^-1, which was about three times more than the national standard. The chemical partitioning of metals analysis showed that Cd was present dominantly in the acetic acid extractable fraction with the average percentage of 37.44%, while the other four elements mostly in residual fraction, which indicated that Cd had the highest bioavailability, mobility and phyto-toxicity. Compared to the well-irrigated soils, the percentages of acetic acid extractable fractions of Cd, Ni, Zn and Cu were obviously higher in the contaminated soils, which increased the potential danger of heavy metals pollution.

Abstract: In the present work, contamination and potential ecological risk of six heavy metals (Pb, Cd, Hg, As, Cu and Zn) in sediments of Aha Lake, one of the five drinking water sources for Guiyang City, were assessed based on a method which is associated with toxic-response factors of contaminants. For comparison, the two sets of reference data representing the pre-industrial and the local baseline pollution levels were employed. When the pre-industrial levels were taken as references, the accumulating coefficients on average diminished in the order of Zn > As > Hg > Cd > Cu > Pb, and the potential ecological risk descended in the order of Hg > Cd > As > Cu > Zn > Pb. When the local baseline values worked as references, the accumulating coefficients on average diminished in the order of Cd > Zn > Hg > Cu > As > Pb, and the potential ecological risk descended in the order of Cd > Hg > As > Cu > Zn > Pb. It is evident that Cd and Hg are the critical elements in terms of potential ecological hazard in Aha Lake among these six heavy metals.

Abstract: There are few indicator systems available for monitoring and assessing the environmental quality of large-scale regions. We constructed an indicator system for integrated assessment of the environmental quality of the Dianchi Basin. First, the definition of regional environmental quality is determined by both the supply of materials and energy in the region and the extent to which the region is polluted. Second, the indicator categories used for assessment mainly comprise vegetation biomass and the concentrations of various pollutants. Third, owing to spatial heterogeneity of a region, evaluation of the regional environment first requires division into sub-regions, each of which should be relatively homogeneous with regard to physical conditions (e.g. marine and terrestrial) and appearance (e.g. vegetation cover). Finally, the mathematical models for assessing regional environmental quality can be built according to the relationships between the various indicators, the sub-regions and regional environmental quality. The indicator system built using this approach can reflect environmental changes over time and identifies reasons for environmental variation.

Abstract: Honey has always been the center of focus, not only because of its valuable nutrition, but also because of its use as an environmental indicator. In this context, 10 honey samples from Taiwan and Mainland China were collected to detect concentration of 17 PCDD/Fs, 12 dioxin-like PCBs and 27 metal elements by HRCG/HRMS and ICP-MS. The main goal was to investigate the difference between honeys of diverse geographical origins and to validate the feasibility of honey being an environmental bioindicator. The result showed lower concentration of PCDD/Fs and dioxin-like PCBs than their MDLs, indicating it was not feasible using honey as the indicator for these compounds in the environment. The result for metal elements showed a higher concentration of K, Na, Mg and Ca in honey from Taiwan than those from the Mainland. Toxic element, As, Ba, Pb, Cd, Cr, Ag, were all found present in honey from the Mainland; while only three of those, Ba, Pb, Cd were detectible in honey from Taiwan. This could imply a much more complex pollution source in the Mainland than in Taiwan

Abstract: Based upon statistics of sediment parameters and sediment moving modes from probability cumulative distribution curves, and combined with topography and hydrodynamics, the sedimentary environment at the intertidal flats of Qing 8 estuary (1996-now) and Diaokou estuary (1964-1976) at the Yellow River Delta was discussed in depth in present study. The results demonstrated that sediment grain size parameters can clearly reveal hydrodynamic condition of the sedimentary environment. Core C1 at current estuary was divided into four layers. The corresponding hydrodynamic conditions from top to bottom varied from strong to fluctuating between strong and weak, and finally to weak. Meanwhile, Core A1 at abandoned estuary can be divided into three layers and corresponding hydrodynamics from top to bottom changed from fairly strong to rather strong. Furthermore, the sedimentary facies of two cores were identified and they depended on water and sediment discharge from the Yellow River.

Abstract: The decolored reaction between cetyltrimethyl ammonium bromide (CTMAB) and nanosilver was studied, and a simple, rapid spectrophotometric method was established to determine CTMAB. In pH 7.8 Na₂HPO₄-NaH₂PO₄ buffer solution, nanosilver exhibited a maximum absorption peak at 395 nm, and it reacted with CTMAB to form larger particles that resulted in the absorption decreasing. Under the chosen conditions, the decreased absorbance was linear to the CTMAB concentration in the range of 2.5×10-7-1.0×10-5mol/L, with the regression equation of ΔA395 = 0.0431C CTMAB + 0.0182, the correlation coefficient of 0.9968 and the detection limit of 0.21μmol/L CTMAB. The proposed method was applied to detect CTMAB in water samples, with simplicity, rapidity and accuracy.

Abstract: Taihu Lake basin is a typical water shortage area for water quality problem in China. Studying the influencing water environment factors in this area provides a scientific basis to propose effective pollution water control. This article selects lakes in the western basin as the study area which has the largest contribution to the pollution in Taihu Lake. Influencing factors of water pollution of Tianmuhu Lake and Gehu Lake have been analyzed based on principal component analysis of SPSS, to study the major influencing factors of water environment. The results show that the major influencing factors of water environment in Taihu Lake is dissolved oxygen, water turbidity, and water N, P and other nutrient elements, and the water environment nutrients is much influenced by the N element. While the major influencing factors of water environment in Gehu Lake is P nutrition elements, physical and chemical factors and nutrients such as N and P element, and P elements are seriously polluted. Thus, the corresponding countermeasures should be forward according to different water characteristics during the process of water Pollution Control at the basin.