Chemical solutions for greywater recycling

Greywater recycling is now accepted as a sustainable solution to the general increase of the fresh water demand, water shortages and for environment protection. However, the majority of the suggested treatments are biological and such technologies can be affected, especially at small scale, by the variability in strength and flow of the greywater and potential shock loading. This investigation presents the study of alternative processes, coagulation and magnetic ion exchange resin, for the treatment of greywater for reuse. The potential of these processes as well as the influence of parameters such as coagulant or resin dose, pH or contact time were investigated for the treatment of two greywaters of low and high organic strengths. The results obtained revealed that magnetic ion exchange resin and coagulation were suitable treatment solutions for low strength greywater sources. However, they were unable to achieve the required level of treatment for the reuse of medium to high strength greywaters. Consequently, these processes could only be considered as an option for greywater recycling in specific conditions that is to say in case of low organic strength greywater or less stringent standards for reuse.     

Accumulation, speciation and cellular localization of copper in Sesbania drummondii

Growth, accumulation and intracellular speciation and distribution of copper (Cu) in Sesbania drummondii was studied using scanning-electron microscopy (SEM), X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The growth of seedlings was assessed in terms of biomass accumulation. The growth of the seedling was enhanced by 73.5% at a low Cu concentration (50 mg l⁻¹) compared to the control treatment. Additionally, seedling growth was inhibited by 18% at 300 mg l⁻¹ Cu with respect to the control. Copper concentration in roots and shoots was increased with increasing Cu concentration in the growth solution. The accumulation of Cu was found to be higher in roots than in the shoots. At a concentration of 300 mg l⁻¹ Cu, the roots accumulated 27,440 mg Cu kg⁻¹ dry weight (dw) while shoots accumulated 1282 mg Cu kg⁻¹ dw. Seedlings were assessed for photosynthetic activity by measuring chlorophyll a fluorescence parameters: F_v/F_m and F_v/F₀ values. Photosynthetic integrity was not affected by any of the Cu treatments. The X-ray absorption spectroscopic (XAS) studies showed that Cu was predominantly present as Cu(II) in Sesbania tissue. In addition, from the XAS studies it was shown that the Cu exists in a mixture of different coordination states consisting of Cu bound to sugars and small organic acids with some possible precipitated copper oxide. From the EXAFS studies, the coordination of Cu was determined to have four equatorial oxygen(nitrogen) ligands at 1.96 Å and two axial oxygen ligands at 2.31 Å. Scanning-electron microscopy studies revealed the distribution of Cu within the seedlings tissues, predominantly accumulated in the cortical and vascular (xylem) regions of root tissues. In the stem, most of the Cu was found within the xylem tissue. However, the deposition of Cu within the leaf tissues was in the parenchyma. The present study demonstrates the mechanisms employed by S. drummondii for Cu uptake and its biotransformation.     

Carrier detection and prenatal diagnosis in Norrie disease

We report the use of DNA probes to determine carrier status in three young women from a large kindred with Norrie disease. One of the women requested prenatal diagnosis during pregnancy. In this pedigree, Norrie disease was not characterized by a deletion at DXS7.     

Fate and transport of monoterpenes through soils. Part II: calculation of the effect of soil temperature, water saturation and organic carbon content

This theoretical study was performed to investigate the influence of soil temperature, soil water content and soil organic carbon fraction on the mobility of monoterpenes (C10HnOn') applied as pesticides to a top soil layer. This mobility was expressed as the amount volatilized and leached from the contaminated soil layer after a certain amount of time. For this, (slightly modified) published analytical solutions to a one dimensional, homogeneous medium, diffusion/advection/biodegradation mass balance equation were used. The required input-parameters were determined in a preceding study. Because the monoterpenes studied differ widely in the values for their physico-chemical properties, the relative importance of the various determinants also differed widely. Increasing soil water saturation reduced monoterpene vaporization and leaching losses although a modest increase was usually observed at high soil water contents. Organic matter served as the major retention domain, reducing volatilization and leaching losses. Increasing temperature resulted in higher volatilization and leaching losses. Monoterpene mobility was influenced by vertical water flow. Volatilization losses could be reduced by adding a clean soil layer on top of the contaminated soil. Detailed insight into the specific behaviour of different monoterpenes was obtained by discussing intermediate calculation results; the transport retardation factors and effective soil diffusion coefficients. One insight was that the air-water interface compartment is probably not an important partitioning domain for monoterpenes in most circumstances. The results further indicated that biodegradation is an important process for monoterpenes in soil.     

Functional mechanisms underlying cetacean distribution patterns: hotspots for bottlenose dolphins are linked to foraging

Many studies have shown that the distribution of cetaceans can be closely linked to habitat, but the underlying function of the preferred habitats often remains unclear. Only when behavioural observations are made in relation to habitat types can functional mechanisms behind the habitat use be revealed. Within the range of a bottlenose dolphin (Tursiops truncatus) population off NE Scotland, dolphins show clear preferences for several discrete areas. If the observed patterns of distribution are related to foraging, we predict that behaviour patterns shown by dolphins would reflect this relationship. In this study we identify behaviours of dolphins at the water surface that were related to feeding events, evaluate whether the patterns of distribution were related to foraging and whether they were related the local submarine habitat characteristics. To investigate whether visible surface evidence of foraging behaviour varied spatially, we analysed data collected from 104 regular boat-based surveys made within the Moray Firth, NE Scotland, between 1990 and 2000. To determine whether underlying bathymetry had any influence on the surface behaviour of dolphins, a land-based observation study was carried out in the populations core region of use. The results of this study show that feeding behaviour by dolphins was significantly higher in areas used intensively by dolphins. Furthermore, there were clear relationships between feeding events and the submarine habitat characteristics; certain forms of feeding occur primarily over steep seabed gradients, and in deeper waters during June and July. These results quantitatively support the hypothesis that the distinctive patterns of distribution shown by these dolphins are related to foraging behaviour or opportunities, and that submarine habitat characteristics may be a significant factor in the foraging efficiency of dolphins. Future work should focus on collecting detailed information on the distribution patterns of prey within the study area to allow direct comparisons between predator and prey distributions.Communicated by J.P. Thorpe, Port Erin     

黄河包头段不同粒径沉积物分形校正下重金属的吸附研究

推导了分粒级的表面分形维数计算公式,根据推导公式计算了分粒级沉积物的分维值.应用已有的表面分形分维计算公式分别计算了黄河包头段沉积物整体的表面分形分维(1.91)及＜63 μm粒级的分维值(1.36),揭示出黄河水环境的磨蚀和分选2个原因引起黄河包头段沉积物低的分维值.用分形校正吸附模型、Freundlich和Langmuir吸附模型对黄河包头段重金属分粒级沉积物吸附进行了拟合,表明分形校正吸附模型具有较好的适用性,同时揭示分形校正吸附模型与MEA理论结合能更好的对热力学吸附结果进行描述;由吸附结果分析得出4种重金属因粒径引起的吸附量变化程度序列为Cu＞Pb＞Zn≈Cd,初始浓度高的吸附量曲线变化较初始浓度低的曲线变化明显,同时指出Cu、Pb的吸附主要与矿物组成有关,而Zn、Cd的吸附则与吸附剂沉积物空间几何性质(或沉积物表面物理特征)有关.     

Linking 3D spatial models of fuels and fire: Effects of spatial heterogeneity on fire behavior

Crown fire endangers fire fighters and can have severe ecological consequences. Prediction of fire behavior in tree crowns is essential to informed decisions in fire management. Current methods used in fire management do not address variability in crown fuels. New mechanistic physics-based fire models address convective heat transfer with computational fluid dynamics (CFD) and can be used to model fire in heterogeneous crown fuels. However, the potential impacts of variability in crown fuels on fire behavior have not yet been explored. In this study we describe a new model, FUEL3D, which incorporates the pipe model theory (PMT) and a simple 3D recursive branching approach to model the distribution of fuel within individual tree crowns. FUEL3D uses forest inventory data as inputs, and stochastically retains geometric variability observed in field data. We investigate the effects of crown fuel heterogeneity on fire behavior with a CFD fire model by simulating fire under a homogeneous tree crown and a heterogeneous tree crown modeled with FUEL3D, using two different levels of surface fire intensity. Model output is used to estimate the probability of tree mortality, linking fire behavior and fire effects at the scale of an individual tree. We discovered that variability within a tree crown altered the timing, magnitude and dynamics of how fire burned through the crown; effects varied with surface fire intensity. In the lower surface fire intensity case, the heterogeneous tree crown barely ignited and would likely survive, while the homogeneous tree had nearly 80% fuel consumption and an order of magnitude difference in total net radiative heat transfer. In the higher surface fire intensity case, both cases burned readily. Differences for the homogeneous tree between the two surface fire intensity cases were minimal but were dramatic for the heterogeneous tree. These results suggest that heterogeneity within the crown causes more conditional, threshold-like interactions with fire. We conclude with discussion of implications for fire behavior modeling and fire ecology.     

The impact of seasonal variations in DOC arising from a moorland peat catchment on coagulation with iron and aluminium salts

Natural organic matter (NOM) is one of the main sources of environmental pollution to drinking water supplies in much of the UK and the US. Whilst traditional treatment with trivalent coagulants has proven a successful strategy in the past, operational problems are now being reported during periods of elevated organic levels in the water. Characterisation of the pollutants in terms of polarity, molecular weight and charge, provides a method to understand the impact of the observed temporal and spatial variations in terms of a mechanistic parameter relevant to the treatment processes. Results from this study demonstrate that it is not simply the increased organic concentration, but also the change in NOM composition and character, which influences the impact on the treatment processes. Consequently, monitoring of these parameters provides an insight into how to manage the impact caused by environmental changes to the catchments.     

Sewage contamination of a densely populated coral 'atoll' (Bermuda)

Bermuda is a densely populated coral 'atoll' located on a seamount in the mid-Atlantic (Sargasso Sea). There is no national sewerage system and the ～20 × 10(6)?L of sewage generated daily is disposed of via marine outfalls, cess pits/septic tanks underneath houses and through waste disposal (injection) wells. Gastrointestinal (GI) enterococci concentrations were measured in surface seawater samples collected monthly at multiple locations across the island over a 5-year period. According to the EU Bathing Water Directive microbial classification categories, 18 of the sites were in the 'excellent' category, four sites in the 'good', five sites were in the 'sufficient' and three sites in the 'poor' categories. One of the sites in the 'poor' category is beside a popular swimming beach. Between 20-30% of 58 sub tidal sediment samples collected from creeks, coves, bays, harbours and marinas in the Great Sound complex on the western side of Bermuda tested positive for the presence of the human specific bacterial biomarker Bacteroides (using culture-independent PCR-based methods) and for the faecal biomarker coprostanol (5β-cholestan-3-β-ol, which ranged in concentration from <0.05-0.77?mg?kg(?-?1). There was a significant statistical correlation between these two independent techniques for faecal contamination identification. Overall the microbial water quality and sedimentary biomarker surveys suggest sewage contamination in Bermuda was quite low compared with other published studies; nevertheless, several sewage contamination hotpots exist, and these could be attributed to discharge of raw sewage from house boats, from nearby sewage outfalls and leakage from septic tanks/cess pits.     

宁夏生态移民社区生活空间融合与重构的影响因素及机理——以宁夏闽宁镇为例

生态移民的空间位移引致了迁入区多因素的相互作用及长期演化,成为多学科深入探究的重要问题之一。以闽宁镇生态移民社区为例,采用主成分分析法和地理探测器分析法,对生态移民社区生活空间融合的影响因素和机理进行了研究,结果发现：（1）生态移民社区生活空间融合与重构受多种因素影响,生活基础设施、经济收入增长、移民社区环境、邻里关系、政府政策、民族生活六个主成分对生态移民社区生活空间融合的影响可以起到解释作用。（2）影响生态移民社区生活空间的因子解释力由强到弱依次排序为：X₁生活基础设施>X₂经济收入增长>X₃邻里关系>X₄政府政策>X₅民族生活>X₆移民社区环境;交互探测结果表明社区各要素因子交互后因子解释力呈双线性增强,即任意两个因子交互作用对于生态移民社区生活空间融合的影响强度都大于单个因子的独自作用强度。（3）各影响因素之间的互动影响,共同促进生态移民社区固有的生活方式、文化习惯、社会交往关系的演化,进而形成了生活空间的融合与重构。