碱减量-印染混合废水的预处理研究

针对碱度大、COD高、组成复杂的碱减量-印染混合废水,采用高碱度下直接混凝再酸析相结合的方法进行预处理,取得理想效果.试验结果表明,在高碱度条件下先加入镁盐及少量高分子絮凝剂,可去除大部分可溶性及不溶性污染物;再通过降低pH的酸析法,能有效去除废水中的色度、浊度,大大降低COD.在MgSO4用量为800～1 500 mg/L,阴离子聚丙烯酰胺用量为2 mg/L,酸析pH小于3.0时,色度去除率达97%,COD去除率达92%,浊度去除率近100%.     

细菌脱氢酶活性生物测试法用于水质毒性检测的改进

从培养基配方、菌种来源、激活时间、菌液用量以及检测方式等几个方面对脱氢酶快速毒性检测法进行了改进,确定了整个体系的操作方法。并用HgCl2和NaN3验证了改进后方法的可行性。结果表明,以天然地表水作为菌种来源,转接培养1次后,混合细菌的脱氢酶活性的稳定性便可达到实验要求。样品液与菌液按照6∶1的比例混合效果较好。混合体系在37℃恒温培养箱中激活50min以上细菌可完全活化,最终检测可用普通分光光度计进行。改进后的方法解决了原方法菌液失活过快,实验稳定性较差的问题,同时克服了检测仪器难以购买的问题,使这一方法得以在普通实验室实现。     

SOME SIMPLE MODELS FOR CONTINUOUS VARIATE TIME SERIES1

ABSTRACT: A survey is given of recently developed models for continuous variate non–Gaussian time series. The emphasis is on marginally specific models with given correlation structure. Exponential, Gamma, Weibull, Laplace, Beta and Mixed Exponential models are considered for the marginal distributions of the stationary time series. Most of the models are random coefficient, additive linear models. Some discussion of the meaning of autoregression and linearity is given, as well as suggestions for higher–order linear residual analysis for non–Gaussian models.     

混合微电解-生物铁-气浮法处理印染废水

印染行业的废水具有高浓度、高色度和含有大量难降解有机物的特点,属于难降解、重污染工业废水,如采用传统处理工艺,很难达到国家一级排放标准.实践证明,采用混合微电解 生物铁 气浮法处理此类生产废水,CODCr去除率达97%,色度去除率达98%.同时,该工艺具有占地面积小,脱色效果好,处理效率高等特点,能广泛应用于纺织印染废水处理的实际工程中.     

Patterns of bird abundance along the agricultural gradient of the Pampean region

Bird and land-use surveys were conducted along the agricultural gradient covering from pure croplands through mixed-farming to pure pastoral-farming scenario in the Pampean region of Argentina. Simple regression analyses were performed to analyse the responses of bird abundance to the percentage of land devoted to crop-production. The specific variables associated to bird abundance within both the crop and pastoral-farming landscapes were identified by running redundancy analyses (RDA). The abundance of 20 out of 43 species (47%) was significantly related to the percentage of cropland, finding negative (65%), positive (25%) unimodal (5%) and bimodal (5%) responses of birds to increasing intensity of crop production. The results showed three types of negative and two types of positive responses of bird abundance to the agricultural gradient. RDA revealed the importance of crop-field types in the crop-production scenario and of cattle presence and grass height in the pastoral-farming scenario for the structuring of the grassland bird community. As most species were negatively affected by crop production, the current land-use homogenisation towards high-intensity croplands will most likely result in population decline of many birds in the region.     

Cosolvent effects on sorption isotherm linearity

Sorption-desorption hysteresis, slow desorption kinetics, and other nonideal phenomena have been attributed to the differing sorptive characteristics of the natural organic polymers associated with soils and sediments. In this study, aqueous and mixed solvent systems were used to investigate the effects of a cosolvent, methanol, on sorption isotherm linearity with natural organic matter (NOM), and to evaluate whether these results support, or weaken, the rubbery/glassy polymer conceptualization of NOM. All of the sorption isotherms displayed some nonlinear character. Our data indicates that all of the phenanthrene and atrazine isotherms were nonlinear up to the highest equilibrium solution concentration to solute solubility in water or cosolvent ratios (Ce/Sw,c) used, approximately 0.018 and 0.070, respectively. Isotherm linearity was also observed to increase with volumetric methanol content (fc). This observation is consistent with the NOM rubbery/glassy polymer conceptualization: the presence of methanol in NOM increased isotherm linearity as do solvents in synthetic polymers, and suggests that methanol is interacting with the NOM, enhancing its homogeneity as a sorptive phase so that sorption is less bimodal as fc increases. When the equilibrium solution concentration was normalized for solute solubility in water or methanol-water solutions, greater relative sorption magnitude was observed for the methanol-water treatments. This observation, in conjunction with the faster sorption kinetics observed in the methanol-water sediment column systems, indicates that the increase in relative sorption magnitude with fc may be attributed to the faster sorption kinetics in the methanol-water systems, and hence, greater relative sorptive uptake for the rubbery polymer fraction of NOM at similar time scales.     

On the behaviour of the residence time at the bottom of the mixed layer

To understand why the findings of Deleersnijder et al. [(2006), Environ Fluid Mech 6: 25–42]—the residence time in the mixed layer in not necessarily zero at the pycnocline—are consistent with those of Delhez and Deleersnijder [(2006), Ocean Dyn 56:139–150]—the residence time in a control domain vanishes at the open boundaries of this control domain—, it is necessary to consider a control domain that includes part of the pycnocline, in which the eddy diffusivity is assumed to be zero. Then, depending on the behaviour of the eddy diffusivity near the bottom of the mixed layer, the residence time may be seen to exhibit a discontinuity at the interface between the mixed layer and the pycnocline. If such a discontinuity exists, the residence time is non-zero in the former and zero in the latter. This is illustrated by analytical solutions obtained under the assumption that the eddy diffusivity is constant in the mixed layer.     

IMPASEA: A methodological framework to monitor and assess the socioeconomic effects of marine protected areas. An English Channel case study

Marine protected areas (MPAs) are increasingly regarded as socio-ecological systems. In addition to their reported ecological effects, MPAs may have important social, economic and cultural effects on local communities and marine and coastal stakeholders. Those effects should be considered within an ecosystem approach to MPA planning, designation and management. Here we present a new framework to monitor and assess the socioeconomic effects of MPAs saliently and soundly: the Integrated MPA Socio-Economic Assessment (IMPASEA). The IMPASEA considers and analyses those factors deemed most important for marine and coastal stakeholders in a spatially referenced, sound and cost-effective manner. The development of the IMPASEA followed a mixed-methods research design in 3 phases: literature review, stakeholder survey and geo-statistical analysis using a Multiple-Paired-Before-After-Control-Impact design (MPBACI). The framework was tested on a set of 6 multiple-use MPAs on the French side of the English Channel. Of the eight socioeconomic variables analysed at the scale of ‘commune’ in the geo-statistical phase, only one variable (‘number of hotel rooms’) might have been affected by the designation of MPAs. Factors such as MPA designation category and management status are likely to have contributed to the non-significant differences shown at the scale of commune for the selected MPAs. In contrast, most of the six variables related to fishing showed differences between ports inside and outside MPAs, although these results need further ground truthing to discriminate attribution of effects. The characteristics of the IMPASEA make it a sound monitoring and assessment framework that could be applied in different contexts and to different types of sustainability assessments involving protected areas or other spatially-defined entities under certain conditions: existence of consistent time series of fine-scale socioeconomic data and avoidance of overlap of designation categories over single spaces.     

Simulation test on mixed water and sand inrush disaster induced by mining under the thin bedrock

Coal seam mining under thin bedrock will make transmission fissure zone go through to the water-rich aquifer under the covering layer, which will cause water flooding and sand gushing in the working face. The test model of the mixed water and sand inrush transfer and inrush was designed and manufactured to simulate the startup, transfer and inrush process of the mixed water and sand inrush in the overburden fracture channel. The characteristics of the mixed water and sand inrush in the fracture channels were researched. The variation characteristics of water pressure in different positions of the fracture channel were revealed through analyzing “\/” type fracture form which is wide at the top and goes narrower down to the base, of various inclination angles under the water pressure of 0.06 MPa and 0.08 MPa. The results show that the water and sand inrush took place instantly in the mined area. Based on the characteristics of water pressure variations, changes in water pressure are divided into two phases: rising phase and lowering to stable phase. Under the other same conditions, when the fissure channel angle increases, the pore water pressure and its sudden drop will increase too, and the inrushing process will get more rapidly; the bigger the water pressure is, the pore water pressure increases more rapidly and violently. From this, the transfer characteristics and dynamic mechanism of the mixed water and sand inrush were explored.     

Public perception of locally unwanted facilities in Hong Kong: implications for conflict resolution

This paper aims to investigate factors affecting public attitude towards the siting of locally unwanted land uses (LULUs) and to explore the possible strategies to resolve such conflicts. Three questionnaire surveys were undertaken in communities with different siting experiences and socio-economic profiles. Over 750 individuals were successfully interviewed in each study district. The three communities were found to share similar risk beliefs but show variations in the level of awareness of and response to LULUs. In communities with a disproportionate share of LULUs, many residents did not trust the government in handling LULU issues and thought that the siting process was unfair. The results of the binary logistic regression analysis show that people are likely to oppose the siting of a LULU in their community if they have a negative siting experience, do not perceive the need, accord a high risk to the facility and have a low level of trust in government. The resolution strategies preferred by the public are greater public participation and effective mitigation of risks and impacts, rather than provision of compensation and incentives. All these call for policy-makers to be sensitive to local concerns, engage the public in the process, communicate risks effectively and foster trust building.