Detection of DDT and its metabolites in two estuaries of South China using a SPME-based device: First report of p,p′-DDMU in water column

A solid-phase microextration-based sampling method was employed to determine the concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (DDE) and 1-chloro-2,2-bis(p-chlorophenyl)ethene (DDMU), in two estuarine bays, Daya Bay and Hailing Bay, of South China. Six DDT components including p,p′-DDT, o,p′-DDD, p,p′-DDD, o,p′-DDE, p,p′-DDE, and p,p′-DDMU were detected in Hailing Bay, while only p,p′-DDD was found in Daya Bay. p,p′-DDD was the most abundant DDT component in both bays, sharply different from the previous finding in the water column of the Palos Verdes Shelf, California, USA that p,p′-DDE was prevalent. In addition, the occurrence of p,p′-DDMU (with a range of 0.047-0.21 ng/L in Hailing Bay) has not been reported around the globe, and its presence in our study region appeared to stem from dehydrochlorination of p,p′-DDD, favored under aerobic conditions, but further investigations are clearly needed to confirm the mechanism for generation of DDMU in estuarine environments.     

Predicting land cover using GIS, Bayesian and evolutionary algorithm methods

Modelling land cover change from existing land cover maps is a vital requirement for anyone wishing to understand how the landscape may change in the future. In order to test any land cover change model, existing data must be used. However, often it is not known which data should be applied to the problem, or whether relationships exist within and between complex datasets. Here we have developed and tested a model that applied evolutionary processes to Bayesian networks. The model was developed and tested on a dataset containing land cover information and environmental data, in order to show that decisions about which datasets should be used could be made automatically. Bayesian networks are amenable to evolutionary methods as they can be easily described using a binary string to which crossover and mutation operations can be applied. The method, developed to allow comparison with standard Bayesian network development software, was proved capable of carrying out a rapid and effective search of the space of possible networks in order to find an optimal or near-optimal solution for the selection of datasets that have causal links with one another. Comparison of land cover mapping in the North-East of Scotland was made with a commercial Bayesian software package, with the evolutionary method being shown to provide greater flexibility in its ability to adapt to incorporate/utilise available evidence/knowledge and develop effective and accurate network structures, at the cost of requiring additional computer programming skills. The dataset used to develop the models included GIS-based data taken from the Land Cover for Scotland 1988 (LCS88), Land Capability for Forestry (LCF), Land Capability for Agriculture (LCA), the soil map of Scotland and additional climatic variables.     

Changes in negative air ions concentration under different light intensities and development of a model to relate light intensity to directional change

The purpose of this research was to determine changes in negative air ion (NAI) concentrations produced by plants grown under different light intensities. NAI concentrations were observed and analyzed in an outdoor green space with five plant species (Aloe arborescens, Clivia miniata, Chlorophytum comosum, Opuntia brunnescens, Crassula portulacea) and A. arborescens was then grown under controlled-light conditions in an enclosed space for the subsequent light intensity experiment.     

针铁矿对Pb~(2+)的吸附特征及影响因素研究

通过恒温振荡平衡法研究了Pb~(2+)在针铁矿上的等温吸附和吸附动力学特征,探讨了吸附的影响因素.结果表明:(1)随Pb~(2+)平衡浓度和pH的增大,针铁矿对Pb~(2+)的吸附量逐渐增大.(2)针铁矿对Pb~(2+)的等温吸附可用Freundlich和Langmuir方程较好地拟合.(3)在相同温度和pH下,随离子强度的提高,针铁矿对Pb~(2+)的吸附量增大.(4)在相同离子强度和pH下,针铁矿对Pb~(2+)的吸附量总体随温度升高而增大.针铁矿对Pb~(2+)的吸附是自发进行的吸热反应.(5)针铁矿吸附Pb~(2+)的过程可分为初始的快吸附和随后的慢吸附2个阶段.pH影响吸附反应快慢,随pH增大吸附速率增大;随着pH的增大,达到平衡吸附的时间缩短.吸附动力学方程用Elovich方程拟合最佳.     

生活垃圾加载介质层填埋法对初期渗滤液污染抑制效果研究

以传统卫生填埋柱R2为对照,通过往生物反应器填埋柱R1内加载可渗透反应介质层1和2进行模拟试验,主要探讨了填埋柱R1垃圾渗滤液COD、总氮、氨氮及总磷的变化趋势,探索一种新型的加载介质层垃圾填埋处理方法。试验结果表明,填埋20周后, R1柱COD浓度基本维持在40 000～45 000 mg/L间,约为R2柱的20%～30%;第24周,R1柱总氮和氨氮分别为206.5 mg/L和167.3 mg/L,在16～24周内,R1总氮和氨氮分别约为R2的14.5%～17.5%和36.2%～43.6%;18周时,R1柱总磷达最大值1.704 mg/L,至第24周降为0.673 mg/L, 整个实验过程R1柱总磷约为R2的0.15%～0.56%。     

高锰酸钾降解地下水中PCE的研究

以氯代有机污染物中常见的PCE为目标污染物,以自制高锰酸钾溶液为氧化剂,采用批实验方法,探讨了高锰酸钾降解PCE的反应动力学、影响因素以及反应机理。反应结果表明,高锰酸钾降解PCE的反应符合一级动力学方程,反应活化能E为57.119 kJ/mol,在30℃条件下,反应速率常数为0.0076 min^-1,半衰期为91.20 min。在pH在3～10,离子强度在0～0.1030 mol/L之间变化时,反应速率不受明显影响。     

超细粉煤灰基成型吸附剂的动态吸附实验

以粉煤灰为原料制备成型吸附剂,对水溶液中亚甲基蓝和Cr⁶⁺进行动态吸附研究,绘制穿透曲线,利用Origin软件对实验数据分析处理,得出穿透曲线的通式C_t=A₁－A₂〖〗1+(t/t₀)^p+A₁。结果表明,初始浓度C₀=25 mg/L,填料高度不同时,达到穿透点的时间随填料高度的增加而增加;填料高度h=200 mm,初始浓度不同时,达到穿透点的时间随初始浓度的增加而减小;该吸附剂对有机染料和重金属离子均有较好的吸附性能;穿透曲线通式的回归线性相关系数表明,该通式可很好地反映超细粉煤灰成型吸附剂的动态吸附过程。     

厌氧序批式反应器内挥发性脂肪酸积累特性研究

小试规模的厌氧序批式反应器（ASBR）,通过人工配水,研究了启动3个月时间以及一个运行周期内反应器内挥发性脂肪酸（VFA）的积累情况,并通过分析期间产甲烷活性的变化说明了控制VFA积累的重要性。经过近120 d的运行,乙酸和丙酸的最大比产甲烷活性分别提高了1.8和2.2倍,说明反应器的启动过程即是微生物群落的优化和选择的过程,ASBR的抗冲击的能力较强说明随启动的进行和种群的优化,活性污泥凝聚性能增强,对VFA的降解能力增强。     

One laptop per child,local refurbishment or overseas donations? Sustainability assessment of computer supply scenarios for schools in Colombia

With the intention of bridging the ‘digital divide’ many programmes have been launched to provide computers for educational institutions, ranging from refurbishing second hand computers to delivering low cost new computers. The fast and economical provision of large quantities of equipment is one of the many challenges faced by such programmes. If an increase is to be achieved in the sustainability of computer supplies for schools, not only must equipment be provided, but also suitable training and maintenance delivered. Furthermore, appropriate recycling has to be ensured, so that end-of-life equipment can be dealt with properly. This study has evaluated the suitability of three computer supply scenarios to schools in Colombia: (i) ‘Colombian refurbishment’, -refurbishment of computers donated in Colombia, (ii) ‘Overseas refurbishment’, -import of computers which were donated and refurbished abroad, and (iii) ‘XO Laptop’, -purchase of low cost computers manufactured in Korea. The methods applied were: Material Flow Assessment, -to assess the quantities-, Life Cycle Assessment, -to assess the environmental impacts, and the application of the Multiple Attribute Utility Theory, -to analyse, evaluate and compare different scenarios. The most sustainable solution proved to be the local refurbishment of second hand computers of Colombian origin to an appropriate technical standard. The environmental impacts of such practices need to be evaluated carefully, as second hand appliances have to be maintained, require spare parts and sometimes use more energy than newer equipment. Providing schools with second hand computers from overseas and through programmes such as ‘One Laptop Per Child’ has the disadvantage that the potential for social improvements – such as creation of jobs and local industry involvement – is very low.     

Experimental study of recycling lightweight concrete with aggregates containing expanded glass

The focus is on the issue of waste management when constructing and recycling lightweight concrete (LWC) with aggregates containing expanded glass. The paper analyses the recycling of concrete from lightweight aggregates, and on the important issue of environmental and waste management. The characteristics of recycling LWC such as density, compressive strength and thermal conductivity are investigated, and compared with normal existing concrete from lightweight aggregates. The results indicate that it is possible to recycle lightweight concrete construction waste. The described method shows great possibilities for increasing the use of construction waste materials from LWC containing expanded glass, in order to benefit from better use of the available capacity from existing construction waste. The characteristics of density, compressive strength and thermal conductivity from the new recycled material were compared with normal existing concrete from lightweight aggregates, such as changes in dependency on the type and parts of waste as well as its new binding components. Thus, a new recycled material has been created with new characteristics of density, compressive strength and thermal conductivity, which is conform to the compressive strength class and rules on heat protection and energy efficiency use in buildings (SI OJ RS No. 42/2002). Laboratory density, compressive strength, and thermal conductivity tests results showed that LWC can be produced by the use of waste LWC with aggregates containing expanded glass. However, the use of waste LWC with aggregates containing expanded glass seems to be necessary for the production of cheaper and environmentally friendly LWC.