Brominated flame retardants in the Australian population: 1993-2009

Brominated flame retardants, including hexabromocyclododecane (HBCD) and polybrominated diphenyl ethers (PBDEs) are used to reduce the flammability of a multitude of electrical and electronic products, textiles and foams. The use of selected PBDEs has ceased, however, use of decaBDE and HBCD continues. While elevated concentrations of PBDEs in humans have been observed in Australia, no data is available on other BFRs such as HBCD. This study aimed to provide background HBCD concentrations from a representative sample of the Australian population and to assess temporal trends of HBCD and compare with PBDE concentrations over a 16 year period. Samples of human milk collected in Australia from 1993 to 2009, primarily from primiparae mothers were combined into 12 pools from 1993 (2 pools); 2001; 2002/2003 (4 pools); 2003/2004; 2006; 2007/2008 (2 pools); and 2009. Concentrations of ∑HBCD ranged from not quantified (nq) to 19 ng g(-1)lipid while α-HBCD and γ-HBCD ranged from nq to 10 ng g(-1)lipid and nq to 9.2 ng g(-1)lipid. β-HBCD was detected in only one sample at 3.6 ng g(-1)lipid while ∑(4)PBDE ranged from 2.5 to 15.8 ng g(-1)lipid. No temporal trend was apparent in HBCD concentrations in human milk collected in Australia from 1993 to 2009. In comparison, PBDE concentrations in human milk show a peak around 2002/03 (mean ∑(4)PBDEs=9.6 ng g(-1)lipid) and 2003/04 (12.4 ng g(-1)lipid) followed by a decrease in 2007/08 (2.7 ng g(-1)lipid) and 2009 (2.6 ng g(-1)lipid). In human blood serum samples collected from the Australian population, PBDE concentrations did not vary greatly (p=0.441) from 2002/03 to 2008/09. Continued monitoring including both human milk and serum for HBCD and PBDEs is required to observe trends in human body burden of HBCD and PBDEs body burden following changes to usage.     

Landscape multifunctionality: a powerful concept to identify effects of environmental change

The interdisciplinary concept of landscape multifunctionality provides a suitable platform to combine or disentangle effects of multiple environmental stressors acting on the landscape. The concept allows mapping of trade-offs, synergies, and priority conflicts between individual landscape functions, thus providing easily accessible, hands-on means to communicate findings of environmental research to decision makers and society. This rapid communication provides an overview of current developments and potential future research avenues in landscape multifunctionality.     

Some heterocyclic aromatic compounds are Ah receptor agonists in the DR-CALUX assay and the EROD assay with RTL-W1 cells

Purpose  

Heterocyclic aromatic compounds containing nitrogen, sulfur, or oxygen heteroatoms (NSO-HET) have been detected in air, soil, marine, and freshwater systems. However, only few publications are available investigating NSO-HET using in vitro bioassays. To support better characterization of environmental samples, selected NSO-HET were screened for dioxin-like activity in two bioassays.     

Emergy Evaluation of a Village Ecosystem in Wolong Nature Reserve in China

Due to historic reasons, there are several human settlements in nature reserves and national parks, which may constitute a threat to biodiversity. Establishment of nature reserves may however generate constraints for development of local communities residing in these reserves. The village ecosystem of Zhuanjinglou Village in Wolong Nature Reserve includes population, farming and livestock （domestic and alpine） and forest ecosystem. An emergy analysis of agro-ecosystem （including the farming and livestock ecosystem） and energy consumption in Zhuanjinglou Village indicates that livestock ecosystem plays an important role in village ecosystem, which may be the source of great pressure on the state of the local environment. The increasing ratio of electricity in energy consumption may play a positive role for environmental conservation. Despite some successful experiences, there are some remaining issues that need to be addressed in the ecological rehabilitation of the village ecosystem.     

An overview of commercially used brominated flame retardants,their applications,their use patterns in different countries/regions and possible modes of release

Brominated flame retardants (BFRs) are used in a variety of consumer products and several of those are produced in large quantities. These compounds have been detected in environmental samples, which can be attributed to the anthropogenic uses of these compounds. Brominated flame retardants are produced via direct bromination of organic molecules or via addition of bromine to alkenes; hence, an overview of the production and usage of bromine over the past three decades is covered. Production, application, and environmental occurrence of high production brominated flame retardants including Tetrabromobisphenol A, polybrominated biphenyls, Penta-, Octa-, Deca-brominated diphenyl ether (oxide) formulation and hexabromocyclododecane are discussed.     

静态浮箱法中不同拟合模型对水-气界面通量估算的影响

水域生态系统是温室气体的重要来源,静态浮箱法（SFC）是目前广泛采用估算水-气界面气体通量的方法之一,然而在利用线性回归（LR）拟合模型估算水-气界面气体通量时存在低估问题。采用密闭式静态浮箱-温室气体分析仪系统,观测了在三峡库区香溪河库湾水-气界面之上通量箱内甲烷和二氧化碳气体浓度的变化,对监测得到的数据进行拟合分析。对比分析了线性回归（LR）、二次回归（QR）和指数回归（ER）三种模型的拟合效果,结果表明非线性回归模型可以更好地拟合静态浮箱内气体浓度随时间的变化情况,从而得到更接近真实值的水-气界面气体通量。认为采用线性回归（LR）模型拟合水-气界面气体通量得到的结果在很大程度上被低估了,该方法得到甲烷和二氧化碳气体通量估算值平均约占实测值的77%和80%。此外,大多数情况下指数拟合模型的效果要优于二次回归拟合模型,而二次回归模型拟合系数没有物理意义,从理论上不适用于气体通量的估算。 关键词： 静态浮箱法;气体通量;线性拟合;非线性拟合     

Remediation of heavy metal polluted sediment by suspension and solid-bed leaching: estimate of metal removal efficiency

Remediation of heavy metal polluted sediment by extracting the metals with sulfuric acid can be performed as follows: abiotic suspension leaching, microbial suspension leaching, abiotic solid-bed leaching, and microbial solid-bed leaching. Abiotic leaching means that the acid is directly added, while microbial leaching means that the acid is generated from sulfur by microbes (bioleaching). These four principles were compared to each other with special emphasis on the effectiveness of metal solubilization and metal removal by subsequent washing. Abiotic suspension leaching was fastest, but suspending the solids exhibits some disadvantages (low solid content, costly reactors, permanent input of energy, high water consumption, special equipment required for solid separation, large amounts of waste water, sediment properties hinder reuse), which prevent suspension leaching in practice. Abiotic solid-bed leaching implies the supply of acid by percolating water which proceeds slowly due to a limited bed permeability. Microbial solid-bed leaching means the generation of acid within the bed and has been proven to be the only principle applicable to practice. Metal removal from leached sediment requires washing with water. Washing of solid beds was much more effective than washing of suspended sediment. The kinetics of metal removal from solid beds 0.3, 0.6 or 1.2m in height were similar; when using a percolation flow of 20lm(-2)h(-1), the removal of 98% of the mobile metals lasted 57-61h and required 8.5, 4.2 or 2.3lkg(-1) water. This means, the higher the solid bed, the lower the sediment-mass-specific demand for time and water.     

Characterisation of polymer fractions from waste electrical and electronic equipment (WEEE) and implications for waste management

There is an increasing interest in the end-of-life management of polymers present in waste electrical and electronic equipment (WEEE). This is mainly due to high recycling and recovery quotas set by the European WEEE directive, which can only be fulfilled by including the plastic fraction in recycling and recovery approaches. Previous studies identified a high material diversity and various contaminants in WEEE plastics, including heavy metals, polybrominated biphenyls (PBB), diphenyl ethers (PBDE), as well as polybrominated dibenzodioxins and dibenzofurans (PBDD/F). These substances are regulated by European directives that limit their levels in marketable products. Consequently, both material diversity and contaminants are strong arguments against material recycling and point to hazardous waste treatment. However, recent developments in the production of flame retardants and electrical and electronic goods aimed to reduce contaminants and material diversity. Thus, the present study summarises updated contaminant levels of plastic fractions of European WEEE, as well as data on materials in waste housing polymers. Material characterisation revealed housing fractions to be interesting sources for polymer recycling, which however has to implement potent material separation and/or bromine elimination techniques. With respect to contaminants, our data indicate an effective phase-out of PBB, but still high levels of PBDE and PBDD/F are found. Sources and implications for the material recycling and thermal recovery approaches are discussed in detail.     

Chelate assisted phytoextraction of heavy metals from soil. Effect, mechanism, toxicity, and fate of chelating agents

The low-cost, plant-based phytoextraction technique has often been described as a promising technique to remediate heavy metal contaminated agricultural land. The application of chelating agents has shown positive effects in increasing the solubility of heavy metals in soil and therefore in enhancing phytoextraction. This paper gives an overview of the chelating agents applied in recent studies. Various synthetic aminopolycarboxylic acids, such as ethylene diamine tetraacetic acid, and natural ones such as, ethylene diamine disuccinate and nitrilotriacetic acid, are described. Additionally, results of the application of natural low molecular weight organic acids, such as citric and tartaric acid are given. The effectiveness of these different chelating agents varies according to the plant and the heavy metals used. Furthermore, a focus is laid on the chelating agents fate after application and on its toxicity to plants and soil microorganisms, as well as it degradation. The rate of degradation is of great importance for the future of chelate assisted phytoextraction as it has a direct impact on the leaching probability. An effective prevention of leaching will be crucial for the acceptance and the economic breakthrough of enhanced phytoextraction, but a satisfactory solution to this key issue has so far not been found. Possibly further experiments in the field of enhanced phytoextraction will be able to solve this major problem, but over decades various greenhouse experiments and recently field experiments have resulted in different observations. Therefore, it is questionable if further research in this direction will lead to a promising solution. Phytoextraction has possibly reached a turning point in which it should distance itself from chelate assisted phytoextraction and focus on alternative options.     

Post-combustion syntheses of PCDD/F and PBDD/F from halogen-rich fuel is suppressed by a pebble heater technology

GOAL, SCOPE AND BACKGROUND: Changes in German and European legislation shifted processing of polymer-rich shredding residues (SR) from landfill to thermal treatment. However, when waste of electric and electronic equipment (WEEE) is the source of SR, thermal treatment is complicated by halogens as well as the presence of polybrominated dioxins and furans (PBDD/F) and brominated flame retardants (BFR). Hence, WEEE requires high temperature incineration with sufficient residence times. Post-combustion synthesis of polyhalogenated dioxins and furans (PXDD/F) is dominant in the temperature range between 250-450 degrees C. Thus, a very rapid gas cooling from 450 degrees to 250 degrees C is important for proper raw gas treatment. The pebble heater technology developed by ATZ Entwicklungszentrum (Sulzbach-Rosenberg, Germany) might serve as an alternative to the state-of-the-art quench cooling. It is based on the application of a pebble bed of natural bulk material, which the exhaust gases flows through radially. It provides an excellent heat transfer and a temperature gradient in the range of 1,500-2,000 K/m. The paper presents data of a pilot application of the pebble heater technology for the treatment of raw gas derived from the incineration of polymeric materials from WEEE. METHODS: A liquid fuel was chosen in order to minimise technical modifications of the plant. It was analysed for halogens by x-ray fluorescence, for brominated flame retardants by HPLC-UV/MS and for PXDD/F by GC-HRMS. Combustion gases were rapidly cooled down to temperatures below 200 degrees C and emissions of PBDD/F and PCDD/ F were estimated without further off-gas treatment. PBDD/F emissions were computed as PCDD/F toxicity equivalents applying two different calculation approaches. RESULTS AND DISCUSSION: PCDD/F emissions accounted for 0.04 ng I-TEQ/Nm3 and are in compliance with European emission limits. Calculated PBDD/F toxicity equivalents exceeded the emission limit of 0.1 ng I-TEQ/Nm3 by factors of 75 and 208 depending on the calculation approach. A mass balance of PBDD/F and PCDD/F congeners revealed an efficient elimination of more than 95% in most cases. Lower reduction rates (76% for 2,3,7,8-TeBDF and 82% for 1,2,3,7,8-PeBDF) were attributed to incomplete combustion. An intended recovery of halogens by one-stage scrubbing downstream of the pebble heater was ineffective, recovering 28% of the applied chlorine and 9% of the bromine, only. CONCLUSIONS: Our pilot incineration test indicates that the pebble heater technology can effectively suppress a post-combustion synthesis of PCDD/F and PBDD/F, resulting in low PCDD/F emission levels without further off-gas treatment. The presented data state that WEEE is sensible to incomplete combustion, which will lead to increased PBDD/F emissions without increasing PCDD/F emission limits. This finding is especially relevant for small and low-technical incineration appliances, which have been reported to treat WEEE in developing countries and are considered to serve as a significant source of PXDD/F these days. RECOMMENDATIONS AND PERSPECTIVES: Monitoring of PCDD/F emissions only might considerably underestimate the total emission of dioxins and dioxin-like compounds. It is therefore an ineffective means for assessing resulting health risks, at least for those waste treatment plants which are considered to handle the increasing amounts of PBDD/ F-containing polymers from WEEE in future. Consequently, it is recommended to initiate a screening programme for PXDD/F emissions in large scale incineration facilities which are capable of treating WEEE shredder residues.