Cyclic volatile methylsiloxanes in fish from the Baltic Sea

Laboratory studies suggest that the cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) will persist in the aquatic environment and bioaccumulate in fish. Here these cVMS were measured in herring collected in the Swedish waters of the Baltic Sea and the North Sea and in grey seals from the Baltic Proper. D4, D5, and D6 were present in herring muscle at concentrations around 10, 200, and 40 ng g⁻¹ lipid weight, respectively. The ratio of these concentrations was similar to the relative magnitude of estimated emissions to water, suggesting that the efficiency of overall transfer through the environment and food web was similar (within a factor 2–3) for the three chemicals. The concentrations of D5 and D6 were similar in herring caught in the highly populated Baltic Proper and in the less populated Bothnian Sea and Bothnian Bay. The D4 concentrations were lower at the most remote northern station, suggesting that D4 is less persistent than D5 and D6. Herring from the North Sea had lower levels of all three chemicals. The concentrations of D4, D5 and D6 in grey seal blubber were lower than the lipid normalized concentrations in herring, indicating that they do not biomagnify in grey seals.     

Junge relationships in measurement data for cyclic siloxanes in air

In 1974, Junge postulated a relationship between variability of concentrations of gases in air at remote locations and their atmospheric residence time, and this Junge relationship has subsequently been observed empirically for a range of trace gases. Here, we analyze two previously-published datasets of concentrations of cyclic volatile methyl siloxanes (cVMS) in air and find Junge relationships in both. The first dataset is a time series of concentrations of decamethylcyclopentasiloxane (D₅) measured between January and June, 2009 at a rural site in southern Sweden that shows a Junge relationship in the temporal variability of the measurements. The second dataset consists of measurements of hexamethylcyclotrisiloxane (D₃), octamethylcyclotetrasiloxane (D₄) and D₅ made simultaneously at 12 sites in the Global Atmospheric Passive Sampling (GAPS) network that shows a Junge relationship in the spatial variability of the three cVMS congeners. We use the Junge relationship for the GAPS dataset to estimate atmospheric lifetimes of dodecamethylcyclohexasiloxane (D₆), 8:2–fluorotelomer alcohol and trichlorinated biphenyls that are within a factor of 3 of estimates based on degradation rate constants for reaction with hydroxyl radical determined in laboratory studies.     

5:3 Polyfluorinated acid aerobic biotransformation in activated sludge via novel "one-carbon removal pathways"

The polyfluorinated carboxylic acids 5:3 acid (C₅F₁₁CH₂CH₂CO₂H) and 7:3 acid (C₇F₁₅CH₂CH₂CO₂H) are major products from 6:2 FTOH (C₆F₁₃CH₂CH₂OH) and 8:2 FTOH (C₈F₁₇CH₂CH₂OH) aerobic biotransformation, respectively. The 5:3 and 7:3 acids were dosed into domestic WWTP activated sludge for 90 d to determine their biodegradability. The 7:3 acid aerobic biodegradability was low, only 1.7 mol% conversion to perfluoroheptanoic acid (PFHpA), whereas no transformation was observed previously in soil. In stark contrast, 5:3 acid aerobic biodegradability was enhanced 10 times in activated sludge compared to soil. The 5:3 acid was not activated by acyl CoEnzyme A (CoA) synthetase, a key step required for further α- or ß-oxidation. Instead, 5:3 acid was directly converted to 4:3 acid (C₄F₉CH₂CH₂CO₂H, 14.2 mol%) and 3:3 acid (C₃F₇CH₂CH₂CO₂H, 0.9 mol%) via “one-carbon removal pathways”. The 5:3 acid biotransformation also yielded perfluoropentanoic acid (PFPeA, 5.9 mol%) and perfluorobutanoic acid (PFBA, 0.8 mol%). This is the first report to identify key biotransformation intermediates which demonstrate novel one-carbon removal pathways with sequential removal of CF₂ groups. Identified biotransformation intermediates (10.2 mol% in sum) were 5:3 Uacid, α-OH 5:3 acid, 5:2 acid, and 5:2 Uacid. The 5:2 Uacid and 5:2 acid are novel intermediates identified for the first time which confirm the proposed pathways. In the biodegradation pathways, the genesis of the one carbon removal is CO₂ elimination from α-OH 5:3 acid. These results suggest that there are enzymatic mechanisms available in the environment that can lead to 6:2 FTOH and 5:3 acid mineralization. The dehydrogenation from 5:3 acid to 5:3 Uacid was the rate-limiting enzymatic step for 5:3 acid conversion to 4:3 acid.     

Volatile organic compounds at swine facilities: A critical review

Volatile organic compounds (VOCs) are regulated aerial pollutants that have environmental and health concerns. Swine operations produce and emit a complex mixture of VOCs with a wide range of molecular weights and a variety of physicochemical properties. Significant progress has been made in this area since the first experiment on VOCs at a swine facility in the early 1960s. A total of 47 research institutions in 15 North American, European, and Asian countries contributed to an increasing number of scientific publications. Nearly half of the research papers were published by U.S. institutions.Investigated major VOC sources included air inside swine barns, in headspaces of manure storages and composts, in open atmosphere above swine wastewater, and surrounding swine farms. They also included liquid swine manure and wastewater, and dusts inside and outside swine barns. Most of the sample analyses have been focusing on identification of VOC compounds and their relationship with odors. More than 500 VOCs have been identified. About 60% and 10% of the studies contributed to the quantification of VOC concentrations and emissions, respectively. The largest numbers of VOC compounds with reported concentrations in a single experimental study were 82 in air, 36 in manure, and 34 in dust samples.The relatively abundant VOC compounds that were quantified in at least two independent studies included acetic acid, butanoic acid (butyric acid), dimethyl disulfide, dimethyl sulfide, iso-valeric, p-cresol, propionic acid, skatole, trimethyl amine, and valeric acid in air. They included acetic acid, p-cresol, iso-butyric acid, butyric acid, indole, phenol, propionic acid, iso-valeric acid, and skatole in manure. In dust samples, they were acetic acid, propionic acid, butyric acid, valeric acid, p-cresol, hexanal, and decanal. Swine facility VOCs were preferentially bound to smaller-size dusts.Identification and quantification of VOCs were restricted by using instruments based on gas Chromatography (GC) and liquid chromatography (LC) with different detectors most of which require time-consuming procedures to obtain results. Various methodologies and technologies in sampling, sample preparation, and sample analysis have been used. Only four publications reported using GC based analyzers and PTR-MS (proton-transfer-reaction mass spectrometry) that allowed continuous VOC measurement. Because of this, the majority of experimental studies were only performed on limited numbers of air, manure, or dust samples. Many aerial VOCs had concentrations that were too low to be identified by the GC peaks.Although VOCs emitted from swine facilities have environmental concerns, only a few studies investigated VOC emission rates, which ranged from 3.0 to 176.5 mg d⁻¹ kg⁻¹ pig at swine finishing barns and from 2.3 to 45.2 g d⁻¹ m⁻² at manure storages. Similar to the other pollutants, spatial and temporal variations of aerial VOC concentrations and emissions existed and were significantly affected by manure management systems, barn structural designs, and ventilation rates.Scientific research in this area has been mainly driven by odor nuisance, instead of environment or health concerns. Compared with other aerial pollutants in animal agriculture, the current scientific knowledge about VOCs at swine facilities is still very limited and far from sufficient to develop reliable emission factors.     

Human–environment interactions: towards synthesis and simulation

Leaders of the PAGES Focus 5 programme ‘Past Ecosystem Processes and Human–Environment Interactions’ identify key issues for research on human–environment interactions for wider discussion. These include the need for long-term perspectives, the opportunities for maximising palaeoenvironmental research, the need for integration and regionalisation and the challenge of developing dynamic simulation models. A new organisational matrix for regional studies is outlined, based on a series of zonal/azonal regions and on the degree of human impact. Future priorities for palaeoenvironmental research include new studies in degraded human-dominated landscapes, highly-valued ecosystems and sites relevant to other IGBP Core Projects. Simulation of future human–environment interactions using modelling approaches that have been tested against long records lags behind global climate modelling, but cellular approaches for biogeophysical and multi-agent systems show promise.     

壳聚糖-钇多孔微球对Cr(Ⅵ)的吸附性能与机理分析

以壳聚糖和Y2(OH)5NO3为原料通过乳液交联法制备了壳聚糖-钇(Ch—Y)复合微球,通过扫描电镜、透射电镜、X射线衍射、红外光谱等方法对其表面形貌、结构进行了表征.探讨了溶液的pH值、反应时间、投加量、离子初始浓度对其吸附性能的影响.研究结果表明,壳聚糖-钇(Ch—Y)复合微球在pH值为3的酸性环境中对Cr(Ⅵ)保持了较高的吸附能力,吸附容量为52.39mg·g-1,其吸附行为符合Langmuir吸附等温模型;通过吸附机理的研究,发现壳聚糖-钇(Ch—Y)对Cr(Ⅵ)吸附是化学吸附静电吸附协同氧化Cr(Ⅵ)离子作用来实现的.     

Characterization and assessment of “Kullar Domestic Wastewater Treatment Plant” wastewaters

We investigated conventional characterization of wastewaters of the "Kullar Domestic Wastewater Treatment Plant." In the study of conventional characterization; 23 composite samples, which were taken during 10 months, were used and analysed as COD, BOD5, TKN, NH3-N, SS, VSS, TP, RP, TS, Alkalinity, oil and grease, detergent, chloride parameters. For determine of the plant efficiency, 8 output grab samples were taken. The COD and BOD5 values of influent, respectively, ranging from 37 to 1,056 mg/L and 8 to 140 mg/L in total wastewater. The meanly BOD5/COD ratio was calculated as 0.34 in total wastewaters.     

1,2,4,5-四氯苯 C 18 Empore TM 膜/水分配系数的研究

研究了1,2,4,5-四氯苯在C18膜／水相之间的分配规律。1,2,4,5-四氯苯在：25℃,80r／min条件下恒温震荡96h可达分配平衡,温度和盐度对1,2,4,5-四氯苯C18膜／水的分配过程影响很小,1,2,4,5-四氯苯C18膜／水分配平衡时间受溶液体积和容器容积的影响,但不受溶液中C18膜膜量的影响,推测脂溶性小于或接近1,2,4,5-四氯苯的有机污染物在恒温震荡条件下C18膜与水之间的分配96h可达到平衡。     

镉铜污染尾矿土中添加耐镉铜菌剂J5后微生物区系多样性的变化

采用酶解法和化学裂解法相结合的方法从安徽铜陵镉铜污染尾矿土中提取出土壤微生物基因组总DNA,并应用PCR-DGGE技术对比研究尾矿土中添加外源硫酸镉、硫酸铜和耐镉铜菌剂J5(Pseudomonassp.)后微生物区系多样性的变化.结果表明,尾矿土中微生物基因组总DNA分子量大小为21kb左右,未复垦的尾矿砂中微生物总DNA量较少,CdSO4处理后的尾矿土中微生物基因组总DNA量明显下降,而添加菌剂J5的尾矿土中微生物基因组总DNA量上升.DGGE电泳图谱进一步显示,尾矿土样中添加镉离子使图谱条带减少,分析表明尾矿土中的细菌种类数减少;而添加菌剂J5使图谱中条带明显增加,表明菌剂J5可提高尾矿土中土著微生物的活性和群落丰富度,可用于复合重金属污染尾矿区的生态恢复.     

厌氧生物降解活性黑KN-B5

研究了在葡萄糖作为共代谢基质时活性黑KN-B5的降解效果。实验结果表明:当葡萄糖质量浓度为1 500m g/L时,活性黑KN-B5初始质量浓度为30m g/L的染料溶液厌氧生物降解24h和48h后的降解率分别达到77.5%和90.3%;活性黑KN-B5的厌氧降解符合一级动力学方程,其反应速率常数为0.043 6h-1,半衰期为15.9h;葡萄糖质量浓度的增大对提高活性黑KN-B5厌氧生物降解效果有利。紫外-可见光谱扫描结果表明,活性黑KN-B5的降解过程中生成了小分子芳香胺类化合物;扫描电子显微镜照片表明污泥中对活性黑KN-B5起降解作用的菌种主要是杆菌和球菌。