Persistence of residues in water and sediment of a fresh-water lake after surface application of technical chlordane

A fresh-water lake, free from detectable pesticide residues before this study, was treated with a commercial formulation of technical chlordane. Water and sediment samples were analysed for chlordane residues 7, 24, 52, 279. and 421 days after treatment. Residues moved rapidly from the water to the lake bottom, supporting earlier results of a laboratory study with other organochlorines. In water, alpha- and gamma-chlordane concentrations remained proportional to total chlordane concentrations, as determined by total-peak area measurements of gas-liquid chromatogrammes. But in bottom sediments, alpha- and gamma-chlordane were more persistent than other constituents of technical chlordane, supporting recent evidence that quantification of technical chlordane residues on the basis of gamma-chlordane quantification only (or that of alpha- and gamma-chlordane only), can lead to incorrect results and that this method, although simple and fast, should no longer be recommended.     

Feasibility of coupling a thermal/optical carbon analyzer to a quadrupole mass spectrometer for enhanced PM2.5 speciation

A thermal/optical carbon analyzer (TOA), normally used for quantification of organic carbon (OC) and elemental carbon (EC) in PM_2.5 (fine particulate matter) speciation networks, was adapted to direct thermally evolved gases to an electron impact quadrupole mass spectrometer (QMS), creating a TOA-QMS. This approach produces spectra similar to those obtained by the Aerodyne aerosol mass spectrometer (AMS), but the ratios of the mass to charge (m/z) signals differ and must be remeasured using laboratory-generated standards. Linear relationships are found between TOA-QMS signals and ammonium (NH₄⁺), nitrate (NO₃^?), and sulfate (SO₄^2-) standards. For ambient samples, however, positive deviations are found for SO₄^2-, compensated by negative deviations for NO₃^?, at higher concentrations. This indicates the utility of mixed-compound standards for calibration or separate calibration curves for low and high ion concentrations. The sum of the QMS signals across all m/z after removal of the NH₄⁺, NO₃^?, and SO₄^2- signals was highly correlated with the carbon content of oxalic acid (C?H?O?) standards. For ambient samples, the OC derived from the TOA-QMS method was the same as the OC derived from the standard IMPROVE_A TOA method. This method has the potential to reduce complexity and costs for speciation networks, especially for highly polluted urban areas such as those in Asia and Africa.

Implications: Ammonium, nitrate, and sulfate can be quantified by the same thermal evolution analysis applied to organic and elemental carbon. This holds the potential to replace multiple parallel filter samples and separate laboratory analyses with a single filter and a single analysis to account for a large portion of the PM_2.5 mass concentration.     

Comparison on surface properties and desulfurization of MnO2 and pyrolusite blended activated carbon by steam activation

In this study, MnO₂ and pyrolusite were used as the catalysts to prepare modified activated carbon, that is, AC-Mn and AC-P, respectively, from coals by blending method and steam activation. The Brunauer–Emmett–Teller (BET) results indicated that the AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The relative contents of basic functional groups (i.e., C = O, π-π*) on AC-P were slightly lower than those on AC-Mn, while both contained the same main metal species, namely, MnO. The desulfurization results showed that with 3 wt% of blending ratio, AC-Mn3 and AC-P3 had higher sulfur capacities at 220 and 205 mg/g, respectively, which were much higher than for the blank one (149.6 mg/g). Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn, which might be attributed to the existence of other metals in pyrolusite. After the desulfurization process, MnO were gradually transferred into MnSO₄, and the relative contents of basic functional groups decreased evidently for both AC-Mn3 and AC-P3. The results demonstrated that pyrolusite could be one good alternative to MnO₂ to prepare modified activated carbon for desulfurization.

Implications: MnO₂ and pyrolusite were used as the additives to prepare modified activated carbon from coals by a blending method and by steam activation, that is, AC-Mn and AC-P, respectively. The AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The AC-Mn and AC-P had higher sulfur capacities than a blank one. Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn. The results demonstrated that pyrolusite could be one good alternative to MnO₂ to prepare modified activated carbon for desulfurizatio.     

回流立式组合人工湿地处理生活污水的效果

针对目前我国农村存在的生活污水随意排放问题,构建了一种安装方便、工艺简单的回流立式组合人工湿地系统用于处理生活污水,研究其对污染物质的去除效果和过程,及不同基质（砾石、陶粒、火山石）间污染物质去除的差异。结果显示,回流立式组合人工湿地系统对COD、NH4+-N、TN、TP的去除率分别高达95%、99%、53%、57%,其中COD、NH4+-N的去除过程符合一级动力学模型。不同基质组湿地对生活污水处理效果存在显著差异（P4+-N、TN的去除效果较好,火山石组对COD、TP去除效果较好,可分别作为人工湿地脱氮除磷的优先选择。结果表明,回流立式组合人工湿地去除能力好、占地面积小、操作方便,是一种具有广阔发展前景的农村污水处理技术。     

The fractionation and geochemical characteristics of rare earth elements measured in ambient size-resolved PM in an integrated iron and steelmaking industry zone

Environmental Science and Pollution Research - Improved understanding of the fractionation and geochemical characteristic of rare earth elements (REEs) from steel plant emissions is important due...     

微好氧预处理对市政污泥厌氧消化产甲烷的影响

针对目前市政污泥处理资源化与减量化效率低的问题,利用微好氧预处理技术进行预处理,提高其甲烷产量。利用有机物溶出效率、VSS减量、甲烷产量3项指标对预处理效果进行了评价;研究了不同参数条件下微好氧预处理对市政污泥厌氧消化产甲烷的影响;探讨了微好氧预处理对污泥胞外聚合物的影响。结果表明,微好氧预处理可以促进污泥溶解性有机物释放、提高VSS去除率;在最佳反应条件下(曝气强度0.30 m³·(min·m³)⁻¹、预处理时间12 h),相对于未经过预处理的工况,甲烷产量可提高26.77%;微好氧预处理对剩余污泥活性细胞的影响主要发生在胞外聚合物部分,同时也存在对活性微生物的破解作用。市政污泥经过微好氧预处理后,可有效提升后续中温厌氧消化或高温厌氧消化的甲烷产量。     

Immobilization of fungal laccase onto a nonionic surfactant-modified clay material: application to PAH degradation

Nonionic surfactant-modified clay is a useful absorbent material that effectively removes hydrophobic organic compounds from soil/groundwater. We developed a novel material by applying an immobilized fungal laccase onto nonionic surfactant-modified clay. Low-water-solubility polycyclic aromatic hydrocarbons (PAHs) (naphthalene/phenanthrene) were degraded in the presence of this bioactive material. PAH degradation by free laccase was higher than degradation by immobilized laccase when the surfactant concentration was allowed to form micelles. PAH degradation by immobilized laccase on TX-100-modified clay was higher than on Brij35-modified clay. Strong laccase degradation of PAH can be maintained by adding surfactant monomers or micelles. The physical adsorption of nonionic surfactants onto clay plays an important role in PAH degradation by laccase, which can be explained by the structure and molecular interactions of the surfactant with the clay and enzyme. A system where laccase is immobilized onto TX-100-monomer-modified clay is a good candidate bioactive material for in situ PAHs bioremediation.     

Upgrading food wastes by means of bromelain and papain to enhance growth and immunity of grass carp (<Emphasis Type="Italic">Ctenopharyngodon idella</Emphasis>)

The fast growing of global aquaculture industry accompanied with increasing pressure on the supply and price of traditional feed materials (e.g., fish meal and soy bean meal). This circumstance has urged the need to search alternative sources of feed stuff. Food waste was used as feed stuff in rearing fish which possess substantial protein and lipid. Grass carp are major species reared in Hong Kong with lower nutritional requirements; it is also an ideal species for investigating the feasibility of using food waste as fish feeds for local aquaculture industry. The growth and immunity, reflected by total protein, total immunologlobulin (IgI), and nitroblue tetrazolium (NBT) activity of grass carp blood, were depressed when feeding with food waste feeds without enzymes. However, the supplementation of bromelain and papain in fish feed enhanced the efficient use of food waste by grass carp, which in turn improved the fish immunity. The present results indicated that the addition of those enzymes could enhance the feed utilization by fish and hematological parameters of grass carp, and the improvement on growth and immunity superior to the control (commercial feed) was observed with the addition of bromelain and papain supplement. Addition of 1 and 2 % mixture of bromelain and papain could significantly enhance the lipid utilization in grass carp.