Studies on polycyclic aromatic hydrocarbons in two sediment cores from the huaxi reservoir,china: Assessment of levels,sources, and ecological risk

This study investigated the levels, sources and ecological risks of 16 polycyclic aromatic hydrocarbons (PAHs) in two sediment cores that were collected along the Huaxi Reservoir. The spatial distributions and residue levels of the 16 priority PAHs in the sediments from the Huaxi Reservoir were analyzed for their potential ecological risk, source apportionment and contribution to the total PAH residue. The concentration level of the total PAHs (TPAHs) was in the range 1805 ng·g^?1 to 20023 ng·g^?1 based on dry weight, and the content of PAHs in the Huaxi Reservoir exhibited a gradual upward trend. The PAH congener ratios fluoranthene/(fluoranthene + pyrene) and indeno[1, 2, 3-cd]pyrene/(indeno[1, 2, 3-cd]pyrene + benzo[g, h, i]perylene) were used to identify the source. The main source of the low molecular weight PAHs was wood and coal combustion, whereas the high molecular weight PAHs were primarily from petroleum combustion sources. The results of an ecological risk assessment demonstrated that ACE poses a potential ecological risk, while FLU, NAP, ANT, BaP, DBA, PHEN and PYR can have serious ecological risks.     

Robust Regression with Data-Dependent Regularization Parameters and Autoregressive Temporal Correlations

We introduce robust procedures for analyzing water quality data collected over time. One challenging task in analyzing such data is how to achieve robustness in presence of outliers while maintaining high estimation efficiency so that we can draw valid conclusions and provide useful advices in water management. The robust approach requires specification of a loss function such as the Huber, Tukey’s bisquare and the exponential loss function, and an associated tuning parameter determining the extent of robustness needed. High robustness is at the cost of efficiency loss in parameter loss. To this end, we propose a data-driven method which leads to more efficient parameter estimation. This data-dependent approach allows us to choose a regularization (tuning) parameter that depends on the proportion of “outliers” in the data so that estimation efficiency is maximized. We illustrate the proposed methods using a study on ammonium nitrogen concentrations from two sites in the Huaihe River in China, where the interest is in quantifying the trend in the most recent years while accounting for possible temporal correlations and “irregular” observations in earlier years.     

Formation of persistent chlorinated aromatic compounds in simulated and real fly ash from iron ore sintering

Effects of carbon concentration and Cu additive in simulated fly ash (SFA) and real fly ash (RFA) on the formation of polychlorinated dibenzofurans (PCDFs), polychlorinated dibenzo-p-dioxins (PCDDs), chlorobenzenes, and polychlorinated biphenyls which were all regarded as persistent chlorinated aromatics in iron ore sintering were investigated. In the annealing process of SFA with various carbon contents, the yield of chlorinated aromatics and the I-TEQ obtained their maximum at 10 wt% carbon content. Active carbon in SFA acted as the carbon source as well as an adsorbent which led to higher production of PCDD/F in solid phase at 10 wt% carbon content. The increase of carbon content will be beneficial on the formation of 2,3,7,8-Chloro-substituted PCDF compared with 2,3,7,8-Chloro-substituted PCDD. In addition, the CuCl₂·2H₂O was a much more powerful catalyst in the formation of chlorinated aromatic compounds compared with elementary Cu, since it served as both a catalyst and a chlorine donor. However, the RFA behaved similarly with SFA with elementary Cu in the formation of chlorinated aromatic compounds. The effect of carbon content and copper additives on formation of 2,3,7,8-chloro-substituted congeners displayed similar characteristics with the tetra- to octa-PCDD/F isomers and even the total PCDD/Fs.     

Hydro-thermal reaction according to the CaO/SiO2 mole-ratio in silico-manganese slag

Journal of Material Cycles and Waste Management - SiMn slag is a by-product of the production of ferroalloy, and has a chemical composition that could be used as a cement admixture. It is not...     

Role of membrane and compound properties in affecting the rejection of pharmaceuticals by different RO/NF membranes

This study was conducted to assess the merits and limitations of various high-pressure membranes, tight nanofiltration (NF) membranes in particular, for the removal of trace organic compounds (TrOCs). The performance of a low-pressure reverse osmosis (LPRO) membrane (ESPA1), a tight NF membrane (NF90) and two loose NF membranes (HL and NF270) was compared for the rejection of 23 different pharmaceuticals (PhACs). Efforts were also devoted to understand the effect of adsorption on the rejection performance of each membrane. Difference in hydrogen bond formation potential (HFP) was taken into consideration. Results showed that NF90 performed similarly to ESPA1 with mean rejection higher than 95%. NF270 outperformed HL in terms of both water permeability and PhAC rejection higher than 90%. Electrostatic effects were more significant in PhAC rejection by loose NF membranes than tight NF and LPRO membranes. The adverse effect of adsorption on rejection by HL and ESPA1 was more substantial than NF270 and NF90, which could not be simply explained by the difference in membrane surface hydrophobicity, selective layer thickness or pore size. The HL membrane had a lower rejection of PhACs of higher hydrophobicity (log D>0) and higher HFP (>0.02). Nevertheless, the effects of PhAC hydrophobicity and HFP on rejection by ESPA1 could not be discerned. Poor rejection of certain PhACs could generally be explained by aspects of steric hindrance, electrostatic interactions and adsorption. High-pressure membranes like NF90 and NF270 have a high promise in TrOC removal from contaminated water.

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Spatial variation and toxicity assessment for heavy metals in sediments of intertidal zone in a typical subtropical estuary (Min River) of China

Environmental Science and Pollution Research - Sediment samples were collected in five marshes (C1, Phragmites australis marsh; C2, P. australis and Cyperus malaccensis marsh; C3, C. malaccensis...     

Optimum ridge-to-furrow ratio in ridge-furrow mulching systems for improving water conservation in maize (Zea may L.) production

Environmental Science and Pollution Research - Water-saving cultivation techniques have been attracting increased attention worldwide. Ridge-furrow mulching system (RFMS), as a prospective...     

Microbial community composition and electricity generation in cattle manure slurry treatment using microbial fuel cells: effects of inoculum addition

Environmental Science and Pollution Research - Microbial fuel cell (MFC) is a sustainable technology to treat cattle manure slurry (CMS) for converting chemical energy to bioelectricity. In this...     

Overview of surface measurements and spatial characterization of submicrometer particulate matter during the DISCOVER-AQ 2013 campaign in Houston,TX

The sources of submicrometer particulate matter (PM₁) remain poorly characterized in the industrialized city of Houston, TX. A mobile sampling approach was used to characterize PM₁ composition and concentration across Houston based on high-time-resolution measurements of nonrefractory PM₁ and trace gases during the DISCOVER-AQ Texas 2013 campaign. Two pollution zones with marked differences in PM₁ levels, character, and dynamics were established based on cluster analysis of organic aerosol mass loadings sampled at 16 sites. The highest PM₁ mass concentrations (average 11.6 ± 5.7 µg/m³) were observed to the northwest of Houston (zone 1), dominated by secondary organic aerosol (SOA) mass likely driven by nighttime biogenic organonitrate formation. Zone 2, an industrial/urban area south/east of Houston, exhibited lower concentrations of PM₁ (average 4.4 ± 3.3 µg/m³), significant organic aerosol (OA) aging, and evidence of primary sulfate emissions. Diurnal patterns and backward-trajectory analyses enable the classification of airmass clusters characterized by distinct PM sources: biogenic SOA, photochemical aged SOA, and primary sulfate emissions from the Houston Ship Channel. Principal component analysis (PCA) indicates that secondary biogenic organonitrates primarily related with monoterpenes are predominant in zone 1 (accounting for 34% of the variability in the data set). The relevance of photochemical processes and industrial and traffic emission sources in zone 2 also is highlighted by PCA, which identifies three factors related with these processes/sources (~50% of the aerosol/trace gas concentration variability). PCA reveals a relatively minor contribution of isoprene to SOA formation in zone 1 and the absence of isoprene-derived aerosol in zone 2. The relevance of industrial amine emissions and the likely contribution of chloride-displaced sea salt aerosol to the observed variability in pollution levels in zone 2 also are captured by PCA.

Implications: This article describes an urban-scale mobile study to characterize spatial variations in submicrometer particulate matter (PM₁) in greater Houston. The data set indicates substantial spatial variations in PM₁ sources/chemistry and elucidates the importance of photochemistry and nighttime oxidant chemistry in producing secondary PM₁. These results emphasize the potential benefits of effective control strategies throughout the region, not only to reduce primary emissions of PM₁ from automobiles and industry but also to reduce the emissions of important secondary PM₁ precursors, including sulfur oxides, nitrogen oxides, ammonia, and volatile organic compounds. Such efforts also could aid in efforts to reduce mixing ratios of ozone.     

模拟阳光下Ag／I-TiO2光催化预处理山核桃加工废水

研究了在模拟太阳光下,采用银修饰的碘掺杂二氧化钛光催化剂（Ag／I—TiO2）对某食品厂山核桃加工废水进行光催化预处理的效果。结合x射线衍射（XRD）、比表面积分析（BET）、紫外-可见漫反射光谱（uV—Vis）的表征结果,来分析催化剂结构对于废水处理效果的影响。探讨了Ag含量、废水初始pH（pHi）和光照时间等因素对化学需氧量（COD）去除及水质可生化性（B／C）提高的影响。并得出适宜的反应参数为：3％Ag含量;pHi为6;光照时间为240min。在最佳条件下,COD去除率45％,废水B／C比由0．17上升到0．31。光催化氧化法能够有效降低山核桃加工废水的COD含量,并达到显著提高废水可生化性的目的。