Bioavailability evaluation of naphthalene in soil using persulfate oxidation and ultrasonic extraction method

Bioavailability is defined as the fraction of a soil contaminant readily available for microbial degradation and for naphthalene it could be estimated by conventional exhaustive extraction methods. In this study, a novel method that employed persulfate oxidation in combination with ultrasonic extraction (POUSE) was developed. Three parameters, temperature, duration of persulfate oxidation, and the ratio of persulfate to soil organic matter (2S,082 /SOM; g g-1), were investigated to obtain an optimum operating conditions. Under the condition, naphthalene bioavailability estimated by the POUSE method was verified and compared with other three exhaustive methods i.e. sonicator, supercritical fluid extraction (SFE), and soxhlet extraction (SE). When the S2,O(8)2-/SOM ratio was controlled at 11.6 g g-1, the optimum operating conditions of the POUSE method were 70 degreesC and 3 hr, for the temperature and duration. Under these conditions, the residual naphthalene concentrations were correlated well with the residual naphthalene concentrations for both the cases of freshly spiked and aged soils. By contrast, the sonicator, SFE, and the SE overestimated the naphthalene bioavailability since these three methods extracted naphthalene much more than that of biodegradation test. These results demonstrated that the POUSE could estimate more precisely the naphthalene bioavailability.     

Integrated estuary management for diffused sediment pollution in Dapeng Bay and neighboring rivers (Taiwan)

This work investigated sediment samples collected from Dapeng Bay and three neighboring rivers (Kaoping River, Tungkang River, and Lingbeng River) in southwestern Taiwan, Republic of China. Multivariate statistical analysis techniques, i.e., factor analysis, cluster analysis, and canonical discriminant analysis were used for the evaluation of spatial variations to determine the types of pollution and to identify pollutant sources from neighboring rivers. Factor analysis results showed that the most important latent factors in Dapeng Bay are soil texture, heavy metals, organic matter, and nutrients factors. Contour maps incorporating the factor scores showed heavy metals accumulate along the lakesides, especially on the southeastern banks of the lakes. A cluster analysis was performed using factor scores computed from these latent factors. We then classified these areas into five distinct classes using sampling stations, and we illustrate that in the three river classes, the sediment properties are influenced by industrial and domestic wastewater and agricultural activities (including livestock rearing and farm activities). However, in Dapeng Bay, the rivers were influenced more by complicated biogeochemical processes; these could be identified as a type of pollution. Canonical discriminant analysis illustrated that two constructed discriminant functions made a marked contribution to most of the discriminant variables, and the significant parameters of porosity and Cd, Cr, Al, and Pb content were combined as the ??heavy metal factor??. The recognition capacities of the two discriminant functions were 82.6% and 17.4%, respectively. It is also likely that the annual mean of the water exchange rate is insufficient (taking about 7 days to eliminate pollutants) and therefore has significantly influenced the carbon and nutrient biogeochemical processes and budgets in the semi-enclosed ecosystem. Thus, the sediment properties are not similar between the lagoon and the neighboring rivers. Our results yield useful information concerning estuary recovery and water resources management and may be applicable to other basins with similar characteristics that are experiencing similar coastal environmental issues.     

Predicting the contents of BTEX and MTBE for the three types of tollbooth at a highway toll station via the direct and indirect approaches

This study was set out to assess the contents of five volatile organic compounds (VOCs), including BTEX (the acronym for benzene, toluene, ethylbenzene, and xylene) and methyl tertiary-butyl ether (MTBE), in three types of tollbooth (including the car lane/ticket-collecting, car lane/cash-collecting, and bus/truck lane tollbooths) at a highway toll station via the direct and indirect approaches. For the direct approach, VOC samples were collected from the breathing zone of booth attendants at all selected tollbooths during the three workshifts. For samples collected during the dayshift, we found VOC contents of BTEX and MTBE in both the car lane/ticket-collecting (=6.23, 21.93, 3.24, 8.56, and 5.63 ppb, respectively) and car lane/cash-collecting tollbooths (=5.98, 21.71, 3.25, 8.59, and 6.04 ppb, respectively) were quite comparable, but both were significantly higher than that in the bus/truck lane tollbooth (=3.13, 13.91, 2.05, 4.52, and 2.70 ppb, respectively). The same pattern can also be found for the other two workshifts. For the indirect approach, we conducted multivariate regression analyses to predict VOC contents for any given type of tollbooth by using the four independent variables of the vehicle flowrate, wind speed, relative humidity, and air temperature. We found that, except the vehicle flowrate, the other three factors did not have a significant effect on VOC contents in the three types of tollbooth. In addition, the magnitudes of the effect of the vehicle flowrate on VOC contents for the three types of tollbooth were: car lane/cash-collecting>bus/truck lane>car lane/ticket-collecting. All regression results yielded R²-values in the range of 0.41−0.74 indicating that the developed indirect approach was able to predict VOC contents for three types of tollbooth.     

Biocompatible self-healing hydrogels based on boronic acid-functionalized polymer and laponite nanocomposite for water pollutant removal

Environmental Chemistry Letters - Global water pollution by organic dyes and metals may be solved by adsorption. In particular, hydrogel adsorbents display unique...     

Novel visible-light-driven SrCoO3/Ag3PO4 heterojunction with enhanced photocatalytic performance for tetracycline degradation

Environmental Science and Pollution Research - The semiconductor photocatalytic technology has been considerably studied due to its excellent catalytic performance in water pollution control....     

Database-driven models of the world's Large Marine Ecosystems

We present a new methodology for database-driven ecosystem model generation and apply the methodology to the world's 66 currently defined Large Marine Ecosystems. The method relies on a large number of spatial and temporal databases, including FishBase, SeaLifeBase, as well as several other databases developed notably as part of the Sea Around Us project. The models are formulated using the freely available Ecopath with Ecosim (EwE) modeling approach and software. We tune the models by fitting to available time series data, but recognize that the models represent only a first-generation of database-driven ecosystem models. We use the models to obtain a first estimate of fish biomass in the world's LMEs. The biggest hurdles at present to further model development and validation are insufficient time series trend information, and data on spatial fishing effort.     

Standardization of BOD₅/COD ratio as a biological stability index for MSW

The control of biodegradable substances is the key issue in evaluating the short and long-term emission potential and environmental impact of a landfill.Aerobic and anaerobic indices, such as respirometric index (RI) and biomethane potential production (GB21), can be used in the estimation of the stability of solid waste samples.Previous studies showed different degrees of relationship between BOD₅/COD ratio compared with RI4.Aim of this study is to standardize the parameter BOD₅/COD ratio and to test the methodology under different operating conditions (dynamic or static leaching and leaching duration, 6 and 24-h) keeping constant temperature and liquid/solid ratio (L/S = 10 l/kg_TS), with the introduction of a COD fractioning method. The COD fractioning is based on the differentiation between the soluble fraction (COD_sol) and the colloidal fraction (COD_coll) using a flocculation method.The BOD₅/COD and the BOD₅/COD_sol indices are both consistent and significant and can be used as stability indices.The BOD₅/COD ratio does not seem to be influenced, for the same test duration, by the type of test, static or dynamic. In the same way the longer test duration (24-h) does not influence significantly the values of BOD₅/COD ratio. As a consequence a leaching test duration of 6-h is preferable to avoid the beginning of the hydrolysis and oxidation processes.     

茚虫威对斑马鱼的急性毒性及遗传毒性

茚虫威属噁二嗪类新型广谱高效杀虫剂,在农业生产中有着重要作用,近年来随着用量的增加,由此产生的对水生生物的影响越来越受到重视。使用斑马鱼进行茚虫威的急性毒性作用实验,并采用微核试验、彗星试验、Annexin V-FITC/PI双染色检测观察染毒后的斑马鱼是否被诱导产生遗传毒性。结果表明:在24 h、48 h、72 h、96 h,茚虫威LC50值分别为2.263mg·L-1、2.184 mg·L-1、2.184 mg·L-1、2.133 mg·L-1。茚虫威对斑马鱼急性毒性属中等毒性。96 h茚虫威浓度为1.98 mg·L-1和2.16 mg·L-1时,斑马鱼的微核率与对照组相比达差异极显著水平(P0.01)。采用彗星试验检测斑马鱼肝脏DNA损伤,结果显示斑马鱼暴露于高浓度1.98 mg·L-1和2.16 mg·L-1茚虫威后,与对照组相比,斑马鱼的DNA损伤均表现为极显著差异(P0.01)。采用Annexin V-FITC/PI双染色流式细胞仪法检测,结果表明染毒后24 h斑马鱼肝细胞出现细胞凋亡现象。实验结果进一步表明,茚虫威对斑马鱼短期染毒后诱导细胞凋亡,表现出遗传毒性。     

农药污染对蚯蚓的群落结构与超微结构影响的研究

报道了农药污染对蚯蚓的群落结构与超微结构影响的研究,结果表明：随着农药污染程度增加,蚯蚓的种类和数量则减少。超微结构在扫描电镜下可观察到重污染区壮伟环毛蚓（Pheretimarobusta）胃粘膜出现溃疡灶,并产生穿孔现象;在中污染区只有微绒毛萎缩病变;在重污染区发现肠粘膜上的纤毛发生紊乱及萎缩,纤毛顶端膨大呈球形。对精子观察可见在中污染区就出现了畸形精子。在透射电镜下观察可见重污染区壮伟环毛蚓胃肠道粘膜上皮细胞中的粗面内质网（RER）出现扩张,高尔基复合体也产生扩张状,线粒体发生肿胀,线粒体嵴消失呈空泡状。另可见细胞核膜间隙扩张、断裂,核染色质边集或减少,胞质呈大片空白。蚯蚓以上病变指标均能很灵敏反映土壤农药污染程度。     

过渡金属对Pt Rh Pd/Al2O3催化剂性能的影响

研究了过渡金属(重点考察了铜)对Pt Rh Pd／Al2O3催化剂尾气净化效能的影响,并应用XRD,TPD,TPR等手段对过渡金属在Pt Rh Pd／Al2O3催化剂中的作用机制进行了探讨．结果表明,过渡金属对Pt Rh Pd／Al2O3催化剂具有较大的改性作用,过渡金属与混合贵金属产生的协同效应有利于催化剂活性的提高．