Microbial dechlorination of polychlorinated biphenyls in anaerobic sewage sludge.

The potential of a chlorophenol (CP)-adapted consortium to dechlorinate polychlorinated biphenyls (PCBs) in sewage sludge was investigated. Results show that dechlorination rates differed significantly depending on sludge source and PCB congener. Higher total solid concentrations in sewage sludge and higher concentrations of chlorine in PCB resulted in slower dechlorination rates. No significant difference was found for 2,3,4,5-CB dechlorination from pH 6.0 to pH 8.0; however, dechlorination did not occur at pH 9.0 during a 41-day incubation period. Results show that at concentrations of 1 to 10 mg/L, the higher the PCB concentration, the faster the dechlorination rate. In addition, dechlorination rates were in the following order: methanogenic conditions > sulfate-reducing conditions > denitrifying conditions. The addition of acetate, lactate, pyruvate, and ferric chloride decreased lag times and enhanced dechlorination; however, the addition of manganese dioxide had an inhibitory effect. Dechlorination rates were also enhanced by the addition of PCB congeners, including 2,3,4-CB, 2,3,4,5-CB and 2,3,4,5,6-CB in mixture. Overall results show that the CP-adapted consortium has the potential to enhance PCB dechlorination. The optimal dechlorination conditions presented in this paper may be used as a reference for feasibility studies of PCB removal from sludge.     

Phylogeographic structure of false clownfish, Amphiprion ocellaris, explained by sea level changes on the Sunda shelf

The phylogenetic structure of the anemonefish Amphiprion ocellaris was established based on sequence data generated for the 5′ end of the cytochrome b (cytb) gene at 11 sites throughout Southeast Asia. Considerable genetic structuring was observed throughout the range of A. ocellaris. The region has a complex geography, with the Sunda shelf having been exposed during the lower sea levels associated with periods of glaciation. The direction of subsequent flooding of the Sunda shelf, as a direct consequence of the retreating glacial sheets, can be predicted based on the major river drainage systems in the region. Much of the phylogeographic structure, including levels of intra-site genetic variation, can be explained in terms of the “seeding” of sites on the Sunda shelf, by those on the shelf rim, as sea levels rose. We often found surface ocean currents in the region, which should influence larval dispersal, to be poorly correlated with phylogeographic structure. Several geographically close sites, which appear to be connected by surface currents, showed significant genetic stratification. We hypothesise that the phylogeographic structure of A. ocellaris is more reminiscent of the Pleistocene sea level changes than surface currents. The high contribution of sea level changes to the phylogeographic structure was also supported by several missing haplotypes in the generated spanning network. Cytb DNA sequences generated for recently recruited A. ocellaris individuals sampled from Singapore indicate that, on a local scale, there is a directional inflow of recruits, which is dependent on the monsoon seasons. The nature of dispersal and genetic structure of reef fish species found on the Sunda shelf is clearly complex, and should take into consideration past phylogeographic events. Received: 13 November 1999 / Accepted: 12 July 2000     

星载SAR差分干涉测量提取汶川地震同震形变场

采用合成孔径雷达差分干涉测量技术对2008年5月12日四川汶川地震(Ms=8.0)的形变信息进行了提取,并开展了研究,利用地震前后ALOS/PALSAR数据,进行重复轨道差分干涉处理,得到了震前—震后的干涉条纹图和形变结果图。由雷达视向形变图可知,此次地震造成了隆起形变,最大形变出现在北川—映秀断裂带上,最大雷达视向形变量超过了90 cm,形变范围较大,川西的大部分地方都出现了不同程度的地表形变。结合川西的地质和地型构造情况,根据地震同震形变场的空间分布特征,对形变特征和震源构造进行了分析,发现二者有很好的一致性。     

Genetic relationship between offspring and guardian adults of a rhacophorid frog and its care effort in response to paternal share

The rhacophorid frog, Kurixalus eiffingeri, is one of only a few frog species that exhibits polyandry and paternal care of eggs. Previous studies predicted that multiple paternity within an egg clutch could influence the degree of paternal care and reproductive strategies. We used microsatellite DNA markers to assess the prevalence of multiple paternity within egg clutches and the relationship between male paternal care and the percent of male’s genetic contribution to the clutch, i.e., paternal share. We conducted field observations of paternal care and collected tissues from both male frogs and tadpoles for parentage analyses. Our results showed that at least five out of 31 egg clutches had multiple paternity. Attending males were always the genetic fathers of some, if not all of the eggs in the clutch they guarded. All egg clutches except one were attended by one male frog but the attending male did not necessarily sire the majority of offspring. Multiple paternity in all cases consisted of two fathers and one mother and most likely resulted from synchronous polyandry. Paternal care effort correlated significantly with the male’s genetic contribution to the clutch, suggesting that male frogs adjust the effort expended in care in response to paternal share. In addition, our results suggest that externally fertilizing species with parental care and multiple paternity may develop novel reproductive and behavioral strategies to safeguard their parental investment and overcome sperm competition.     

Adsorptive conversion of nitrogen dioxide from etching vent gases over activated carbon

Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO₂ fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO₂ in the gases. The gases contained 5–55 ppm NO₂ and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO₂ of 54 ppm could be removed, and 47% of the removed NO₂ was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO₂ adsorption. Within EBRTs of 0.076–0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design.

Implications: Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO₂ fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO₂ in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution.     

Decomposition of Gas Phase 1,3-Butadiene by Ultraviolet/Ozone Process

Abstract

A pilot-scale plug-flow reactor was built to investigate its performance in treating airborne 1,3-butadiene (BD) via ozonation (O₃) and ultraviolet (UV)/O₃ technologies. Governing factors, such as the initial molar ratio of ozone to BD, UV volumetric electric input power, and moisture content in the influent airstream, were investigated. Experiments were conducted at an influent BD concentration of ～50 ppm, an ambient temperature of 26 °C, and a gas retention time of 85 sec. Results show that an initial molar ratio of ozone to BD of 3.5 and 2 sufficed to obtain BD decompositions of >90% for ozonation and UV/O₃, respectively. The UV irradiance did not directly promote the decomposition of BD, rather, it played a role in promoting the production of secondary oxidants, such as hydroxyl radicals. Kinetic analyses indicate that both types of BD decomposition are peudo–first-order with respect to BD concentrations. Moisture content (relative humidity = 40–99%) and UV volumetric electric input power (0.147 and 0.294 W/L) are both factors that weakly affect the rate of BD decomposition. Economic evaluation factors, including both energy of ozone production and UV electric input power, were also estimated.     

Delayed association of acute particulate matter 2.5 air pollution exposure with loss of complexity in cardiac rhythm dynamics: insight from detrended fluctuation analysis

Environmental Science and Pollution Research - There is a delayed (lag 1 to 2 days) correlation between acute PM 2.5 (particulate matter <?2.5 μm in aerodynamic...     

Determination of source contributions to ambient PM2.5 in Kaohsiung, Taiwan, using a receptor model

Ambient particulates of PM2.5 were sampled at three sites in Kaohsiung, Taiwan, during February and March 1999. In addition, resuspended PM2.5 collected from traffic tunnels, paved roads, fly ash of a municipal solid waste (MSW) incinerator, and seawater was obtained. All the samples were analyzed for twenty constituents, including water-soluble ions, organic carbon (OC), elemental carbon (EC), and metallic elements. In conjunction with local source profiles and the source profiles in the model library SPECIATE EPA, the receptor model based on chemical mass balance (CMB) was then applied to determine the source contributions to ambient PM2.5. The mean concentration of ambient PM2.5 was 42.69-53.68 micrograms/m3 for the sampling period. The abundant species in ambient PM2.5 in the mass fraction for three sites were OC (12.7-14.2%), SO4(2-) (12.8-15.1%), NO3- (8.1-10.3%), NH4+ (6.7-7.5%), and EC (5.3-8.5%). Results of CMB modeling show that major pollution sources for ambient PM2.5 are traffic exhaust (18-54%), secondary aerosols (30-41% from SO4(2-) and NO3-), and outdoor burning of agriculture wastes (13-17%).     

Chemical speciation,transport and contribution of biomass burning smoke to ambient aerosol in Guangzhou,a mega city of China

Intensive measurements of aerosol (PM₁₀) and associated water-soluble ionic and carbonaceous species were conducted in Guangzhou, a mega city of China, during summer 2006. Elevated levels of most chemical species were observed especially at nighttime during two episodes, characterized by dramatic build-up of the biomass burning tracers levoglucosan and non-sea-salt potassium, when the prevailing wind direction had changed due to two approaching tropical cyclones. High-resolution air mass back trajectories based on the MM5 model revealed that air masses with high concentrations of levoglucosan (43–473 ng m^?3) and non-sea-salt potassium (0.83–3.2 μg m^?3) had passed over rural regions of the Pearl River Delta and Guangdong Province, where agricultural activities and field burning of crop residues are common practices. The relative contributions of biomass burning smoke to organic carbon in PM₁₀ were estimated from levoglucosan data to be on average 7.0 and 14% at daytime and nighttime, respectively, with maxima of 9.7 and 32% during the episodic transport events, indicating that biomass and biofuel burning activities in the rural parts of the Pearl River Delta and neighboring regions could have a significant impact on ambient urban aerosol levels.