Size-dependent mating and gender choice in a simultaneous hermaphrodite, Bulla gouldiana

Simultaneous hermaphrodites are predicted to optimally divide resources between male and female function, which can result in both size-dependent mating behaviors and conflict between potential mates. Predicted strategies include size-assortative mating, conditional exchange of gametes, and mating patterns where relative size affects investment in each sexual role. This study investigated the effect of body size on the mating strategies of a hermaphroditic opisthobranch, Bulla gouldiana. Although individuals were spatially aggregated in the field with high levels of movement and size variation, there was little evidence for predictions. Laboratory experiments, however, revealed complicated effects of mass on the probability and duration of mating, as well as gender choice. Pairs were more likely to mate if they included at least one large animal, with the larger animal typically inseminating the smaller. When both individuals were large, they were more likely to each mate in both sexual roles by switching roles once. Although B. gouldiana did not usually alternate between sexual roles multiple times within mating events, paired individuals behaved similarly (neither or both mating as sperm donors) more often than expected by chance. This suggests some level of reciprocity, which is unlikely to be conditional given rates of unilateral mating. When the larger member of the mating pair inseminated the smaller, the duration of insemination increased with the size of the smaller sperm recipient. Copulations lasted longer in pairs that switched sexual roles than in those that did not switch roles. This study suggests that variation in body size can lead to size-dependent mating patterns, but only some of the patterns in B. gouldiana support theoretical predictions. We review other studies that have addressed similar issues, providing inconsistent mating patterns in sperm-storing hermaphrodites.     

Photo-assisted fenton oxidation of refractory organics in UASB-pretreated leachate

Nearly 91% of organic pollutants in Hong Kong leachate could be effectively removed by the UASB(upflow anaerobic sludge blanket)process followed by the fenton coagulation.The COD(chemical oxygen demand)of leachate was lowered from an average of 5620 mg/L to 1910 mg/L after the UASB treatment at 37℃,and was further lowered to 513 mg/L after fenton coagulation.The remaining refractory residues could be further removed by plotochemical oxidation with the addition of H2O2.The BOD/COD ratio was greatly increased from 0.062 to 0.142,indicating the biodegradability of organic residues was improved.The photochemical oxidation for the fenton-coagulation supernatant was most effective at pH3-4,with the addition of 800 mg/L of H2O2,and UV radiation time of 30 minutes.The final effluent contained only 148 mg/L of COD,21 mg/L of BOD(biochemical oxygen demand)and 56 mg/L of TOC (total organic carbon).     

Use of spent mushroom compost to bioremediate PAH-contaminated samples

Spent mushroom compost (SMC) is a bulky waste byproduct of mushroom industry and produced abundantly. The SMC of Pleurotus pulmonarius immobilized laccase (0.88 mmoles min(-1) g(-1)) and manganese peroxidase (0.58 mmoles min(-1) g(-1)) of which the optimal temperatures were 45 and 75 degrees C, respectively. In laboratory test, complete degradative removal of individual naphthalene, phenanthrene, benzo[a]pyrene and benzo[g,h,i]perylene (200 mg PAH kg(-1) sandy-loam soil) by 5% SMC was obtained in two days under continuous shaking at 80 degrees C. The SMC-treated PAH samples had significantly reduced or removed their toxicities as revealed by the Microtox bioassay. These results were confirmed by gas chromatography-mass spectrometry analysis on the breakdown products. A phthalic derivative which is reported as a degradative product of PAHs by ozonation or ligninolysis was also detected in the SMC-treated samples. The results demonstrate the potential in employing SMC in ex situ bioremediation.     

Toxicity of methyl tert-butyl ether to marine organisms: ambient water quality criteria calculation

In response to increasing concerns over the detection of methyl tert-butyl ether (MTBE) in groundwater and surface water and its potential effects in aquatic ecosystems, industry and the United States Environmental Protection Agency (USEPA) began to collaborate in 1997 to develop aquatic toxicity databases sufficient to derive ambient water quality criteria for MTBE consistent with USEPA requirements. Acute toxicity data for seven marine species, chronic toxicity data for an invertebrate, and plant toxicity data were developed to complete the saltwater database. The species tested were Cyprinodon variegatus, Gasterosteus aculeatus, Callinectes sapidus, Mytilus galloprovincialis, Palaemonetes pugio, Rhepoxynius abronius, Americamysis bahia, and Skeletonema costatum. The toxicity tests were conducted in accordance with USEPA and American Society for Testing and Materials testing procedures and Good Laboratory Practice guidelines. Data developed from this study were consistent with existing data and showed that MTBE has low acute and chronic toxicity to the marine species tested. Based upon measured MTBE concentrations, acute effects were found to range from 166 mg MTBE/l for the grass shrimp to 1950 mg MTBE/l for marine mussel. The no-observed effect concentration for the reproduction and growth of mysids was 26 mg MTBE/l during the life cycle test. The toxicity of MTBE to saltwater organisms is comparable to its toxicity to the freshwater species tested. Reported MTBE concentrations in coastal waters are several orders of magnitude lower than concentrations observed to cause effects in marine organisms.     

Observations of 2,4,6-trichlorophenol degradation by ozone

The aqueous reactivity of 2,4,6-trichlorophenol (TCP) with ozone has been studied at laboratory-scale using a simple gas bubble/liquid contacting system. Degradation rate constants were measured directly and found to be 7.6 and 77.2 M(-1)s(-1) at pH 2 and 7.5, respectively. At pH 7.5, 10 min of ozonation ( identical with 15 mM ozone consumption) achieved a 90% degradation of TCP, which corresponded to the release of approximately 2 mol Cl(-) per mol TCP. The presence of hydrogen peroxide in solution did not significantly increase the TCP degradation but increased the overall dechlorination to 2.7 mol Cl(-) per mol TCP. The presence of humic acid (HA) in solution was found to enhance the degradation rate of TCP at low relative HA concentrations (<0.6 g/g HA:TCP), but to reduce the rate at higher HA concentrations.     

Removal of biocide pentachlorophenol in water system by the spent mushroom compost of Pleurotus pulmonarius

Pentachlorophenol (PCP) has been widely used as a wood preservative since 1980s. Although it has been banned worldwide, residues of PCP are still commonly found. The spent compost of oyster mushroom Pleurotus pulmonarius (SMC) which was a degraded paddy straw-based substrate, contained 25% chitin. Five percentage of the SMC could remove 89.0 +/- 0.4% of 100 mg PCPl(-1) within 2 days at room temperature predominantly by biodegradation. The maximum removal capacity was 15.5 +/- 1.0 mg g(-1) SMC. The sorption kinetics of PCP by SMC can be described by the Freundlich monolayer model with a theoretical sorption capacity similar to that found for chitin. A PCP-degradative bacterium was isolated from the SMC. Yet, biodegradation was predominantly contributed by the immobilized ligninolytic enzymes secreted by the mushroom to the SMC. Degradation of PCP involves dechlorination, methylation, carboxylation and ring cleavage as verified by GC-MSD and ion chromatography. Thus, the SMC has a potential for treating PCP-contaminated water.     

The degradation of endocrine disruptor di-n-butyl phthalate by UV irradiation: a photolysis and product study

The direct photolysis of an important endocrine disruptor compound, di-n-butyl phthalate (DBP), has been investigated under monochromatic UV irradiation at 254 nm over a wide pH range (3-11). The investigation was carried out under idealized conditions and has considered both reaction kinetics and the degradation mechanism. It was found that more than 90% of DBP can be degraded within an hour of irradiation in water. A simple model has been developed and used to predict the initial DBP photolysis rate constant at different pH values and initial DBP concentrations. The major decomposition mechanism of DBP is believed to involve the hydrolytic photolysis of the carbon in the alpha and/or beta-position of the ester chain with the production of aromatic carboxylic derivatives. Additionally, multi-degradation pathways are proposed for acid-catalyzed hydrolytic photolysis (pH 3-5), which was found to be useful in explaining the photo-degradation of DBP under acidic conditions. The use of 254 nm UV to photo-degrade DBP was found to be a relatively fast and clean process, especially in neutral to basic conditions.     

肠道微生物群和水生毒理学: 环境健康的新概念

高通量测序技术极大地方便了深度考察不同种群中宿主相关微生物群的组成和功能。研究表明微生物在动物包括人类的健康和疾病发病中扮演着必要的角色。微生物已成为环境毒理学中新兴的重要研究主题。这是因为微生物在免疫系统中起着重要的交互的作用,同时在化学解毒中也有作用。污染物扰动肠道微生物,引起胃肠组织的病理生理变化,导致一系列系统效应,致使营养摄入变差和肠道发炎。本文检索了关于环境污染物对水生物种微生物影响的文献,重点关注了肠道微生物。我们强调了脊柱动物宿主中的一些已知的肠道上皮细胞的主要蛋白,这些均是化合物破坏的靶标,这些蛋白可以与微生物直接对话。我们提出了一个有害结局路径(adverse outcome pathway)的总体框架,将肠道生态失调作为有害效应终点事件的主要贡献因子。我们展示了两个案例研究,分别是(1)纳米材料;(2)碳氢化合物,我们参考了Deepwater Horizon港口的石油泄漏事件, 生态失调在案例中展示了微生物的考察如何改善有害结局的研究。最后,我们提出了一些策略以建立化合物诱导的肠道生态失调与有害结局的关联。我们通过实验建立了特定微生物与肠道生态失调的关联。对毒物与微生物关系的深入研究将成为改善动物及人类健康的重大突破。 精选自Ondrej Adamovsky, Amanda N. Buerger, Alexis M. Wormington, Naomi Ector, Robert J. Griffitt, Joseph H. Bisesi Jr., Christopher J. Martyniuk. The gut microbiome and aquatic toxicology: An emerging concept for environmental health. Environmental Toxicology and Chemistry,2018,37:2758-2775.
详情请见 https://doi.org/10.1002/etc.4249
     

Management, disposal and recycling of waste industrial organic solvents in Hong Kong.

An attempt has been made to establish a mass balance of industrial organic solvents in Hong Kong. It is estimated that only a small portion, less than 4%, of all the organic solvents consumed in Hong Kong are collected as waste solvents and properly treated, while the remainder are used either in the formulation of solvent containing products, or are lost to the environment through vapour emissions, leaks and spills, or dumped illegally. It was found that solvent recycling has been a common practice in some industries but the existing level of solvent recycling in Hong Kong is difficult to estimate. About 87.4% of all the waste organic solvents disposed of at the licensed facilities are potentially recyclable although whether they can be recycled in practice depends on many factors. Examples of existing waste organic solvent management and recycling practices from selected industries in Hong Kong are presented. The economic feasibility of current and future potential recycling systems is evaluated for a few selected cases. An integrated waste organic solvent management strategy is proposed to minimize adverse impacts of organic solvents to the environment and human health.