Carbonization of johkasou sludge using batch-type equipment

The carbonization of dehydrated johkasou sludge was examined using batch-type equipment. Based on the temperature changes in the carbonization room and the gas combustion room, the carbonization process was divided into three phases: phase I, drying the sludge; phase II, thermal decomposition of the dried sludge; phase III, after phase II. The times required for phases I and II were strongly correlated with the amounts of water and solid matter, respectively, in dehydrated sludge. The reduction rate of the sludge on completion of phase I was about 90% on average, and the decomposition rate of solid matter increased with time during phase II or phase II plus phase III until it reached about 50%. TOC concentration of the eluate from the carbonized sludge was used as an index to evaluate the progress of the carbonization process, and the highest temperature in the carbonization room was recognized as an important operational factor. The specific surface area and pore volume of carbonized sludge were smaller than those of charcoals and activated carbons by 1–3 orders of magnitude and 1–2 orders of magnitude, respectively. No elution of heavy metals was observed from any of the carbonized sludges examined. The reduced amount of carbon in dehydrated johkasou sludge was estimated to be about 25% of the decomposed organic matter.     

A Natural Experiment on the Impact of Overabundant Deer on Forest Invertebrates

Abstract:  In large parts of North America and Europe, deer overabundance threatens forest plant diversity. Few researchers have examined its effects on invertebrate assemblages. In a natural experiment on Haida Gwaii (British Columbia, Canada), where Sitka black-tailed deer ( Odocoileus hemionus sitkensis ) were introduced, we compared islands with no deer, with deer for fewer than 20 years, and with deer for more than 50 years. We sampled invertebrates in three habitat categories: forest edge vegetation below the browse line, forest interior vegetation below the browse line, and forest interior litter. In forest edge vegetation, invertebrate abundance and species density decreased with increasing length of browsing history. In forest interior vegetation, decrease was significant only on islands with more than 50 years of browsing. Insect abundance in the vegetation decreased eightfold and species density sixfold on islands browsed for more than 50 years compared with islands without deer. Primary consumers were most affected. Invertebrates from the litter showed little or no variation related to browsing history. We attributed the difference between vegetation-dwelling and litter-dwelling invertebrates to differences in the effect of browsing on their habitat. In the layer below the browse line deer progressively removed the habitat. The extent of litter habitat was not affected, but its quality changed. We recommend more attention be given to the effect of overabundant ungulates on forest invertebrate conservation with a focus on edge and understory vegetation in addition to litter habitat.     

环境中的氧化多环芳烃综述

氧化多环芳烃(OPAHs)是芳环上具有至少一个羰基氧(C=O)的PAH衍生物,广泛存在于环境中.氧化多环芳烃主要通过含碳燃料的燃烧和PAHs的转化释放到环境中,且其较稳定难降解,因此OPAHs被称为生物和化学降解的"末端产物".目前,在多种动物组织样本中都可检测出OPAHs,并发现OPAHs可能比亲代PAHs具有更强的毒性.本文阐述了OPAHs的理化性质、来源、测定方法、环境分布、转运和转化、(生态)毒理学效应及其毒性作用机制,并对今后的研究方向进行了展望,进而为该类化合物的环境污染及生态风险评估提供相应参考.     

Fe/沸石对偶氮染料活性黑5的催化降解

为了对水中偶氮染料活性黑5的去除进行研究,通过沉淀法在沸石上负载Fe2O3制备出一种具有较高催化活性的催化剂,采用X-射线衍射仪（XRD）和扫描电镜（SEM）对其结构和形貌进行了表征,并利用Fe/沸石进行非均相Fenton反应处理模拟染料废水的研究,考察不同操作条件对活性黑5降解效果的影响。实验结果表明,活性黑5的脱色率随催化剂投加量的升高而升高,但是随着染料初始浓度的升高而降低。H2O2浓度和pH的升高均使得活性黑5的脱色率先升高而后降低。在最佳pH为3,最佳H2O2浓度为200 mg·L-1的条件下,活性黑5的脱色率达到最大,为95.7%。通过对催化剂Fe/沸石稳定性研究,发现经5次连续循环使用后,活性黑5脱色率仍然可保持在94%以上,说明该催化剂具有良好的循环使用性能。     

Aqueous free radical chemistry of mercury in the presence of iron oxides and ambient aerosol

The effect of goethite (α-FeOOH), hematite (α-Fe₂0₃) and maghemite (γ-Fe₂0₃) on the aqueous photoreduction of divalent mercury with organic acids (oxalate, formate and acetate) is investigated. Laboratory photochemistry experiments with synthetic iron oxides and simulated sunlight were performed to assess the role of the oxides on the photoreduction. Ambient aerosol was also collected and introduced as the solid phase to compare its effect with that of synthetic oxides. It is observed that the presence of various iron oxides or aerosol particles enhances the photoreduction. It is also found that the hydroxyl radicals produced in the hematite-oxalate systems can re-oxidize the reduced mercury back to Hg(II). Based on the experimental observations, mechanisms responsible for the Hg(II) reduction are proposed. The kinetics of Hg⁰ oxidation by hydroxyl radicals was also studied by a steady-state kinetic technique using nitrate photolysis as the * OH radical source. The second-order rate constant is determined to be 2.0 × 10⁹ M⁻ s⁻¹. The implications of the studied reactions on the atmospheric chemistry of mercury are discussed.     

The neglected burden of agricultural intensification: a contribution to the debate on land-use change

ABSTRACT

Between 1992 and 2015 Argentina lost 17% of its tree cover. Regionally, deforestation continues, but net forest loss recently came to a halt. Some scholars argue that this was facilitated by industrial agricultural intensification. This view is debated, but we focus on the neglected costs associated with this intensification. An almost tenfold increase of pesticide use in Argentina during the last two decades caused the pollution of soil, water and sediments. The widespread use of pesticides is impairing the health of agricultural workers and people living near agricultural fields, and is putting the health of vulnerable parts of the population (children and pregnant women) at risk. More than 50 pesticide active ingredients marketed in Argentina have been banned in the European Union for safety reasons. We contend that health and pollution aspects need to be taken into account when assessing the benefits and drawbacks of different types of land use.     

静脉注射多壁碳纳米管后大鼠脏器的病理学观察(Pathological Observations of Rat Tissues After Intravenous Injection of Mutil-Wall Carbon Nanotubes)

以Wistar大白鼠为研究对象,观察了多壁碳纳米管(MWNTs)体内暴露后脏器的病理学变化.采用尾静脉注射的方法将直径为40～60nm的多壁碳纳米管(40～60MWNTs)和直径小于10nm的多壁碳纳米管(10MWNTs)暴露于大白鼠体内,同时分别采用纳米二氧化硅(SiO2)和乙炔碳黑(Cb)作为阳性和阴性对照.实验结果表明:1、3、5mg·kg-1(以大鼠体重计)多壁碳纳米管进入大鼠体内90d后,大鼠心脏、肾脏、肝脏和胃结构正常,未见明显的病理损伤.但是多壁碳纳米管均可在大鼠肺部沉积,随着暴露时间的延长,多壁碳纳米管一部分被肺巨噬细胞清除体外,但是残余的多壁碳纳米管引起了肺部的病理学改变.     

The Paradox of the Long‐Term Positive Effects of a North American Crayfish on a European Community of Predators

Abstract: Invasions of non‐native species are one of the major causes of losses of native species. In some cases, however, non‐natives may also have positive effects on native species. We investigated the potential facilitative effects of the North American red swamp crayfish (Procambarus clarkii) on the community of predators in southwestern Spain. To do so, we examined the diets of predators in the area and their population trends since introduction of the crayfish. Most predator species consumed red swamp crayfish, which sometimes occurred in over 50% of their diet samples. Moreover, the abundance of species preying on crayfish increased significantly in the area as opposed to the abundance of herbivores and to predator populations in other areas of Europe, where those predators are even considered threatened. Thus, we report the first case in which one non‐native species is both beneficial because it provides prey for threatened species and detrimental because it can drive species at lower trophic levels to extinction. Increases in predator numbers that are associated with non‐native species of prey, especially when some of these predators are also invasive non‐natives, may increase levels of predation on other species and produce cascading effects that threaten native biota at longer temporal and larger spatial scales. Future management plans should include the complexity of interactions between invasive non‐natives and the entire native community, the feasibility of successful removal of non‐native species, and the potential social and economic interests in the area.     

Investigating Potential for Depensation in Marine Turtles: How Low Can You Go?

Abstract:  Where mechanisms inherent within the biology of a species affect individual fitness at low density, demographic-scale depensation may occur, hastening further decline and leading ultimately to population extirpation and species extinction. Reduction in fertility at low population densities has been identified in marine and terrestrial species. Using data on hatch success and hatchling-emergence success as proxies for fertilization success, we conducted a global meta-analysis of data from breeding aggregations of green turtles ( Chelonia mydas ) and loggerhead turtles ( Caretta caretta ). We found that there has been no reduction in fertility in small nesting aggregations in either of these species worldwide. We considered mechanisms within the mating strategies and reproductive biology of marine turtles that may allow for novel genetic input and facilitate enhanced gene flow among rookeries. Behavioral reproductive mechanisms, such as natal philopatry and polyandry, may mitigate potential impacts of depensation and contribute to the resilience of these species.     

纳米碳黑与重金属对BEAS-2B细胞的联合毒性作用模式评价

通过研究空气颗粒物的代表性组分纳米碳黑(nano particle carbon black,NPCB)与重金属(Pb/Cr/Cd)联合染毒对BEAS-2B细胞存活率和LDH漏出率的影响,旨在阐明NPCB与重金属对细胞毒性的联合作用模式。检测NPCB与重金属(Pb/Cr/Cd)联合染毒24 h后BEAS-2B细胞存活率(CCK-8法)和LDH漏出率(LDH活性比色法)的变化,采用析因方差分析判断其是否存在联合毒性作用及联合作用模式。NPCB与重金属(Pb/Cr/Cd)联合染毒在细胞存活率和LDH漏出方面存在联合作用;与对照组和单独染毒组相比,低剂量Pb(125μmol·L-1)与NPCB联合染毒对细胞存活率无交互作用,对LDH漏出表现为拮抗作用;高剂量Pb(1 000μmol·L-1)与NPCB联合染毒对细胞存活率表现为协同作用,对LDH漏出无交互作用;Cr和Cd与NPCB联合染毒在细胞存活率方面均表现为协同作用;低剂量Cr和Cd与NPCB联合染毒在LDH漏出方面无交互作用,高剂量时表现为协同作用。NPCB与重金属存在联合作用,金属不同、剂量不同以及评价指标不同,其联合作用模式不尽相同。