Hierarchical modeling for extreme values observed over space and time

We propose a hierarchical modeling approach for explaining a collection of spatially referenced time series of extreme values. We assume that the observations follow generalized extreme value (GEV) distributions whose locations and scales are jointly spatially dependent where the dependence is captured using multivariate Markov random field models specified through coregionalization. In addition, there is temporal dependence in the locations. There are various ways to provide appropriate specifications; we consider four choices. The models can be fitted using a Markov Chain Monte Carlo (MCMC) algorithm to enable inference for parameters and to provide spatio–temporal predictions. We fit the models to a set of gridded interpolated precipitation data collected over a 50-year period for the Cape Floristic Region in South Africa, summarizing results for what appears to be the best choice of model.

Combustion products toxicity risk assessment in an offshore installation

Products of a hydrocarbon fire accident have both chronic and acute health effects. They cause respiratory issues to lung cancer. While fire is the most frequent phenomenon among the offshore accidents, predicting the contaminants’ concentration and their behavior are key issues. Safety measures design, such as ventilation and emergency routes based only on predicted contaminants’ concentration seems not to be the best approach. In a combustion process, various harmful substances are produced and their concentration cannot be added. The time duration that any individual spends in different locations of an offshore installation also varies significantly. A risk-based approach considers the duration a person is exposed to contaminants at various locations and also evaluates the hazardous impacts. A risk-based approach has also an additivity characteristic which helps to assess overall risk.Through the current study, an approach is proposed to be used for risk assessment of combustion products dispersion phenomenon in a confined or semi-confined facility. Considering CO, NO₂ and CH₄ as the contaminants of concern, the dispersion of the substances over the layout of the facility after a LNG fire is modeled. Considering different exposure times for three major parts of the facility including the processing area, office area and the accommodation module, the risk contours of CO, NO₂ and CH₄ over the entire facility are developed. The additivity characteristic of the risk-based approach was used to calculate the overall risk. The proposed approach helps to better design safety measures to minimize the impacts and effective emergency evacuation planning.     

藻源性黑水团环境效应Ⅲ:对水-沉积物界面处Fe-S-P循环的影响

利用静态模拟实验装置研究了藻源性黑水团发生过程中沉积物表层上覆水和沉积物间隙水中Fe-S-P的变化过程.结果表明:加入藻细胞后很快形成厌氧、还原环境,使得沉积物中Fe-S-P发生强烈的生物地球化学变化;实验第1d,表层上覆水中的Fe2+、SO42-、S2-含量高达4.993,242.0,387.57mg/L,为对照样柱中的1.8倍、2.2倍和18.8倍;在沉积物4cm处其浓度分别为8.5,40.0,65.3mg/L.随后,沉积物表层上覆水中Fe2+、S2-含量表现出一个先快速增加、随后降低的趋势,其浓度分别在实验的第3,2d达到最大值为11.1,634.6mg/L. 沉积物中PO43--P浓度受Fe-P解析等具有滞后性,从实验的第2d后开始直至实验结束时表现为其含量持续增加,到实验结束时其浓度为39.450mg/L,为对照样柱中的242倍.上覆水和间隙水中Fe-S-P含量的变化,反映了藻华聚集形成的厌氧环境中发生了剧烈的生物地球化学反应,从而使得沉积物中形成的Fe2+、S2- 和 PO43--P不断向上覆水体中扩散,对形成黑水团的水体生态系统的恢复造成阻碍和不良影响.     

多壁碳纳米管长期作用对活性污泥系统的影响

为研究MWCNTs(multi-walled carbon nanotubes,多壁碳纳米管)对活性污泥长期作用的影响,建立3组(每组包括3个平行反应器)序批式活性污泥反应器,研究了2种质量浓度(1、20 mg/L)的MWCNTs长期(120 d)作用对活性污泥系统废水处理效果的影响,并采用Illumina MiSeq高通量测序技术研究MWCNTs长期作用后活性污泥中细菌群落结构的变化. 结果表明:20 mg/L的MWCNTs对生物脱氮效果存在明显的抑制作用,TN平均去除率由83.4%降至71.7%;1 mg/L的MWCNTs长期作用后TN平均去除率由83.7%降至79.7%. 1和20 mg/L的MWCNTs对磷的去除均有抑制作用,TP平均去除率分别由98.0%和98.2%降至52.0%和34.0%. Illumina MiSeq高通量测序结果表明,不同质量浓度的MWCNTs长期作用后降低了活性污泥中细菌群落的多样性. 同时,活性污泥中细菌群落结构也发生了变化,其中α-Proteobacteria和γ-Proteobacteria的丰度升高,Bacteroidetes的丰度降低. 1 mg/L的MWCNTs长期作用可致以Defluviicoccus和Micropruina为代表的一类聚糖菌(glycogen-accumulating organisms, GAOs)丰度显著升高,20 mg/L的MWCNTs长期作用可致16个核心属的丰度明显降低.      

Occupancy Patterns of Regionally Declining Grassland Sparrow Populations in a Forested Pennsylvania Landscape

Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systems, whereas relatively little is known regarding how occurrence and abundance of grassland birds vary in reclaimed surface mine grasslands. Using distance sampling and single‐season occupancy models, we investigated how the occupancy probability of Grasshopper (Ammodramus savannarum) and Henslow's Sparrows (A. henslowii) on 61 surface mine grasslands (1591 ha) in Pennsylvania changed from 2002 through 2011 in response to landscape, grassland, and local vegetation characteristics . A subset (n = 23; 784 ha) of those grasslands were surveyed in 2002, and we estimated changes in sparrow density and vegetation across 10 years. Grasshopper and Henslow's Sparrow populations declined 72% and 49%, respectively from 2002 to 2011, whereas overall woody vegetation density increased 2.6 fold. Henslow's Sparrows avoided grasslands with perimeter–area ratios ≥0.141 km/ha and woody shrub densities ≥0.04 shrubs/m². Both species occupied grasslands ≤13 ha, but occupancy probability declined with increasing grassland perimeter–area ratio and woody shrub density. Grassland size, proximity to nearest neighboring grassland ( = 0.2 km), and surrounding landscape composition at 0.5, 1.5, and 3.0 km were not parsimonious predictors of occupancy probability for either species. Our results suggest that reclaimed surface mine grasslands, without management intervention, are ephemeral habitats for Grasshopper and Henslow's Sparrows. Given the forecasted decline in surface coal production for Pennsylvania, it is likely that both species will continue to decline in our study region for the foreseeable future. Patrones de Ocupación de Poblaciones Regionalmente Declinantes de Gorriones de Pastizales en un Paisaje Boscoso de Pennsylvania     

环境浓度下壬基酚对秀丽隐杆线虫时间依赖性的毒性兴奋效应

为研究暴露时间对壬基酚生态毒理学效应的影响,选取秀丽隐杆线虫(Caenorhabditis elegans)作为受试生物,采用急性(24 h和72 h)、慢性(10 d) 3个不同时间点,进行壬基酚环境浓度下(0、0.0001、0.001、0.01、0.1、0.2 mg·L~(-1))的暴露实验,以秀丽隐杆线虫的生理指标(体长、运动行为)、生化指标(氧化应激、细胞凋亡、脂褐素)为终点进行评估。结果表明:急性暴露24 h后,活性氧自由基(ROS)在0.01 mg·L~(-1)时即出现了明显的下降,其他生理生化指标无统计学意义上的明显变化。72 h暴露条件下,体长随壬基酚浓度的增加呈现倒U型趋势,在0.0001 mg·L-1时表现出最大刺激效应,比对照组高出26.4%(P0.01);头部摆动频率和身体弯曲频率在2个较高浓度(0.1和0.2 mg·L~(-1))时表现出明显的刺激效应;细胞凋亡水平在0.0001 mg·L~(-1)时显著性下降,呈现负剂量-效应关系(P0.05),在0.2 mg·L~(-1)时表现出最大刺激效应,比对照组降低了45.5%; ROS及脂褐素在壬基酚暴露浓度范围内呈正相关性增加。慢性暴露条件下,脂褐素在0.001 mg·L~(-1)时表现出最大效应,和对照组相比下降了65.4%,并且随着壬基酚浓度的增加呈现U型趋势;其他生理生化指标随着壬基酚浓度的增加表现出明显的负面效应。研究揭示了环境浓度水平的壬基酚对秀丽隐杆线虫的生态毒理效应是时间依赖性的,急性暴露以引起刺激作用为主,表现为毒性兴奋效应,而长期暴露后壬基酚对生理生化指标的负面效应更为明显。上述结果为进行壬基酚的毒性评价及更好地理解其毒性作用机理提供基础数据。     

Strengthening effects of ammonia nitrogen on the harmless biological treatment of oily sludge

To improve the efficiency of oil degradation and strengthen the harmless treatment of oily sludge, three dominant strains identified as Chryseomicrobium sp. YL2, Gordonia sp. YL3 and Acinetobacter sp. YL5 were isolated from soil near a refinery, and the effects on the bioremediation of the oily sludge from the refinery were investigated. The results showed that the efficiency of oil degradation increased by 31.5% compared with the control when the dominant strains were added to the treatment of oily sludge. Furthermore, the dominant strains could use oil as a carbon source for heterotrophic nitrification–aerobic denitrification. The addition of ammonia nitrogen resulted in a large number of remaining microbes and heightened dehydrogenase activity in the oily sludge, further accelerating oil degradation, mainly for C₁₁ to C₂₅ saturated hydrocarbons, and the oil degradation efficiency increased by 40.8%. After 120 days of bioremediation, the biotoxicity of oily sludge, which was expressed by the equivalent phenol concentration, decreased by 40.0% compared with that of the control, indicating that the addition of ammonia nitrogen enhanced the biodegradation of oil. This method can be used to strengthen the harmless treatment of oily sludge in practical engineering applications.     

多氯联苯羟基化代谢物及其雌激素效应研究进展

多氯联苯作为一种环境内分泌干扰物,具有一定的雌激素干扰效应,导致动物雌激素水平紊乱或功能异常,从而影响生殖、发育或行为。羟基多氯联苯是多氯联苯最主要的活性代谢产物,已经在动物和人体组织中被检出。羟基多氯联苯的化学性质和分子空间构象使其雌激素干扰效应可能较母体化合物更强。因此,它们对人类和动物机体的潜在影响以及由此带来的新的毒理学问题成为内分泌干扰研究领域的热点之一,相关的毒性作用机制需要进一步探索。本文对多氯联苯的代谢途径、羟基多氯联苯在生物体内的暴露水平、雌激素干扰效应及作用机制进行综述。     

多溴联苯醚及其衍生物在土壤中的分布、转化和生物效应研究进展

多溴联苯醚（polybrominated diphenyl ethers,PBDEs）作为一种良好的溴系阻燃剂被大量地添加到工业产品中,随着产品的使用、回收和废弃处理会进入各种环境介质中,是一类分布十分广泛的持久性有机污染物.PBDEs的衍生物羟基化多溴联苯醚（hydroxylated polybrominated diphenyl ethers,OH-PBDEs）和甲氧基化多溴联苯醚（methoxylated polybrominated diphenyl ethers,MeO-PBDEs）,由于具有比母体化合物更大的毒性效应和更复杂的环境行为也受到人们广泛关注.通过对PBDEs及其衍生物在土壤中的分布特征、转化规律及生物效应研究的最新进展进行综述发现,PBDEs在土壤中的分布浓度随离工业区距离增加而减小,且大多数污染地区土壤中以高溴代PBDEs为主,偏远地区土壤中则以低溴代PBDEs为主.进入土壤的PBDEs在动物、植物体内及微生物作用下均可发生脱溴代谢转化产生低溴代PBDEs,也可发生羟基化生成OH-PBDEs和甲氧基化生成MeO-PBDEs,与此同时,OH-PBDEs和MeO-PBDEs之间也会发生相互转化.PBDEs及其衍生物作为一种环境内分泌的干扰物对大部分的植物、动物都有显著的毒性效应,对植物而言能够抑制植物种子萌发、幼苗生长、损伤细胞结构以及影响植物代谢活动等;对动物而言能够影响动物的内分泌功能、妨碍动物生殖系统的发育以及对神经系统产生毒性等.目前,关于PBDEs及其衍生物在土壤生态系统中环境化学行为和生态毒性的报道十分有限,探讨土壤中PBDEs的代谢转化过程和毒性效应可为全面深刻地认识PBDEs的环境行为和潜在生态风险提供科学参考.      

三丁基锡和菲对鳗鲡的毒性效应（Toxic Effects of Tributyltin and Phenanthrene on Eels）

采用腹腔注射方式(每周1次,共5次)将生活于淡水或海水中的日本鳗鲡(Anguilla japonica)暴露于三丁基锡氯化物(TBTCl)和菲(Phe),以研究这两种污染物对鳗鲡的毒性效应以及该效应与鱼体所处环境盐度的关系.鳗鲡暴露于TBTCl或Phe1w后,其肝脏和脾脏的组织结构就已发生明显病变,且病变程度随着暴露时间的延长而加剧,其中海水鳗鲡比淡水鳗鲡表现更为严重;但肝体指数(HSI)和性腺组织结构均无明显变化.暴露于TBTCl4～5w后,海水鳗鲡肝脏的谷胱甘肽-S-转移酶(GST)活性比对照组显著升高,而淡水鳗鲡组无明显变化;暴露于TBTCl或Phe3w后,淡水鳗鲡的血浆皮质醇水平显著升高,但海水鳗鲡组无明显变化.TBTCl和Phe对淡水或海水鳗鲡的血浆雌二醇(E2)水平均无明显影响.以上结果表明:有机锡和菲对鳗鲡的肝脏、脾脏有毒性作用,对皮质醇分泌具有内分泌干扰作用,且该效应与暴露时间和鱼体所处环境盐度有关.