Acceleration of Exotic Plant Invasion in a Forested Ecosystem by a Generalist Herbivore

Abstract: The successful invasion of exotic plants is often attributed to the absence of coevolved enemies in the introduced range (i.e., the enemy release hypothesis). Nevertheless, several components of this hypothesis, including the role of generalist herbivores, remain relatively unexplored. We used repeated censuses of exclosures and paired controls to investigate the role of a generalist herbivore, white‐tailed deer (Odocoileus virginianus), in the invasion of 3 exotic plant species (Microstegium vimineum, Alliaria petiolata, and Berberis thunbergii) in eastern hemlock (Tsuga canadensis) forests in New Jersey and Pennsylvania (U.S.A.). This work was conducted in 10 eastern hemlock (T. canadensis) forests that spanned gradients in deer density and in the severity of canopy disturbance caused by an introduced insect pest, the hemlock woolly adelgid (Adelges tsugae). We used maximum likelihood estimation and information theoretics to quantify the strength of evidence for alternative models of the influence of deer density and its interaction with the severity of canopy disturbance on exotic plant abundance. Our results were consistent with the enemy release hypothesis in that exotic plants gained a competitive advantage in the presence of generalist herbivores in the introduced range. The abundance of all 3 exotic plants increased significantly more in the control plots than in the paired exclosures. For all species, the inclusion of canopy disturbance parameters resulted in models with substantially greater support than the deer density only models. Our results suggest that white‐tailed deer herbivory can accelerate the invasion of exotic plants and that canopy disturbance can interact with herbivory to magnify the impact. In addition, our results provide compelling evidence of nonlinear relationships between deer density and the impact of herbivory on exotic species abundance. These findings highlight the important role of herbivore density in determining impacts on plant abundance and provide evidence of the operation of multiple mechanisms in exotic plant invasion.     

Numerical simulation of evaporation of volatile liquids

The paper presents the results of the validation of the developed pool evaporation model using literature and our own experimental data. The proposed model was used to examine the effect of wind velocity and pool sizes on the evaporation rate of volatile liquid (hexane). Contrary to the semi-empirical evaporation model widely used in hazard assessment, stronger dependence of evaporation rate on pool size at low wind speeds is obtained.     

Fire accident investigation of an explosion caused by static electricity in a propylene plant

This study investigated a 2010 fire and explosion that occurred at a polypropylene (PP) and copper-clad laminate high-tech plant in Taiwan. Liquid acetone leakage caused the fire and explosion. One person was killed and five were injured; property damage was estimated at US$20 million. In contrast to conventional plants, high-tech plants have sophisticated instrumentation, highly complex pipelines, and confined spaces. In addition, the floor area in a high-tech plant is large and frequently contains a channel through the ground floor to the second or third floor. This channel design enables the fire compartment to be destroyed. Therefore, the system cannot confine the fire to a specific area, thus hindering fire-relief operations. In this study, the original fire outbreak occurred in the PP processing area on the ground floor. The acetone storage tank was located on the third floor. The investigation conducted at the fire site of the situations of the burning (bursting) loss determined that the acetone liquid leaked and dripped from floor cracks and tunnel oven to the PP processing area. Because the PP manufacturing process rapidly generates static electricity, the flammable liquids made contact with the source of ignition, which caused the explosion and fire. Various procedures, such as those involving the operating environment of production, packaging, and processing in a high-tech plant, are likely to produce static electricity in a workplace. Improved electrostatic management can prevent the loss of property and lives, liquid acetone leakage, and loss of equipment caused by static electricity fire.     

Do environmental right-to-know laws affect markets? Capitalization of information in the toxic release inventory

This paper investigates how information contained in the U.S. Environmental Protection Agency's Toxic Release Inventory (TRI) program, one of the largest environmental right-to-know programs, affects prices in the housing market. I use a strengthening of the reporting requirements for the chemical lead in 2001 as exogenous variation to test for housing price changes near existing firms who must now report. Using a difference-in-differences specification, I find that listing an existing firm in the Toxic Release Inventory lowers housing prices up to 11% within approximately 1 mile. The results suggest that housing market participants do capitalize into prices at least some information conveyed by the TRI program.     

全氟化合物前体物质生物转化与毒性研究进展

全氟化合物前体物质在环境和人体中广泛分布,是全氟化合物污染的重要间接来源.由于这些前体物质可以转化为具有生物富集性、多器官毒性,并且半衰期更长的全氟磺酸(PFSAs)和全氟烷酸(PFCAs),近年来受到了越来越多的关注.此外,一些全氟化合物前体物质自身或者代谢中间体也具有一定的生物学毒性,如类激素作用、蛋白偶联、细胞毒性等等,这些都可能造成人群暴露的潜在健康危害.本篇综述针对于全氟烷酸和全氟磺酸类的前体物质,总结了该类化合物在环境分布、生物转化和相关毒性研究方面的最新进展.     

Phosphorus speciation and effects of environmental factors on release of phosphorus from sediments obtained from Taihu Lake,Tien Lake,and East Lake

Phosphorus is considered the primary nutrient limiting eutrophication. The release of phosphorus from sediments not only provides hydrophytes with essential nutrients, but can also produce entrophication in lakes. In this study, the sediment characteristics, phosphorus speciation, and environmental factors affecting phosphorus release from sediments from Taihu Lake, Tien Lake, and East Lake were investigated. The results indicated that phosphorus levels of sediments ranged from 647 ± 67 to 2343 ± 122 mg/kg. Inorganic phosphorus comprised the majority of total phosphorus. The main phosphorus speciation of sediments obtained from Taihu Lake and Tien Lake was Residual-P, and the main phosphorus speciation of sediment obtained from East Lake was NaOH-P. Phosphorus release occurred in acidic and alkaline conditions but more frequently under alkaline conditions. The amount of phosphorus released from the sediments increased as the disturbing intensity rose. In addition, less phosphorus was released in natural than anaerobic conditions. The amount of phosphorus released was elevated as temperature increased.     

液/液界面电化学及在环境监测分析中的应用

介绍了液/液界面电化学四种基本结构和主要实验方法,综述了液/液界面电化学分析方法在环境监测分析中的应用。作为一种新方法测定离子载体及能与其形成络合物的金属离子组分的浓度,它具有简便、快捷、经济实用等特点。     

凤眼莲对铜绿微囊藻生长及藻毒素与营养盐释放的影响

针对目前我国凤眼莲治理富营养化水体技术的规模化应用现状,考虑到大面积控养的凤眼莲与暴发的水华蓝藻(尤其是产毒铜绿微囊藻)会在湖湾区短期内密集共存的情况,开展了凤眼莲对产毒铜绿微囊藻生长、生理特性、藻毒素生产与释放影响的研究,另外,也考察了短期共存下藻类营养盐释放与凤眼莲对藻毒素积累的情况.半连续共培养实验结果表明,凤眼莲能够有效抑制铜绿微囊藻的生长,促进藻细胞的衰亡.虽然凤眼莲未对铜绿微囊藻光合系统Ⅱ的电子传递产生影响,但减少了其光合系统中的藻蓝蛋白(PC)含量和藻蓝蛋白/别藻蓝蛋白(PC/APC)水平,10%和20%水体交换率处理的PC/APC水平第8 d时分别降至相应空白对照的54.93%±7.07%和55.81%±1.97%.凤眼莲对铜绿微囊藻形成了一定的氧化伤害,最终促进其抗氧化系统中超氧化物歧化酶比活显著下降,丙二醛含量显著提高,10%和20%水体交换率处理的丙二醛含量第8d时分别升至相应空白对照的2.95倍±0.074倍和2.22倍±0.086倍.凤眼莲通过促进蓝藻的衰亡和分解,加速了营养盐的释放.12 d内,可溶性总氮浓度回升到初始水平,而水体可溶性总磷的释放速度比氮营养盐更快.另一方面,凤眼莲并没有促进铜绿微囊藻毒素的生产,也没有使水体藻毒素含量显著提高.相反,和自然衰减不同,短期内显著促进了水体藻毒素的降解,第12 d时10%和20%水体交换率处理的水体藻毒素分别下降至12.07μg·L-1±0.63μg·L-1和11.36μg·L-1±0.04μg·L-1.而凤眼莲整株的藻毒素短期积累量(FW)仅为5.95 ng·g-1±0.76 ng·g-1.增加水体交换率能够在一定程度上减缓凤眼莲对铜绿微囊藻的伤害,减缓营养盐的释放速度,但对水体藻毒素消减的影响不显著.     

沙蚕生物扰动对河口沉积物中菲释放的影响

生物扰动是一个重要沉积物-水界面过程,影响沉积物中污染物的归趋.为了探究生物扰动对沉积物中多环芳烃释放的影响.在室内进行30 d的沙蚕生物扰动对河口沉积物中菲释放的影响实验.结果表明,相对于对照,生物扰动提高水体中颗粒态菲达到2.96~10.35倍,溶解态菲为9.55~17.44倍.由此可见,沙蚕的生物扰动极大的促进了沉积物中菲向水体释放.在生物扰动处理中,两种形态的菲所占比例不同,其中溶解态菲占释放总量的80%以上,表明沙蚕的生物扰动主要是提高水体中溶解态菲.由于溶解态菲能被生物所利用,通过食物链威胁人类健康.因此,沙蚕生物扰动造成的沉积物中的污染物释放具有潜在的生态风险.     

Comparison of biochemical characteristics between PAO and DPAO sludges

A successful enhanced biological phosphorus removal(EBPR) was observed in both anaerobicaerobic sequencing batch reactor(An-Ox SBR) to induce growth of phosphorus accumulating organism(PAO) and anaerobic-anoxic(An-Ax) SBR to induce growth of denitrifying PAO(DPAO).Although the EBPR performance of An-Ox SBR was higher by 11.3% than that of An-Ax SBR,specific phosphorus release rates in the An-Ax SBR(22.8 ± 3.5 mg P/(g VSS·hr)) and the An-Ox SBR(22.4 ± 4.8 mg P/(g VSS·hr)) were similar. Specific phosphorus uptake rates under anoxic and aerobic conditions were 26.3 ± 4.8 mg P/(g VSS·hr)(An-Ax SBR) and 25.6 ± 2.8 mg P/(g VSS·hr)(An-Ox SBR), respectively, which were also similar. In addition, an analysis of relationship of poly-β-hydroxyalkanoates(PHA) synthesized under anaerobic conditions with phosphorous release(Preleased/PHAsynthesized) and of PHA utilized under anoxic and aerobic conditions with phosphorous uptake(Puptaked/PHAutilized) verified that biological activities of EBPR per unit biomass between DPAO and PAO were similar. An analysis of the specific denitrification rate of DPAO showed that NO-3-N can be denitrified at a rate that does not substantially differ from that of an ordinary denitrifier without additional consumption of organic carbon when the PHA stored inside the cell under anaerobic conditions is sufficiently secured.