A 13-Week Comparison of Passive and Continuous Ozone Monitors at Forested Sites in North-Central Pennsylvania

ABSTRACT

Ogawa passive O₃ samplers were used in a 13-week study (June 1-September 1, 1999) involving 11 forested and mountaintop sites in north-central Pennsylvania. Four of the sites were collocated with TECO model 49 O₃ analyzers. A significant correlation (p < 0.0001) was found for 24-hr average weekly O₃ concentrations between the two methodologies at the four sites with collocated monitors. As expected, there were positive relationships between increasing elevation of the sites and increasing O₃ concentrations. No O₃ exposure patterns were found on a west-to-east or south-to-north basis; however, the area known for lower O₃ exposures within a smaller subsection of the study area showed consistently lower O₃ exposures. Preliminary results regarding relationships of symptom responses within O₃-sensitive bioindicators are also presented with black cherry (Prunus serotina, Elirli.) and common milkweed (Asclepias syriaca, L.) showing clear evidence of increasing injury with increasing O₃ exposures. Due to the extremely dry conditions encountered in north-central Pennsylvania during the 1999 growing season, O₃-induced symptoms were sporadic and quite delayed until late-season rains during the latter portion of the observation period.     

Small island developing states: coastal systems, global change and sustainability

The intent of this paper is to place the concepts of exposure, vulnerability, resilience and risk in the context of the consequences of global change for the sustainable development of small island developing states (SIDS). Many such states face a number of global climate change risks, such as an increase in the proportion of more intense storms, along with other global change threats that include energy security and costs. All these threats come on top of local development threats, such as increased run-off, often with increasing levels of contaminants due to unsustainable agricultural and industrial practices. When taken together, the resulting pressures on islands and their communities lead to significant increases in vulnerability to change due to reduced resilience to these changes. Vulnerability is also increasing as a result of contemporary processes that heighten the exposure of material and other assets. The capacity to address hazard risk also influences vulnerability. This includes the level of awareness of coastal hazards and exposure, and access to critical life support infrastructure, especially for people living in hazard-prone areas. Vulnerability and resilience are considered to be important integrating concepts when managing the local consequences of global changes. There are many initiatives that will help reduce the vulnerability and enhance the resilience of SIDS to such changes. These include improving risk knowledge and coastal resource and land use management, while also strengthening socio-economic systems and livelihoods. In this way, managing global change can be closely aligned with local development and humanitarian processes, thereby enhancing the overall sustainability of development processes and outcomes.     

A high-resolution historical sediment record of nutrients,trace elements and organochlorines (DDT and PCB) deposition in a drinking water reservoir (Lake Brêt,Switzerland) points at local and regional pollutant sources

The ¹³⁷Cs and ²¹⁰Pb dating of a 61-cm long sediment core retrieved from a drinking water reservoir (Lake Brêt) located in Switzerland revealed a linear and relatively high sedimentation rate (～1 cm year^?1) over the last decades. The continuous centimeter scale measurement of physical (porewater and granulometry), organic (C_org, P, N, HI and OI indexes) and mineral (C_min and lithogenic trace elements) parameters therefore enables reconstructing the environmental history of the lake and anthropogenic pollutant input (trace metals, DDT and PCBs) at high resolution. A major change in the physical properties of the lowermost sediments occurred following the artificial rise of the dam in 1922. After ca. 1940, there was a long-term up-core increase in organic matter deposition attributed to enhance primary production and anoxic bottom water conditions due to excessive nutrient input from a watershed predominantly used for agriculture that also received domestic effluents of two wastewater-treatment plants. This pattern contrasts with the terrigenous element input (Eu, Sc, Mg, Ti, Al, and Fe) which doubled after the rising of the dam but continuously decreased during the last 60 years. By comparison, the trace metals (Cu, Pb and Hg) presented a slight enrichment factor (EF) only during the second part of the 20th century. Although maximum EF Pb (>2) occurred synchronously with the use of leaded gasoline in Switzerland (between ca. 1947 and 1985) the Hg and Cu profiles exhibited a relatively similar trend than Pb during the 20th century, therefore excluding the alkyl-lead added to petrol as the dominant (atmospheric) source of lead input to Lake Brêt. Conversely, the Cu profile that did not follow the decrease registered in Pb and Hg during the last 10 years, suggests an additional source of Cu probably linked to the impact of agricultural activities in the area. In absence of heavy industries in the catchment, the atmospheric deposition of DDT and PCBs via surface runoff followed the historical emissions of POPs in Switzerland. Such result highlights the regional contamination of freshwater resources by the large-scale emission of toxic industrial chemicals in the 1960s and 1970s as well as the efficiency of the regulatory measures subsequently taken.     

Production of semiochemical and allelobiotic agents as a consequence of aphid feeding

Aphids have an extremely intimate relationship with their plant hosts. Although this might suggest that aphid infestation would be largely cryptic, there are a wide range of changes that can be detected behaviourally, chemically and also at the molecular genetic level. Colonisation by aphids can cause release of semiochemicals characteristic of the aphid species and besides reducing acceptability to incoming aphids; these can enable recruitment of specific parasitoids. Some semiochemicals involved in these processes can also influence the defence status of neighbouring intact plants through air or the rhizosphere. Electrophysiological and behavioural studies on the aphids, their parasitoids and other organisms facilitate the identification of compounds having direct effects on plant defence. New developments from work on semiochemicals such as (Z)-jasmone and 6-methyl-5-hepten-2-one, and allelobiotic agents such as 6-hydroxy-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one, as well as new work on these compounds and others as potential phytopheromones are discussed.     

Global climate change and the politics of disaster

The paper explores the potential political impact of global climate change and, more generally, of natural disaster. Because the affluent West has largely tamed the natural and the social domains, popular clamor for government to anticipate, prevent, and redress disaster increases. I delineate several consequences of the new politics of disaster.     

Female mimicry and resource defense polygyny by males of a tropical rove beetle,Leistotrophus versicolor (Coleoptera : Staphylinidae)

Summary Adults of the staphylinid beetle Leistotrophus versicolor Grav. aggregate at vertebrate dung and carrion where males and females forage for adult Diptera. Some males aggressively exclude others from dung and carrion. Winners in male combat gain access to many females, which are often receptive at these foraging sites. The mating system can be categorized as resource defense polygyny. Males vary greatly in size, are larger than females on average, and have allometrically enlarged mandibles that they use in fighting. Large males consistently defeat smaller ones. Some males employ female mimicry in order to avoid aggression, remaining at dung where they forage and even obtain copulations while being courted by rival males. Female mimicry is most often practiced by males that are smaller than their rivals or by males that are unable to use their jaws aggressively because they are feeding or courting females when encountered by an opponent. Female mimicry is a conditional tactic of mature males; some individuals behave like females toward larger males but attack smaller rivals. Offprint requests to: J. Alcock     

Evaluating Causes of Population Change in North American Insectivorous Songbirds

Although the North American Breeding Bird Survey (BBS) is a principal source of information regarding populations of most North American bird species, many features of the survey complicate analysis of population change. Correlation studies based on BBS data cannot be used to define cause and effect relationships unambiguously. Recently, Böhning-Gaese et al. (1993) presented an analysis of population trends in insectivorous songbirds using data from the BBS. They concluded that predation has played an important role in influencing population trends. We review aspects of the analysis methods for estimating population trends (e.g., observer effects, data subset) and for associating mean trends with species attributes (e.g., confounding of attributes). Using alternative analyses of the same BBS data, we demonstrate that the evidence that predation is associated with population declines is weaker than they suggested. Based on our analyses the only factor among those tested that was consistently associated with population trends was migration status (short-distance migrant/resident versus long-distance migrant) during the period 1978–1987. Also, we present evidence that the harsh winters of the mid-1970s severely depressed populations of short-distance migrant species and may have been responsible for the observed associations between migration status and population trends.     

Miscanthus for Renewable Energy Generation: European Union Experience and Projections for Illinois

Mitigation and Adaptation Strategies for Global Change -