Gravimetric and Chemical Features of Airborne PM10 AND PM2.5 in Mainland Portugal

This paper describes concentration amounts of arsenic (As), particulate mercury (Hg), nickel (Ni) and lead (Pb) in PM₁₀ and PM_2.5, collected since 1993 by the Technological and Nuclear Institute (ITN) at different locations in mainland Portugal, featuring urban, industrial and rural environments, and a control as well. Most results were obtained in the vicinity of coal- and oil-fired power plants. Airborne mass concentrations were determined by gravimetry. As and Hg concentrations were obtained through instrumental neutron activation analysis (INAA), and Ni and Pb concentrations through proton-induced X-ray emission (PIXE). Comparison with the EU (European Union) and the US EPA (United States Environmental Protection Agency) directives for Ambient Air has been carried out, even though the sampling protocols herein – set within the framework of ITN's R&D projects and/or monitoring contracts – were not consistent with the former regulations. Taking this into account, 1) the EU daily limit for PM₁₀ was exceeded a few times in all sites except the control, even if the number of times was still inferior to the allowed one; 2) the EU annual mean for PM₁₀ was exceeded at one site; 3) the EPA daily limit for PM_2.5 was exceeded one time at three sites; 4) the EPA annual mean for PM_2.5 was exceeded at most sites; 5) the inner-Lisboa site approached or exceeded the legislated PMs; 6) Pb levels stayed far below the EU limit value; and 7) concentrations of As, Ni and Hg were also far less than the reference values adopted by EU. In every location, Ni appeared more concentrated in PM_2.5 than in coarser particles, and its levels were not that different from site to site, excluding the control. The highest As and Hg concentrations were found in the neighbourhood of the coal-fired, utility power plants. The results may be viewed as a “worst-case scenario” of atmospheric pollution, since they have been obtained in busy urban-industrial areas and/or near major power-generation and waste-incineration facilities.     

Interactions betweenLythrum salicaria and native organisms: A critical review

Seventy-one articles concerningLythrum salicaria (purple loosestrife), a European herb introduced to North America, were reviewed for evidence of utilization by North American fauna and the effect of loosestrife on native plant species. In contrast to popular claims, 29 species of organisms were found to utilize this plant, and no evidence of species declines due to purple loosestrife were found. Evidence that loosestrife out-competes cattails and other plant species was found to be lacking or contradictory. Thus detailed, quantitative data are needed to understand loosestrife's natural history, population dynamics, and impacts on native ecosystems if we are to effectively manage this plant.     

Using native plants as problem-solvers

The Federal Highway Administration encourages state highway agencies to use native plants in erosion control, revegetation, and landscaping solutions. This paper explains both policy reasons and technical reasons for the use of native plants. How native species can be used is shown through a roadside case study. Other applications of native plant use will be explained through a plant community approach.     

Circuit riding for managing small community sewage systems

Providing wastewater treatment services for small communities can be expensive, so many communities have chosen part-time or inadequately trained operators. This can result in neglect and poor plant performance. Indiana County, Pennsylvania, in the USA, has established an authority to provide operation and maintenance through a circuit riding arrangement. Two operators travel to eight plants five days a week. This has resulted in more consistent operation and maintenance at affordable rates. Homeowners pay $12.60–$18.00 and commercial customers pay $25–$150 a month. Even with regular attention, these small plants are not able to meet their effluent requirements at all times.     

THE USE OF OVERWINTER DRAW DOWN FOR AQUATIC VEGETATION MANAGEMENT1

ABSTRACT: Overwinter draw down can be a useful technique for aquatic plant management. Its effectiveness depends largely on the susceptibility of nuisance species to draw down. A single overwinter draw down provided good control of aquatic plants in a flowage dominated by Potamogeton robbinsii Little additional control was gained by a second draw down the following winter. Rapid reinvasion of plants after draw down ceased dictates continued management. To avoid fish kills caused by low dissolved oxygen levels caution is advised when using overwinter draw down. The growth of Zizania aquatica was not negatively influenced by draw down. The influence on water quality of nutrient release from decaying vegetation and exposed bottom sediments was uncertain.     

Assessing impacts of introduced aquatic species: Grass carp in large systems

Introduced species have created environmental benefits and unanticipated disasters so a priori assessments of species introductions are needed for environmental management. A checklist for assessing impacts of introduced species was developed from studies of introduced species and recommendations for planning introductions. Sterile, triploid grass carp (Ctenopharyngodon idella) are just beginning to be used as a biocontrol agent for the management of aquatic vegetation in open waterways. Potential impacts of grass carp in open systems were identified by reviewing grass carp biology relative to the impact assessment checklist. The potential consequences of introduced grass carp were reviewed for one case study. The case study demonstrated that conclusions about potential impacts and monitoring needs can be made despite incomplete information and uncertainty. Indicators of environmental impact and vulnerability of host systems were grouped into six categories: population control, hybridization, diseases and parasites, habitat alterations, biological effects, and management issues. Triploid grass carp can significantly alter habitat and biological resources through the secondary effects of reductions in aquatic vegetation. Potential impacts and significant uncertainties involve fish dispersions from plant control areas, inability to control vegetation loss, loss of diverse plant communities and their dependent species, and conflicts with human use of the water resource. Adequate knowledge existed to assess most potential consequences of releasing large numbers of triploid grass carp in Guntersville Reservoir, Alabama. However, the assessment of potential impacts indicated that moderate, incremental stockings combined with monitoring of vegetation and biological resources are necessary to control the effects of grass carp and achieve desirable, intermediate plant densities. Cooperators: Auburn University (Alabama Agricultural Experiment Station, Department of Fisheries and Allied Aquacultures, Department of Zoology and Wildlife Sciences), US Fish and Wildlife Service, Alabama Game and Fish Division, and the Wildlife Management Institute.     

Impact of Grazing Intensity during Drought in an Arizona Grassland

Abstract:  The ecological benefits of changing cattle grazing practices in the western United States remain controversial, due in part to a lack of experimentation. In 1997 we initiated an experimental study of two rangeland alternatives, cattle removal and high-impact grazing, and compared grassland community responses with those with more conventional, moderate grazing practices. The study was conducted in a high-elevation, semiarid grassland near Flagstaff, Arizona (U.S.A.). We conducted annual plant surveys of modified Whittaker plots for 8 years and examined plant composition shifts among treatments and years. High-impact grazing had strong directional effects that led to a decline in perennial forb cover and an increase in annual plants, particularly the exotic cheatgrass ( Bromus tectorum L.). A twofold increase in plant cover by exotic species followed a severe drought in the sixth year of the study, and this increase was greatest in the high-impact grazing plots, where native cover declined by one-half. Cattle removal resulted in little increase in native plant cover and reduced plant species richness relative to the moderate grazing control. Our results suggest that some intermediate level of cattle grazing may maintain greater levels of native plant diversity than the alternatives of cattle removal or high-density, short-duration grazing practices. Furthermore, episodic drought interacts with cattle grazing, leading to infrequent, but biologically important shifts in plant communities. Our results demonstrate the importance of climatic variation in determining ecological effects of grazing practices, and we recommend improving conservation efforts in arid rangelands by developing management plans that anticipate this variation.     

Distribution of larval host plants of the fruit piercing moth,Othreis fullonia

Summary The adult fruit piercing moth,Othreis fullonia, a native of the indo-Malaysian region, causes severe damage to fruits grown throughout the tropical and subtropical belt from Africa through Asia and Australia to the Pacific Islands. Plants of the family Menispermaceae and the genusErythrina (Fabaceae) serve as larval hosts but the adult moths prefer Menispermaceae plants for oviposition. In Africa, Asia and Australia, the moth does not lay eggs onErythrina since members of the Menispermaceae are abundant. However in the insular Pacific region, where most islands have few or no species of Menispermaceae, the introduced fruit piercing moth utilizesErythrina as an alternate larval host, and either depletes, endangers or causes the possible extinction of Menispermaceae.     

Hazard identification and risk assessment procedure for genetically modified plants in the field--GMHAZID

The safe application of genetically modified organisms (GMOs) requires a risk assessment prior to their proposed use. Based on methods from the chemical industry, we developed a hazard identification procedure for the risk assessment of field tests with genetically modified plants. This risk assessment method, GMHAZID, is carried out in the form of guided brainstorm sessions. GMHAZID was tested with a case study for which a risk assessment had previously been made, and the results of the assessments were compared. The results showed that some new hazards potentially leading to uncontrolled spreading, in addition to those from the previous assessment, were identified using GMHAZID. GMHAZID also recognised some hazards leading to failures in the field experiments. We suggest that GMHAZID provides systematics, reliability, and transparency to the risk assessment procedure.