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811.
Baer SG Engle DM Knops JM Langeland KA Maxwell BD Menalled FD Symstad AJ 《Environmental management》2009,43(2):189-196
Vast areas of arable land have been retired from crop production and “rehabilitated” to improved system states through landowner
incentive programs in the United States (e.g., Conservation and Wetland Reserve Programs), as well as Europe (i.e., Agri-Environment
Schemes). Our review of studies conducted on invasion of rehabilitated agricultural production systems by nontarget species
elucidates several factors that may increase the vulnerability of these systems to invasion. These systems often exist in
highly fragmented and agriculturally dominated landscapes, where propagule sources of target species for colonization may
be limited, and are established under conditions where legacies of past disturbance persist and prevent target species from
persisting. Furthermore, rehabilitation approaches often do not include or successfully attain all target species or historical
ecological processes (e.g., hydrology, grazing, and/or fire cycles) key to resisting invasion. Uncertainty surrounds ways
in which nontarget species may compromise long term goals of improving biodiversity and ecosystem services through rehabilitation
efforts on former agricultural production lands. This review demonstrates that more studies are needed on the extent and ecological
impacts of nontarget species as related to the goals of rehabilitation efforts to secure current and future environmental
benefits arising from this widespread conservation practice. 相似文献
812.
Thomas G. Measham 《Environmental management》2009,43(6):1096-1107
Conventional approaches to evaluation of environmental programs have tended to limit themselves to restricted measures of
program effectiveness. This paper shows how a social learning approach can be incorporated into evaluating public environmental
programs. A social learning approach is particularly suited to complex environmental challenges which are inherently difficult
to understand, predict, and manage, thus complicating the evaluation process. The paper presents an Australian case study
of dryland salinity management where there are major knowledge barriers impeding conventional management techniques. The research
presented in this paper focused on evaluating a public demonstration program to track its impact through its design, implementation,
and monitoring phases. The paper shows that, by incorporating social learning principles and practices, program evaluation
can promote collective action, critical reflection, and increased knowledge to underpin improved environmental management. 相似文献
813.
Ecological disturbances of forests by insects have a complex array of associated human dimensions presenting complications
for natural resource decision making and relationships between stakeholders and managers. This article discusses the human
context of forest disturbances by insects by reviewing four cases of bark beetle forest disturbance from British Columbia
in Canada, Bavarian Forest National Park in Germany, the Kenai Peninsula in Alaska, and the north central region of Colorado.
Findings and lessons learned from these studies are outlined along with their implications for managing forest disturbances
by insects in general. Conclusions focus on the need to assess the broad array of impacts and risks perceived by local residents
and the capacity for local action and involvement in managing forest disturbances. Communication and interaction between resource
managers and local stakeholders can facilitate the identification of management priorities and potentially reduce some of
the risks associated with forest disturbances by insects. 相似文献
814.
Fertilization with 2.5 t/ha limestone: (83% CaCO3, 8% MgO, 6% K2O, 3% P2O5) reduces the 137Cs transfer from spruce forest soil into plants like fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus) by a factor of 2–5 during at least 11 years as measured by the aggregated transfer factor Tag. In 1997 and 2006 these results were confirmed by additional measurements of the 137Cs transfer factor TF, related to the root zone (Oh horizon), which were explained by the selective sorption of 137Cs in the root zone by measurements of the Radiocaesium Interception Potential (RIP) in fertilized (RIP > 179 meq/kg) and non-fertilized soils (RIP < 74 meq/kg). 相似文献
815.
Mohammednoor Altarawneh Daniel Carrizo Artur Ziolkowski Eric M. Kennedy Bogdan Z. Dlugogorski John C. Mackie 《Chemosphere》2009,74(11):1435-1443
This article reports the computational and experimental results of the thermal decomposition of permethrin, a potential source of dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). We have performed a quantum chemical analysis by applying density functional theory to obtain the decomposition pathways of permethrin and the formation mechanism of dibenzofuran. We have conducted the pyrolysis experiments in a tubular reactor and identified the pyrolysis products to demonstrate the agreement between the experimental measurements and quantum chemical calculations. The initiation of the decomposition of permethrin involves principally the aromatisation of permethrin into 3-phenoxyphenylacetic acid, 2-methylphenyl ester (J) and concomitant loss of 2HCl. This rearrangement is followed by the rupture of the O–CH2 linkage in J, with a rate constant derived from the quantum chemical results of 1 × 1015 exp(−68 kcal/mol/RT) s−1 for temperatures between 700 and 1300 K. This is confirmed by finding that the rate constant for unimolecular rearrangement of permethrin into J is 1.2 × 1012 exp(−53 kcal/mol/RT) s−1 over the same range of temperatures and exceeds the direct fission rate constant at all temperatures up to 850 ± 120 °C as well as by the experimental detection of J prior to the detection of the initial products incorporating diphenyl ether, 1-methyl-3-phenoxybenzene, 3-phenoxybenzaldehyde and 1-chloromethyl-3-phenoxybenzene. As the temperature increases, we observe a rise in secondary products formed directly or indirectly (via phenol/phenoxy) including aromatics (naphthalene), biphenyls (biphenyl, 4-methyl-1,1′-biphenyl) and dibenzofuran (DF). In particular, we discover by means of quantum chemistry a direct route from 2-phenoxyphenoxy to naphthalene. We detect no polychlorinated dibenzo-p-dioxins and dibenzofurans. Unlike the case of oxidative pyrolysis [Tame, N.W., Dlugogorski, B.Z., Kennedy, E.M., 2007b. Formation of dioxins in fires of arsenic-free treated wood: Role of organic preservatives. Environ. Sci. Technol. 41, 6425–6432] where significant yields of both PCDD and PCDF were obtained, under non-oxidative conditions the thermal decomposition of permethrin does not form appreciable amounts of PCDD or PCDF and the presence of oxygen (and/or a sizable radical pool) appears necessary for the formation of dibenzo-p-dioxin itself or PCDD/F from phenol/phenoxy. 相似文献
816.
A global assessment of chromium pollution using sperm whales (Physeter macrocephalus) as an indicator species 总被引:1,自引:0,他引:1
John Pierce Wise Sr. Roger Payne Sandra S. Wise Carolyne LaCerte James Wise Christy Gianios Jr. W. Douglas Thompson Christopher Perkins Tongzhang Zheng Cairong Zhu Lucille Benedict Iain Kerr 《Chemosphere》2009,75(11):1461-1467
Chromium (Cr) is a well-known human carcinogen and a potential reproductive toxicant, but its contribution to ocean pollution is poorly understood. The aim of this study was to provide a global baseline for Cr as a marine pollutant using the sperm whale (Physeter macrocephalus) as an indicator species. Biopsies were collected from free-ranging whales around the globe during the voyage of the research vessel The Odyssey. Total Cr levels were measured in 361 sperm whales collected from 16 regions around the globe detectable levels ranged from 0.9 to 122.6 μg Cr g tissue−1 with a global mean of 8.8 ± 0.9 μg g−1. Two whales had undetectable levels. The highest levels were found in sperm whales sampled in the waters near the Islands of Kiribati in the Pacific (mean = 44.3 ± 14.4) and the Seychelles in the Indian Ocean (mean = 19.5 ± 5.4 μg g−1). The lowest mean levels were found in whales near the Canary Islands (mean = 3.7 ± 0.8 μg g−1) and off of the coast of Sri Lanka (mean = 3.3 ± 0.4 μg g−1). The global mean Cr level in whale skin was 28-times higher than mean Cr skin levels in humans without occupational exposure. The whale levels were more similar to levels only observed previously in human lung tissue from workers who died of Cr-induced lung cancer. We conclude that Cr pollution in the marine environment is significant and that further study is urgently needed. 相似文献
817.
Chinstrap and gentoo penguins are endemic species that live year round south of the Antarctic Convergence. South polar skua is a migratory seabird that can be observed in Antarctica during the breeding season (i.e., austral summer). This study compares concentration and pattern of polybrominated diphenyl ethers (PBDEs) in eggs of seabirds breeding at King George Island, Antarctic Peninsula. PBDEs in south polar skua eggs are approximately 20 times higher than in penguin eggs suggesting that skuas are more exposed to contaminants during the non-breeding season when they migrate to waters of the northern hemisphere. The pattern of PBDE congeners also differs between south polar skua and penguin eggs. The latter exhibited a pattern similar to that found in the local biota. In contrast, the congener pattern in south polar skua eggs suggests that birds breeding at King George Island may winter in the northwestern Pacific Ocean. 相似文献
818.
Influence of titanium dioxide nanoparticles on speciation and bioavailability of arsenite 总被引:2,自引:0,他引:2
Sun H Zhang X Zhang Z Chen Y Crittenden JC 《Environmental pollution (Barking, Essex : 1987)》2009,157(4):1165-1170
In this study, the influence of the co-existence of TiO2 nanoparticles on the speciation of arsenite [As(III)] was studied by observing its adsorption and valence changing. Moreover, the influence of TiO2 nanoparticles on the bioavailability of As(III) was examined by bioaccumulation test using carp (Cyprinus carpio). The results showed that TiO2 nanoparticles have a significant adsorption capacity for As (III). Equilibrium was established within 30 min, with about 30% of the initial As (III) being adsorbed onto TiO2 nanoparticles. Most of aqueous As (III) was oxidized to As(V) in the presence of TiO2 nanoparticles under sunlight. The carp accumulated considerably more As in the presence of TiO2 nanoparticles than in the absence of TiO2 nanoparticles, and after 25-day exposure, As concentration in carp increased by 44%. Accumulation of As in viscera, gills and muscle of the carp was significantly enhanced by the presence of TiO2 nanoparticles. 相似文献
819.
Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation 总被引:1,自引:0,他引:1
Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 ± 20 mg Pb kg−1) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO4, PbSO4·PbO, α-PbO and Pb0. Morphology investigations revealed that PM2.5 (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 μm or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl2 extraction. 相似文献
820.
Mechanistic effect models for ecological risk assessment of chemicals (MEMoRisk)—a new SETAC-Europe Advisory Group 总被引:1,自引:1,他引:0