Microplastics have recently become a major environmental issue due to their ubiquitous distribution, uncontrolled environmental occurrences, small sizes and long lifetimes. Actual remediation methods include filtration, incineration and advanced oxidation processes such as ozonation, but those methods require high energy or generate unwanted by-products. Here we tested the degradation of fragmented, low-density polyethylene (LDPE) microplastic residues, by visible light-induced heterogeneous photocatalysis activated by zinc oxide nanorods. The reaction was monitored using Fourier-transform infrared spectroscopy, dynamic mechanical analyser and optical imaging. Results show a 30% increase of the carbonyl index of residues, and an increase of brittleness accompanied by a large number of wrinkles, cracks and cavities on the surface. The degree of oxidation was directly proportional to the catalyst surface area. A mechanism for polyethylene degradation is proposed.
This paper argues that important issues of sustainable development have been addressed through single-issue landscape plans, and that these plans have carried little weight within the land use decision-making process. A more consolidated approach, based on multi-function landscape plans, is proposed. After reviewing the range of plans which, in the UK, cover woodland, farmscapes, visual amenity, coasts, catchments and biodiversity, the case is made for an integrative plan capable of addressing natural resource issues at the landscape scale. The preliminary character of an integrative plan is outlined. Whilst landscape plans have a relatively weak basis for implementation, it is concluded that a sufficient range of powers is available to ensure some progress. 相似文献
Although many conventional physical remediation methods are viewed as proven, they often only relocate wastes to other sites or into the air. How do the emerging biological and chemical in situ methods perform in the same applications? This article reviews their results (much of it in the laboratory) as well as their promise of more complete neutralization of hazardous wastes, lower capital costs, and longer-duration cleanup processes. The optimal method may be a combination of chemical and biological in situ techniques with physical pump-and-treat methods. 相似文献
Environmental factors have long been shown to influence species distributions, with range limits often resulting from environmental
stressors exceeding organism tolerances. However, these abiotic factors may differentially affect species with multiple life-history
stages. Between September 2004 and January 2006, the roles of temperature and nutrient availability in explaining the southern
distributions of two understory kelps, Pterygophora californica and Eisenia arborea (Phaeophyceae, Laminariales), were investigated along the coast of California, USA and the Baja California Peninsula, Mexico,
by limiting either: (a) tissue nitrogen uptake and storage by adult sporophytes during periods of elevated temperature, and/or
(b) production of embryonic sporophytes by microscopic gametophytes. Results suggest that while adult sporophytes of both
species are tolerant of high temperatures and low nutrients, reproduction by their microscopic stages is not. Specifically,
while E. arborea produced embryonic sporophytes at both 12 and 18°C, temperatures commonly observed throughout the southern portion of its
range, P. californica produced sporophytes at 12 but not at 18°C. As a result, it appears that the southern distribution of P. californica, which ends in northern Baja California, Mexico, may be limited by temperature acting on its microscopic stages. In contrast,
the ability of E. arborea’s microscopic and adult stages to tolerate elevated temperatures allows it to persist in the warmer southern waters of Baja
California, as well as to the north along the California coast where both species co-occur. 相似文献