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451.
Ione M. Smith Ken J. Hall Les M. Lavkulich Hans Schreier 《Journal of the American Water Resources Association》2007,43(6):1455-1467
Abstract: Effects of agricultural intensification and a naturally occurring landslide of asbestos material upon water and sediment quality in a transboundary watershed were investigated. The water and sediments of the Sumas River watershed were analyzed for copper (Cu), zinc (Zn), chromium (Cr), and nickel (Ni) concentrations in 1993/1994 and 2003/2004 and differences within sites over time were examined. Based upon a review of the literature, Cu and Zn were used as indicators of agricultural impacts while Cr and Ni were used as indicators of impacts from an asbestos landslide. Animal unit equivalents (AUEs) were calculated on a per area basis as an indicator of livestock density using detailed statistical census data. Whatman #42 filtered metals, bioavailable metals, and sediment‐bound metals (in the <63 μm fraction) were determined at 22 sites along the mainstem and tributaries, including two reference sites. Temperature, pH, and dissolved organic carbon (DOC) were also measured. The bioavailable metal fraction was determined using the diffusive gradient thin film technique (DGT). Sediment‐bound results were compared with British Columbia’s Interim Sediment Quality Guidelines (ISQGs) and Severe Effects Levels (SELs). A Wilcoxon signed rank test was used to determine if the concentrations of metals changed significantly within sites between 1993/1994 and 2003/2004. Spearman rank correlation analysis was used to determine relationships between trace metals, water quality parameters, and AUEs/hectare. The results indicate that Cu and Zn levels in sediments increased significantly to concentrations above the ISQGs of 35.7 mg/kg and 123 mg/kg, respectively from 1993/1994 to 2003/2004 in streams, where associated land use was dominated by intensive agriculture. Higher AUEs/hectare were significantly correlated with greater bioavailable levels of Zn as well as higher sediment‐bound Zn concentrations. Neither Cu nor Cr were detected by the DGTs on any of the sampling occasions. The Cr and Ni sediment concentrations were highest in Swift Creek, the headwater tributary affected by the natural landslide of asbestos material, and decreased in the Sumas River downstream from the point of input. Cr and Ni concentrations have increased in the mid‐region of the Sumas River since 1993/1994, suggesting downstream movement of the asbestos material over time. DGT results indicated that bioavailable Zn is significantly positively correlated to sediment‐bound Zn and livestock density, and bioavailable Ni is significantly correlated to sediment‐bound Ni. 相似文献
452.
453.
Rosario Vidal Pilar Martínez Elena Mulet Rosa González Belinda López-Mesa Paul Fowler J. M. Fang 《Journal of Polymers and the Environment》2007,15(3):159-168
Multilayer films exhibit excellent properties for food packaging. However, existing products are not biodegradable. Conventional
plastics, manufactured from fossil fuels, not only consume non-renewable and finite resources, but also impact heavily on
waste disposal. For this reason, a new multilayer film has been developed in the Multibio Project for the production of food
packaging. In this paper, the environmental impacts of the new biodegradable multilayer film—based on modified starch and
polylactic acid (PLA)—and those of the conventional multilayer film—based on PP and PA6—are quantified in the categories of
climate change, fossil fuel depletion, acidification and eutrophication. Conventional multilayer film has a 90% higher impact
than the Multibio multilayer film. The main difference between the LCA presented and the cited literature is the inventory
data obtained in the phase of polymer processing to obtain multilayer film, and the assessment of the disposal phase of the
multilayer film wastes. 相似文献
454.
Characterization of Biodegradable Composite Films Prepared from Blends of Poly(Vinyl Alcohol), Cornstarch,and Lignocellulosic Fiber 总被引:4,自引:0,他引:4
S.?H.?ImamEmail author P.?Cinelli S.?H.?Gordon E.?Chiellini 《Journal of Polymers and the Environment》2005,13(1):47-55
Several composite blends of poly(vinyl alcohol) (PVA) and lignocellulosic fibers were prepared and characterized. Cohesive and flexible cast films were obtained by blending lignocellulosic fibers derived from orange waste and PVA with or without cornstarch. Films were evaluated for their thermal stability, water permeability and biodegradation properties. Thermogravimetric analysis (TGA) indicated the suitability of formulations for melt processing, and for application as mulch films in fields at much higher temperatures. Composite films were permeable to water, but at the same time able to maintain consistency and composition upon drying. Chemical crosslinking of starch, fiber and PVA, all hydroxyl functionalized polymers, by hexamethoxymethylmelamine (HMMM) improved water resistance in films. Films generally biodegraded within 30 days in soil, achieving between 50–80% mineralization. Both starch and lignocellulosic fiber degraded much more rapidly than PVA. Interestingly, addition of fiber to formulations enhanced the PVA degradation. 相似文献
455.
Sustainable Bio-Composites from Renewable Resources: Opportunities and Challenges in the Green Materials World 总被引:28,自引:0,他引:28
Sustainability, industrial ecology, eco-efficiency, and green chemistry are guiding the development of the next generation of materials, products, and processes. Biodegradable plastics and bio-based polymer products based on annually renewable agricultural and biomass feedstock can form the basis for a portfolio of sustainable, eco-efficient products that can compete and capture markets currently dominated by products based exclusively on petroleum feedstock. Natural/Biofiber composites (Bio-Composites) are emerging as a viable alternative to glass fiber reinforced composites especially in automotive and building product applications. The combination of biofibers such as kenaf, hemp, flax, jute, henequen, pineapple leaf fiber, and sisal with polymer matrices from both nonrenewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention, i.e., biofiber–matrix interface and novel processing. Natural fiber–reinforced polypropylene composites have attained commercial attraction in automotive industries. Natural fiber—polypropylene or natural fiber—polyester composites are not sufficiently eco-friendly because of the petroleum-based source and the nonbiodegradable nature of the polymer matrix. Using natural fibers with polymers based on renewable resources will allow many environmental issues to be solved. By embedding biofibers with renewable resource–based biopolymers such as cellulosic plastics; polylactides; starch plastics; polyhydroxyalkanoates (bacterial polyesters); and soy-based plastics, the so-called green bio-composites are continuously being developed. 相似文献
456.
457.
D. Briassoulis 《Journal of Polymers and the Environment》2004,12(2):65-81
The mechanical behavior of various types of biodegradable materials depends, mainly, on their chemical composition and the application conditions. Various additives are added into the bioblends to improve their properties, which sometimes even reach the levels of the conventional plastics. It is well known that the environmental conditions during production, storage, and usage of these materials influence their mechanical properties. Ageing during the useful lifetime also causes great losses in the elongation. In the present paper, the overall mechanical behavior of biodegradable films, which may be considered suitable for agricultural applications, but also of partially biodegradable films, is reviewed and analyzed. Selected critical mechanical properties of films before their exposure to biodegradation are investigated and compared against those of conventional agricultural films. 相似文献
458.
介绍东深供水工程生化预处理挂膜启动过程中,氨氮,CODMn去除效果和填料上生物膜变化的特点。根据氨氮去除(≥50.0%),生物膜形状,生物膜上动物种类和数量可判断挂膜启动过程是否完成。本试验挂膜启动25天,比小型试验增加了10天左右,气温低是该工程挂膜启动过程时间延长的主要原因。 相似文献
460.
溶胶-凝胶工艺制备掺铅TiO_2纳米薄膜及其光催化性能的研究 总被引:19,自引:0,他引:19
通过sol-gel工艺在玻璃表面制得了均匀透明的掺铅和未掺铅TiO2纳米薄膜;在宏观上,膜层表面光滑平整;在微观上,TiO2薄膜由TiO2球形颗粒组成,其颗粒大小在50~150nm范围内。掺铅TiO2镀膜玻璃在紫外光附近的透光率明显小于未掺铅TiO2镀膜玻璃的透光率,这说明掺铅TiO2镀膜玻璃对紫外光具有明显的吸收。敌敌畏水溶液的光摧化降解实验表明,掺铅TiO2镀膜玻璃对有机磷农药的光解率明显高于未掺铅TiO2镀膜玻璃的光解率。这为进一步提高TiO2的光催化效率开辟了新的途径。 相似文献