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121.
Species interactions such as predation or competition can have notable implications for fish population dynamics. Stock status and associated biological reference points can be misrepresented if these interactions are not considered. Here we present a multispecies, biomass production model (MS-PROD) developed by incorporating modifications to the Schaefer production model. The modifications explicitly emphasize a functional group approach, highlighting the effects of species interactions that include competition between species within a group, competition between groups, and predation. The mathematical formulation also includes constraints on carrying capacity for both the entire system and for individual groups. We applied the model as initialized to the Northeast U.S. Large Marine Ecosystem finfish community. We then executed simulations designed to explore the behavior of the model with respect to fishery exploitation and ecological interactions. Collectively, the results demonstrated the utility, and the need, for incorporating ecological effects into fisheries models. 相似文献
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124.
Xiaojiang Tang Yang Bai Anh Duong Martyn T. Smith Laiyu Li Luoping Zhang 《Environment international》2009,35(8):1210-1224
Formaldehyde, an economically important chemical, is classified as a human carcinogen that causes nasopharyngeal cancer and probably leukemia. As China is the largest producer and consumer of formaldehyde in the world, the Chinese population is potentially at increased risk for cancer and other associated health effects. In this paper we review formaldehyde production, consumption, exposure, and health effects in China. We collected and analyzed over 200 Chinese and English documents from scientific journals, selected newspapers, government publications, and websites pertaining to formaldehyde and its subsequent health effects.Over the last 20 years, China's formaldehyde industry has experienced unprecedented growth, and now produces and consumes one-third of the world's formaldehyde. More than 65% of the Chinese formaldehyde output is used to produce resins mainly found in wood products — the major source of indoor pollution in China. Although the Chinese government has issued a series of standards to regulate formaldehyde exposure, concentrations in homes, office buildings, workshops, public places, and food often exceed the national standards. In addition, there have been numerous reports of formaldehyde-induced health problems, including poisoning and cancer. The lack of quality epidemiological studies and basic data on exposed populations emphasizes the need for more extensive studies on formaldehyde and its related health effects in China. 相似文献
125.
China is the largest steel producer and consumer around the world. Quantifying the Chinese steel flow from cradle to grave can assist this industry to fully understand its historical status and future options on production route transformation, capacity planning, scrap availability, resource and energy consumption. With the help of the systematic methods combined dynamic MFA (material flow analysis) with scenario analysis, the Chinese steel cycle during the first half of the 21st century was quantified and several thought-provoking conclusions were draw. In the past decade, lots of pig iron or molten iron was fed into EAF (electric arc furnace) and the scrap usage of EAF fluctuated slightly. Thus, the real scrap-EAF route share is much lower than the EAF production share. On the other hand, we reconfirmed that the scrap supply in China will rise significantly in the future. Meanwhile, the secondary production route share will grow sharply and exceed primary production share before or after 2050 depending on our options. The scrap recycling rate and construction's lifetime play a vital role in this trend. In the end, an intensive discussion on production capacities’ adjustment and energy and resource consumption was conducted and relative policy suggestions were given. It is worth noting that scrap usage is crucial to future energy saving and emissions reduction of Chinese steel sector and its energy consumption might peak as early as 2015. 相似文献
126.
大量数据表明,烟草在生产加工过程中会产生和排放煤尘、烟草尘、恶臭气体、生产废水、烟草废弃物等各类污染和工业噪声,不仅对生产现场和周边环境造成污染,还会对作业工人造成呼吸道和听力损害及其他疾病危害。卷烟烟气中含有很多危及身体的毒性成分,吸烟场所空气中的尼古丁、颗粒物和有机物浓度均明显高于无烟和禁烟场所。吸烟是导致肺癌的首要危险因素,也是导致慢性阻塞性肺病的主要原因,更是多种癌症、心脑血管疾病等的重要诱因,被动吸烟的危害更为严重,全社会应正确引导烟草的生产和消费,最大可能地减轻烟草对人类造成的危害。 相似文献
127.
张福生 《中国环境管理干部学院学报》2004,14(3):23-26
长期以来,在"两种生产"理论指导下,我国计划生育工作取得举世瞩目的成就.但"两种生产"理论的不足之处却随着经济社会的发展日益显露.可持续发展观则避免了这种不足.它不仅涵盖人口与经济的关系,而且要求在前者适应后者的同时必须考虑资源和环境的承受能力.最近中央提出的科学发展观更赋予可持续发展丰富而深刻的内涵. 相似文献
128.
《安全生产法》是我国安全生产领域的第一部基本法,其颁布实施意义深远。本文就《安全生产法》不尽完善的地方,提出了自己的看法,并提出立法建议,旨在今后进一步完善《安全生产法》,以及做好实施《安全生产法》的相关配套和细化的立法工作。 相似文献
129.
通过离子膜法与隔膜法制碱有关特性的比较,表明离子膜法制碱在技术,经济效益及环境效益方面均占有很大优势,是目前烧碱行业实行清洁的首工艺。 相似文献
130.
MBR工艺较传统生化水处理工艺有着出水水质好且稳定度高,污泥膨胀现象不会对处理出水水质带来影响,无需污泥沉淀,处理效率高,占地空间少,操作简便等优越条件.但膜污染一直是MBR发展道路上最严重的阻碍,本文以此为主体,将清洁生产理念与之进行有机结合.利用清洁生产的从源头控制、减污增效的思想,在应用MBR处理废水的过程中,减少反应池中可造成膜污染的因子的产生.从而,在清洁生产理念的指引下,为膜污染的防治和减缓带来了新的途径,促进了MBR工艺在水处理和净化领域中的发展,展现了清洁生产理念在水处理领域的应用. 相似文献