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201.
通过对莱州湾地区11个剖面60多个观测井进行测定,统计分析了水样的氯度、矿化度数据,得出了莱州湾地区海水入侵的时空变化规律。结果表明,在时间上,海水入侵的状况基本上保持稳定,受月季变化影响较小;空间上,地下水水质呈从沿岸向内陆由咸变淡的梯度变化趋势,海水入侵程度由近海岸至内陆逐渐降低,入侵面积和过渡带面积进一步扩大,表明莱州湾海水入侵程度日趋严重。  相似文献   
202.
污泥制备活性炭过程中重金属含量的变化趋势   总被引:1,自引:0,他引:1  
对采集的两类污泥(城市污泥、制药污泥)及其制备的活性炭进行消解处理,采用火焰原子吸收法对消解液中重金属的含量进行测定,初步探讨了污泥资源化过程中重金属的变化规律。研究结果表明:两类污泥中重金属的含量变化范围很大,其中Zn含量最高,最高值达2859.4mg/kg,其次为Cu、Pb、Cr,Cd最少;除Cr元素外,城市污泥中重金属元素Zn、Cu、Pb、Cd含量普遍高于制药污泥;由污泥烧制的活性炭中重金属含量明显减少,表明污泥烧制成活性炭后Cu、Cr、Pb、Cd更加稳定。  相似文献   
203.
进入21世纪以来,我国的消防服行业得到了迅速的发展,消防服在材料、舒适性、行业标准要求等方面取得了比较大的进步。但是随着城市构造的变化,火灾原因向着多样性方向的趋势发展,整个行业潜在的问题将再次暴露于行业关注者的视线下。本文就我国消防服行业现状做出了总结,在此基础之上,分析预测了该行业未来发展趋势。  相似文献   
204.
The cyclooxygenase-2 (COX-2) inhibitor rofecoxib was withdrawn from the US market on September 30, 2004, and valdecoxib was withdrawn on April 7, 2005. The impact of these actions on COX-2 inhibitor exposures reported to poison control centers was unknown. The objective of this study was to describe the pattern of COX-2 inhibitor exposures reported to Texas poison control centers before and after rofecoxib and valdecoxib were withdrawn. The number of celecoxib, rofecoxib, and valdecoxib exposures reported to Texas poison control centers each month during 1999–2006 was identified and examined for changes over time. Comparisons were made with respect to those exposures reported immediately prior to withdrawal (October 2003–September 2004) and to exposures after withdrawal (April 2005–December 2006). The mean monthly number of reported exposures prior to withdrawal was 18.8 for celecoxib, 20.3 for rofecoxib, 13.3 for valdecoxib, and 51.5 for total COX-2 inhibitors. The mean monthly number of reported exposures after withdrawal was 9.3 for celecoxib, 1.8 for rofecoxib, 1.3 for valdecoxib, and 12.3 for total COX-2 inhibitors, representing declines of 51, 91, 90, and 76%, respectively. The withdrawal of rofecoxib and valdecoxib from the market resulted in a decrease in the number of COX-2 inhibitor exposures reported to Texas poison control centers. However, rofecoxib and valdecoxib exposures continued to be reported for a long time after withdrawal. Reported celecoxib exposures declined even though it was not withdrawn from the market.  相似文献   
205.
为了阐明厌氧环境下全氟羧酸(PFCAs)等全氟化合物的迁移归趋,研究了8:2氟调聚醇(8:2FTOH)的厌氧降解性能.结果表明,取自市政污水处理厂的污泥在厌氧条件下可还原降解8:2FTOH,并生成氟离子、全氟类和多氟类降解产物,且降解过程可采用双指数衰减模型拟合.在为期120d的培养中,8:2FTOH的摩尔降解率高达(93.2±0.9)%;摩尔回收率则随着培养时间的增加有下降的趋势,由培养初期(1d)的(97.5±5.1)%下降至末期(120d)的(68.9±4.0)%,这说明在培养后期可能产生了未知的降解产物或生成了未知的挥发性产物.8:2不饱和氟调聚酸(8:2FTUA)和全氟辛酸(PFOA)分别是摩尔产率最高的多氟类和全氟类降解产物,分别介于(6.94±0.10)%~(24.2±1.5)%和(2.67±0.22)%~(14.9±1.0)%的范围内.多氟类降解产物的摩尔产率随培养时间的增加先增加后降低,而全氟类降解产物的摩尔产率则随培养时间的增加持续增加,这说明其可能分别为中间降解产物和最终降解产物.  相似文献   
206.
Understanding the trends in PM2.5 levels is essential for formulating clean air plans. This paper analyzes PM2.5 data from various published sources for the years 2000 to 2010 in the Pearl River Delta Economic Zone (PRDEZ). The long-term variation in PM2.5 mass concentration is analyzed. Results show that PM2.5, organic carbon (OC), elemental carbon (EC), and SO42 show a similar trend, increasing before 2005 and then decreasing slightly. The annual average PM2.5 concentration ranges from 49.1 μg·m−3 in 2000 to 64.3 μg·m−3 in 2010, with a peak of 84.1 μg·m−3 in 2004. None of these 11 years meets the new National Ambient Air Quality standard (NAAQS) for PM2.5 (35 μg·m−3). Overall average concentrations of OC, EC, and SO42 are 13.0, 6.5, and 11.8 μg·m−3, respectively. NO3 and NH4+ respectively have concentrations of 1.5 μg·m−3 and 2.9 μg·m−3 in 2000 and 6.4 μg·m−3 and 5.3 μg·m−3 in 2010, with a statistically significant average annual trend of+ 0.2 μg·m−3·yr−1 and+ 0.1 μg·m−3·yr−1. In certain geographic regions, OC and EC contribute most of the PM2.5, while in other regions secondary water-soluble ions are more important. In general, OC and SO42 are the dominant components of PM2.5, contributing 20.6% and 18.6%, respectively. These results provide, for the first time, a better understanding of the long-term PM2.5 characteristics and trends, on a species-by-species basis, in the PRDEZ. The results indicate that PM2.5 abatement needs to prioritize secondary species.  相似文献   
207.
利用三峡库区33站1961~2006年逐日降水量、平均气温、最高气温、雾、雷暴资料,分析了库区干旱、洪涝、连阴雨、高温、雾、雷暴主要气象灾害的变化趋势。统计结果表明:近46年来,三峡库区平均年干旱日数呈不明显的增加趋势,春、夏、冬季干旱日数的年际间基本没有变化趋势,但秋季干旱日数年际间有明显的增多趋势,增多速率为41 d/10 a;春、夏季雨涝日数变化趋势不明显,秋季雨涝日数有微弱的减少趋势;三峡库区年平均连阴雨过程次数有微弱的减少趋势,连阴雨日数的减少趋势较明显;近34年三峡库区年雷暴日数呈明显减少趋势,减少速度为29 d/10 a;库区平均年雾日数没有明显变化趋势,但1999年以来减少趋势明显;近46年三峡库区平均年高温日数、危害性高温日数有微弱的减少趋势,平均年极端最高气温均没有明显变化趋势。  相似文献   
208.
天津市大气降水化学组分变化趋势及来源研究   总被引:7,自引:1,他引:7  
2001—2013年对天津市降水样品进行了采集,分析了p H、电导率(EC)、主要离子浓度(SO2-4、NO-3、Cl-、F-、NH+4、Ca2+、Mg2+、Na+、K+).结果表明:2001—2013年,降水的雨量加权平均p H、EC分别为5.48、87μS·cm-1.降雨的p H、EC及总离子当量浓度呈现上升趋势,酸雨频率呈现下降趋势.降水中各离子雨量加权平均当量浓度排列顺序为:SO2-4Ca2+NH+4NO-3Cl-Mg2+Na+F-K+,SO2-4、Ca2+、NH+4和NO-3是降水中的主要离子,占离子总量的84.8%.SO2-4雨量加权平均当量浓度表现为先轻微上升,后显著下降趋势.NO-3、Ca2+雨量加权平均当量浓度表现为明显上升趋势.NH+4雨量加权平均当量浓度显示为下降趋势.F-、Cl-、K+、Mg2+、Na+等雨量加权平均当量浓度变化趋势基本保持平稳.SO2-4对总阴离子的分担率、NH+4总阳离子的分担率均呈现下降趋势.NO-3对总阴离子的分担率、Ca2+对总阳离子的分担率均呈现明显上升趋势.[NO-3]/[SO2-4]、[Ca2+]/[NH+4]呈现出明显上升趋势.富集因子计算结果表明:Ca2+主要来自地壳.Mg2+和K+部分来自海源输入,但绝大部分来自地壳.大部分Cl-来自海源的输入,其余小部分来自地壳和人为排放.降水中SO2-4、NO-3主要来自人为活动.  相似文献   
209.
Estimates of temporal trends in species’ occupancy are essential for conservation policy and planning, but limitations to the data and models often result in very high trend uncertainty. A critical source of uncertainty that degrades scientific credibility is that caused by disagreement among studies or models. Modelers are aware of this uncertainty but usually only partially estimate it and communicate it to decision makers. At the same time, there is growing awareness that full disclosure of uncertainty is critical for effective translation of science into policies and plans. But what are the most effective approaches to estimating uncertainty and communicating uncertainty to decision makers? We explored how alternative approaches to estimating and communicating uncertainty of species trends could affect decisions concerning conservation status of freshwater fishes. We used ensemble models to propagate trend uncertainty within and among models and communicated this uncertainty with categorical distributions of trend direction and magnitude. All approaches were designed to fit an established decision-making system used to assign species conservation status by the New Zealand government. Our results showed how approaches that failed to fully disclose uncertainty, while simplifying the information presented, could hamper species conservation or lead to ineffective decisions. We recommend an approach that was recently used effectively to communicate trend uncertainty to a panel responsible for setting the conservation status of New Zealand's freshwater fishes.  相似文献   
210.
The first target of the Convention for Biological Diversity (Aichi target 1) was to increase public awareness of the values of biodiversity and actions needed to conserve it—a key prerequisite for other conservation targets. Monitoring success in achieving this target at a global scale has been difficult; however, increased digitization of human life in recent decades has made it easier to measure people's interests at an unprecedented scale and allows for a more comprehensive evaluation of Aichi target 1 than previously attempted. We used Google search volume data for over a thousand search terms related to different aspects of biodiversity and conservation to evaluate global interest in biodiversity and its conservation. We also investigated the correlation of interest in biodiversity and conservation across countries to variables related to biodiversity, economy, demography, research, education, internet use, and presence of environmental organizations. From 2013 to 2020, global searches for biodiversity components increased, driven mostly by searches for charismatic fauna (59% of searches were for mammal species). Searches for conservation actions, driven mostly by searches for national parks, decreased since 2019, likely due to the COVID-19 pandemic. Economic inequality was negatively correlated with interest in biodiversity and conservation, whereas purchasing power was indirectly positively correlated with higher levels of education and research. Our results suggest partial success toward achieving Aichi target 1 in that interest in biodiversity increased widely, but not for conservation. We suggest that increased outreach and education efforts aimed at neglected aspects of biodiversity and conservation are still needed. Popular topics in biodiversity and conservation could be leveraged to increase awareness of other topics with attention to local socioeconomic contexts.  相似文献   
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