不同林分土壤有机碳密度研究

在全球气候变化背景下,森林土壤有机碳作为土壤碳库的重要组成部分,已成为森林生态系统碳循环研究的重点之一;而森林土壤有机碳在剖面上具有明显的垂直分布差异,根据土壤发生层次特点,分别研究各层土壤有机碳含量分布规律,对于准确确定森林土壤碳储量具有重要意义。2008年7月在北京西山妙峰山林区侧柏（Platycladus orientalis）林、刺槐（Robinia pseudoacacia）林、栓皮栎（Quercus variabilis）林和侧柏、油松（Pinus tabulaeformis）混交林内,分别随机选取3个位置挖土壤剖面,然后根据土壤发生层次性特点,把各剖面划分为四个土层（0～10 cm,10～20 cm,20～40 cm和40～60 cm）,每层用环刀取样测定土壤容重,用土壤袋采集1 000 g的土壤样品,经除杂、风干、过筛等程序后,对土样的有机碳含量和碳密度进行了测定和初步研究。结果表明：4种林分下土壤有机碳平均含量和土壤有机碳密度不同,不同林分土壤0～10 cm有机碳含量和碳密度最高,并且均随土壤深度增加呈降低的趋势;其土壤有机碳密度的大小顺序为：栓皮栎林〉侧柏、油松林〉侧柏林〉刺槐林。4种林分类型0～20 cm土层单位面积有机碳储量占总有机碳储量分别为：栓皮栎林51.1%,刺槐林44.2%,侧柏林43.0%,侧柏、油松混交林37.7%,平均为44.0%。     

水污染控制规划与GIS

在水污染控制规划中,总量控制是新手段,概率模型是新方法,ＧＩＳ是新工具。利用上述新手段,新方法和新工具,系统地介绍了水污染控制规划,初步探索了基于ＧＩＳ的水污染控制规划的实施途径。     

紫外导数分光光度法直接测定饮用水中的硝酸根含量

在酸性条件下,用二阶导数及零交技术,取２２３．５ｎｍ处的导数值可消除水中常见离子的干扰。该法的线性范围为０－１３０μｇ－５０ｍｌ,检出限为０．０８μｇ．ｍｌ＾－１,加标回收率在９５％－１０１％之间,适用于自来水,井水及泉水等饮用水中ＮＯ＾－３含量的测定。     

Tracking Chinese newspaper coverage of elephant ivory through topic modeling

Mass media worldwide has contributed to increasing awareness of the illegal wildlife trade and its significant impact on wildlife conservation. We used mass media coverage as a proxy for macro-level public opinion to analyze the media framing of elephant ivory in 6394 Chinese newspaper articles published from 2000 to 2021 and thus determine the effects of wildlife policies on public opinion. We focused on 2 events: the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) approval of China as a trading partner in the purchase and import of ivory stockpiles from Africa in July 2008 and the Chinese government's announcement of a domestic ivory ban in December 2016. Using latent Dirichlet allocation topic modeling, we identified 8 topics about elephant ivory and grouped them into 3 frames: ivory arts and culture, ivory crimes, and elephant conservation. Over the last 2 decades, topics related to ivory crimes remained the most prevalent in news articles. Topics about ivory arts and culture showed a significant shift in media salience before and after the 2 events (from 0.44 to 0.19 and from 0.08 to 0.15, respectively, p < 0.05), whereas the other 2 frames did not change significantly. Contrary to popular belief, our results indicated that Chinese macro-level public opinion on ivory had become more negative following the CITES approval of ivory importation and less negative after the ivory ban announcement, at least for certain periods. The relationship between mass media, public opinion, and wildlife trade policies is complex and requires further examination of the sociopolitical dynamics that influence media narratives. Our results showed the value of topic modeling in monitoring and assessing media representations of wildlife issues in the era of big data. Conservationists should remain vigilant of mass media coverage and collaborate with media practitioners to produce comprehensive narratives on wildlife issues if resources permit.     

New insights into the formation of ammonium nitrate from a physical and chemical level perspective

● Factor analysis of ammonium nitrate formation based on thermodynamic theory. ● Aerosol liquid water content has important role on the ammonium nitrate formation. ● Contribution of coal combustion and vehicle exhaust is significant in haze periods. High levels of fine particulate matter (PM_2.5) is linked to poor air quality and premature deaths, so haze pollution deserves the attention of the world. As abundant inorganic components in PM_2.5, ammonium nitrate (NH₄NO₃) formation includes two processes, the diffusion process (molecule of ammonia and nitric acid move from gas phase to liquid phase) and the ionization process (subsequent dissociation to form ions). In this study, we discuss the impact of meteorological factors, emission sources, and gaseous precursors on NH₄NO₃ formation based on thermodynamic theory, and identify the dominant factors during clean periods and haze periods. Results show that aerosol liquid water content has a more significant effect on ammonium nitrate formation regardless of the severity of pollution. The dust source is dominant emission source in clean periods; while a combination of coal combustion and vehicle exhaust sources is more important in haze periods. And the control of ammonia emission is more effective in reducing the formation of ammonium nitrate. The findings of this work inform the design of effective strategies to control particulate matter pollution.     

河鲈锚首吸虫及其宿主鳜鱼组织器官中铅含量的比较

利用原子吸收分光光度计分析了寄生鳜鱼（Sinipercachuatsi）鳃部的河鲈锚首吸虫（Ancyrocephalusmogurndae）及其宿主组织器官,包括肌肉、鳃、头肾和肝脏的铅含量.结果表明,来自三湖连江水库和牛山湖两个采样点的河鲈锚首吸虫的铅含量都显著地高于其宿主组织器官中的铅含量.在所检测的宿主组织器官中,肝脏的铅含量最高,在两个采样点分别为0.138和0.114μg/g（湿重）.河鲈锚首吸虫富集铅的机理及其较高水平铅含量的特点是否与其体外寄生的特性有关,尚有待于进一步研究.     

半干半湿法烟气脱硫主要影响因素分析

建立了半干法气流床烟气脱硫实验反应装置。实验研究了温度、绝对含湿量和飞灰对烟气脱硫的影响。烟气温度在65～130℃之间,绝对含湿量通过改变蒸汽量调节,在0%～10%之间,并且采用飞灰一次加入来模拟返灰,石灰与粉煤灰的比例分别为1∶3,1∶5和1∶8。结果表明,没有水蒸气加入时,温度的升高对脱硫效率影响不大,加入水蒸气后温度为68℃左右时,脱硫效率最高;65℃时,绝对含湿量在73%时脱硫效率最高;在T=68℃、Ca/S=12时,与不加粉煤灰的脱硫剂相比,利用石灰/粉煤灰=1∶8的混合脱硫剂时,脱硫效率提高了128%。     

大庆市贴不贴纳污泡表层水及沉积物中总石油烃分布

贴不贴纳污泡是大庆市某石油化工厂生产废水排放场地,其石化废水的排放历史约 30年左右.按泡内水流方向采集水及沉积物样品,并对其中的总石油烃 （TPH）含量进行检测分析.结果显示：氧化塘出口处水及沉积物中 TPH含量最高,沿水流方向,其它各采样点含量逐渐降低.说明该纳污泡内氧化塘对 TPH的降解能力较弱,而植物对水体中 TPH迁移的阻滞能力较强,沉积物对 TPH的吸附和固着能力较强.     

One way to reduce the NOX Emission of biodiesels: The increase of cetane number

Compared to conventional diesel fuels, biodiesels normally have lower smoke and particulate matter, while higher nitrogen oxides (NO_X) emissions. In our study, an attempt was made to reduce the NO_X emissions of biodiesels by increasing the cetane numbers (CNs). Three kinds of biodiesels with extremely high CNs (70.1, 76.9, 80.9, respectively) were developed. Their main physical and chemical properties were tested. With a two-cylinder direct injection diesel engine, their emission performances were experimentally investigated. The results indicate that, CN, freezing point, as well as viscosity of biodiesels are linearly increased with the increase of carbon number. The NO_X emission for biodiesels with high CNs is lower than that of conventional diesel fuels. High CN promotes smoke formation as well while lower smoke emissions are still obtained for biodiesels when certain oxygen contents are present. That is, the smoke/NO_X tradeoff is broken. Besides, as fuel CN is elevated, NO_X for biodiesels decreases but smoke and carbon monoxide emissions are increased.     

中国省域碳排放总量控制目标分解研究

为确保实现中国CO2排放在2030年左右达到峰值的承诺,在"十三五"期间探索开展省级层面的碳排放总量控制目标分解是关键措施。基于地区差异构建碳排放总量控制目标分解模型,综合考虑公平、效率和可行三类因素,本研究以浙江省为例,将2013-2020年碳排放总量控制目标分解到各个地市。研究结果表明,浙江省11个地市的碳排放总量控制目标在四类不同情景下基本保持一致。不同权重情景下的结果均有效反映出各地市在经济发展、人民生活和技术水平等方面的差异,表明通过该模型分解碳排放总量控制目标基本合理可行。偏重公平的方案在协调区域经济发展差异方面具有较大优势,该方案一定程度上可倒逼传统经济发展模式向低碳经济转型;偏重效率的方案可最大效率地利用碳排放空间,但需给予足够的资金和技术支持;"十三五"期间我国建成统一的碳交易市场后,偏重可行的分配方案可通过碳交易市场手段实现各地市碳减排和经济发展的双赢。此外,充分发挥战略预留碳排放指标的作用可有效保证各省实现碳排放总量控制目标。尽管在选择分配指标项和分解战略预留目标时仍然存有不确定性,但可随着省级应对气候变化统计体系的建立与完善,以及各省"国民经济和社会发展十三五规划"的出台而逐步减小。本研究创新性地为中国经济发达省份开展碳排放总量控制目标的地市分解工作提供兼顾公平、效率和可行的方案。