探讨富集因子背景值的选择

为探讨富集因子(EF)背景值的选择,利用黑龙江省甘南县大气降尘重金属元素数据,分别选用黑龙江省A层土壤环境、平均大陆地壳、大陆上地壳为背景,计算Cr、Mn、Ni、Pb、As、Cu、Zn的EF值.研究表明,采用平均大陆地壳和大陆上地壳元素丰度作为背景值时,Pb、Zn、As等元素的EF均值大于2,元素富集一定程度上与人为输入作用有关;采用黑龙江省A层土壤作为背景,As元素EF均值小于2,元素在大气中的富集主要为自然输入;通过相关性分析,As与Cr、Mn、Ni、Cu同为自然源,结果与选用黑龙江省A层土壤为背景时判别结果较一致.本文认为,导致不同背景值取得的EF值差异较大的原因为自然条件下元素的富集和亏损,采用区域土壤元素背景值能够较为准确地判断大气降尘中元素的主要来源.     

太原市采暖期PM10中PAHs的碳同位素组成及源贡献率

在太原市7个点位采集采暖期PM10样品,用气相色谱-同位素质谱仪测定环境空气PM10和污染源(煤烟尘和机动车尾气)中9种多环芳烃(PAHs)的碳同位素组成(δ13C),并根据碳同位素质量平衡原理定量环境空气PAHs的源贡献率.结果表明:煤烟尘中PAHs随环数增加贫13C,机动车尾气中PAHs随环数增加富13C;各点位PAHs的δ13C值差别不大,变化趋势与煤烟尘基本一致,煤烟尘是城市PAHs的主要污染源;煤烟尘对各点位荧蒽和苯并[a]蒽的贡献率都大于机动车尾气,对 的贡献率与机动车尾气相当,煤烟尘是各点位荧蒽和苯并[a]蒽的主要来源, 是二者共同作用的结果;煤烟尘和机动车尾气对全市环境空气中荧蒽、苯并[ghi]荧蒽、苯并[a]蒽和苯并[b+k]荧蒽贡献率比都约为7:3,太原市环境空气PAHs污染属于煤烟尘和机动车尾气的复合污染.     

环境空气背景值中PM2．5和PM10的相关性分析

四川省大气背景站颗粒物PM2．5和PM10实时监测结果表明,两个点位的PM2．5浓度占PM10浓度分别为80．15％、68．9％,两个点位的PM2．j浓度和PM10浓度均呈显著线性关系,点位1：y=0．8634x-0．2212,R^2=0．9823;点位2：y=0．7352x-0．2142,R^2=0．7767。     

The need for formal reflexivity in conservation science

Conservation issues are often complicated by sociopolitical controversies that reflect competing philosophies and values regarding natural systems, animals, and people. Effective conservation outcomes require managers to engage myriad influences (social, cultural, political, and economic, as well as ecological). The contribution of conservation scientists who generate the information on which solutions rely is constrained if they are unable to acknowledge how personal values and disciplinary paradigms influence their research and conclusions. Conservation challenges involving controversial species provide an opportunity to reflect on the paradigms and value systems that underpin the discipline and practice of conservation science. Recent analyses highlight the ongoing reliance on normative values in conservation. We frame our discussion around controversies over feral horses (Equus ferus caballus) in the Canadian West and New Zealand and suggest that a lack of transparency and reflexivity regarding normative values continues to prevent conservation practitioners from finding resilient conservation solutions. We suggest that growing scrutiny and backlash to many normative conservation objectives necessitates formal reflexivity methods in conservation biology research, similar to those required of researchers in social science disciplines. Moreover, given that much conservation research and action continues to prioritize Western normative values regarding nature and conservation, we suggest that adopting reflexive methods more broadly is an important step toward more socially just research and practice. Formalizing such methods and requiring reflexivity in research will not only encourage reflection on how personal and disciplinary value systems influence conservation work but could more effectively engage people with diverse perspectives and values in conservation and encourage more novel and resilient conservation outcomes, particularly when dealing with controversial species.