Relative Contribution of Inbreeding Depression and Eroded Adaptive Diversity to Extinction Risk in Small Populations of Shore Campion

Abstract:  To study the relative importance of inbreeding depression and the loss of adaptive diversity in determining the extinction risk of small populations, we carried out an experiment in which we crossed and self-fertilized founder plants from a single, large population of shore campion ( Silene littorea Brot.). We used the seeds these plants produced to colonize 18 new locations within the distribution area of the species. The reintroduced populations were of three kinds: inbred and genetically homogeneous, each made up of selfed seed from a single plant; inbred and mixed, made up of a mixture of selfed seeds from all founder plants; and outbred and mixed, made up of a mixture of seeds obtained in outcrosses between the founders. We compared the inbred homogeneous populations with the inbred mixed to measure the effect of genetic diversity among individuals and the inbred mixed with the outbred mixed to measure the effect of inbreeding. Reintroduction success was seriously limited by inbreeding, whereas it was not affected by genetic diversity. This observation and the nonsignificant interaction between family and reintroduction location for individual plant characters suggest that the fixation of overall deleterious genes causing inbreeding depression posed a more serious threat to the short-term survival of the populations than the loss of genes involved in genotype and environment interactions. Thus, reintroduction success was related to adaptive diversity. Preventing such fixation might be the most important consideration in the genetic management and conservation of shore campion populations.     

Transformation of N-, O-, and S- heterocycles (NOSHs) in estuarine sediments: Effects of redox potential and sediment particle size

The transformation of 19 N-, O-, and S- heterocycles (NOSHs) was examined in estuarine sediment-water microcosms. The effects of redox potential (Eh) and sediment particle size on compound transformation rates were evaluated, and stable products were identified. Results from stirred, controlled Eh/pH microcosms (CEPMs) showed that most of the NOSHs were significantly transformed under oxidized and reduced conditions over 15 week incubations, and the resulting product distributions were similar. In general, the rates and extent of transformation were greater in oxidized sediments of low surface area vs. those with high particle surface area and reduced redox conditions. Further experiments in sealed, unstirred microcosms also showed that NOSH transformation proceeded more slowly and on fewer compounds in fine vs. coarser grained sediments under oxidized conditions. Unlike the stirred systems, however, NOSH transformation rates were similar or greater under reduced vs. oxidized conditions. Thus, reduced, methanogenic clay of high surface area displayed some of the fastest rates of NOSH transformation. Data from liquid-liquid partitioning experiments suggested that this effect was related to the formation of NOSH complexes with iron and perhaps other redox-active metals in sediments.     

The Effects of Acidity on Carbon Fluxes from Ombrotrophic Peat

Replicate intact peat/vegetation monoliths were collected along a pollution gradient in the UK and subjected over one year to 1200 mm of simulated rainfall of the same chemical composition as they received in the field. Drainage water was analysed periodically for DOC and pH, and the decomposition rates of Calluna vulgaris and Eriophorum angustifolium leaves were measured, as well as soil atmosphere CO₂ contents and peat matric potentials. the chemical characteristics of the peats as initially sampled from the field also were determined. the results suggest that acidic precipitation has induced chemical changes in ombrotrophic peats, lowering their pH and base status, when due account is taken of calcium deposition or any mineral content. Greater DOC fluxes were observed from the more acid peats, and litter decomposition rates from these peats were reduced.     

四川省自然资源开发潜力分析

四川省自然资源丰富。但其开发潜力具有两重性:合理开发,资源可永续利用;不合理开发,会导致资源危机或枯竭。该省石油、煤炭后备资源不足,应引起重视。还就黑色金属、有色金属、非金属、能源、水源、耕地、森林、草地等资源的开发前景作了预测。     

最后间冰期至未来2070s中国潜在自然植被时空分布格局及其对气候变化的响应

潜在自然植被（PNV）对生态环境的修复与重建、自然保护区的规划与建设和农牧业的生产与发展均有着重要的指导作用。研究基于综合顺序分类系统（CSCS）,利用最后间冰期至未来2070s六个时期的温度和降水量数据,模拟中国PNV的时空分布格局及其对气候变化的响应。研究结果表明：（1）CSCS将六个时期中国PNV分别划分为39、37、38、40、40和40类以及10个类组。（2）寒冷干旱型类组主要分布在西北,温暖湿润型和炎热潮湿型则分布在中东部和南方。除冻原和高山草地、冷荒漠、半荒漠和温带森林草地4个类组呈现下降趋势外,其余均为上升趋势。（3）温带森林草地转变为亚热带森林草地的面积最大,占总变化面积的35.4%。（4）CSCS既未包含人类活动影响因素,又能模拟长时间序列的PNV演替。（5）最后间冰期至未来2070s,森林类组向纬度和海拔高度更高的北方及青藏高原移动。研究结果进一步明确了PNV概念的界限,揭示了气候变化对PNV演替的作用机理。     

武汉市夏季大气挥发性有机物实时组成及来源

利用在线监测仪器获取了武汉市2019年6～7月环境大气中102种挥发性有机物（VOCs）小时浓度数据.观测期间ρ（VOCs）范围为24.9～254μg·m^-3,平均值为（67.7±32.2）μg·m^-3.依据臭氧浓度标准,将观测期间划分为清洁日和污染日,对比分析清洁日和污染日气象条件、 VOCs浓度、组成、臭氧生成潜势和来源差异.污染日NO_x、 CO和VOCs的平均值分别超出清洁日34.9%、 25.0%和27.8%.污染日烷烃、烯烃、芳香烃和含氧VOCs分别比清洁日高40.7%、 39.5%、 26.9%和21.5%.污染日总臭氧生成潜势为（102±69.6）μg·m^-3,超出清洁天33.5%.污染日液化石油气燃烧、工业排放、机动车排放、天然源和溶剂使用的平均贡献率分别比清洁日低3.4%、 2.5%、 0.2%、 1.3%和1.4%,油气挥发源平均贡献率比清洁日高8.8%.机动车排放源和油气挥发源的日变化均呈现早晚高、午后低的特征,与早晚高峰排放有关;LPG燃烧的日变化与餐饮油烟排放变化一致.浓度...     

基于卫星和地面监测的河西走廊O3浓度时空分布及潜在源区分析

基于2005~2020年OMI遥感卫星O₃柱浓度数据,结合河西走廊地区10个国控点环境自动监测站大气污染物数据和全球资料同化系统（GDAS）气象资料,利用克里金插值法、相关性分析和后向轨迹（HYSPLIT）模型,探讨河西走廊近地面O₃时空分布特征、气象因素、传输路径和潜在来源.结果表明：①从时间变化来看,O₃柱浓度在2005~2010年和2014~2020年呈上升趋势,2010~2014年呈下降趋势,2010年和2014年分别达到最大值和最小值,分别为332.31 DU和301.00 DU,季节变化表现为春季和冬季明显大于夏季和秋季.②在空间分布上,O₃柱浓度大体呈现由西南向东北递增的纬向带状分布特征,高值区主要分布在地势低平的城市区域,中值区呈纬向带状与祁连山山麓走向基本一致.③气象条件分析发现,温度、风速和日照时数与O₃呈现正相关,相对湿度与O₃呈现负相关.④通过对武威市模拟受点气流输送轨迹发现,O₃输送路径方向较为单一,各季节的主导气流均以西部和西北部为主,所占比例分别为71.62%、66.85%、61.22%和77.78%;O₃潜在贡献源区存在一定的季节差异：春季、夏季和秋季的O₃潜在源高值区域均分布于白银市和兰州市等地,为东南风源,冬季高值区分布于巴丹吉林沙漠和腾格里沙漠之间,为北风源.     

华北典型工矿城镇土壤重金属来源解析及潜在生态风险评价

为掌握典型工矿城镇土壤重金属状况,定量解析潜在来源,以河北省张家口市宣化区部分区域土壤为研究对象,采集并测定150个表层土壤中Cd、As、Pb、Cr、Cu、Ni和Zn这7种重金属含量;采用地累积指数法和潜在生态风险指数法评估重金属污染状况和潜在生态风险;使用主成分分析法和正定矩阵因子分解（PMF）模型对7种重金属元素进行综合污染源解析,并结合地统计学法识别各潜在源的高贡献区域.结果表明：①研究区7种重金属含量的平均值范围为0.23~103.34 mg ·kg^-1,其中,Cd、Pb、Cu和Zn的含量平均值高于河北省土壤背景值,Cd污染最为严重,平均含量为背景值的2.43倍.②地累积指数和潜在生态风险指数结果显示,7种重金属污染程度依次为：Cd>Pb>Cu>Zn>Ni>As>Cr,16%点位的Cd含量处于中度污染以上水平,95%以上的点位重金属潜在生态风险处于轻度风险等级.③研究区的7种重金属积累主要来源为工业与交通的混合源、自然源和农业源,贡献率分别为33.1%、48.7%和18.2%.其中,Cd受到工业与交通的混合源和农业源的影响,Cr、Ni和As主要受自然源影响,Pb和Cu受到工业与交通的混合源和自然源的共同作用,Zn主要受工业与交通的混合源影响.主成分分析法、PMF模型与地统计学方法的有机结合,彼此印证,增加了重金属源解析结果的可信度.     

西安市冬季道路扬尘中有机质组成特征及其氧化潜势

道路是城市人群户外活动暴露大气颗粒物的主要场所,道路颗粒物中含有的某些氧化活性物质是诱导产生活性氧,进而危害人体健康的重要组分.探索西安市道路扬尘中水溶性(WSM)和甲醇溶性组分(MSM)中有机质组成特征及其氧化潜势(OP),并基于平行因子分析(PARAFAC)研究了有机组分以及分布状况,还分析有机质类型与OP之间的相关性.结果表明,西安市道路扬尘中水不溶性组分含有更多的发色团有机物质,其总浓度平均值为(4.71±1.27)×10⁴ R.U.,是WSM的12倍[(3.96±1.10)×10³ R.U.],其中低氧化性类腐殖质(HULIS)是主要有机质(占总有机质的34.8%～43.7%).聚类分析结果显示西安市道路扬尘中有机质的重要来源为燃料燃烧和工业生产.扬尘氧化毒性(以DTT计)的平均值是(0.34±0.08) pmol·(min·μg)^-1,其中水不溶性组分提供了扬尘颗粒物总氧化毒性的70%,是水溶性组分的2.4倍.扬尘颗粒物氧化毒性的主要前驱物为金属元素,特殊类型的有机物质也是重要氧化毒性前驱物质之一,其中发色团...     

北京市道路扬尘重金属污染特征及潜在生态风险

以北京市代表性道路扬尘2004年的PM_(10)与PM_(2. 5)和2013年的PM_(2. 5)中21种无机元素含量为基础,分析和探讨北京市道路扬尘重金属污染特征及其潜在生态风险.结果表明,北京市道路扬尘中6种主要元素为Si、Ca、Al、Fe、Mg和K,其含量之和占所有被测元素含量的比例分别为:2004年PM_(10)为96. 51%、2004年PM_(2. 5)为96. 42%和2013年PM_(2. 5)为96. 53%.2004年北京市道路扬尘中元素富集水平、重金属污染程度和潜在生态风险总体表现为:PM_(2. 5) PM_(10);燃煤烟尘特征元素Se在2004年的PM_(2. 5)中、Cd在2004年的PM_(10)与PM_(2. 5)中均为极强富集,富集因子分别为1024. 03、68. 15和871. 55; Co、Zn、Ca和Cu属显著富集,其富集因子在2004年PM_(10)中分别为12. 93、12. 33、8. 30和8. 07,在PM_(2. 5)中分别为17. 41、21. 80、12. 83和19. 73;但Na和Si在道路扬尘中均无富集.重金属的污染载荷指数(PLI)在2004年PM_(10)中为3. 95,PM_(2. 5)为7. 71. 2013年北京市道路扬尘PM_(2. 5)中重金属污染水平和潜在生态风险较2004年均显著降低,在2013年PM_(2. 5)中,Cd和Se的富集因子分别下降为98. 47和0. 95; Cu、Ca和Zn富集因子分别下降为11. 90、8. 84和8. 20; PLI下降为2. 56.研究表明,北京市道路扬尘多种重金属总的潜在生态风险极强,重金属Cd为极显著污染因子和主要的潜在生态风险来源,其潜在生态风险指数(RI)对重金属总的RI贡献超过85%. 2004年北京市道路扬尘主干道重金属污染程度明显高于其它道路类型,PM_(10)表现为:主干道高速进京口次干道环路,PM_(2. 5)表现为:主干道环路高速进京口次干道;而2013年PM_(2. 5)表现为:高速进京口主干道环路次干道,且次干道重金属污染水平显著低于其它道路类型. 2013年北京市道路扬尘PM_(2. 5)中,重金属Ti、Zn、V、Cr、Cu、Pb和Ni相关性显著,主要来源于与交通有关的排放.