Ant colonization increased total mercury but reduced methylmercury contents in boreal mires, Northeast China

Soil macroinvertebrates as ecosystem engineers play significant, but largely ignored, roles in affecting mercury (Hg) cycle by altering soil physical-chemical properties. Ant is likely expanded into boreal mires with climate warming, however, its impacts on Hg cycle remained poorly understood. We compared total Hg (THg) and methylmercury (MeHg) contents in soils from antmounds (Lasius flavus) and the nearby ambient in a boreal mire in Northeast China. The present work seeks to unravel factors that controlling MeHg levels in case of ant appearance or absence. The average THg was 179 µg/kg in the ant mound and was 106.1 µg/kg in nearby soils, respectively. The average MeHg was 10.9 µg/kg in the ant mound and was 12.9 µg/kg in nearby soils, respectively. The ratios of MeHg to THg (%MeHg) were 7.61% in ant mounds and 16.75% in nearby soils, respectively. Ant colonization caused THg enrichment and MeHg depletion, and this change was obvious in the 10-20 cm depth soil layer where ants mainly inhabited. Spectrometry characteristics of soil dissolved organic matter (DOM) exert a stronger control than microorganisms on MeHg variation in soils. A structural equation model revealed that the molecular weight of DOM inhibited MeHg irrespective of ant presence or absence, while humification conducive to MeHg significantly in ant mound soils. Microorganisms mainly affected Hg methylation by altering the molecular weight and humification of DOM. We propose that the effects of ant colonization on MeHg rested on DOM feature variations caused by microorganisms in boreal mires.     

基于EVI相似性分区的冬小麦面积提取及其动态监测

及时、准确地获取冬小麦种植面积及时空变化信息对提升作物估产精度和保障粮食安全具有重要意义。冬小麦物候期受地理条件和人为因素影响差异很大，利用遥感进行大尺度种植面积提取时其精度容易受物候差异的影响。根据MODIS EVI数据和Landsat影像，在定量评价冬小麦EVI相似性并结合高程信息对研究区进行分区的基础上，通过对比冬小麦参考时序曲线与待分类像元时序曲线之间相似性提取冬小麦种植面积，并对湖北省2009～2017年冬小麦种植面积时空变化过程进行分析。结果表明：（1）冬小麦面积提取平均精度达95.3%，R ²大于0.90，明显优于未分区提取结果；（2）冬小麦主要集中分布于中部和北部地区，其中，襄阳县、枣阳市的种植面积尤为集中；（3）冬小麦空间分布大致呈现向西北、东南部地区扩张的时空变化格局；（4）在2009～2017年期间，冬小麦种植面积先增后减，总体呈上升趋势，2017年比2009年增加了4%。基于EVI相似性的作物分区提取方法可提高种植面积精度，为大区域内冬小麦面积时空变化遥感监测提供有效方法。     

南京北郊地区黑碳气溶胶对光解系数的影响

采用2018年6月以及2017年10月南京黑碳气溶胶（BC）垂直观测数据和Mie散射理论计算BC光学厚度（AOD_BC）,并将结果输入TUV辐射传输模型,探讨BC对光解系数J[O¹D]和J[NO₂]日变化及垂直变化的影响.结果表明,在地面,J[O¹D]和J[NO₂]日变化均呈单峰型分布,峰值在正午12：00,但BC对J[O¹D]和J[NO₂]的衰减作用正午时最小,在6：00和18：00左右较大,最大分别可达-13.7%和-19.0%.AOD_BC与光解系数呈非线性负相关,BC对光解系数的衰减能力随着AOD_BC增大而下降.当天顶角为0°时,光解系数对AOD_BC的变化最敏感.在边界层0~1km内,光解系数与高度呈线性正相关,这与紫外辐射密切相关,J[O¹D]和J[NO₂]在垂直高度上与紫外辐射的相关系数R均高达0.99.BC对光解系数的衰减程度随高度下降而增大,但幅度较小,距平的最大值仅0.1%.     

农业干旱与气象干旱关联性——以淮河蚌埠闸以上地区为例

基于淮河蚌埠闸以上地区60个站点1961—2015年气象数据,计算作物水分亏缺指数（Crop Water Deficit Index,CWDI）与相对湿润度指数（Relative Moisture Index,M）,以冬小麦干旱作为农业干旱的代表,分析生育期内冬小麦干旱与气象干旱时空特征,并通过游程理论识别30场主要干旱事件的历时、烈度及重现期频率,展开农业干旱与气象干旱关联性研究,结果表明：（1）时间上,冬小麦生育期内农业干旱旱情年占比均高于气象干旱,年际差最多年份均发生在冬前生长期;（2）空间上,全生育期和各个生育期内的冬小麦干旱和气象干旱呈纬向分布,由南至北旱情逐渐加重,冬小麦干旱75%以上中旱占比发生在越冬期至灌浆成熟期,气象干旱仅在越冬期出现;（3）冬小麦干旱相较气象干旱存在延时,且烈度大于气象干旱,平均历时分别为18.8旬和17.3旬,平均烈度分别为12.2和9.9;（4）气象干旱历时达到1.28旬或干旱烈度达到3.35时,便会引发冬小麦干旱,且冬小麦干旱历时、烈度重现期频率大于气象干旱,农业干旱较气象干旱持续周期更长、频率及强度更大,气象干旱加剧农业干旱旱情。     

Mesoporous cobalt monoxide-supported platinum nanoparticles: Superior catalysts for the oxidative removal of benzene

Mesoporous Co_3 O_4(meso-Co_3 O_4)-supported Pt(0.53 wt.% Pt/meso-Co304) was synthesized via the KIT-6-templating and polyvinyl alcohol(PVA)-assisted reduction routes.Mesoporous CoO(meso-CoO) was fabricated through in situ reduction of meso-Co304 with glycerol,and the 0.18-0.69 wt.% Pt/meso-CoO samples were generated by the PVA-assisted reduction method.Meso-Co_3 O_4 and meso-CoO were of cubic crystal structure and the Pt nanoparticles(NPs) with a uniform size of ca.2 nm were well distributed on the mesoCo_3 O_4 or meso-CoO surface.The 0.56 wt% Pt/meso-CoO(0.56 Pt/meso-CoO) sample performed the best in benzene combustion(T_(50%)=156℃and T_(90%)=186℃at a space velocity of 80,000 mL/(g h)).Introducing water vapor or C02 with a certain concentration led to partial deactivation of 0.56 Pt/meso-CoO and such a deactivation was reversible.We think that the superior catalytic activity of 0.56 Pt/meso-CoO was intimately related to its good oxygen activation and benzene adsorption ability.     

辽东湾北部河口区土壤重金属污染源识别及健康风险评价

选取我国北方典型河口区—辽东湾北部区为研究对象,共采集129个表层土样,测定了Cu、Cr、Cd、Ni、Zn和Pb等土壤重金属含量,利用地统计分析、地累积指数（I_geo）、内梅罗指数、潜在生态风险指数（RI）、多元统计分析及健康风险模型对研究区土壤重金属的空间分布特征、污染来源及健康风险进行系统分析,并对区域人居环境改善提出对策建议.结果表明：①研究区土壤中Cu、Cr、Cd、Ni、Zn和Pb的平均含量分别为17.87、148.97、1.31、40.91、102.86和12.42 mg·kg^-1,除Cu和Pb以外都超过了辽宁省土壤背景值;②6种重金属污染程度排序为Cd > Cr > Zn > Ni > Cu > Pb,其中Cd元素污染最严重;土壤重金属综合生态风险指数RI为325.689,处于重度生态风险水平,Cd是主要的生态风险因子;③多元统计分析表明,重金属Cu、Zn和Pb主要受自然因素影响,Cr和Ni主要源于生活及工业废水排放,Cd以磷肥的大量使用、石油化工生产及工业活动作为主要的人为来源;④健康风险评价结果表明,皮肤接触暴露途径中儿童的非致癌风险大于成人,呼吸暴露途径中成人的致癌风险大于儿童,元素Cr的总致癌风险R_all<10^-6,不存在致癌风险,Cd的总致癌风险10^-4 < R_all < 10^-6,存在可接受致癌风险;⑤河口海岸区对我国海湾及沿海区域经济发展意义重大,土壤重金属污染和人居健康问题已经不容忽视,希冀本研究可为当地政府及同类区域提供科学借鉴.     

基于水化学和氢氧同位素的东宫河流域不同水体转化关系研究

为明晰秦皇岛东宫河流域水环境特征,以该流域大气降水、地下水及地表水为研究对象,通过对水化学和氢氧稳定同位素样品测试及特征分析,揭示其时空变化特征及大气降水、地下水和地表水的相互转化关系.结果表明:①东宫河流域地下水（第四系孔隙水、岩溶水、裂隙水）和地表水（河水、泉水）的水化学类型,枯水期较丰水期丰富.丰水期水化学类型主要以HCO₃-Ca型、HCO₃·SO₄-Ca型和HCO₃-Ca·Mg型为主;枯水期水化学类型以HCO₃-Ca型、HCO₃-Ca·Mg型、HCO₃·SO₄-Ca型、HCO₃·SO₄-Ca·Mg型为主.②研究区第四系孔隙水和泉水的离子含量变化受季节影响较大,枯水期离子含量变化较丰水期显著;岩溶水和裂隙水各离子含量变幅较小,基本趋于稳定.岩溶含水层和裂隙含水层中富含石膏,为SO₄2-的主要来源;Na+和Cl-主要来源于易溶解盐NaCl,Ca2+和Mg2+主要来源于方解石的风化溶解.③东宫河流域地下水、地表水及大气降水之间存在密切的水力联系,针对氢氧同位素的组成分析表明,大气降水为地下水和河水的主要来源;不同泉水补给来源存在差异性,泉水主要接受岩溶水补给,同时也受蒸发作用影响;第四系孔隙水接受大气降水和河水的双重补给;裂隙水主要接受山区降水径流补给.研究显示,东宫河流域不同水体中离子含量受降雨量、温度和地质背景等影响,不同水体间联系密切,相互补给排泄.      

Scale and benefit of global carbon markets under the 2 °C goal: integrated modeling and an effort-sharing platform

Global climate change mitigation needs all countries’ efforts under the United Nations Framework Convention on Climate Change’s guideline of equity and common but differentiated responsibilities and respective capabilities. The medium-to-long term regional emissions pathways simulated by integrated assessment models with global mitigation costs minimized to achieve the 2 °C goal might be very different from the regional emissions allowances allocated based on effort-sharing principles. Global carbon trading is a cost-effective mechanism to bridge the gap. Insight of previous papers has mainly focused on the impact of a single effort-sharing scheme on global carbon market, while this study attempts to explore the scale and benefit of global carbon market under different effort-sharing principles to achieve the 2 °C goal, with the application of a consistent modeling framework, consisting of an integrated assessment model and an effort-sharing platform. The results indicate that scale of global carbon market would be highly related with the effort-sharing principles. The global trading volumes would change from 1.8 Gigatons (Gt) carbon dioxide (CO₂) to over 12 GtCO₂ per year and largely peak between 2030 and 2040 under different kinds of effort-sharing principles. Correspondingly, annual global finance flows in the carbon market would increase gradually and reach the scale of hundreds of billions United States (US) dollars since 2020. Global carbon market would lower the abatement costs of developed countries, and the overall global abatement costs would drop by 0.4–2.6% during 2011–2050. The developing countries would not only acquire revenues from global carbon trading but also be provided with an opportunity to accelerate their domestic low-carbon energy transformation, local environmental improvement, job creation, and economic development. Linking national and regional carbon markets to develop global carbon market will be critical to maximize the utility of the market mechanism.     

船舶排放清单研究方法及进展

远洋船舶在港口和近海范围的排放清单是研究大气复合污染的形成和应对机制的迫切需求,船舶因其动态、多源、跨国注册等特点,是源清单研究中难度较大的部门.本文对现有研究在全球、区域、港口尺度的数据需求、方法学和适用性进行了综述,对比评价了各方法的优缺点和适用范围,归纳了能提供高分辨率排放清单的方法体系.其中燃油法更适用于全球清单计算,但不适用于区域清单;贸易法对基础数据要求较低,但不确定度较大;统计法依赖统计数据,更适用于港口范围;动力法准确性最高,但对基础数据有较高要求.此外,从全球、区域、港口尺度方面介绍了船舶清单的研究进展,提出了未来改进清单面临的排放因子和AIS数据方面的挑战,并展望了我国船舶排放清单研究的发展方向.