Mass Balances of Mercury and Nitrogen in Burned and Unburned Forested Watersheds at Acadia National Park, Maine, USA

Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in two watersheds at Acadia National Park, Maine, and analyzed for mercury (Hg) and dissolved inorganic nitrogen (DIN, nitrate plus ammonium). Cadillac Brook watershed burned in a 1947 fire that destroyed vegetation and soil organic matter. We hypothesized that Hg deposition would be higher at Hadlock Brook (the reference watershed, 10.2 μg/m²/year) than Cadillac (9.4 μg/m²/year) because of the greater scavenging efficiency of the softwood vegetation in Hadlock. We also hypothesized the Hg and DIN export from Cadillac Brook would be lower than Hadlock Brook because of elemental volatilization during the fire, along with subsequently lower rates of atmospheric deposition in a watershed with abundant bare soil and bedrock, and regenerating vegetation. Consistent with these hypotheses, Hg export was lower from Cadillac Brook watershed (0.4 μg/m²/year) than from Hadlock Brook watershed (1.3 μg/m²/year). DIN export from Cadillac Brook (11.5 eq/ha/year) was lower than Hadlock Brook (92.5 eq/ha/year). These data show that ∼50 years following a wildfire there was lower atmospheric deposition due to changes in forest species composition, lower soil pools, and greater ecosystem retention for both Hg and DIN.     

碳市场对能源结构低碳转型的影响及作用路径

选取中国2000～2018年30个省市的面板数据,构建了能源消费结构低碳化指数,基于多期双重差分、三重差分等方法实证检验碳交易政策与能源消费结构低碳转型之间的关系及异质性影响,并进一步利用多重中介效应模型探讨碳交易政策推动地区能源消费结构低碳转型的作用路径.结果表明:碳交易政策可以显著提升地区能源消费结构低碳化水平且作用效果逐年增强.从作用路径看,“四大效应”激励作用彰显,作用效果由大到小依次为结构优化效应、行为驱动效应、生态创新效应和环保支出效应;从异质性影响看,GDP增速较慢地区的政策实施加快了能源消费结构低碳转型,影响明显高于GDP增速较快地区;碳交易政策对东部地区的正向推动效应显著,对中西部地区无明显促进作用.     

Spatial and Temporal Variation of Ozone Concentrations at High Altitude Monitoring Sites in Germany

The present study deals with the characterisation and interpretation of hourly taken maximum ozone concentrations of each day at various high altitude monitoring sites in Germany and contributes to the understanding of ozone transport processes. The relation between long range transport of ozone as well as its precursors and high ozone concentrations is of special interest. Aim of this paper is to investigate the influence and importance of large scale meteorological circulation and source regions of anthropogenic ozone precursors to local ozone concentrations using 2-dimensional backward trajectories. Further, reasons for the spatial and temporal variation of ozone concentration levels will be shown. Investigating numerous cases a similar origin of air masses causing high ozone concentrations in Germany and uniform patterns at various sites could be identified.     

垃圾按量收费政策效应的实证研究

垃圾按量收费是管制城市垃圾的最直接的环境经济政策。它根据垃圾排放量向居民征收（不同的）费用。从而实现有效率的资源配置。本文通过对城市居民的问卷调查．采用描述性统计分析、方差分析、回归分析等方法。对垃圾按量收费的政策效应进行实证研究。以期为中国垃圾按量收费政策的制定和实施提供借鉴。我们的研究旨在解决两个问题：一是测度垃圾按量收费政策的总体效应;二是考察垃圾按量收费政策对不同居民的效应差异。结果表明。从总体上看．超过半数的居民认为垃圾按量收费更合理,但多数人还是更喜欢每月固定收费;从对不同居民的具体分析看,中高收入者倾向认为垃圾按量收费更合理,年长者更喜欢每月固定收费。实行垃圾按量收费后．年轻者更可能减少倒垃圾的量．但也更可能偷偷倒垃圾。     

小麦异源细胞质遗传效应的比较研究

本文以稳定的同核异质异核杂种小麦为材料,对小麦属和山羊草属的细胞质遗传效应进行了比较研究,分析了异源细胞质遗传疚的特点,并初步筛选出了一批在小麦雄性不育性应用中以及在小麦核质杂种优势利用中有价值的细胞质材料。     

Cost-benefit analysis of implementing policy measures for reducing PM and O3 concentrations: the case of Israel

This paper aims to identify the most suitable and economically feasible policy measures to reduce concentrations of particulate matter (PM) and ozone (O₃) in Israel. It describes a comprehensive methodology that takes into account the effects of PM and O₃ and describes the overall costs and benefits expected from their reduction. Cost-benefit analysis of a series of proposed policy measures allows us to identify and recommend those that are most feasible and effective. These policy measures have a significant impact on reducing air pollution on one hand, while constituting the highest net benefit to the economy on the other.     

Threats to biodiversity from cumulative human impacts in one of North America's last wildlife frontiers

Land‐use change is the largest proximate threat to biodiversity yet remains one of the most complex to manage. In British Columbia (BC), where large mammals roam extensive tracts of intact habitat, continued land‐use development is of global concern. Extant mammal diversity in BC is unrivalled in North America owing, in part, to its unique position at the intersection of alpine, boreal, and temperate biomes. Despite high conservation values, understanding of cumulative ecological impacts from human development is limited. Using cumulative‐effects‐assessment (CEA) methods, we assessed the current human footprint over 16 regional ecosystems and 7 large mammal species. Using historical and current range estimates of the mammals, we investigated impacts of human land use on species’ persistence. For ecosystems, we found that bunchgrass, coastal Douglas fir, and ponderosa pine have been subjected to over 50% land‐use conversion, and over 85% of their spatial extent has undergone either direct or estimated indirect impacts. Of the mammals we considered, wolves were the least affected by land conversion, yet all species had reduced ranges compared with historical estimates. We found evidence of a hard trade‐off between development and conservation, most clearly for mammals with large distributions and ecosystems with high levels of conversion. Rather than serve as a platform to monitor species decline, we strongly advocate these data be used to inform land‐use planning and to assess current conservation efforts. More generally, CEAs offer a robust tool to inform wildlife and habitat conservation at scale.     

汾渭平原至黄土高原不同海拔高度地区近地面臭氧浓度差异

利用2017~2019年中国生态环境监测总站逐小时地面臭氧(O₃)和二氧化氮(NO₂)数据, 结合再分析气象数据集,分析了从汾渭平原至黄土高原三个不同海拔高度的典型城市郊区(西安:500m、榆林:1100m和鄂尔多斯:1300m)O₃浓度的季-月-日变化特征,以及导致三地O₃浓度差异可能的化学和气象成因.结果表明:与其他季节比较,夏季三地的O₃浓度都较高且差值较小,其中西安昼间O₃的净增量最大、夜间净减量也最大且前体物NO₂浓度最高,说明西安夏季白天O₃光化学反应最强烈、夜间NO滴定O₃效应也最强,榆林其次、鄂尔多斯最弱;冬季三地的O₃浓度都较低且差异较大,其中西安最低、鄂尔多斯最高,可能是由于冬季白天光化学反应都弱、夜间NO滴定O₃效应差异和高海拔地区背景O₃浓度高共同导致的,反映了三地O₃浓度水平差异不仅受不同NO_x水平下局地化学作用影响,还由区域背景值决定.分析还发现,高海拔的鄂尔多斯和榆林二地O₃浓度在上午升高的速率快于西安,与二地边界层向上发展的速率一致,可能是由于此时的夹卷效应将高海拔自由对流层的高背景O₃向下湍流输送所致.在每个季节雨天夜间,三地的O₃浓度均高于其阴、晴天,但是这一差异在西安较弱,而在榆林和鄂尔多斯较强,这进一步意指高海拔地区近地面O₃在雨天夜间更强烈地受到高浓度背景O₃的影响,一方面是通过降水的拖曳作用,另一方面是因为雨天夜间NO的滴定作用减弱.本研究通过长期观测资料分析,推测了不同海拔高度对近地面O₃的影响机制,还需在更多地区进行分析和利用模式开展验证.     

Assisted species migration and hybridization to conserve cold-adapted plants under climate change

Temperature rise due to climate change is putting many arctic and alpine plants at risk of extinction because their ability to react is outpaced by the speed of climate change. We considered assisted species migration (ASM) and hybridization as methods to conserve cold-adapted species (or the genes thereof) and to minimize the potential perturbation of ecosystems due to climate change. Assisted species migration is the deliberate movement of individuals from their current location to where the species’ ecological requirements will be matched under climate projections. Hybridization refers to crossbreeding of closely related species, where for arctic and alpine plants, 1 parent is the threatened cold-adapted and the other its reproductively compatible, warm-adapted sibling. Traditionally, hybridization is viewed as negative and leading to a loss of biodiversity, even though hybridization has increased biodiversity over geological times. Furthermore, the incorporation of warm-adapted genes into a hybrid may be the only means for the persistence of increasingly more maladapted, cold-adapted species. If approached with thorough consideration of fitness-related parameters of the source population and acknowledgement of the important role hybridization has played in shaping current biodiversity, ASM and hybridization could help save partial or whole genomes of key cold-adapted species at risk due to climate change with minimal negative effects on ecosystem functioning.     

基于受体作用理论的类雌激素效应测试方法

以17β雌二醇为标准参考物质,对基于受体作用理论的环境激素分析方法实验条件进行了重构和优化,建立了环境类雌激素分析方法。结果表明:用营养缺陷型培养基30℃恒温振荡66 h培养时间进行重组基因酵母的复苏与增殖,20℃～35℃水浴样品与酵母混合液培养3～6 h暴露,优先选用机溶剂处理法释放β-半乳糖苷酶,35℃恒温水浴进行酶活测试反应,采用反应终止后2.5 h 420 nm波长进行分析测试,同时实际样品的分析,加测不少于一个的稀释水样效应值,可使方法更加科学高效、准确度高,应用于各类实际样品分析。