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Journal of environmental sciences 2023年第7期129卷 79-89页

作者： Yong He Xiangyu Wang Zhaobin Zhang college of urban and environmental sciences Peking UniversityBeijing 100871China

Sediment core is the recorder of polycyclic aromatic hydrocarbon(PAH)pollutions and the associated sedimentary organic matter(SOM),acting as crucial supports for pollution control and environmental management.Here,the sedimentary records of PAHs and SOM in the past century in Lake Taihu,China,were reconstructed from a 50-cm sediment core.On the one hand,the presence of PAHs ranged from 8.99 to 199.2 ng/g.Vertically,PAHs declined with the depth increased,and the sedimentation history of PAHswas divided into two stages with a discontinuity at 20 cm depth.In composition,PAHs in the sediment core were dominated by three-ring PAHs(44.6%±9.1%,mean±standard deviation),and were followed by four-ring(27.0%±3.3%),and five-ring(12.1%±4.0%)PAHs.In toxicity assessment,the sedimentary records of benzo[a]pyrene-based toxic equivalency were well described by an exponential model with R-square of 0.95,and the environmental background toxic value was identified as 1.62 ng/g.On the other hand,different components of SOM were successfully identified by n-alkanemarkers(penvironmental processes such as biogenic factors should attract more attentions as well as PAH emissions to reduce the impacts of PAHs.

关键词： Polycyclic aromatic hydrocarbons (PAHs) N-alkanes Sedimentary records Composition Toxicity assessment Lake Taihu

Threshold of climate extremes that impact vegetation productivity over the Tibetan Plateau

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Science China Earth sciences 2024年第6期67卷 1967-1977页

作者： Zhenggang PIAO Xiangyi LI Hao XU Kai WANG Shuchang TANG Fei KAN Songbai HONG college of urban and environmental sciences Peking UniversityBeijing 100871China

Vegetation growth is adversely impacted by multiple climate extremes related to the water and thermal stress over the Tibetan Plateau(TP).However,it remains unknown at which stress level these climate extremes can trigger the abrupt shifts of vegetation response to climate extremes and result in the maximum vegetation response across TP.To fill this knowledge gap,we combined the hydrometeorological data and the satellite-derived vegetation index to detect two critical thresholds that determine the response of vegetation productivity to droughts,high-temperature extremes,and low-temperature extremes,respectively,during 2001-2018.Our results show that the response of vegetation productivity to droughts rapidly increases once crossing -1.41±0.6 standard deviation(σ)below the normal conditions of soil moisture.When crossing-2.98σ±0.9σ,vegetation productivity is maximum damaged by droughts.High-temperature extremes,which have the two thresholds of 1.34σ±0.4σand 2.31σ±0.4σover TP,are suggested to trigger the strong response of vegetation productivity at a milder stress level than low-temperature extremes(two thresholds:-1.44σ±0.5σand-2.53σ±0.8σ).Moreover,we found the compounded effects of soil moisture deficit in reducing the threshold values of both high-and low-temperature extremes.Based on the derived thresholds of climate extremes that impact vegetation productivity,Earth System Models project that southwestern TP and part of the northeastern TP will become the hotspots with a high exposure risk to climate extremes by 2100.This study deciphers the high-impact extreme climates using two important thresholds across TP,which advances the understanding of the vegetation response to different climate extremes and provides a paradigm for assessing the impacts of climate extremes on regional ecosystems.

关键词： Tibetan Plateau Climate extremes Thresholds Vegetation productivity

高山植物花中央的温度比边缘高:来自青藏高原的证据

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Journal of Plant Ecology 2023年第6期16卷 108-121页

作者： Yan Zhang Yanhong Tang Department of Ecology College of Urban and Environmental SciencesPeking UniversityBeijing 100871China

花表面温度对植物繁殖有重要作用,但花表面温度的空间分布规律仍不清楚,尤其是在高山植物中。为探讨花表面温度空间分布,我们分析了青藏高原东北部冷龙岭海拔3200至4000 m的18种植物的热成像照片,发现在直射辐射环境下花或花序表面温度... 详细信息

花表面温度对植物繁殖有重要作用,但花表面温度的空间分布规律仍不清楚,尤其是在高山植物中。为探讨花表面温度空间分布,我们分析了青藏高原东北部冷龙岭海拔3200至4000 m的18种植物的热成像照片,发现在直射辐射环境下花或花序表面温度空间变化很大,大多数花或花序的中央温度比边缘高出约1℃,最大可达11℃。太阳辐射和花的形状显著影响花表面温度的空间分布,如温度的空间变化范围、空间变化的标准差以及花中心与边缘部分的温度比值。花冠越大,表面温度的空间变异性越高。菊科植物表面花温及其空间变异性都比较高,花中央温度比边缘温度也比其它观测的物种更高更稳定。大多数物种花中央与边缘部分温度的比值随海拔上升而增大。这些结果表明,在高山植物中花或花序中央区域的热积累可能很普遍,其生态和进化意义有待进一步探索。

关键词：花形状花性状青藏高原繁殖成功温度分布

青藏高原东北部39种阔叶草本植物叶大小随海拔增加而减少

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Journal of Plant Ecology 2022年第6期15卷 1227-1240页

作者： Xinran Ke Huixing Kang Yanhong Tang Department of Ecology College of Urban and Environmental SciencesPeking UniversityBeijing 100871China

种间或种内的叶大小随环境变化存在很大的差异,但这些差异如何随海拔变化一直都在争论。我们在青藏高原东北缘的冷龙岭和达坂山,沿海拔3200–4400 m的山坡上选取生长在开阔环境下的39种阔叶草本植物,观测了叶大小、叶长、叶宽和比叶重... 详细信息

种间或种内的叶大小随环境变化存在很大的差异,但这些差异如何随海拔变化一直都在争论。我们在青藏高原东北缘的冷龙岭和达坂山,沿海拔3200–4400 m的山坡上选取生长在开阔环境下的39种阔叶草本植物,观测了叶大小、叶长、叶宽和比叶重。研究结果表明,随海拔增加叶片显著减小,而且叶片面积的减小主要受叶片长度的影响,即随海拔增加叶长度减小明显。此外,叶片面积与海拔之间的关系随物种、叶倾角和叶表面特征而不同。利用局地环境观测数据驱动的能量平衡模型分析发现:叶温能更密切地追随气温变化,叶大小变化对叶温的影响在高海拔更为强烈。同时,基于上述能量平衡的计算结果,我们认为青藏高原东北部阔叶草本植物的海拔分布上限大约为5400 m。

关键词：海拔叶面积叶能量平衡叶长比叶重

Beyond city expansion:multi-scale environmental impacts of urban megaregion formation in China

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National Science Review 2022年第1期9卷 79-91页

作者： Weiqi Zhou Wenjuan Yu Yuguo Qian Lijian Han Steward T.A.Pickett Jing Wang Weifeng Li Zhiyun Ouyang State Key Laboratory of urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences college of Resources and Environment University of Chinese Academy of Sciences Cary Institute of Ecosystem Studies Beijing urban Ecosystem Research Station Research Center for Eco-Environmental Sciences Chinese Academy of Sciences

environmental degradation caused by rapid urbanization is a pressing global issue.However,little is known about how urban changes operate and affect environments across multiple scales.Focusing on China,we found urbanization was indeed massive from 2000 to 2015,but it was also very uneven,exhibiting high internal city dynamics.urban areas in China as a whole became less green,warmer,and had exacerbated PM2.5 pollution.However,environmental impacts differed in newly developed versus older areas of cities.Adverse impacts were prominent in newly urbanized areas,while old urban areas generally showed improved environmental quality.In addition,regional environmental issues are emerging as cities expand,connect and interact to form urban megaregions.To turn urbanization into an opportunity for,rather than an obstacle to,sustainable development,we must move beyond documenting urban expansion to understand the environmental consequences of both internal city dynamics and the formation of urban megaregions.

关键词： urbanization urban and regional sustainability landscape change air pollution urban heat island

Delineation of an urban Community Life Circle Based on a Machine-Learning Estimation of Spatiotemporal Behavioral Demand

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Chinese Geographical Science 2021年第1期31卷 27-40页

作者： LI Chunjiang XIA Wanqu CHAI Yanwei college of urban and environmental sciences Peking UniversityBeijing 100871China

Delineating life circles is an essential prerequisite for urban community life circle planning. Recent studies combined the environmental contexts with residents’ global positioning system(GPS) data to delineate the life circles. This method, however, is constrained by GPS data, and it can only be applied in the GPS surveyed communities. To address this limitation, this study developed a generalizable delineation method without the constraint of behavioral data. According to previous research, the community life circle consists of the walking-accessible range and internal structure. The core task to develop the generalizable method was to estimate the spatiotemporal behavioral demand for each plot of land to acquire the internal structure of the life circle, as the range can be delineated primarily based on environmental data. Therefore, behavioral demand estimation models were established through logistic regression and machine learning techniques, including decision trees and ensemble learning. The model with the lowest error rate was chosen as the final estimation model for each type of land. Finally, we used a community without GPS data as an example to demonstrate the effectiveness of the estimation models and delineation method. This article extends the existing literature by introducing spatiotemporal behavioral demand estimation models, which learn the relationships between environmental contexts, population composition and the existing delineated results based on GPS data to delineate the internal structure of the community life circle without employing behavioral data. Furthermore, the proposed method and delineation results also contributes to facilities adjustments and location selections in life circle planning, people-oriented transformation in urban planning, and activity space estimation of the population in evaluating and improving the urban policies.

关键词： community life circle spatiotemporal behavioral demand demand estimation model decision tree ensemble learning

Paleoglacial and paleoclimate reconstructions during the global Last Glacial Maximum in the Longriba area, eastern Tibetan Plateau

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Journal of Mountain Science 2021年第2期18卷 307-322页

作者： YANG Wei-lin HAN Ye-song PENG Xu RAN Ze-ze LIU Qing LIU Geng-nian college of urban and environmental sciences Peking UniversityBeijing 100871China

Owing to the remoteness of the Longriba area and the lack of dating records,it is extremely challenging to reconstruct the chronology and extent of the paleoglaciers in this area.In this paper,we combined limited observational data with automated modelling for paleoglacial reconstructions.We first identified a broadly distributed paleoglacier from satellite imagery and field investigation based on the sediment-landform assemblage principle and dated it to 23.1±1.4~19.5±1.2 ka by ^(10)Be exposure dating,corresponding to the global Last Glacial Maximum(gLGM).Then,we reconstructed the extent and ice surface of 171 paleoglaciers formed during the similar period based on geomorphological evidence and‘ice surface profile’modelling.The results showed that the paleoglacial coverage was 426.5 km2,with an ice volume of 38.1 km^(3),in the Longriba area.The reconstructed equilibrium line altitudes(ELAs)based on modelled ice surfaces yielded an average of 4245±66 m above sea level(asl),~725±73 m lower than the present ELA(4970±29 m asl).The temperature was~5.51-6.68℃lower,and the precipitation was~30-34%less in Longriba,during the gLGM compared to the present day.This glacial advance was mainly driven by colder climate that was synchronous with Northern Hemisphere cooling events.

关键词： Ice surface profile ^(10)Be surface exposure dating Paleoglacial reconstruction Paleoclimate reconstruction Global Last Glacial Maximum Eastern Tibetan Plateau

Measurement of water-leaving radiance on smooth water surfaces at different viewing angles using high-resolution spectroradiometer

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Chinese Optics Letters 2012年第6期10卷 77-80页

作者：吕云峰孙仲秋赵云升 college of urban and environmental sciences Northeast Normal University college of urban and environmental sciences Changchun Normal University

This letter describes a method for calculating water-leaving radiance on smooth surfaces at different angles based on Fresnel law and the polarized measurements using an ASD FS3 spectroradiometer. The spectroradiometer is mounted on a goniometer so that it views the water surface from a height of several decimeters at different viewing angles through a linear polarizing filter. The incident angles equal the viewing angles. The water-leaving radiance spectra acquired by other methods are compared with the polarized measurements from the smooth water surface, and the radiance spectra obtained by the proposed method are found to be consistent with the results of the reference methods. The current study provides another effective technique for measuring water-surface reflectance via remote sensing. Moreover, the method does not avoid the sun glint during the detection of water-leaving radiance in cases where the viewing geometric position is clear.

关键词： Radiometers Remote sensing

Emission factors of particulate matter, CO and CO_2 in the pyrolytic processing of typical electronic wastes

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Journal of environmental sciences 2019年第7期31卷 93-101页

作者： Liyuan Chen Chuanyang Cai Shuangyu Yu Yu Liu Shu Tao Wenxin Liu Key Laboratory for Earth Surface Processes College of Urban and Environmental Sciences Peking University

A self-designed experimental device was employed to simulate the pyrolytic dismantling process of selected electronic wastes(E-wastes), including printed wiring boards(PWBs)and plastic casings. The generated particulate matter(PM) of different particle sizes, carbon monoxide(CO) and carbon dioxide(CO_2) were determined, and the corresponding emission factors(EFs) were estimated. Finer particles with particle sizes of 0.4–2.1 μm accounted for78.9% and 89.3% of PM emitted by the pyrolytic processing of PWBs and plastic casings,respectively, and the corresponding EFs were 9.68 ± 4.81 and 18.49 ± 7.2 g/kg, respectively.The EFs of CO and CO_2 from PWBs and plastic casings were 55.9 ± 26.9 and 1182 ± 439 g/kg,and 133.6 ± 34.6 and 2827 ± 276 g/kg, respectively. Compared with other emission sources,such as coal, biomass, and traffic exhaust, the EFs of E-wastes were relatively higher,especially for PM. There were significant positive correlations(p < 0.05) of the initial contents of carbon and nitrogen in PWBs with the related EFs of PM, CO, and CO_2, while the correlations for plastic casings were insignificant. The EFs of CO of PWBs were significantly positively correlated with the corresponding EFs of PM and the parent polycyclic aromatic hydrocarbons(PAHs); however, the same result was not observed for plastic casings.

关键词： Pyrolytic processing of electronic-wastes Particulate matter CO CO2 Emission factor

Biogeochemistry of methanogenesis with a specific emphasis on the mineral-facilitating effects

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Acta Geochimica 2017年第3期36卷 379-384页

作者： Yahai Lu Wei Zhang college of urban and environmental sciences Peking University Beijing 100871 China

The Earth surface contains various oxic and anoxic environments. The later include natural wetlands,river and lake sediments, paddy field soils and landfills. In the last few decades, the biogeochemical cycle of carbon in anoxic environments, which leads to the production and emission of methane, a potent greenhouse gas in the atmosphere, has drawn great attentions from both scientific and public sectors. New organisms and mechanisms involved in methanogenesis and carbon cycling have been uncovered. Interspecies electron transfer is considered as a crucial step in methanogenesis in anoxic environments.Electron-carrying mediators, like H_2 and formate, are known to play the key role in electron transfer. Recently, it has been found that in addition to the conventional electron transfer via chemical mediators, direct interspecies electron transfer(DIET) can occur. In this Review, we describe the ecology and biogeochemistry of methanogenesis and highlight the effect of microbe-mineral interaction on microbial syntrophy. Recent advances in the study of DIET may pave the way towards a mechanistic understanding of methanogenesis and the influence of microbe-mineral interaction on this process.

关键词：生物地球化学循环产甲烷过程矿物甲烷微生物缺氧环境电子转移电子传递化学介质