分类： 环境科学技术及资源科学技术 >> 环境学 分类： 计算机科学 >> 计算机科学技术其他学科 提交时间： 2024-01-07
摘要： 目的 本研究的目标是开发一种便携式气相色谱仪，结合机器学习实现现场的VOC采集和快速的气味评价。 方法 我们使用卷积神经网络-长短期记忆（CNN-LSTM）建立了气味强度的预测模型。由于收集的数据量较小，我们使用生成对抗网络（GAN）对每个气味强度类别的VOC数据进行了生成，以增强模型的训练。 结果 在生成数据后，我们再次使用CNN-LSTM建立了模型，并与人工神经网络（ANN）、支持向量机（SVM）和梯度提升决策树（XG-Boost）进行了比较。结果表明，使用GAN生成数据后的测试准确率优于原始数据。 局限 未来的工作将集中在进一步优化模型和扩大数据集上，以提高预测的准确性和稳定性。 结论 这项研究表明，通过使用深度学习和生成对抗网络，我们可以有效地预测车内的气味强度，从而改善车内的空气质量。此外，我们还将探索将这种方法应用于其他环境条件下的空气质量预测。这为未来的空气质量监测和改善提供了新的可能性。由于我们的设备是便携式的，且模型结构较小可以直接嵌入到设备上，从而实现现场的VOC采集和快速的气味评价。这为未来的空气质量监测和改善提供了新的可能性。
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2023-02-15 合作期刊: 《干旱区科学》
摘要： Water risk early warning systems based on the water environmental carrying capacity (WECC) are powerful and effective tools to guarantee the sustainability of rivers. Existing work on the early warning of WECC has mainly concerned the comprehensive evaluation of the status quo and lacked a quantitative prejudgement and warning of future overload. In addition, existing quantitative methods for short-term early warning have rarely focused on the integrated change trends of the early warning indicators. Given the periodicity of the socioeconomic system, however, the water environmental system also follows a trend of cyclical fluctuations. Thus, it is meaningful to monitor and use this periodicity for the early warning of the WECC. In this study, we first adopted and improved the prosperity index method to develop an integrated water risk early warning framework. We also constructed a forecast model to qualitatively and quantitatively prejudge and warn about the development trends of the water environmental system. We selected the North Canal Basin (an essential connection among the Beijing- Tianjin-Hebei region) in China as a case study and predicted the WECC in 25 water environmental management units of the basin in 20182023. We found that the analysis of the prosperity index was helpful in predicting the WECC, to some extent. The result demonstrated that the early warning system provided reliable prediction (root mean square error of 0.0651 and mean absolute error of 0.1418), and the calculation results of the comprehensive early warning index (CEWI) conformed to the actual situation and related research in the river basin. From 2008 to 2023, the WECC of most water environmental management units in the basin had improved but with some spatial differences: the CEWI was generally poor in areas with many human disturbances, while it was relatively good in the upstream regions with higher forest and grass covers as well as in the downstream areas with larger water volume. Finally, through a sensitivity analysis of the indicators, we proposed specific management measures for the sustainability of the water environmental system in the North Canal Basin. Overall, the integrated water risk early warning framework could provide an appropriate method for the water environmental administration department to predict the WECC of the basin in the future. This framework could also assist in implementing corresponding management measures in advance, especially for the performance evaluation and the arrangement of key short-term tasks in the River Chief System in China.
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2022-10-13 合作期刊: 《干旱区科学》
摘要：There is a lack of research on soil microplastics in arid oases considering the rapid economic development of northwestern China. Here, we studied the occurrence and sources of microplastics in soil, as well as the relationships between microplastics and adsorbed heavy metals in the Ebinur Lake Basin, a typical arid oasis in China. Results showed that (1) the average microplastic content in all soil samples was 36.15 (±3.27) mg/kg. The contents of microplastics at different sampling sites ranged from 3.89 (±1.64) to 89.25 (±2.98) mg/kg. Overall, the proportions of various microplastic shapes decreased in the following order: film (54.25%)>fiber (18.56%)>particle (15.07%)>fragment (8.66%)>foam (3.46%); (2) among all microplastic particles, white particles accounted for the largest proportion (52.93%), followed by green (24.15%), black (12.17%), transparent (7.16%), and yellow particles (3.59%). The proportions of microplastic particle size ranges across all soil samples decreased in the following order: 1000–2000 µm (40.88%)>500–1000 µm (26.75%)>2000–5000 µm (12.30%)>100–500 µm (12.92%)>0–100 µm (7.15%). FTIR (Fourier transform infrared) analyses showed that polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polyethylene (PE), and polystyrene (PS) occurred in the studied soil; (3) random forest predictions showed that industrial and agricultural production activities and the discharge of domestic plastic waste were related to soil microplastic pollution, in which agricultural plastic film was the most important factor in soil pollution in the study area; and (4) seven heavy metals extracted from microplastics in the soil samples showed significant positive correlations with soil pH, EC, total salt, N, P, and K contents (P<0.01), indicating that these soil factors could significantly affect the contents of heavy metals carried by soil microplastics. This research demonstrated that the contents of soil microplastics are lower than other areas of the world, and they mainly come from industrial and agricultural activities of the Ebinur Lake Basin.
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2022-05-09 合作期刊: 《干旱区科学》
摘要： Abstract: High Mountain Asia (HMA) region contains the world's highest peaks and the largest concentration of glaciers except for the polar regions, making it sensitive to global climate change. In the context of global warming, most glaciers in the HMA show various degrees of negative mass balance, while some show positive or near-neutral balance. Many studies have reported that spatial heterogeneity in glacier mass balance is strongly related to a combination of climate parameters. However, this spatial heterogeneity may vary according to the dynamic patterns of climate change at regional or continental scale. The reasons for this may be related to non-climatic factors. To understand the mechanisms by which spatial heterogeneity forms, it is necessary to establish the relationships between glacier mass balance and environmental factors related to topography and morphology. In this study, climate, topography, morphology, and other environmental factors are investigated. Geodetector and linear regression analysis were used to explore the driving factors of spatial variability of glacier mass balance in the HMA by using elevation change data during 20002016. The results show that the coverage of supraglacial debris is an essential factor affecting the spatial heterogeneity of glacier mass balance, followed by climatic factors and topographic factors, especially the median elevation and slope in the HMA. There are some differences among mountain regions and the explanatory power of climatic factors on the spatial differentiation of glacier mass balance in each mountain region is weak, indicating that climatic background of each mountain region is similar. Therefore, under similar climatic backgrounds, the median elevation and slope are most correlated with glacier mass balance. The interaction of various factors is enhanced, but no unified interaction factor plays a primary role. Topographic and morphological factors also control the spatial heterogeneity of glacier mass balance by influencing its sensitivity to climate change. In conclusion, geodetector method provides an objective framework for revealing the factors controlling glacier mass balance.
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2022-03-15 合作期刊: 《干旱区科学》
Mona KARAMI
Mehdi HEYDARI
Ali SHEYKHOLESLAMI
Majid ESHAGH NIMVARI
Reza OMIDIPOUR
YUAN Zuoqiang
Bernard PREVOSTO
摘要： The relationships between different aspects of diversity (taxonomic, structural and functional) and the aboveground biomass (AGB) as a major component of global carbon balance have been studied extensively but rarely under the simultaneous influence of forest dieback and management. In this study, we investigate the relationships between taxonomic, functional and structural diversity of woody species (trees and shrubs) and AGB along a gradient of dieback intensity (low, moderate, high and no dieback as control) under two contrasted management conditions (protection by central government vs. traditional management by natives) in a semi-arid oak (Quercus brantii Lindl.) forest ecosystem. AGB was estimated and taxonomic diversity, community weighted average (CWM) and functional divergence indices were produced. We found that the aerial biomass was significantly higher in the intensively used area (14.57 (1.60) t/hm2) than in the protected area (8.70 (1.05) t/hm2) due to persistence of some large trees but with decreasing values along the dieback intensity gradient in both areas. CWM of height (H), leaf nitrogen content (LNC) and leaf dry matter content (LDMC) were also higher in the traditional managed area than in the protected area. In contrast, in the protected area, the woody species diversity was higher and the inter-specific competition was more intense, explaining a reduced H, biomass and LDMC. Contrary to the results of CWM, none of the functional diversity traits (FDvar) was affected by dieback intensity and only FDvar values of LNC, leaf phosphorus content (LPC) and LDMC were influenced by management. We also found significantly positive linear relationships of AGB with CWM and FDvar indices in the protected area, and with taxonomic and structural diversity indices in the traditional managed area. These results emphasize that along a dieback intensity gradient, the leaf functional traits are efficient predictors in estimating the AGB in protected forests, while taxonomic and structural indices provide better results in forests under a high human pressure. Finally, species identity of the dominant species (i.e., Brant's oak) proves to be the main driver of AGB, supporting the selection effect hypothesis.
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2022-03-15 合作期刊: 《干旱区科学》
摘要： Invasive species have been the focus of ecologists due to their undesired impacts on the environment. The extent and rapid increase in invasive plant species is recognized as a natural cause of global-biodiversity loss and degrading ecosystem services. Biological invasions can affect ecosystems across a wide spectrum of bioclimatic conditions. Understanding the impact of climate change on species invasion is crucial for sustainable biodiversity conservation. In this study, the possibility of mapping the distribution of invasive Prosopis juliflora (Swartz) DC. was shown using present background data in Khuzestan Province, Iran. After removing the spatial bias of background data by creating weighted sampling bias grids for the occurrence dataset, we applied six modelling algorithms (generalized additive model (GAM), classification tree analysis (CTA), random forest (RF), multivariate adaptive regression splines (MARS), maximum entropy (MaxEnt) and ensemble model) to predict invasion distribution of the species under current and future climate conditions for both optimistic (RCP2.6) and pessimistic (RCP8.5) scenarios for the years 2050 and 2070, respectively. Predictor variables including weighted mean of CHELSA (climatologies at high resolution for the Earth's land surface areas)-bioclimatic variables and geostatistical-based bioclimatic variables (19792020), physiographic variables extracted from shuttle radar topography mission (SRTM) and some human factors were used in modelling process. To avoid causing a biased selection of predictors or model coefficients, we resolved the spatial autocorrelation of presence points and multi-collinearity of the predictors. As in a conventional receiver operating characteristic (ROC), the area under curve (AUC) is calculated using presence and absence observations to measure the probability and the two error components are weighted equally. All models were evaluated using partial ROC at different thresholds and other statistical indices derived from confusion matrix. Sensitivity analysis showed that mean diurnal range (Bio2) and annual precipitation (Bio12) explained more than 50%of the changes in the invasion distribution and played a pivotal role in mapping habitat suitability of P. juliflora. At all thresholds, the ensemble model showed a significant difference in comparison with single model. However, MaxEnt and RF outperformed the others models. Under climate change scenarios, it is predicted that suitable areas for this invasive species will increase in Khuzestan Province, and increasing climatically suitable areas for the species in future will facilitate its future distribution. These findings can support the conservation planning and management efforts in ecological engineering and be used in formulating preventive measures.
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2017-09-20 合作期刊: 《中国科学院院刊》
摘要： 准确地说，特朗普退出《巴黎协定》是美国联邦政府的决定，并非涵盖全部美国地方政府和企业。由于《巴黎协定》积极而稳妥的开放和进取属性，个别缔约方的单边行为不足以终止甚至改变“巴黎气候进程”。美国退出《巴黎协定》，并不必然表明美国会退出全球气候治理的领导地位，也不必然意味着世界温室气体排放第一大国、经济体量第二大国的中国可以填补美国退出所产生的空缺。国际社会和美国国内所作出的反应表明，美国退出《巴黎协定》产生的负面冲击，继而带来的却是正向效果。推进“巴黎气候进程”，中国的引领地位不可或缺，但也不可急于求成，只能有限担当，顺势作为。
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2017-09-20 合作期刊: 《中国科学院院刊》
摘要： 青藏高原构造隆升强烈、地形地貌复杂、气候敏感多变，是地震、泥石流、崩塌、滑坡、冰湖溃决、山洪、雪灾、干旱和冻胀融沉等灾害的多发区。受区域地质构造、地形条件、水文气象和人类活动影响，青藏高原自然灾害的分布呈现为沿断裂构造带密集分布、沿深切的高山峡谷区成带状分布、地带性分布、在高强度人类活动区集中分布的特征。灾害活动呈现高强度与高频率、突发性、季节性、准周期性、群发性和链生性的特点。在气候变暖与地壳运动活跃的环境背景下，青藏高原自然灾害的危险性逐渐加剧，灾害风险也会随着人口数量和社会经济水平提升不断增加。进而分析了当前青藏高原自然灾害成灾机理、灾害防治以及风险管理等方面所面临的问题，并在此基础上提出成灾因素变化与灾害发育的区域规律、自然灾害动力学过程与灾变机理、气候变化与地震耦合作用下的巨灾演化规律、青藏高原自然灾害风险评估与风险管理、适宜高寒区特点的监测预警和防治关键技术等未来应该关注的科学技术问题以及需要开展的相应工作。
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2017-09-20 合作期刊: 《中国科学院院刊》
摘要： 泛第三极地区主要包括了青藏高原和其北侧的亚洲内陆干旱区，西至高加索等山脉，东至黄土高原西部。该区地处欧亚大陆腹地，是史前和历史时期东西方交流的主要通道，不同民族和多种文化历经了复杂而长期的接触、交流、冲突、融合和沉淀，开辟了东西方文明交流的便利通道，深刻地影响了人类文明发展的进程。研究泛第三极地区人类扩散、人类活动、环境变化和丝路文明兴衰及其相互关系，分析这一关键区域的社会环境发展规律，对于增强丝绸之路沿线各国的历史文化认同、揭示丝绸之路沿线地区的自然和社会演变规律，具有十分重要的理论与现实意义，同时也将为绿色丝绸之路建设提供历史借鉴和决策参考。泛第三极地区人类活动历史、文明演化过程及其与环境变化的相互作用应当成为我国的重点研究领域。
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2017-09-20 合作期刊: 《中国科学院院刊》
摘要： 在我国藏北渐新世地层中发现了攀鲈和鲃类新属种，其现生近缘类型都生活在亚洲和非洲的热带地区。这不仅在鱼类的系统发育和动物地理上具有重要意义，并且表明青藏高原腹地在距今26 Ma前仍然为温暖湿润的低地，伴生的棕榈、菖蒲等植物化石也指示同样的环境，说明当时由印度洋来的暖湿气流至少可以深入到藏北地区。自那时起，高原内部的地理特征与自然环境经历了巨大的变化。青藏高原在中新世持续隆升，至上新世达到现代高度，形成冰冻圈环境。在札达盆地的上新世沉积中发现了披毛犀、雪豹、北极狐和盘羊的祖先类型，显示适应严寒环境的第四纪冰期动物群起源于青藏高原，由此提出和进一步完善了寒冷适应性动物起源与扩散的“走出西藏”理论。
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2017-09-20 合作期刊: 《中国科学院院刊》
摘要： 亚洲内陆是北半球最大、最广阔的中纬度干旱区，且不同于世界上分布于副热带高压控制下的干旱区。现今的亚洲中纬度干旱区深居内陆，远离各大洋的水汽来源。亚洲中纬度干旱区究竟如何形成?历经了怎样的干旱化过程?其形成演化的动力机制是什么?这些一直是悬而未决的问题。事实上，亚洲中纬度干旱区发展成今天所见的干旱荒漠，并不是短时间内实现的，而是经历了漫长的阶段性演化进程，是在新生代以来印度、阿拉伯、非洲板块与欧亚大陆的碰撞，青藏高原的隆升，新特提斯海的退却以及新生代全球气候变冷与海平面下降等区域和全球要素共同作用下，从半湿润—半干旱—干旱—极端干旱渐进演化而来。历经了始新世的半湿润气候，渐新世的半湿润-半干旱气候和中新世末期以来的干旱-极端干旱气候。
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2017-09-20 合作期刊: 《中国科学院院刊》
摘要： 羌塘与拉萨地块处于青藏高原的核心位置。青藏高原北羌塘及拉萨地块的年代学及古地磁学研究表明，北羌塘地块在距今约3亿年前位于南半球（21.9o±4.7oS）冈瓦纳大陆附近，因而不支持北羌塘地块来自北方劳亚大陆。北羌塘随后开始其持续的北向漂移过程，在约2.1亿年前到达当前纬度位置（34oN），形象地表明其是一只“冈瓦纳大陆的早飞鸟”。拉萨地块从冈瓦纳大陆裂离后的漂移演化史则与北羌塘地块差别明显。自晚古生代—中生代（石炭纪—三叠纪）拉萨地块从冈瓦纳大陆北缘裂离后，其运动学演化过程更显得“犹豫不决”。最新的古地磁研究表明拉萨地块自冈瓦纳大陆裂离后并未显示出明显的快速北向漂移趋势，而是呈现出较为慢速的漂移，直到距今约1.8亿年前（早侏罗世）到达位于南半球赤道附近（3.7o±3.4oS），随后与北面的羌塘地块在晚侏罗世首先从东部发生碰撞，随后于早白垩世时期两个地块完成拼贴。之后的印度次大陆快速向北漂移并在早新生代（距今6 500万年前）发生印度-亚洲大陆碰撞，继而对新生代时期欧亚大陆地形地貌格局产生了深远影响。
分类： 环境科学技术及资源科学技术 >> 环境学 提交时间： 2017-09-20 合作期刊: 《中国科学院院刊》
摘要： 青藏高原对我国、亚洲甚至北半球的人类生存环境和可持续发展起着重要的环境和生态屏障作用。以青藏高原为核心的第三极以及受其影响的东亚、南亚、中亚、西亚、中东欧等泛第三极地区，面积约2 000多万平方公里，涵盖20多个国家的30多亿人口，是“一带一路”的核心地带和全球人口分布最密集区。随着“一带一路”重大倡议的推进，泛第三极环境变化的重要性受到全球关注。泛第三极地区已经出现重大资源环境问题，如何保护这一地区资源环境的可持续性是“一带一路”建设实施面临的重大挑战。实施“泛第三极环境变化与绿色丝绸之路建设”专项，将从区域甚至全球尺度深入研究这一地区的资源环境科学问题，前瞻、科学地提出区域可持续发展协同应对战略，为“守护好世界上最后一方净土”和“一带一路”建设服务。
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