餐厨垃圾制备的外源有机碳对土壤团聚体的影响

为了阐明外源有机碳对土壤碳库的作用机制,以餐厨垃圾为原料,制备了4种不同分子量级的外源有机碳,通过室内试验,研究了外源有机碳对土壤有机碳组分及土壤团聚体的影响.结果表明:①以分子量≤1 ku为主的小分子有机碳处理组土壤中w（DOC）（DOC为水溶性有机碳）比CK组增加了0.383 g/kg,CO₂累积释放量达到（6.595±0.259）mg/kg（以C计）;微生物活性增强,>5 mm水稳大团聚体质量分数相对于CK组提升了25.06%,表明小分子有机碳增强了土壤微生物活性,微生物通过菌根网络缠绕作用促进大团聚体形成,增强土壤团聚体稳定性.②以分子量≥5 ku的大分子有机碳为主的大分子有机碳处理组w（POC）（POC为颗粒态有机碳）为CK组的5.65倍,0.5~1 mm水稳大团聚体质量分数增加了10.84%,有机碳贡献率提升了14.79%,表明大分子有机碳通过增加土壤中w（POC）,促进0.5~1 mm水稳大团聚体形成,提高团聚体有机碳贡献率.研究显示,不同分子量级外源有机碳通过不同的方式改善土壤团聚体结构进而促进土壤有机碳固定,餐厨垃圾生物强化有机肥中各量级有机碳比例合理,能够明显提升土壤有机碳水平,增加土壤团聚体稳定性.      

喀斯特地区植被恢复下土壤活性有机碳与碳库管理指数的演变特征

植被恢复通过改变碳输入和转化速率,影响陆地生态系统的碳循环.为探明喀斯特地区植被恢复过程中土壤活性有机碳组分与碳库管理指数的演变特征,以喀斯特地区草地序列（5、10、15和20 a）、灌木序列（5、10、15和20 a）和园地序列（5、10和15 a）土壤为研究对象,以相邻农田为对照（CK）,分析了不同植被恢复年限对土壤有机碳（SOC）、易氧化有机碳（ROC₃₃₃、ROC₁₆₇和ROC₃₃,即能被333、167和33 mmol·L^-1 KMnO₄氧化的土壤活性有机碳）、微生物量碳（MBC）、溶解性有机碳（DOC）及碳库管理指数（CPMI）演变的影响.结果表明,与CK相比,0~40 cm土层草地、灌木和园地序列平均SOC含量分别增加了70.77%、114.40%和50.17%.在0~20 cm土层,随恢复年限增加,草地序列和园地序列的SOC含量呈先升后降势态,灌木序列呈先升后降再升势态,ROC₃₃₃、ROC₁₆₇和ROC₃₃与对应序列的SOC变化势态一致;在20~40 cm土层,各序列的ROC₃₃₃、ROC₁₆₇和ROC₃₃与对应序列的SOC的变化势态不一致.在0~40 cm土层,草地序列MBC含量呈先降后升再降势态,各土层MBC最大值均在G15;灌木序列在0~10 cm土层为先升后降再升势态,在10~40 cm土层为先升后降势态;园地序列在0~30 cm土层为先升后降势态,在30~40 cm土层为逐渐升高势态.3个序列K_os大致呈先降后升再降势态,L和LI与K_os相反;CPI呈先升后降势态;草地和园地序列的碳库管理指数（CPMI）呈先升后降势态,而灌木序列CPMI的则呈先升后降再升势态.SOC、ROC₃₃₃、ROC₁₆₇、ROC₃₃和MBC含量及K_os的年增长量大小为：灌木>草地>园地,DOC和CPMI的年增长量大小为：园地>草地>灌木.3个序列SOC及其组分含量均总体随土层增加而降低,具有明显的表聚性.冗余分析结果显示碱解氮（AN）是影响喀斯特地区植被恢复下土壤活性有机碳组分和土壤有机碳库的主要环境因子.综上,土壤活性有机碳组分和CPMI随植被恢复时间发生演变,不同植被恢复均能一定程度地提高喀斯特地区SOC及其组分含量,灌木恢复促进SOC的积累.     

2021年春节期间陕西省烟花爆竹燃放对PM2.5的影响

通过对比2021年春节烟花爆竹集中燃放时段和前期非集中燃放时段的PM_2.5浓度及特征组分浓度,分析了烟花爆竹集中燃放对陕西省PM_2.5的影响情况。分析结果显示,2021年春节烟花爆竹集中燃放时段,关中和陕南地区PM_2.5浓度增幅大且高值持续时间长,陕北地区PM_2.5浓度增幅小且高值持续时间短。陕北和陕南地区PM_2.5小时浓度峰值出现在2月12日(初一)00:00前后,关中地区略晚。西安市PM_2.5特征组分中,K⁺、Cl^-、SO₄^2-、NO₃^-、Mg²⁺、Al³⁺、Cu²⁺、Si²⁺、Ba²⁺的浓度分别为6.61、7.20、12.83、23.96、1.36、2.91、0.23、0.27、0.86 μg/m³,明显高于非集中燃放时段。烟花爆竹燃放对陕南地区PM_2.5的贡献率和贡献量均高于关中和陕北地区;对郊县PM_2.5的贡献率高于城区,且对郊县的贡献率正值的出现时间早于城区。除榆林市外,陕西省其他城市的城区均受到了相关郊县烟花爆竹燃放的影响。     

基于多源数据的西安大气重污染过程案例分析

基于大气污染六要素（PM_2.5、PM₁₀、SO₂、NO₂、CO和O₃）、PM_2.5化学组分数据、地面气象观测数据、微波辐射计数据和大气再分析数据,采用物质平衡和硫/氮氧化速率（SOR/NOR）等方法对2019年1月西安市一次重污染事件过程和成因机制进行综合分析.将该次污染过程划分为累积阶段（P1）、维持阶段（P2）和消散阶段（P3）,本次重污染过程主要是由于不利天气形势叠加反馈效应造成的,P1和P2阶段西安在500hPa都受平直西风气流影响,海平面气压为均压场,等压线稀疏,天气形势稳定,且925hPa以偏东风为主,不利于大气污染扩散.地基微波辐射计可辅助反映气象条件与重污染间的反馈机制,其反演的水汽密度和逆温均与PM_2.5存在显著线性相关关系,相关系数分别为0.86和0.38.反馈机制主要表现为：当污染达到一定程度时产生辐射冷却效应使地面降温,进而导致或加强逆温,混合层高度降低,水汽积聚,高湿条件通过加速二次转化和促进气溶胶吸湿增长使污染进一步维持,因此P2阶段二次无机离子（SO₄^2-+NO₃^-+NH₄⁺,SNA）和"其他"组分对PM_2.5的贡献率较大,分别为43.2%和23.1%,且SOR、NOR和消光系数均在P2阶段达到峰值.NH₄NO₃、有机物（OM）、（NH₄）₂SO₄和元素碳（EC）对消光系数的总贡献率超过85%,但各组分占比排序在每个阶段略有不同.     

Experimental Investigation of Potassium and Nitrate Dynamics in A Headwater Stream in Mid-Wales

Potassium and nitrate were added experimentally to a small moorland stream in the headwaters of the River Wye, mid-Wales, during summer and winter low-flow conditions. Nutrient losses at three downstream sampling locations were calculated using concentrations of an added bromide tracer to correct for dilution effects. During the summer experiment, approximately 18% of the added nitrate and 58% of the potassium were removed from the stream water between the point of addition and the catchment outlet. During the winter experiment, nitrate depletion was not observed and the added nitrate travelled along the stream at the same rate as the bromide tracer, while approximately 93% of the added potassium passed through the stream but, at a slower rate than the bromide and nitrate. the results show that in-stream processes, probably related to biological activity of macrophytes and microflora, can regulate stream water concentrations of nitrate and potassium in the summer under stable flow conditions. During the winter, no removal of nitrate or potassium was observed but ion exchange processes involving biofilms, Sphagnum and/or stream sediment may explain the temporary retention of potassium within the stream channel. If similar ion exchange processes operate at high flows, they may account for the hysteresis relationship observed between potassium and discharge during storm events in many upland streams.     

Distribution of Alkalinity, Ph, Salinity and Carbon Dioxide Components in the Coastal Waters of Alexandria

The ara studied is located between El-Dikheila Harbour in Elmex Bay and Mandara, at longitude 29° 47' and 30° East and latitude 31° 17' North. the aim of the work is to look at carbon dioxide components in this areA and the effect of waste water discharged on their concentrations. Surface and bottom water samples were collected from 12 stations during January, April, August and November, 1995. Total alkalinity, salinity, temperature and pH were measured. Carbonate alkalinity, total alkalinity, partial pressure and dissolved carbon dioxide, carbonate and bicarbonate ions were calculated, since the studied area includes two differetn sources of pollution. It wAs found conventient to refer El-Mex Bay as region “A” which contains stations from I to VI and the area located between Kayet Bey outfall and Mandara which contains stations from VII to XII as region “B”. When specific alkalinity is used As A tracer for El-Umum drain water it is observed that the drain water could reach Sidi Bishr area especially in August and November, while in January and April drain water did not reach this area.     

PM10可替代源成分谱的建立方法及其应用

对收集到的我国35个城市的PM10有效实测源成分谱进行系统聚类,应用系统聚类和方差分析方法,对源成分谱进行聚类和区域的划分.对聚为一类的各城市源成分谱进行主成分分析,所得主成分得分系数作为权重,加权运算建立可替代源成分谱.利用R、CD以及CMB模型解析所得源贡献值的相对误差,评价所建立的可替代源成分谱的合理性及可行性.得到6种污染源的13个可替代源成分谱,煤烟尘与扬尘各三类,土壤风沙尘、钢铁尘与建筑水泥尘各两类,机动车尾气尘一类.煤烟尘与钢铁尘可以直接进行替代;建筑水泥尘不存在明显区域特征;机动车尾气尘由于数据代表性不足,建议采用实测源成分谱;土壤风沙尘与扬尘的替代标准有待进一步的研究.     

“U+L”型通风综采工作面采空区漏风特性研究

为了掌握“U+L”型通风综采工作面采空区的漏风规律,以某矿综采工作面为试验地点,先采用Fluent软件对综采工作面采空区的漏风流场进行了数值模拟,后结合数值模拟结果制定了综采工作面示踪气体SF6的测漏风技术方案,并现场实测了“U+L”型综采工作面采空区的漏风风流分布特征.数值模拟结果与现场实测结果十分吻合.结果表明:1)“U+L”型综采工作面全程向采空区漏风,漏风汇至滞后联络巷后经专用排瓦斯巷排出;2)“U+L”型综采工作面漏风量随联络巷距离工作面距离增大而逐渐降低;3)“U+L”型综采工作面漏风量沿工作面倾向方向(从进风至回风)呈逐渐减少趋势.     

Validation of the lagrangian particle dispersion model FLEXPART against large-scale tracer experiment data

A comprehensive validation of FLEXPART, a recently developed Lagrangian particle dispersion model based on meteorological data from the European Centre for Medium-Range Weather Forecasts, is described in this paper. Measurement data from three large-scale tracer experiments, the Cross-Appalachian Tracer Experiment (CAPTEX), the Across North America Tracer Experiment (ANATEX) and the European Tracer Experiment (ETEX) are used for this purpose. The evaluation is based entirely on comparisons of model results and measurements paired in space and time. It is found that some of the statistical parameters often used for model validation are extremely sensitive to small measurement errors and should not be used in future studies. 40 cases of tracer dispersion are studied, allowing a validation of the model performance under a variety of different meteorological conditions. The model usually performs very well under undisturbed meteorological conditions, but it is less skilful in the presence of fronts. The two ETEX cases reveal the full range of the model’s skill, with the first one being among the best cases studied, and the second one being, by far, the worst. The model performance in terms of the statistical parameters used stays rather constant with time over the periods (up to 117 h) studied here. It is shown that the method used to estimate the concentrations at the receptor locations has a significant effect on the evaluation results. The vertical wind component sometimes has a large influence on the model results, but on the average only a slight improvement over simulations which neglect the vertical wind can be demonstrated. Subgrid variability of mixing heights is important and must be accounted for.     

服装面料选取时难降解成分鉴定分析研究

当前面料中难降解成分对环境造成很大程度污染,在服装面料选取时,为避免难降解面料的使用,提出基于近红外光谱的面料难降解成分鉴定分析方法.通过分析服装面料中难降解成分对环境的影响,提取面料中难降解成分,得出三种成分类型,通过对不同成分造成环境污染程度进行鉴定分析,完成服装面料选取时难降解成分的鉴定.实验结果表明,该方法误差控制在-0.2~0.2范围内,能够准确鉴定出服装面料中难降解成分,为降低环境污染提供了有效帮助.