我国典型秸秆露天燃烧黑碳的高时间分辨率排放特征及其排放清单

农作物秸秆燃烧是大气中黑碳(black carbon,BC)气溶胶的主要来源之一。目前农作物秸秆燃烧排放黑碳的研究主要集中在通过离线样品分析获得的BC排放特征,缺少实时在线排放特征的研究。本研究收集了我国具有代表性的4种农作物秸秆(小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆),通过在实验室燃烧平台模拟农作物秸秆露天燃烧的过程,利用黑碳仪获得农作物秸秆燃烧过程中BC的实时浓度排放变化;利用质量重建,获得BC在线排放因子。结果表明:农作物秸秆在明燃过程中BC的排放因子较为稳定。通过平均排放因子的计算,获得小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆的BC排放因子分别为(0.32±0.05) g?kg~(-1)、(0.31±0.13) g?kg~(-1)、(0.31±0.09) g?kg~(-1)和(0.44±0.01) g?kg~(-1)。在排放因子的基础上,结合我国农作物秸秆露天燃烧量,最终建立了2015年我国省级(不含港澳台地区)典型农作物秸秆燃烧的BC排放清单。     

Degradation of duloxetine: Identification of transformation products by UHPLC-ESI(+)-HRMS/MS, in silico toxicity and wastewater analysis

Duloxetine (DUL), an antidepressant drug, has been detected in surface water and wastewater effluents, however, there is little information on the formation of its transformation products (TPs). In this work, hydrolysis, photodegradation (UV irradiation) and chlorination experiments were performed on spiked distillated water, under controlled experimental conditions to simulate abiotic processes that can occur in the environment and wastewater treatment plants (WWTPs). Eleven TPs, nine from reaction with UV light and two from chlorine contact, were formed and detected by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry, and nine of them had their chemical structures elucidated upon analyses of their fragmentation patterns in MS/MS spectra. The formation and degradation of the TPs were observed. The parent compound was completely degraded after 30?min in photodegradation and after 24?hr in chlorination. Almost all TPs were completely degraded in the experiments. The ecotoxicity and mutagenicity of the TPs were predicted based on several in silico models and it was found that a few of these products presented more ecotoxicity than DUL itself and six TPs showed positive mutagenicity. Finally, wastewater samples were analyzed and DUL and one TP, possibly formed by chlorination process, were detected in the effluent, which showed that WWTP not only did not remove DUL, but also formed a TP.     

镇江市秋季典型天气污染过程的PM2.5在线源解析

大气细颗粒物(PM2.5)是灰霾天气形成的主要原因,通过利用在线源解析的仪器对镇江市秋季典型天气下每类污染源实时的贡献比例的变化趋势解析,初步摸清镇江市典型天气下污染过程中颗粒物的来源.结果显示,监测期间发生的五次污染成因有所不同,但大多与机动车尾气源相关.入秋后,大气边界层高度降低,在静稳天气下,近地面排放的尾气源颗粒物极易累积集聚,造成或加剧污染的发生.此外,随着秋收季节的到来,秸秆焚烧现象有所抬头,生物质燃烧源对大气造成的影响需引起重视.     

Assessing the Impact of Areal Precipitation Input on Streamflow Simulations Using the SWAT Model1

Masih Ilyas, Shreedhar Maskey, Stefan Uhlenbrook, and Vladimir Smakhtin, 2011. Assessing the Impact of Areal Precipitation Input on Streamflow Simulations Using the SWAT Model. Journal of the American Water Resources Association (JAWRA) 47(1):179‐195. DOI: 10.1111/j.1752‐1688.2010.00502.x Abstract: Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soil Water Assessment Tool (SWAT) uses the data of a precipitation gauge nearest to the centroid of each subcatchment as an input for that subcatchment. This may not represent overall catchment precipitation conditions well. This paper suggests an alternative – using areal precipitation obtained through interpolation. The effectiveness of this alternative is evaluated by comparing its simulations with those based on the standard SWAT precipitation input procedure. The model is applied to mountainous semiarid catchments in the Karkheh River basin, Iran. The model performance is evaluated at daily, monthly, and annual scales by using a number of performance indicators at 15 streamflow gauging stations each draining an area in the range of 590‐42,620 km². The comparison suggests that the use of areal precipitation improves model performance particularly in small subcatchments in the range of 600‐1,600 km². The modified areal precipitation input results in increased reliability of simulated streamflows in the areas of low rain gauge density. Both precipitation input methods result in reasonably good simulations for larger catchments (over 5,000 km²). The use of areal precipitation input improves the accuracy of simulated streamflows with spatial resolution and density of rain gauges having significant impact on results.     

Assessing effects of digital elevation model resolutions on soil–landscape correlations in a hilly area

The effect of different grid sizes of digital elevation models (DEMs) on the relationship between soil properties and terrain attributes was examined by comparing six DEMs (4, 6, 8, 10, 20 and 30 m). The study site was representative of a broad region of hilly landscapes in the southwestern China. The results showed that elevation, topographic wetness index (TWI), slope and natural logarithm of specific catchment area (SCA) varied with DEM grid size in a relatively clear direction except aspect and plan curvature. Different soil–landscape relationships were found across various DEM resolutions. The observations from this study indicate that the most accurate predict model is not always produced by the highest resolution DEM. The knowledge of which DEM resolution produces an appropriate model for a particular landscape can be used as a guideline for optimizing field sample strategies.     

DEM格网尺度对AnnAGNPS预测山地小流域径流和物质输出的影响

为了解流域地形空间参数和其它参数的精度对农业非点源污染模型AnnAGNPS预测准确性的影响,利用三峡库区黑河小流域观测资料校准了AnnAGNPS模型,分析了1.5-12.5m格网尺度DEM对地形参数和模型负载输出的影响.结果表明,1.5～12.5m格网尺度DEM对流域径流量、洪峰流量、总N输出影响不显著,但对泥沙、总P、有机碳输出影响显著.三峡库区类似小流域宜采用5m格网尺度DEM,AnnAGNPS模型较不适合于尺度较小、坡度较大的小流域泥沙负载预测.     

青藏高原短波辐射分布式模拟及其时空分布

论文基于太阳辐射参数化传输模型,结合MODIS每日两次的大气产品和DEM,构建了太阳短波辐射分布式模型,对青藏高原2007年的太阳直接辐射、散射辐射与总辐射分布状况进行了模拟,并利用研究区站点实测值对模型精度进行了验证,其中日值数据直接辐射的相关性分别为0.72(拉萨)和0.82(格尔木),散射辐射分别为0.71(拉萨)和0.70(格尔木),总辐射相关性大都在0.70以上;旬值数据实测值与模拟值的相关性大都在0.90以上。模拟结果表明:实际天气情形下青藏高原年平均直接辐射量为4 244 MJ/m2,年平均散射辐射量为2 348 MJ/m2,年平均总辐射量为6 592 MJ/m2。直接辐射与总辐射的空间分布主要受纬度地带性与垂直地带性的影响,且地形对地表短波辐射的影响大于纬度的影响;散射辐射的空间分布主要取决于当地的地形起伏与大气状况。     

扰动法在风网解算中的应用研究*

为简化矿井通风复杂风网的解算,提出将扰动法引入到风网解算中,并介绍扰动法的原理、风网解算的基本定律;给出常见的固定风压、固定风量和给定风机性能函数3种风机工况下的扰动方程矩阵表达式及详细的计算过程;对所提风网解算方法进行实例验证。结果表明:扰动法作为固定运算次数的近似方法,在工程实际允许的误差范围内,相比于以牛顿法为代表的迭代法耗时少、不依赖初值,是1种简单实用的风网解算方法。     

基于DEM的白云山区域三维景观模型的建立和应用

数字高程模型DEM是对地形地貌的一种离散的数字表达,是构建三维模型的基础数据。DEM的一种数据格式GRID通过二维的格网灰度描述地形的起伏,另一种数据格式TIN通过连续三角面模拟地形表面。文章根据DEM对地形高程变化敏感这一特性,选取地形起伏大和地貌类型多样的山地丘陵地区—白云山区域作为研究区,在ARCGIS环境下将二维等高线数据转化为三维地形表面,以TIN为基准高程叠加区域内的矢量图层和遥感影像图,最终构建区域环境的三维景观模型.并以模型为基础,假设区域内的磨刀坑水库在无源淹没的情况下,应用三维分析功能计算水库淹没地形的表面积和体积。     

高分辨质谱在环境科学领域应用综述

探究复杂环境介质中有机污染物分析检测新方法,建立复杂环境介质中可疑和非目标化合物的快速筛选及确证方案,已成为环境科学领域的研究热点。高分辨质谱仪（HR-MS）具有质量范围宽、扫描速度快、灵敏度高等优点,使其在环境科学领域得到广泛应用。综述了混合高分辨率质谱（Q-TOF/Q Orbitrap）等HR MS技术的特点和工作原理,基于目标化合物分析、可疑化合物分析以及非目标化合物分析这3类研究策略,阐述了HR-MS在环境研究、药品监管及生物代谢物研究等领域的应用现状,进而分析了现阶段HR MS在环境科学领域中的应用局限性和发展前景。