BP网络框架下MODIS气溶胶光学厚度产品估算中国东部PM2.5

近年来随着中国经济的快速发展,中国区域的大气污染情况日趋严重,大气污染监测与治理已刻不容缓.由于卫星遥感具有较广的空间覆盖、成本低等优点,卫星遥感反演气溶胶光学厚度(AOD)产品被普遍认为是地面PM2.5浓度的重要指标,且已被广泛地应用于地面PM2.5遥感监测.利用2007～2008年的MODIS/Terra气溶胶光学厚度产品,考虑中国东部地区5个大气成分站点风速、风向、温度、湿度和边界层高度等气象数据,构建后向(BP)神经网络,提出了基于MODIS AOD产品估算PM2.5的模型.利用5个大气成分站点PM2.5观测数据对模型进行散点拟合和时间序列拟合验证,结果表明:①从PM2.5观测值与估算值的散点回归分析来看,PM2.5估算值与观测值相关系数最好的为庐山站(R=0.6),其它4个站次之,但其相关系数均在0.4(中强相关)以上;②从PM2.5观测值与估算值的时间序列比对分析来看,PM2.5估算值和观测值差值随时间变化而变化,且存在明显的日际振荡现象,但经相邻5 d滑动平均处理,5个站点的PM2.5估算值与观测值相关系数得到普遍提升,滑动后的相关系数RMA均在0.7以上(除郑州外),庐山RMA达到0.83.结果表明在BP网络框架下,基于MODIS AOD产品估算PM2.5的模型能较好地应用于PM2.5监测.     

基于复合指纹图谱和贝叶斯模型的茅尾海悬浮颗粒物源解析

为明确茅尾海中悬浮颗粒物的来源,采集了茅尾海流域红树林土壤、堤岸土、河口颗粒物、茅尾海沉积物以及湾外颗粒物等悬浮颗粒物潜在源样品.基于多元统计复合指纹图谱方法,筛选出最佳指纹因子组合,进而通过贝叶斯混合模型得出五种潜在源对茅尾海悬浮颗粒物的贡献率.结果表明:Mg、Al、Mn、Pb、Fe五种指纹元素可作为最佳指纹因子组合,累计判别正确率为78%.贝叶斯混合模型结果显示,茅尾海悬浮颗粒物主要来源于河口和湾外输送,贡献率最高达到58.9%和68.6%.其中,靠近河口区域主要受河流汇入影响,其贡献率达到42.2%~58.9%;靠近湾外区域则以湾外颗粒物贡献为主,贡献率达到44.9%~68.6%.各点位的沉积物贡献率均较低,红树林土壤和堤岸土的贡献率都在10%左右.总的来说,由河口汇入和潮汐作用带入的颗粒物是茅尾海悬浮颗粒物的主要来源.     

Effect of spectral resolution on the measurement of monoaromatic hydrocarbons by DOAS

The excellent response characteristics and detection sensitivity with much lower operational cost and the capability to discriminate between the isomer of some monoaromatic hydrocarbons (MAHCs) make di erential optical absorption spectroscopy (DOAS) a powerful tool to trace concentration variation of MAHCs. But due to the similarity in chemical structure, those MAHCs have the similar overlapped characteristic absorption structures, which make the selection of instrumental parameter critical to the accurate detection of MAHCs. Firstly, the spectral resolution used in DOAS system determines the nonlinear absorption of O2 and the mass dependence of characteristic absorption structure; thereby it determines the effect of elimination error of O2 absorption in the atmospheric spectra for the detection of MAHCs. Secondly, spectral resolution determines the di erential absorption characteristics of twelve MAHCs representing major constituents in technical solvents used in the automobile industry and the interference of spectral overlapping. Thirdly, the spectral resolution determines the sensitivity, time resolution and linear range. So the spectral resolution range with the best ratio of signal to noise is used to determine the most suitable spectral resolution range, as well as the spectral resolution range that ensure the characteristic absorption structure of MAHCs and the minimization of O2 absorption interference. Finally, 0.15–0.16 nm (FWHM: full width at half maximum) is assumed to be closest to the optimum spectral resolution and it is confirmed by the results of practical measurement of MAHCs by DOAS.     

A classification framework for interspecific trade-offs in aquatic ecology

In some cases, wildlife management objectives directed at multiple species can conflict with one another, creating species trade-offs. For managers to effectively identify trade-offs and avoid their undesirable outcomes, they must understand the agents involved and their corresponding interactions. A literature review of interspecific trade-offs within freshwater and marine ecosystems was conducted to illustrate the scope of potential interspecific trade-offs that may occur. We identified common pitfalls that lead to failed recognition of interspecific trade-offs, including, single-species management and limited consideration of the spatial and temporal scale of ecosystems and their management regimes. We devised a classification framework of common interspecific trade-offs within aquatic systems. The classification can help managers determine whether the conflict is species based through direct relationships (i.e., predator–prey, competition, other antagonistic relationships) or indirect relationships involving intermediate species (i.e., conflict-generating species) or whether the conflict is driven by opposing management objectives for species that would otherwise not interact (i.e., nontarget management effects). Once the nature and scope of trade-offs are understood, existing decision-making tools, such as structured decision-making and real-options analysis, can be incorporated to improve the management of aquatic ecosystems. Article Impact Statement: A synthesis of interspecific trade-offs in aquatic ecosystems supports their identification and resolution.     

基于介度熵的机场飞行区关键冲突点识别*

为了探究机场航班流量增大和作业车辆增多而导致机场飞行区内频繁出现活动目标冲突情况，提出1种基于介度熵的机场飞行区关键冲突点识别方法。首先，以飞行区内活动目标为节点，活动目标之间的潜在冲突关系为连边，建立飞行区交通态势网络模型。然后，采用介度熵法评价交通态势网络中各活动目标的冲突指数，得到冲突指数最大的活动目标即关键冲突点。最后，将介度熵法与度中心性、介数中心性和邻接信息熵3种识别方法进行对比，并以西安咸阳国际机场为例进行验证。研究结果表明:识别飞行区关键冲突点时，介度熵法较其他3种方法更有效。通过建立飞行区交通态势网络，采用介度熵法识别飞行区关键冲突点并进行调配，一定程度上可以有效预防冲突发生，保障飞行区运行安全。     

Socioeconomic development and ecological traits as predictors of human–bird conflicts

Because of the significant impacts on both human interests and bird conservation, it is imperative to identify patterns and anticipate drivers of human–bird conflicts (HBCs) worldwide. Through a global systematic review, following the PRISMA 2020 guidelines, we analyzed the socioeconomic factors and bird ecological traits driving the degree of knowledge and extent of HBCs. We included 166 articles published from 1971 to 2020 in our analyses through which we built a profile of the socioeconomic conditions of 52 countries with reported conflicts and the ecological traits of the 161 bird species involved in HBCs. Although HBC expanded worldwide, it had the greatest impact in less-developed countries (estimate 0. 66 [SE 0.13], p< 0.05), where agriculture is critical for rural livelihoods. Species with a relatively greater conflict extent had a relatively broader diet (estimate 0.80 [SE 0.22], p<0.05) and an increasing population trend (estimate 0.58 [SE 0.15], p<0.05) and affected human interests, such as agriculture and livestock raising. In countries with greater biodiversity, HBCs caused greater socioeconomic impacts than in more developed countries. Our results highlight the importance of understanding and addressing HBCs from multiple perspectives (ecological, sociocultural, and political) to effectively protect both biodiversity and local livelihoods.     

京津冀地区散煤燃烧大气污染物排放清单

为研究京津冀地区民用散煤燃烧大气污染物的排放情况，结合散煤燃烧活动水平与燃用特征，根据排放因子法自下而上建立了2018年京津冀地区民用散煤燃烧污染物排放清单，研究了污染物排放的时空分布特征并使用蒙特卡罗方法对排放清单进行了不确定性分析.结果表明：2018年京津冀地区民用散煤燃烧量共计3799.22万t，PM_2.5、CO、SO₂、NO_x的排放量分别为9.27，341.31，5.17，5.44万t.污染物排放集中在11月份~次年3月份，大多数地区呈现出相同的日排放趋势.8：00、11：00、18：00、21：00左右出现污染物排放峰值，小时排放系数平均值分别为11%，6%，7%，13%.PM_2.5排放高值区主要集中在北部、东部及部分南部地区，CO主要集中在北京和天津地区，SO₂和NO_x主要集中在天津和承德地区.