青藏高原中晚全新世人类活动的孢粉记录

利用孢粉记录追踪过去人类活动历史及其环境效应的研究较少。本文选取青藏高原28处地层化石孢粉序列,采用直接提取和集成方法获得568条具有年代的伴人孢粉（禾本科、石竹科、杨属、十字花科、委陵菜属、车前属、紫菀属、藜科、狼毒属）数据,经标准化处理后建立高原4个分区的人类活动指数。同时结合本区已有研究资料,探讨了中晚全新世以来的人类活动历史。研究表明：（1）Ⅰ区东北区,6.0~5.3 ka B.P.早期人类已开始活动,但低水平的生产方式对植被影响较弱;5.3~4.5 ka B.P.人类活动得到扩展,环境效应开始显现;4.5~3.5 ka B.P.人类活动强度明显增强,加剧了对植被的破坏;3.5~2.0 ka B.P.随着人类活动的进一步加强,导致过度放牧、森林面积减少及风沙活动增强。（2）Ⅱ区东南区,5.0 ka B.P.左右人类活动的环境效应开始显现;4.5~3.5 ka B.P.植被受人为干扰显著;3.5~2.0 ka B.P.人类活动扩张至高海拔地区,对植被影响范围随之扩大;（3）Ⅲ区西南区,5.7~4.5 ka B.P.农业生产活动开始且得到发展,环境效应逐渐凸出;4.5~2.0 ka B.P.人类活动进一步增强,对植被影响亦进一步加剧;（4）Ⅳ区西北无人区,受资料所限并未充分讨论,但已有研究表明,全新世早中期本区已有人类进行狩猎采集活动。     

人类活动对河流沉积物中反硝化厌氧甲烷氧化菌群落特征的影响

河流生态系统是陆地生态系统输出营养盐和有机质的主要接收器,是水-气界面CO2和CH4全球碳循环的重要环节.人类活动导致大量未经处理的硝酸盐和有机物质汇入河流,影响了N-DAMO(N-DAMO,Nitrate/nitrite-dependent anaerobic methane oxidation,反硝化厌氧甲烷氧化菌)细菌的群落特征.本文选取北运河作为研究区域,通过对比分析北运河中游和下游沉积物理化参数和N-DAMO细菌群落特征的差异性,探究由于人类活动的影响,河流沉积物中N-DAMO细菌的群落组成结构特征,及其与沉积物中NH+4-N、NO-3-N的响应关系.结果表明,北运河沉积物中NH+4-N为中游和下游氮素的主要形态,且下游NH+4-N浓度显著高于中游;人类活动对N-DAMO细菌16S rRNA和pmo A功能基因群落分布有影响,16S rRNA和pmo A功能基因均分别聚为中游和下游两类;系统发育树分析显示,人类活动影响北运河N-DAMO细菌高同源性菌群的来源,其高同源性菌群来源与北运河主要污染物氨氮的来源一致;RDA分析显示,人类活动影响N-DAMO细菌相关环境因子,沉积物中高浓度的NH+4-N、NO-3-N与16S rRNA和pmo A功能基因有显著的响应关系.沉积物N-DAMO细菌16S rRNA和pmo A功能基因的共生关系分析显示,北运河下游沉积物中N-DAMO细菌彼此之间的共存关系更强,细菌群落形成的模块化程度较高,其对环境变化的敏感程度更高,受人类活动的影响更大.     

嘉兴市2015年人为源VOCs排放清单

根据收集的嘉兴市人为源活动水平数据,采用科学合理的估算方法和排放因子,建立了该地区2015年人为源挥发性有机物（VOCs）排放清单.结果表明,嘉兴市2015年VOCs排放总量为10.21×10⁴ t,其中工业源、移动源、生活源、储运源、废弃物处理源、农业源的排放量分别占排放总量的78.15%、12.08%、5.83%、3.24%、0.26%和0.44%.工业源中包装印刷、表面喷涂、纺织印染、化学原料制造、石化是重点排放行业.海宁市、桐乡市和平湖市VOCs排放量位居前三,约占嘉兴市总排放量的50%,经开区、海宁市、南湖区VOCs平均排放强度均超过30 t·km^-2.     

阿拉善沙漠高原降水化学特征与离子来源判别

为查明我国北方沙漠地区降水化学组成及来源,在阿拉善沙漠高原阿右旗气象站采集了2013—2015年的降水样品,测定了降水pH、EC（电导率）及主要离子当量浓度.结果表明:阿拉善沙漠阿右旗气象站降水pH和EC的范围分别为6.66~8.05和35~1 237 μS/cm;Ca2+、SO₄2-、Na+和Cl-为降水中的主要离子,其总和占总离子的85%以上.降水pH、EC和主要离子当量浓度是反映空气质量的基本参数,较高的降水pH反映出当地降水具有明显的碱性特征.与其他地区相比,该地区降水的EC和可溶性离子日均湿沉降通量也较高,且随月份有较大的变化,表明干旱沙漠粉尘对当地降水水化学的贡献较大.根据离子来源相对贡献的计算结果发现,降水中92.8%的SO₄2-和98%的NO₃-来自人为源,98.8%的Ca2+和88.7%的K+为陆地来源,55%的Mg2+为海洋源,24.8%的Na+来自矿物风化,极少部分Cl-为人为源.研究显示:除降水中的NH₄+外,其他主要离子之间的相关性表明各种成因物质在风力作用下同时进入了大气;基于[NH₄+]（NH₄+的当量浓度）与[K+]（K+的当量浓度）相关性分析,降水中的NH₄+来自生物质燃烧、肥料使用、动物粪便等.      

缺水地区人类活动净氮输入与河流响应特征——以海河流域为例

人类活动净氮输入(NANI)是影响河流氮输出的重要因素,研究两者的响应关系对制定氮污染的削减策略具有重要意义.基于NANI核算模型,评估了海河流域人为氮输入强度,并采用实测数据估算了同期的河流氮输出,最终得到干旱缺水区河流氮输出对NANI的响应特征.结果表明,海河流域2008—2012年均NANI输入强度为13258 kg·km~(-2)·a~1,化肥施用、食品与饲料输入、大气沉降和农作物固氮分别占76%、17%、5%和2%;在空间分布上,黑龙港运东子流域的NANI负荷最高,达到24238 kg·km~(-2)·a~(-1),最小的是永定河子流域,为5320 kg·km~(-2)·a~(-1);海河流域主要河流的氮通量与子流域NANI输入呈现显著正相关关系(p0.05),NANI变化可解释67%的河流氮通量变化.然而,仅2%的NANI由河流输出,这一比例低于其他地区研究成果,表明缺水地区河流作为氮输出的功能被削弱,河流不是流域氮输出的主要途径.     

Biotic homogenization and differentiation of plant communities in tropical and subtropical forests

Anthropogenic impacts on biodiversity can lead to biotic homogenization (BH) and biotic differentiation (BD). BH is a process of increasing similarity in community composition (including taxonomic, functional, and phylogenetic components), whereas BD is a process of decreasing similarity over space and time. Here, we conducted a systematic review of BH and BD in plant communities in tropical and subtropical forests to identify trends and knowledge gaps. Our bibliometric search in the Web of Science returned 1989 papers, of which 151 matched our criteria and were included in the analysis. The Neotropical region had the largest number of articles, and Brazil was the most represented country with 92 studies. Regarding the type of change, homogenization was more frequent than differentiation (noted in 69.6% of publications). The taxonomic diversity component was measured more often than functional and phylogenetic diversity components. Most studies (75.6%) assessed homogenization and differentiation based on a single observation in time; as opposed to few studies that monitored plant community over multiple years. Forest fragmentation was cited as the main determinant of homogenization and differentiation processes (57.2% of articles). Our results highlight the importance of evaluating community composition over time and more than taxonomic components (i.e., functional and phylogenetic) to advance understanding of homogenization and differentiation. Both processes were scale dependent and not mutually exclusive. As such, future research should consider differentiation as a potential transition phase to homogenization and that potential differences in both processes may depend on the spatial and temporal scale adopted. Understanding the complexity and causes of homogenization and differentiation is essential for biodiversity conservation in a world increasingly affected by anthropogenic disturbances.     

Natural and Anthropogenic Effects On Phytoplankton Primary Productivity in Mangroves

Spatial and temporal variations and the factors influencing primary production have been studied in three different mangrove waters (Pichavaram, Ennore Creek and Adyar Estuary) of South India characterised by different anthropogenic impacts. the gross primary productivity in the unpolluted Pichavaram mangrove was 113 g Cm^-2yr^-1 exhibiting natural variability with the environmental forcing factors. Human activities have elevated primary productivity in the Ennore Creek mangrove (157g Cm^-2yr^-1) primarily through the direct discharge of fertilizer effluents. By contrast, a combination of domestic and industrial effluent discharges into the Adyar Estuary mangrove has considerably reduced phytoplankton primary productivity 83g Cm^-2yr^-1 the Redfield N: P ratio varies from 0.96 N: 1P at Ennore Creek, 1.75N: 1P at Adyar Estuary to 15.2 N: 1P at Pichavaram mangroves. This suggests that the Pichavaram mangroves represent a well equilibrated ecosystem with N: P ratio close to steady-state values in contrast to the anthropogenically altered mangrove ecosystems studied. Results show a significant temporal variability in nutrient concentration in the three mangrove areas. Distinct differences in nutrient concentrations between the dry and the wet seasons have been observed.     

长江三角洲城市群人为热排放特征研究

基于常规可获取的能源、交通、人口等统计资料,利用“自上而下”的能源清单法,研究了2010年长江三角洲(以下简称“长三角”)城市群地区各类人为热排放量及其时空分布特征.结果表明:该地区人为热排放总量为1.4′1019J/a,其中工业、交通、建筑、新陈代谢分别占75.1%、12.5%、9.9%和2.5%.上海、苏州、无锡、杭州和南京五个城市的人为热排放总量约占研究区域总量的71%.长三角城市群的人为热年平均排放通量为5.3W/m2,大部分地区介于5~30W/m2,城市高值区一般介于20~70W/m2,上海明显高于其他城市.为方便有关环境气候模式的输入,本文提供了人为热排放的网格化空间分布和简单的时间变化廓线.     

A Three-Dimensional Model Study of the Impact of AVOC and BVOC Emissions on Ozone in an Urban Area of the Eastern Spain

This study concentrated on the effects of Biogenic Volatile Organic Compounds (BVOC) emissions on ozone (O₃) in an area of the Eastern Spain on June 12, 1997, a day characterised by sea breeze. Simulation of meteorology was performed with the three-dimensional model ADREA-I. Comparisons of the model results with observations have revealed overall a good agreement in temperature and wind velocity. Two runs were performed with UAM-IV for the photochemical calculations. The first simulated the effects of the anthropogenic emissions only (run A) and the second the combined effects of anthropogenic and biogenic emissions, (run B). Comparisons of the model O₃ concentrations with measurements showed a general agreement with the experimental data. Discrepancies between the calculated results and the observations during the early morning hours could be attributed to inaccuracies in nitrogen oxides (NO_x) from the anthropogenic emissions inventory. Comparisons between runs A and B yielded differences up to 30% in the morning, over inland areas. It was deduced that the inclusion of BVOC in total emissions could result in an increase or decrease of tropospheric O₃, depending on the available amounts of anthropogenic emissions.     

Anthropogenic Calcium Particles Observed in Beijing and Qingdao, China

Analysis of individual particles collected at Beijing in northern China revealed that particles abundant in calcium (Ca) always constituted a large fraction of mineral particles in the urban atmosphere. The particles were characterized by cubic morphologies. The major mineral element in the particles was Ca and few or no other mineral elements were detected. A large number of the particles were in the range of diameter <1 μm, where common natural mineral particles were rarely detected. The contribution of the Ca particles to the volume of total mineral particles greatly exceeded that of other mineral particles during non-dust-storm periods and was comparable to that during dust-storm periods. Reagent film tests showed that particulate sulfate and nitrate formation on the Ca particles was similar to that on common mineral particles. These results indicate that a large portion of Ca in the atmospheric particulate matter in Beijing was from anthropogenic sources rather than from natural sources, and the anthropogenic Ca particles acted as a significant medium for the formation of sulfate and nitrate. Similar particles were also detected at Qingdao, a coastal city in northern China. Data of a dust storm event showed that Ca-abundant particles from East China arrived there and moved out of the continent, similarly to Asian dust storm particles, suggesting possible contributions of anthropogenic Ca even in Asian dust storm samples in the downstream areas. Therefore, Ca may not be a good indicator of Asian dust from natural sources. However, the Ca particles, due to their unique shapes and elemental compositions, may provide an indicator for the atmospheric dispersion of anthropogenic particulate matters in East Asia.