Cloud chemistry measurements and estimates of acidic deposition on an above cloudbase coniferous forest

The wet, dry and cloud water deposition of acidic substances on the forest canopy are considered as major mechanisms for pollutant induced forest decline at high elevations. Direct cloud capture plays a predominant role of intercepting acidic substances in above cloud-base forests. We conducted a field study at Mt. Mitchell, North Carolina (35°44′05″N, 82°17′15″W; 2038 m MSL)—the highest peak in the eastern U.S.—during May–September 1986 and 1987 in order to analyze the chemistry of clouds in which the red spruce and Fraser fir stands stay immersed. It was found that Mt. Mitchell was exposed to cloud episodes 71% of summer days, the cloud immersion time being 28% for 1986 (a record drought summer in southeastern U.S.) and 41% for 1987. Sulfate, NO₃⁻, NH₄⁺ and H⁺ ions were found to be the major constituents of the cloud water, which was collected atop a 16.5 m tall meteorological tower situated among 6–7 m tall Fraser fir trees. The initiation of precipitation in clouds invariably diluted the cloud water acidity. The cloud water pH during short episodes (8 h duration or less), which resulted from the orographic lifting mechanisms, was substantially lower than that during long episodes, which were associated with meso-scale and synoptic-scale disturbances. Sulfate accounted for 65% acidity in cloud water, on the average, and contributed 2–3 times more than the NO₃⁻. Inferential micrometeorological models were used to determine deposition of SO₄²⁻ and NO₃⁻ on the forest canopy and the hydrological input due to direct cloud capture mechanism. The cloud water deposition ranged between 32 and 55 cm a⁻¹ in contrast to the bulk precipitation which was about 130 cm a⁻¹ as measured by an on-site NADP (National Atmospheric Deposition Program) collector. For S compounds, wet, dry and cloud water deposition accounted for 19%, 11% and 70%, respectively for 1986, and 16%, 8% and 76%, respectively for 1987. For N compounds, dry deposition contributed 35% and 23% for 1986 and 1987, respectively, whereas, cloud water deposition contributed 50% and 65% for 1986 and 1987, respectively. Our estimates are compared with the reported literature values for the other sites.     

Effect of acidic deposition on productivity of forest ecosystem and estimation of its economic losses in southern suburbs of Chongqing

In accordance with principle sand methods of ecology,this paper studied the effects of acidic deposition on productivity and volume increment of masson pine and Cinnamomum campora forest which are widely distributed in southern suburbs of Chongqing. Based on the field data and measurements, a multivariable stepwise regression model was established to analyze the effects of multiple environmental factors on the productivity of the forest ecosystems. This model was used to assess the volume and economic losses of these two forest ecosystems caused by acidic deposition. The results showed that, among the environmental factors, pH value of precipitation, soil depth, soil organic contents and slope are the dominant ones influencing the growth of masson pine forest. It is also shown that the acidic deposition has no clear relation to the growth of C.Campora forest, so development of such broad-leaved forest is suitable in the area.     

Factor analysis of trends in Texas acidic deposition

Precipitation chemistry data collected between 1980 and 1987 for 11 NADP/NTN sites in Texas have been analyzed using factor analysis and a trend analysis of monthly averages. Factor analysis identified four major factors which differed significantly from site to site: (1) a Gulf factor of Na⁺, Cl^-, and Mg²⁺; (a) a soil factor of Ca²⁺, K⁺, Na⁺, and Mg²⁺; (3) an acid factor of H⁺, NO₋³, and SO₄⁴⁻; and (4) an aged aerosol factor of NO₃⁻, SO₄²⁻, and NH₄⁺. At Longview, the acid and Gulf factors accounted for 18 and 46%, respectively, of the variation of the data. A trend analysis was performed on the logarithm of the monthly averages at the Longview and Victoria sites, the two sites with the largest and most complete data. Results suggest that hydrogen ions have been increasing at both sites, while calcium ions have been decreasing.     

Effect of acidic deposition on productivity of forest ecosystem and estimation of its economic losses in southern suburbs of Chongqing, China

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Characterization of pollen deposition in a forest environment

Measurements of the dry deposition of pollen were made during the months of May and June 1987 in northern Wisconsin, using a smooth surrogate surface. Samples were taken on a raft located on Little Rock Lake and at a nearby field monitoring station. Rain samples were also collected at the field station. The wet SO₄²⁻ flux was 102.7 mg m⁻², compared with a dry SO₄²⁻ flux of 118 mg m⁻² at the field monitoring site and 45 mg m⁻² at the lake site.The SO₄²⁻ content of pollen ranged from 0.2 to 0.8% of the weight of the pollen, and NO₃⁻ concentrations were an order of magnitude lower. Between 9 and 22% of the pollen weight was available as total organic carbon (TOC) upon addition to water.The addition of pollen to distilled water produced an acid reaction, due to organic acids and not inorganic acidity.     

洞庭湖大气氮湿沉降的时空变异

为研究洞庭湖大气氮素湿沉降的时空变化规律,于2016年1—12月对洞庭湖不同生态区的4个监测点的湿沉降进行了为期1年的观测.结果表明:采桑湖(CSH)、断港头(DGT)、蒋家嘴(JJZ)3个监测点的全年大气氮湿沉降量分别为49.9、38.7和90.9 kg·hm~(-2),其中NO_3~--N沉降量分别占30.3%、25.8%和33.1%,NH_4~+-N沉降量分别占32.9%、41.7%和51.1%,DON沉降量分别占36.8%、32.5%和15.9%;沅江(YJ)监测点7—12月的大气氮湿沉降量为19.0 kg·hm~(-2),NO_3~--N、NH_4~+-N和DON分别占62.2%、25.1%和12.7%,除YJ监测点外,其他各监测点NH_4~+-N沉降量高于NO_3~--N沉降量.湿沉降量与降雨量呈正相关,而湿沉降浓度与降雨量呈负相关;在CSH、DGT和JJZ监测点,湿沉降量均在春季最高,分别占全年总沉降量的54.4%、60.2%和49.7%,JJZ监测点在各个季节的总氮沉降量均高于CSH和JJZ监测点.     

相约玉珠峰

向西，向西，雄壮的青藏高原，巍巍玉珠雪峰。我们一行十几人从青海省格尔木市出发，踏上了前往玉珠峰的征程。车子开出据说是世界上面积最大城市的格尔木市市区后很快就上了青藏公路．此时天高云淡，清冷洁净的空气中我们仿佛嗅到了雪山的味道。公路两旁，荒凉的戈壁滩给我们这些异乡人更多的是令人震撼的凄美，偶尔出现的红柳等植物在此刻显现了它们生命的顽强。     

杭嘉湖地区大气氮、磷沉降特征研究

通过2013年9月~2014年8月杭嘉湖地区杭州、嘉兴和湖州3个典型站点大气氮、磷沉降数据,探讨了杭嘉湖地区大气氮、磷沉降的污染特征.结果表明,目标地区内大气氮、磷沉降通量水平较高,分别为4950.74~5585.80,65.25~69.72kg/(km2·a);直接降入水域中的氮、磷素分别为6038.4,77.8t,分别相当于农业源的氮、磷入河量的39.6%和5.9%.氮沉降以湿沉降形式为主,磷沉降以干沉降形式为主;氮、磷湿沉降通量主要受降雨量影响,且随降雨量的增加而增加;氮、磷沉降存在时空差异性,大气氮干沉降通量以杭州、嘉兴地区为较高,大气磷干沉降通量以嘉兴地区为最高,大气氮湿沉降通量则以湖州、嘉兴地区为较高,大气磷湿沉降以湖州地区最高;时间尺度上,氮沉降夏秋两季最高,磷沉降以秋冬两季最高.     

氮沉降对缙云山柑橘林不同季节土壤微生物群落结构的影响

土壤微生物积极参与生态系统的物质循环和转化.人类活动造成全球氮沉降量激增,引起土壤微生物群落结构和功能的改变,进而导致生态系统失衡.2014年6月—2015年5月在缙云山柑橘林建立野外模拟氮沉降试验样地,原位设置4个施肥水平:对照(N0,0 g·m~(-2)·a~(-1))(以N计,下同)、低氮(N20,20 g·m~(-2)·a~(-1)),中氮(N4 0,40 g·m~(-2)·a~(-1))和高氮(N60,60 g·m~(-2)·a~(-1)).施氮处理2 d后,采用磷脂脂肪酸(PLFA)标记法和ACE(Automated Soil CO_2Exchange Station,UK)自动土壤呼吸监测系统对土壤微生物群落结构、土壤温湿度进行测定.研究表明:(1)不同季节土壤微生物对氮沉降的响应各异,春季氮沉降抑制土壤微生物量,夏、秋、冬季N40处理提高了土壤微生物量,N20、N60表现为抑制土壤微生物量;氮沉降对土壤温度有显著影响,但对土壤湿度影响不明显(p0.05).(2)土壤微生物丰富度指数和Shannon-Wiener多样性指数在中氮沉降条件下达最大;Pielou均匀度指数则表现不一致,春季和夏季在中氮浓度下最大,秋季在高氮处理下最大,冬季则在低氮处理下最大.(3)土壤温度与放线菌呈显著负相关(p0.01);土壤湿度与细菌和总PLFA呈显著正相关(p0.01),与放线菌呈显著正相关(p0.05).综合分析表明,土壤微生物受土壤温度和含水量的共同影响,氮沉降降低了土壤微生物含量,此研究结果支持了氮沉降抑制土壤微生物的认识.     

Trace elements and rare earth elements in wet deposition of Lijiang, Mt. Yulong region, southeastern edge of the Tibetan Plateau

In order to investigate the compositions and wet deposition fluxes of trace elements and rare earth elements (REEs) in the precipitation of the southeastern edge of the Tibetan Plateau, 38 precipitation samples were collected from March to August in 2012 in an urban site of Lijiang city in the Mt. Yulong region. The concentrations of most trace elements and REEs were higher during the non-monsoon season than during the monsoon season, indicating that the lower concentrations of trace elements and REEs observed during monsoon had been influenced by the dilution effect of increased precipitation. The concentrations of trace elements in the precipitation of Lijiang city were slightly higher than those observed in remote sites of the Tibetan Plateau but much lower than those observed in the metropolises of China, indicating that the atmospheric environment of Lijiang city was less influenced by anthropogenic emissions, and, as a consequence, the air quality was still relatively good. However, the results of enrichment factor and principal component analysis revealed that some anthropogenic activities (e.g., the increasing traffic emissions from the rapid development of tourism) were most likely important contributors to trace elements, while the regional/local crustal sources rather than anthropogenic activities were the predominant contributors to the REEs in the wet deposition of Lijiang city. Our study was relevant not only for assessing the current status of the atmospheric environment in the Mt. Yulong region, but also for specific management actions to be implemented for the control of atmospheric inputs and the health of the environment for the future.     

Modelling the dry deposition velocity of aerosol particles to a spruce forest

A mathematical model is presented to calculate the size-specific deposition velocity of aerosol particles to coniferous forests, taking into account the plant morphology and micrometeorological parameters. In contrast to former studies on this topic the diffusion of the particles through laminar sublayers surrounding the plant surfaces was considered in detail. This necessitated the introduction of a formulation of the microscale roughness of the needle surfaces. Furthermore the ability of bursts in the sublayer to accelerate the particle transport was included.In order to calculate the overall deposition velocity the canopy was subdivided into a variable number of homogeneous height intervals. An analytical solution of the mass transfer equations containing the measured parameters was applied to each interval. The calculation scheme was then based on an initial value approach. The input parameters were the vertical profiles of wind speed and temperature and the height-specific vegetation density.The model was applied to a real spruce stand (Picea abies (L.) Karst.), and some typical results are presented. Finally, errors associated with inhomogeneities of the terrain are discussed.     

丹江口水库淅川库区大气磷沉降特征

大气磷沉降是向地表水体输送营养元素的重要途径.以丹江口水库淅川库区为研究区,在库区周围设置了6个采样点,于2020年1—12月期间采集并分析了大气总磷干、湿沉降样品,探讨了总磷沉降的时空分布特征及其对库区水体外源磷输入的贡献.结果表明：研究区大气 总磷沉降量为1.19 kg·hm^-2·a^-1,其中,干沉降占比为49.73%,湿沉降占比为50.27%;总磷干、湿沉降量在空间上均具有显著差异性（p_s<0.05）, 湿沉降量在季节上具有极显著差异性（p<0.01）;总磷干沉降量受到气温、气压和风速的显著影响,湿沉降量受到降雨量的显著影响;总磷年沉降量为65.17 t·a^-1,占河流总磷入库量的42.18%.     

A study on the environmental background values in the Mt. Namjagbarwa region, Tibet

A study on the elemental composition of aerosol, water and soil in the Mt. Namjagbarwa region, Tibet, was carried out in the period of 1982 to 1984. Samples of aerosol particles were collected by cascade impactor and analyzed for 10 elements by PIXE. Samples of ice, snow and water were collected and analyzed for trace metals, major cations and anions. The pH values of water were at quasi-neutrality or neutrality, and the hardness of water was low. Contents and physico-chemical composition of 20 elements in the major types of soil were determined by physico-chemical methods. Levels of elements in soil varied with soil type and their parent materials. Contents of some elements were higher in the substratum soil derived from in situ than in the surface soil. The region was in a remote area with negligible pollution and could be considered as a good location for measuring the baskground value of environmental sample.     

珠穆朗玛峰绒布河源区河水化学特征

为了研究绒布河源区夏季河水的基本化学特征 ,野外采集水样 117份 ,采用 PE-2380型原子吸收光谱仪测定样品的阳离子 ,Dionex-100型离子色谱仪测定阴离子 .结果表明 :①绒布河源区河水为 HCO₃,SO₄^- Ca型 .其离子浓度顺序为 :Ca²⁺>K⁺>Na⁺>Mg²⁺,SO^2-₄>Cl^->NO^-₃ .②河水中离子 Ca²⁺、Mg²⁺、SO^2-₄ 之间 ,以及 K⁺和 Na⁺之间有很好的正相关关系 ,河水化学组成大部分来源于当地岩石的风化分解 .③整个夏季河水各月离子平均浓度和流量有良好的正相关关系 ,流量大的月份 ,各离子平均浓度也大 ,反之亦然 .     

希夏邦马峰北坡地区夏末降水化学特征探讨

1 997年 8— 9月野外工作期间 ,在希夏邦马峰北坡达索普冰川高海拔区 ( 2 8°33′N ,85°44′E)采集到一批大气降水样品 .样品化学分析结果表明 ,达索普冰川高海拔区夏末降水化学成分中NO3- 浓度最高 ,Mg2 浓度最低 .海盐离子浓度在海洋性气团降水中高于局地大陆性气团降水 .同全球其它偏远地区比较 ,本区夏末降水的主要离子浓度较低 ,与南极和格陵兰冰盖内陆地区雪冰相当 ,表明希夏邦马峰北坡地区夏末大气环境相当“洁净” ,可代表全球偏远地区大气降水的本底状况 .达索普冰川区夏末降水的 pH值 (平均值为 6.0 )和主要离子浓度表明 ,本区夏末大气降水受人类排放污染物的影响很小 ,同时降水的电导率较低而且变化较小 .     

红壤丘陵区森林植被恢复的增湿效应初探

红壤丘陵区森林植被恢复后，对水分和热量均有明显的调节作用，尽管林内穿透雨只占林外降水量的90％左右，但相对湿度始终高于林外，森林可以增湿、调湿，提高水分利用效率。同时，林内气温、地温始终低于林外，随着林龄的增长，这种作用愈加明显。     

Effect of lime application on microbial community in acidic tea orchard soils in comparison with those in wasteland and forest soils

Lime application is a conventional technology to control acidification in tea orchard soils. We investigated the e ect of lime application on soil microbial community diversity in the soils of three tea orchards, wasteland and forest. The BIOLOG data showed that both the average well color development of all carbon sources and the functional diversity index increased with the liming rate in the tea orchards and the forest, but decreased in the wasteland. The phospholipid fatty acid (PLFA) analysis showed that the structural diversity index of soil microbial community increased with the liming rate in all the tea orchards, the wasteland and the forest. Lime application also increased the soil-bacterial PLFA content in all the soils. Soil fungal and actinomycete PLFAs in the tea orchards showed an increasing trend from 0 to 3.2 g CaCO3/kg application and then a decreasing trend from 3.2 to 6.4 g CaCO3/kg application. The principal component analysis of BIOLOG and PLFA data suggested that lime application had a significant e ect on soil microbial community structure, and land use had a greater e ect on soil microbial community structure compared to lime application.     

基于GIS的上海城市灰尘重金属空间分布特征研究

基于ArcGIS地统计分析模块,以上海市外环以内为研究区域,对上海城市道路和公园灰尘中重金属Pb、Cr、Cu、Ni、Zn含量水平和空间分布特征进行了研究.研究表明:上海城市灰尘重金属平均含量水平普遍较高,Pb、Cr、Cu、Ni、Zn平均含量分别为273.45、144.01、190.01、86.26、708.25 mg·kg-1,分别高出上海土壤背景值10.7、1.9、6.6、2.7、8.2倍;外环区域Pb、Zn、Ni污染严重,尤以工业区、商业区以及交通繁忙区最突出.地统计分析表明,Pb和Cu呈较弱的空间相关性,说明Pb和Cu的空间变异以人为影响为主;Zn、Cr和Ni为中等相关,说明随机性因素和结构因素对这3种元素都有较大影响;基于ArcGIS的地统计学分析工具能够较好地反映重金属污染的空间分布格局.     

旅游对尼泊尔珠穆朗玛峰国家公园步行道的影响

本文总结了在尼泊尔珠穆朗玛峰国家公园所做的旅游影响的研究结果,调查了旅游利用和环境特点对步行道的影响.7条步行道分成208个路段,评估的总长度为90km.采用了4级评估体系对步行道的路况进行评价,用Arc/Info和Arc/View地理信息系统(GIS)对旅游利用影响的空间格局进行分析.研究表明旅游利用和道路破坏之间密切相关,但步行道位置和环境因素是同等重要的变量.本研究认为较系统、实验性的研究是必要的,这些工作能够将人类活动导致的步行道损坏和自然因素影响明确地区别开.