中国西南地区近千年湖泊水位变化

重建湖泊水位历史、掌握其演变规律和机制,对水资源管理、生态环境保护、旱涝灾害防治以及认识区域水文气候变化机制皆有重要意义.中国西南地区拥有大量湖泊,其水位变化及驱动机制广受关注.本文通过汇总历史文献记录并将其与邻近地区的其他湖泊水位重建进行比较,总结了过去一千年中国西南地区湖泊水位的变化.结果显示中国西南地区近千年的湖...     

近38年安徽省夏季降水日数和强度的分布与变化特征

选用1971～2008年安徽省78个地面气象站的观测资料,分析夏季降水和暴雨的气候变化规律。从结果来看安徽省夏季降水主要受到地理位置、地形地貌和风、温、湿等气象因素的影响。根据主要影响因子的不同,按照降水特性以及行政边界将安徽省划分成了10个区,不同区域内降水特征和分布结构各有差异。在时间变化上,雨日出现概率有下降的趋势,但暴雨日比重和降水量均有升高的变化特征。综合而言,安徽省的降水朝着具有局地性、突发性的强降水过程方面发展,从而导致部分区域内突发性暴雨过程频发     

重庆地区石笋δ13C记录的全新世气候环境变化

本文利用重庆市青木关镇狮子洞石笋QM09铀系测年数据和氧碳稳定同位素数据,重建了研究区9.4~0 ka BP的古气候环境演化历史。依据狮子洞石笋δ~(13)C记录变化趋势,将其划分为2个阶段:(1)9.4~3.0 ka BP期间,狮子洞石笋δ~(13)C记录除了在4.2 ka BP附近发生一次短暂的偏重事件外,整体变化比较平缓,石笋δ~(13)C值比较偏轻;同时石笋δ~(18)O值在该期也较为偏轻,暗示了此时段季风强盛,气候温暖湿润,地表植被变化稳定。此时人类活动比较弱,对自然环境的影响小,植被变化主要受自然气候环境的影响;(2)3.0~0 ka BP期间,石笋δ~(13)C记录不再呈现如第一阶段般平稳变动的趋势,在3.0 ka BP时开始波动下降,在经历1.7 ka BP大幅下降后,δ~(13)C便频繁波动大幅升降。石笋δ~(18)O记录显示该时段季风减弱,气候变干,植被退化,土壤水中溶解的CO_2含量减少。加之该期人类活动剧烈,地表自然植被遭到破坏,当地无机环境更多的参与到地下水循环体系中来,使得石笋δ~(13)C逐渐加重。     

An Analysis of the Daily Radial Activity of 7 Boreal Tree Species, Northwestern Quebec

In the `Des Vieux Arbres' ecological reserve situated within northwestern Québec, 40 band dendrometers were installedon 7 of the major boreal tree species. The late Spring–early Summer daily radial activity registered in 1997 was related todaily weather variables. For each tree species, the daily mean i) cumulative radial increment and ii) radial activity indexedseries obtained by first-difference standardization were analyzed. The results indicate the existence of strong similarities among the 7 species. All showed strong synchronousfluctuations in radius during late winter and early spring. Thisperiod ended with a short but sharp increase in radial increments that marked the passage of water into the stem. Thisinitial swelling, less obvious in Pinus species was followed by a prolonged period of little change in radial activity. Meteorological data indicated that air temperature waspositively related to stem swelling during the late winter–earlyspring period. Both air and soil temperatures became negatively related to radial expansion once the passage of water has occurred in the stem. Starting in early June, all species registered a sustained increase in radial increments possiblyassociated with active cell division. After this, radial expansion was negatively related to air temperature and positively to rainfall.     

Variation in spatial pattern of criteria air pollutants before and during initial rain of monsoon

Spatial patterns of various criteria air pollutants,like SO₂, NO₂, O₃, and TSP were studied atShahdara National Ambient Air Quality Monitoring stationin Delhi (India) in July 1999. The minimum pollutantconcentrations were observed during morning hours,whereas the highest concentrations were found during thelate night hours, which seem to be related with thevehicular emission. Pre-monsoon daily ambient airquality spatial pattern was compared with the spatialpattern during initial and subsequent rain shower ofmonsoon. These spatial patterns were found to beessentially the same before and during rain, however asignificant decrease in SO₂, NO₂ and TSPconcentrations (40-45%) was observed after initial andsubsequent rains of the monsoon, demonstrating theimportance of rainfall in the scavenging of thesecriteria air pollutants.     

Monitoring of Organochlorine Pesticide Residues in Summer and Winter Vegetables from Agra, India – A case study

Analysis of summer and winter vegetable samples during 2002–2003 for pesticidal contamination was carried out on Gas Chromatograph-Electron Capture Detector with capillary columns. The contamination levels of winter vegetables (average concentration of 4.57, 6.80 and 5.47 ppb respectively for Lindane, Endosulphan and DDT) were found to be slightly higher than the summer vegetables (average concentration of 4.47, 3.14 and 2.82 ppb respectively for Lindane, Endosulphan and DDT). The concentration of these organochlorine pesticides in summer and winter vegetables were well below the established tolerances but continuous consumption of such vegetables even with moderate contamination level can accumulate in the receptor's body and may lead to chronic effects that could be fatal.     

珠江三角洲干线公路夏季臭氧污染特征

基于国家干线公路交通量信息,运用GIS的路网线性参考系统,计算珠三角地区夏季NO_x和VOCs排放量,使用最大增量反应活性（MIR）和经验公式,分别估算VOCs和NO_x的O₃生成及其强度的空间分布特征.结果表明,夏季VOCs的排放量占比总体上与各类型车辆数占比一致,而汽油车的NO_x排放量占比与车辆数差异较大;VOCs排放的分布与NO_x基本相似,广州市是NO_x和VOCs排放量最高的城市,珠海、中山和江门3个城市的排放量较小;NO_x的O₃生成总量与生成能力成反比,所有车型中烯烃和芳香烃对O₃生成贡献率都是最大的,而排放量较大的烷烃生成O₃量最低;路网密度大的广州市、深圳市,汽车排放的NO_x和VOCs量相对较高,其产生的O₃浓度也较高,对于路网密度较小的城市（如珠海市）,其O₃污染主要以交通干线为中心,向外扩散,O₃生成量较小.     

大气环流模式CAM4对亚洲气候的高分辨率模拟

中小尺度地形不仅在区域尺度上影响降水和环流形势分布,还会影响季风、西风急流等大尺度的天气系统。新的全球模式分辨率得到明显提高,本研究通过对比分析CAM4高分辨率配置下的模拟结果与高分辨率APHRO降水和ERA-Interim再分析资料,评估高分辨率CAM4对亚洲地区气候系统的模拟性能。结果表明,该模式不仅对亚洲季风-干旱气候系统的大尺度分布特征有良好的模拟能力,还能很好地模拟出季风区和内陆干旱半干旱区年均和季节平均降水的高、低值中心以及水平风场、地表温度和海平面气压的区域差异性特征,尤其是山脉地形附近的降水极值和风场变化。此外,CAM4与气象资料间在不同空间尺度上的空间相关性均很好,其中地表温度的相关系数在0.9以上,降水在亚洲地区超过0.7。     

Projected Climate‐Induced Habitat Loss for Salmonids in the John Day River Network,Oregon, U.S.A.

Abstract: Climate change will likely have profound effects on cold‐water species of freshwater fishes. As temperatures rise, cold‐water fish distributions may shift and contract in response. Predicting the effects of projected stream warming in stream networks is complicated by the generally poor correlation between water temperature and air temperature. Spatial dependencies in stream networks are complex because the geography of stream processes is governed by dimensions of flow direction and network structure. Therefore, forecasting climate‐driven range shifts of stream biota has lagged behind similar terrestrial modeling efforts. We predicted climate‐induced changes in summer thermal habitat for 3 cold‐water fish species—juvenile Chinook salmon, rainbow trout, and bull trout (Oncorhynchus tshawytscha, O. mykiss, and Salvelinus confluentus, respectively)—in the John Day River basin, northwestern United States. We used a spatially explicit statistical model designed to predict water temperature in stream networks on the basis of flow and spatial connectivity. The spatial distribution of stream temperature extremes during summers from 1993 through 2009 was largely governed by solar radiation and interannual extremes of air temperature. For a moderate climate change scenario, estimated declines by 2100 in the volume of habitat for Chinook salmon, rainbow trout, and bull trout were 69–95%, 51–87%, and 86–100%, respectively. Although some restoration strategies may be able to offset these projected effects, such forecasts point to how and where restoration and management efforts might focus.     

夏季东海北部近海鱼类群落结构变化

根据1964、1982、1999和2005年6月渔业生物资源底拖网监测资料,分析了东海北部近海鱼类群落结构的变化。结果表明,1964、1982、1999和2005年间,4次监测中出现的鱼类种类数分别为64、78、64和47种;4次监测中主要优势种类均为带鱼,但其资源量正逐渐降低;其它优势种类由20世纪60年代的底层优质鱼类,转变为80年代的中上层鱼类,随后转变为现在的群落结构简单、底层和中上层鱼类均较少的状况;鱼类生物多样性指数均呈现由1964年到1982年升高,随后又逐渐降低的趋势;1964-2005年间鱼类群落长度谱变化状况表明,该海域内的鱼类呈现小型种类和小个体增多,大个体减少,且长度范围变小的趋势。