东亚冬、夏季风的年代际振荡及其对夏季西太平洋副高和贵州降水的影响

主要研究了东亚冬、夏季风不同长度的年代际振荡特点及其对夏季百太平洋副高和贵州降水的影响。分析表明：冬季风与赤道东太平洋海温存在着大体一致的约３０年左右年代际振荡，７０年代末发生突变；夏季风与青藏高原位势高度存在着大体一致的约２０年左右的年代际振荡，６０年代末和８０年代末发生突变。由于冬、夏季风不同长度的年代际振荡，它们同位相增阶段夏季西太平洋副高位置容易偏北，贵州降水偏少；它们同位相减弱阶段夏季西太平洋副高易偏南，贵州降水偏多；但它们反位相组合时夏季西太平洋副高位置偏北、偏南的机会及贵州降水偏少、偏多几乎均等。     

Estimation and comparison of nitrogen loads and attenuation in agricultural catchments of Japan and Korea.

To help in clarifying the relationship between the time lag and attenuation of nitrogen (N) loads generated in agricultural catchments, long-term trends in activities that generate N loads and in environmental N loads were estimated in catchments in Japan and Korea dominated by non-point-source emissions. Our approach used statistical data and geographical information system software to analyze pollutant loads. The method was successful in both countries because of the availability of well-developed statistics, geographical information, and weather and water quality monitoring systems, and the accumulation of research data concerning the generation of N loads and the fate of N in soils. Comparison of environmental loads with the loads observed in river water at the outlet of each catchment revealed that: (1) the effect of changes in the environmental load in a catchment appeared almost immediately in the river water quality in Korea, but did not appear clearly even 10 years later in Japan; and (2) the strength of the attenuation appeared to be much lower in Korea than in Japan. These findings suggest that regional characteristics play important roles in the sensitivity of water quality to load-generating activities.     

Post-dreissenid Increases in Transparency During Summer Stratification in the Offshore Waters of Lake Ontario: Is a Reduction in Whiting Events the Cause?

Since the dreissenid invasion of the lower Great Lakes, calcium concentrations in the offshore waters of Lake Ontario have decreased by approximately 4–5 mg/L. This decline has coincided with a three-fold reduction in August turbidity values and nearly a doubling of Secchi depths, presumably due to reduced summer calcite precipitation events in the lake. The reductions in calcium have followed a dramatic reduction in alkalinity in the central and eastern basins of Lake Erie, which provides most of the inflow to Lake Ontario. This reduction in alkalinity in Lake Erie corresponds to a period of rapid dreissenid growth in that lake, strongly suggesting calcium uptake by dreissenid mussels as a causative factor. The mass of calcium resident in the dreissenid population in Lake Erie, estimated from published lake-wide census data, is sufficient to account for the observed decreases in alkalinity. In addition, observed changes in alkalinity in Lake Ontario closely match those expected to result from inflows from Lake Erie, based on mass balance considerations. Considered in sum, our data strongly suggest that calcium uptake by dreissenid mussels in Lake Erie has resulted in decreases in the calcium concentration in Lake Ontario, reducing the frequency and/or intensity of whiting events in the latter lake. We believe this is the first report of an increase in transparency that can be reasonably attributed to a chemical change brought about by Dreissena. These increases in transparency may have very different consequences than those of dreissenid filtration activities. For example, rather than decreasing phytoplankton populations, the improved light climate might increase summer phytoplankton populations, particularly sub-epilimnetic ones.     

The World's Great Lakes

Most of the large lakes lie in glacial scour basins in the northern hemisphere. These lakes are closely similar in physicochemical characteristics and in their biota. Most of the other large lakes are tectonic in origin and they differ greatly among themselves and from other lakes since they occur in a diversity of terrestrial environments under a broad range of climatic conditions. Large lakes have a great diversity of habitats resulting in great species diversity and endemism in ancient lakes. The pronounced horizontal gradients in physicochemical conditions in large lakes contribute to the diversity of habitats. Conditions found in Lakes Michigan and Skadar are examples.     

A Comparison of Lake Trout Spawning,Fry Emergence,and Habitat Use in Lakes Michigan,Huron, and Champlain

Restoration of self-sustaining populations of lake trout is underway in all of the Great Lakes and Lake Champlain, but restoration has only been achieved in Lake Superior and in Parry Sound, Lake Huron. We evaluated progress toward restoration by comparing spawning habitat availability, spawner abundance, egg and fry density, and egg survival in Parry Sound in Lake Huron, in Lake Michigan, and in Lake Champlain in 2000–2003. Divers surveyed and assessed abundance of spawners at 5 to 15 sites in each lake. Spawning adults were sampled using standardized gill nets, eggs were sampled using egg bags, and fry were sampled using emergent fry traps and egg bags left on spawning reefs overwinter. Spawning habitat was abundant in each lake. Adult lake trout abundance was low in Lake Michigan and Parry Sound, and very high at one site in Lake Champlain. Egg deposition was lowest in Lake Michigan (0.4–154.5 eggs•m⁻², median = 1.7), intermediate in Parry Sound (39–1,027 eggs•m⁻², median = 278), and highest in Lake Champlain (0.001–9,623 eggs•m⁻², median = 652). Fry collections in fry traps followed the same trend: no fry in Lake Michigan, 0.005–0.06 fry•trap⁻¹ day⁻¹ in Parry Sound, and 0.08–3.6 fry•trap⁻¹ in Lake Champlain. Egg survival to hatch in overwinter egg bags was similar in Lake Michigan (7.6%) and Parry Sound (2.3–8.9%) in 2001–02, and varied in Lake Champlain (0.4–1.1% in 2001–02, and 1.8–18.2 in 2002–03). Lake trout restoration appears unlikely in northern Lake Michigan at current adult densities, and failure of restoration in Lake Champlain suggests that there are sources of high mortality that occur after fry emergence.     

1960-2016年贵州喀斯特山区干旱时空动态分析

干旱是造成喀斯特地区损失最为严重的自然灾害之一。以我国西南喀斯特集中分布区域为研究区,基于研究区33个气象站1960-2016年的逐日降水数据,利用PA指数和Mann-Kendall检验方法分析了1960-2016年干旱时空分布特征。结果表明:研究区降雨量有减少趋势,PA指数呈减小趋势,干旱呈增强趋势,2011年PA均值最小;研究区各季干旱强度均呈上升趋势,且冬旱强度最强、发生干旱年份最多,秋旱次之,春旱和夏旱强度较弱、发生干旱的年份较少;年际干旱频次高发区集中于研究区南部、西北部及中东部地区;仅秋、冬季西部和东南部部分地区出现特旱且频次低,秋、冬季发生重旱、中旱和轻旱的频次高,春、夏季较低;春季干旱频次西高东低,夏季中部高,秋季南高北低,冬季西高东低;干旱与地形因子显著相关,重、特旱易发生在高陡地区。综上所述,研究区干旱有增强趋势且秋、冬季趋势较强,空间上呈现明显的季节性和区域性,且与地形因子显著相关。     

近100多年来香港和澳门气温时序变化特征及其与ENSO的关联性

基于近 100 多年来的均一化气温数据,从趋势变化、季节差异、突变特征、周期振荡方面诊断香港和澳门的气温变化特征。结果表明: ( 1) 港澳年平均气温和不同季节气温在近 100 多年来均呈显著增加趋势,其中春冬季节增加速率较大,夏秋季节增加速率较小。除秋冬季节外,其它时间上的香港气温增加趋势均大于澳门。港澳夏冬季节气温差异均呈减少趋势。( 2) 香港和澳门年平均气温分别于 1963 年和 1991 年发生突变。在季节上,港澳地区的气温突变均在秋季发生年份最晚,冬季次之,夏季再次之,春季最早。( 3) 香港年平均气温分别存在 3 a、7 a、15 a 和 30 a、60 a 和 120 a 的周期振荡特征。澳门年平均气温存在 3 a、6 a、12 a、24 a 和 48 a 左右的周期振荡特征。( 4) ENSO 与香港年平均气温在 4 a 以下尺度以同位相或提前 1 a 位相变化关系为主,在 4 a 以上尺度以同位相变化关系为主。ENSO 与澳门年平均气温在不同时频域均以同位相变化关系为主。     

坝后背管运行期温度应力分析

采用ANSYS软件,针对黄河李家峡水电站坝后背管,计算分析运行期冬、夏2个特殊阶段管壁内外温降、温升作用下的温度场和温度应力,以及温度场和内水压力叠加产生的应力。夏季管腰环向温度应力反映出从内壁到外壁、由受拉到受压的变化规律;冬季管腰环向温度应力反映出从内壁到外壁、由受压到受拉的变化规律。冬夏不同的温度梯度产生的拉压应力变化使背管混凝土裂缝处于闭合、张开的交替状态,会使裂缝的分布规律与纯粹的简支梁受弯构件的裂缝分布有所不同。     

台湾石门水库泥沙处理的启示--略论陕西省石门水库泥沙防治对策

台湾石门水库与陕西石门水库都存在着比较严重的泥沙淤积问题。本文通过对台湾石门水库泥沙处理经验的论述 ,分析指出陕西石门水库防沙减淤的急迫性及其应采取的防治对策。     

三峡库区消落带土壤金属污染特征的研究进展

三峡库区蓄水后的生态环境问题受到人们和政府的高度重视,库区消落带是水库生态环境的重要组成部分。近年来,针对库区消落带土壤金属环境问题,国内外相关学者开展了大量的研究工作。基于近十年相关研究成果,本文对三峡库区消落带土壤金属含量、时空分布特征及生态环境风险进行了梳理、归纳和分析。结果表明,三峡库区消落带土壤金属含量总体呈现库区上游及下游较高,库区中游较低的空间格局,不同水位高程不同土壤层中各金属元素的分布特征存在一定差异。与蓄水前期相比,库区消落带土壤金属含量随干湿交替周期的增加呈现动态变化,且存在向江水中迁移的环境风险。由土壤环境质量评价结果可知,研究区域土壤总体上为二类土,处于轻度污染等级,存在轻微生态风险,主要风险元素为Cd,其次为As和Hg,但目前其含量并未影响人体生命健康。针对库区消落带的研究现状,本文提出今后相关研究的着眼方向,以期为三峡库区消落带土壤重金属污染防控及库区水生态环境保护提供参考。     

云南中北部地区1954-2012年干旱评价研究

利用云南中北部地区6个气象站点1954-2012年资料,选用标准化指数计算各站点干旱指数,统计分析了云南中北部地区1954-2012年发生干旱的年份及发生不同干旱的频次。研究结果表明:1临沧站出现干旱的年份较多,但蒙自站出现极端干旱的年份明显高于其他5站;2各站点在不同季节出现干旱的频次不同,其中腾冲在春季相比于其他5站,发生干旱的频率较高35.6%,临沧站在夏季和冬季发生干旱频率均较大,分别为35.6%和37.9%,蒙自站在秋季发生干旱频率最大,为34.8%。研究成果可为云南中北部地区的干旱评价分析和水资源保护提供一定的参考价值。     

Convergence of trophic state and the lower food web in Lakes Huron,Michigan and Superior

Signs of increasing oligotrophication have been apparent in the open waters of both Lake Huron and Lake Michigan in recent years. Spring total phosphorus (TP) and the relative percentage of particulate phosphorus have declined in both lakes; spring TP concentrations in Lake Huron are now slightly lower than those in Lake Superior, while those in Lake Michigan are higher by only about 1 μg P/L. Furthermore, spring soluble silica concentrations have increased significantly in both lakes, consistent with decreases in productivity. Transparencies in Lakes Huron and Michigan have increased, and in most regions are currently roughly equivalent to those seen in Lake Superior. Seasonality of chlorophyll, as estimated by SeaWiFS satellite imagery, has been dramatically reduced in Lake Huron and Lake Michigan, with the spring bloom largely absent from both lakes and instead a seasonal maximum occurring in autumn, as is the case in Lake Superior. As of 2006, the loss of cladocerans and the increased importance of calanoids, in particular Limnocalanus, have resulted in crustacean zooplankton communities in Lake Huron and Lake Michigan closely resembling that in Lake Superior in size and structure. Decreases in Diporeia in offshore waters have resulted in abundances of non-dreissenid benthos communities in these lakes that approach those of Lake Superior. These changes have resulted in a distinct convergence of the trophic state and lower food web in the three lakes, with Lake Huron more oligotrophic than Lake Superior by some measures.     

上覆水磷浓度对沉积物孔隙水中磷垂向分布的影响

为探究上覆水磷浓度对沉积物孔隙水中磷垂向分布的影响,通过室内实验,利用薄膜扩散平衡技术(DET)对孔隙水中磷浓度进行测量,分析孔隙水磷浓度的垂向变化规律,并揭示平衡时上覆水磷浓度与孔隙水磷浓度以及上覆水-沉积物界面孔隙水磷浓度的关系。结果表明:上覆水磷浓度越高,则沉积物孔隙水中磷垂向分布达到平衡所需的时间越长,相同垂向位置处孔隙水磷浓度及其浓度梯度越大;孔隙水磷浓度及其浓度梯度随深度增加而降低,表层沉积物孔隙水中磷的扩散作用最强,下层沉积物孔隙水磷浓度受上覆水磷浓度变化影响较小;吸附平衡后,沉积物孔隙水磷浓度和上覆水-沉积物界面孔隙水磷浓度均与上覆水磷浓度呈幂函数关系,而留存在沉积物孔隙水中的磷浓度仅占2.26%～3.80%,上覆水中减少的磷大部分被沉积物吸附。     

“中四角”工业废水排放时空格局演变及其重心迁移研究

基于探索性空间分析(ESDA)方法和重心迁移模型研究2006-2017年"中四角"工业废水排放的时空格局演变及其重心迁移轨迹。研究结果表明:2006-2017年"中四角"工业废水排放整体呈下降趋势,并存在明显空间分异特征,呈西南从高到低、中东从低到高的演变规律;总体空间内无明显的空间集聚特征,但局部空间存在明显的集聚特征且以低高集聚状态为主;2006-2017年间"中四角"工业废水排放重心主要在东经114.38°E^114.95°E、北纬29.18°N^29.34°N区域内移动,总体向东北方向移动,移动总距离为107.88 km;"中四角"工业总产值重心总体向西北方向移动,移动总距离为94.39 km,除2011和2012年外其他年份的重心移动距离变化较小。2006-2017年间"中四角"工业总产值重心逐渐偏离几何中心,而工业废水排放重心逐渐向几何中心靠拢且移动速度明显高于工业总产值重心移动速度。     

Phytoplankton trends in the Great Lakes, 2001–2011

We describe recent trends in phytoplankton composition and abundance in the Laurentian Great Lakes using synoptic spring (April) and summer (August) sampling events from 2001 through 2011, a period of rapid shifts in pelagic food webs and water quality. Data analysis identified qualitative and quantitative changes in algal densities, biovolume, and taxonomic composition of assemblages. Since 2001, Lake Superior has changed subtly with an increase in small-celled blue-green algae in spring and a recent decline in summer centric diatoms, possibly a result of lake warming and changes in water quality. Spring phytoplankton declines mainly attributed to diatoms occurred in Lakes Huron and Michigan, a probable result of invasions by non-native dreissenids that have reduced pelagic nutrients and selectively consumed certain taxa. The decline in Lake Huron's spring phytoplankton biovolume was earlier and more severe than that in Lake Michigan, despite a faster and more abundant dreissenid invasion in Lake Michigan. Lake Erie's central basin had a notable increase in spring centric diatoms (largely Aulacoseira), while the whole of Lake Erie shows a summer increase in cyanobacteria, complementing that found in coastal regions. The composition of Lake Ontario's species assemblage shifted, but little overall change in algal abundance was observed with the exception of higher summer densities of cyanophytes. Additional mechanisms for shifts in the pelagic primary producers are described or hypothesized in the context of concurrent shifts in water quality and invertebrate populations. Tracking these trends and explaining driving factors will be critical to the management of lake conditions.     

溢流面板堆石坝应遵循的若干设计准则与施工要求

通过研究和总结国内已建溢流混凝土面板堆石坝工程的建设经验,就坝身溢洪道的平面布置、坝料的选择与变形控制、溢洪道泄槽结构设计、地基排水措施与渗流控制等方面提出了在设计中应遵循的若干准则以及施工过程中应注意的事项;除此之外,对已建工程的设计和施工经验也进行了相关介绍。     

对广东省水库移民项目扶持模式多元化的探讨

以广东省为例,总结了其水库移民后期扶持工作的特点,一直走在时代的前列,取得了阶段性成果.为保持其创新性和先进性,针对广东省现阶段注重基础设施建设的“一村一策整村推进”后期扶持方式特点,进一步提出了人力资源综合开发,金融信贷,农业综合开发,第二及第三产业开发等5种水库移民扶持模式,建立了多元化项目扶持的框架,为广东省丰富水库移民扶持方式提供了参考.     

湖北省水资源压力与经济发展脱钩的时空演化

以水资源压力指数为指标,采用Mann-Kendall检验分析2011—2020年湖北省水资源压力的变化趋势及突变点,并利用Tapio脱钩模型揭示水资源压力与经济发展脱钩关系的时空演化规律。结果表明：除2016年与2020年外,湖北省水资源压力整体偏大,空间上呈现鄂西最大、鄂东居中、鄂中最小的态势;湖北省水资源压力整体呈下降趋势,突变点在2012年与2019年前后;全省水资源压力与经济发展之间的脱钩关系因水文特征波动,在时序上从2012—2016年的强脱钩发展到2017—2019年的扩张负脱钩,再到2020年的衰退脱钩;因自然气候及发展战略差异,在空间上各区域的平均脱钩率从2012—2016年鄂西最低、鄂东居中、鄂中最高,发展到2017—2019年鄂东最低、鄂中居中、鄂西最高,2020年趋于平衡。为此,湖北省未来应重视制定基于水文波动的水资源压力变化应对预案,并对鄂东和鄂中地区实施产业结构调整。     

新疆奎屯河流域地下水砷超标原因分析

新疆奎屯河流域是我国大陆第一个地方性砷中毒的区域,然而在人类活动与自然条件下,对该区地下水砷超标的原因未得到清楚的解释.通过2017年在研究区采集地表水、地下水样品51组,分析了主、微量元素组分;2019年在典型的高砷区钻井2个孔,采集沉积物样品44组,分析了粒径、化学成分.结果表明,研究区地下水砷浓度范围为10～88...     

我国地下水地球物理勘查中的问题及对策

针对我国地下水地球物理勘查目前面临的成淡水地区寻找淡水体、基岩山区裂隙水勘查、深层含水体勘查、岩溶石山地区岩溶水勘查、红层地区浅层地下水勘查等主要问题，从水文地质问题、采用的物探技术方法及其结合实例解决上述问题的对策等角度进行综述，同时对地球物理勘查地下水发展趋势予以分析。