Chemical forms of heavy metal contaminants in sediments of Miyun reservoir

The chemical forms, spatial distribution and sources of As, Hg, Cd, Pb and Zn in sediments of the Miyun reservoir were studied. The results of sequential extraction demonstrate that most of As, Pb and Zn were bound to the residual fraction, Hg was associated with the sulfide fraction while Cd was associated with the carbonate fraction and the residual fraction. On the vertical profiles the concentrations of the heavy metals in total and each fractions mostly decreased with increasing depths in sediments, suggesting that the heavy metals input from the upstream watershed increases yearly. Summation of the residual fraction, the sulfide fraction and the carbonate fraction accounts for 60.03%―85.60% of the total heavy metal contents in the sediments, which represent the geochemical background values of the elements and relate closely to soil erosion. Results of the main factor analysis show that most sediments of the reservoir come from the upstream soil erosion, the point source pollution and domestic waste. Moreover, the microbial activities taking place on the sediment-water interface are also one of the major factors to cause the increasing content of the organic matter fraction and the iron-manganese oxide fraction. Environmental change of the reservoir water could make the removability of the heavy metals increase, leading to the increase of their concentrations in pore water in sediments, and imperiling water quality of the reservoir.     

南海晚第四纪浮游有孔虫类群变化所表征的古海洋学特征

通过对南海4个岩心的74个样品进行Q型因子分析,求得4个浮游有孔虫组合:亚热带-热带组合,温凉组合,热带易溶组合和亚热带组合。亚热带-热带组合为优势组合,它的发育状况反映了晚第四纪西太平洋热带海水对南海的影响程度,其因子载荷作为古海流特征的参数。温凉组合的发育与南海存在冷涡有关。利用转换函数FP-12E计算了南海南部表层古水温,冰期与间冰期的表层水温平均变化冬季为4.7℃和2.9℃,夏季为3.0℃和2.1℃,季节性温差冰期最大可达8.6℃,间冰期最大可达5.0℃,均比太平洋同一纬度海区的大。冬季表层古水温波动比夏季的大。全新世的表层水温呈上升趋势,但在NS86-43柱中有一变冷现象,这可能和the younger Younger Dryas有关。     

海口地区杂交早稻产量构成因素的气象条件分析

利用海口地区1982～2004年共23年杂交早稻生产的农业气象观测资料,对杂交稻早稻产量及其构成因素的气象条件分析得出:温度和日照是影响海口地区杂交早稻产量的主要气象因子。影响时期主要为分蘖期和灌浆期。     

内蒙古二连盆地岩性油气富集因素分析

根据近年来在内蒙古二连盆地有关岩性油藏方面取得了很多勘探成果,通过对4个主力凹陷的岩性油气富集因素进行分析,认为形成岩性油气富集的3大主要因素是:(1)丰富的油源;(2)优质的砂岩体圈闭;(3)存在汇流通道。丰富的油源是油气富集的物质基础,二连盆地发育的2套有效烃源岩层系厚度大、分布面积广、资源规模大,与储集砂体之间具多种接触关系。优质的砂岩体圈闭具有圈闭规模大、发育有利的储集相类型和良好储集层的特点,这些是油气富集的关键因素。圈闭规模大表现为单一大规模砂岩体圈闭或多个小型圈闭叠合连片,扇三角洲、辫状河三角洲和湖底扇是有利的储集相类型,油气富集往往形成于良好的储集层中。此外,存在汇流通道是油气富集的重要因素,充足的油气通过指状砂体侧向汇流通道和断层垂向汇流通道运移,在优质的砂岩体圈闭中聚集成藏。     

多因素复杂系统最佳因素权重确定的一种新思路——以深港西部通道工程深圳湾公路大桥为例

为了客观地反映各因素对目标问题的影响程度,本文首次提出了最佳因素权重概念。定义最佳因素权重为研究区域内系统质量处于极限状态时的各因素权重之组合。结合深港西部通道工程深圳湾公路大桥桥址比选方案,详细说明了本方法的研究思路及其确定方法。通过最佳因素权重方法,能客观地、定量地确定出多因素复杂系统中的最优场址。     

Lake surface water-heat flux variation and its correlations with meteorological factors on multiscale in the Yamzhog Yumco,south Tibet

Lake surface water-heat exchange and its climatic attribution critically influence alpine lakes'evaporation mechanism and water storage balance with climate change.Here,this paper first explored the hourly,daily,and monthly water-heat flux variations of the lake surface and their correlations with meteorological factors based on the eddy covariance tur-bulent flux observation over the Yamzhog Yumco,an alpine lake in south Tibet in the non-freezing period(April-December)in 2016 and 2017.We found that the average latent heat flux was much higher than the sensible heat flux on the lake surface from April to De-cember.Meanwhile,the water-heat flux exhibited remarkable seasonal variation,with a prominent role of higher air temperature and humidity in summer jointly controlling the lake-air energy exchange.Moreover,the main controlling meteorological factors for the water-heat flux variation of the lake surface differed with diversified timescales.First,the lake-air tem-perature difference was the most significant meteorological factor related to sensible heat flux on the half-hourly,daily,and monthly timescales.Second,the latent heat flux was strongly positively correlated with wind speed and the synergies of wind speed and water vapor pressure deficit on the daily and half-hourly timescales.Third,the lake surface heat flux was significantly negatively correlated with net radiation flux on the daily and monthly scales.The negative correlation can be attributed to the seasonal variation of the water surface net radi-ation,and the phase difference in heat flux intensity caused by the lake-air temperature dif-ference and heat capacity contrast.Our findings will hopefully improve the understanding of energy exchange and evaporation mechanisms for alpine lakes in a warming climate.     

重庆市滑坡灾害时空特征分析

重庆市是滑坡灾害高发的城市,滑坡灾害每年都会造成大量的人员伤亡和经济损失。本文结合历年滑坡统计资料,基于GIS平台,分析重庆市滑坡灾害的时空分布特征。自1980年起,重庆发生滑坡的次数明显增加,且集中发生在5~9月,尤其是7月。80%以上的滑坡为降雨引发,其次是自然灾害和人类活动,人类活动诱发滑坡灾害增长速度最快。重庆滑坡密度大的地区为市区以及万州区、忠县等三峡库区核心地带,滑坡高发地区有东北向西南方向变化的趋势。     

江西瑞昌1995年ML4.9级地震前后九江地震台倾斜固体潮汐变化分析

通过月整点值数据文件和滑动值数据文件这两种数据处理形式。对九江台地倾斜资料进行调和分析计算。分析了M2潮汐因子与瑞昌ML4.9级地震的关系。认为存在震前短临异常或震后异常,并与趋势异常得到相互印证。     

我国铀矿床水文地质分类的探讨

本文总结了近三十年来所取得的各类铀矿床的水文地质勘探资料和部分矿床开采验证的结果。根据铀矿床围岩特征和含水条件,归纳出坚硬裂隙岩层、半坚硬孔隙岩层、岩溶和赋存温热水岩层四种含水特点。总结出了引起矿床充水的三个主要因素,即矿体与当地侵蚀基准面的相对位置、地表水体(主要是河流)的影响程度和地质构造发育程度及形态特征。在此基础上,将矿床水文地员条件共分为十六种不同情况,得出一个比较简单、直观的分类表,进一步划分出水文地质条件简单、中等、复杂和极复杂四种类型,并作了简要阐述,列举了典型矿床实例。最后得出铀矿床水文地质条件多数不复杂,而复杂和极复杂类型仅占矿床总数的20％,河水、岩溶和温热水是造成矿床水文地质条件复杂的三个主要因素等结论。     

岩质边坡稳定性分析的探讨

通过最大剪应力等值线来确定边坡的滑动面,并与其结构面抗剪强度相比较,给出了确定边坡的稳定系数的方法。