欢迎胡锦涛主席队伍中的河南地矿人

日前,中国驻纳米比亚大使馆专门致函河南省地矿局亚非地矿公司,感谢他们在胡锦涛主席对纳米比亚进行国事访问期间为圆满完成欢迎任务做出的努力。     

Effects of Sediment-induced Stratification on Floc Breakup in an Idealized Tidal Estuary： A Numerical Modelling Study

Floc breakup dynamics are studied by a sediment transport numerical model in an idealized tidal estuary that has a constant water depth and rapid flocculation of cohesive sediments. The focus is placed on the effects of boundary layer stratification induced by a bottom nepheloid layer on floc breakup and size distribution in the water column. In a neutrally stratified estuary, the floc size distribution follows a parabolic function with maximum values at the surface and bottom. The sediment-induced stratification in the bottom boundary layer increases the median floc sizes. Furthermore, sediment-voided convection caused by the settling lutocline generates significant turbulent kinetic energy dissipation and reduces floc size at the depth where the convective mixing happens. Below that depth, a weak local maxima in the floc size is predicted due to presence of the lutocline. The effect of sediment-stratified bottom boundary layer on the floc breakup can be consistently approximated by a linear regression between the maximal floc size and flux Richardson number.     

The spatial dimension of Chinese urbanization

This paper focuses on four interrelated aspects of the spatial dimension of city development. Attention is paid initially to the basic geography of urbanization, before turning to an analysis of recent trends in the pattern of urbanization. Spatial biases throughout the present-day hierarchy are then investigated and, finally, the relationships between urbanization patterns and economic planning belts are considered.     

Distribution of polychlorinated biphenyls in the water, sediment and fish from the Pearl River estuary, China

The concentrations and distribution of polychlorinated biphenyls were determined in water, surface sediments and fishes from the estuaries of Pearl River, PR China. The results showed that the concentrations ranged from 2.47 ng l-1 to 6.75 ng l-1 in water, from 11.13 ng g-1 to 23.23 ng g-1 in sediments (dry weight) and from 68.64 ng g-1 to 316.85 ng-1 in fish (lipid weight). It was found that the feeding habits of fish were very significant in the accumulation of polychlorinated biphenyls and pattern of congeners. Carnivorous and benthic fishes such as eel (Anguilla japonica) and Chinese sea catfish (Arius sinensis) were found to have high concentrations of polychlorinated biphenyls and of high-chlorinated congeners, while herbivores such as shad (Clupanodon punctatus) and mullet (Mugil cephalus) exhibited an opposite trend. Congeners IUPAC Nos. 153, 138, 118, 87/81, 170 and 52 were found frequently in most samples (both sediment and fish). In comparison with other places in the world, the concentration of polychlorinated biphenyls in sediment and fish from the estuary of Pearl River were low.     

Impact of the intensive shrimp farming on the water quality of the adjacent coastal creeks from Eastern China

The effects of shrimp aquaculture on the adjacent water bodies over a crop cycle period were evaluated by studying the water quality of inlet and outlet creeks located within Xuwei Salt Field, Lianyungang City of Jiangsu Province. The characterization of the water consisted of the evaluation of the variation of 10 parameters along the inlet and outlet creeks and during the period of March-September. These parameters were pH, temperature, dissolved oxygen, nutrients (ammonium, nitrite, nitrate and inorganic phosphorus), Chlorophyll a, chemical oxygen demand (COD) and total organic carbon (TOC). Average concentrations of inorganic nitrogen (1.5 mg/l), inorganic phosphorus (0.024 mg/l), Chlorophyll a (0.0025 mg/l), COD (5.77 mg/l) and TOC (6.57 mg/l) at the discharge site in the outlet creek were significantly higher than in the inlet creek (0.33, 0.012, 0.0018, 4.72 and 3.68 mg/l, respectively). There were no significant differences between the inlet and outlet creeks in pH, temperature and DO. With a water quality criteria based on local laws, a significant pollution was observed in the area, with inorganic nitrogen being the most significant pollutant, followed by COD and inorganic phosphorus.     

A preliminary study of heavy metal contamination in Yangtze River intertidal zone due to urbanization

Three short sediment cores (<20 cm) were collected in the high, middle and low tidal flats in the Yangtze River Estuary near the Southern (Nanqu) Sewage Outlet, one of the three largest sewage outlets in Shanghai, China. All samples were analyzed for Al, Cu, Pb, Zn, 210Pb and 7Be. The 210Pbxs profile shows a non-steady-state sedimentation pattern in the study area and 7Be is only found in the upper 1 cm layer of sediment in high and middle tidal flats. In this study, we found that Cu, Pb and Zn contaminants are present in the upper 20 cm of the tidal flat sediment and, after normalizing with Al, the contamination is more striking in the upper approximately 5 cm sediment. Relationships between the metal (Cu, Pb and Zn) enrichment factor and 210Pbxs activity suggest that contamination increases with time. Factor analyses shows that differences in sediment grain size have insignificant effects on Cu and Pb concentrations, but have some influence on Zn concentration in the study area. This preliminary study shows that urbanization and recent coastal wetland reclamation have had an environmental impact on this area.     

Selenium-induced teratogenicity in Sacramento splittail (Pogonichthys macrolepidotus)

Selenium is a potent reproductive and teratogenic environmental contaminant and there are concerns over possible reproductive effects of selenium on the Sacramento splittail (Pogonichthys macrolepidotus) population, a threatened species, in California, USA. In this study, the teratogenic effects of selenium were examined in splittail embryos exposed to 0.0, 5.0, and 15.0 mg l(-1) sodium selenite for 48-h at 18.0 degrees C under static conditions, with renewal every 12 h. Embryo development was evaluated daily for abnormalities from initiation of exposure (stage 27) to initiation of exogenous feeding. At the end of evaluation, prelarvae were preserved for histological analysis. There were no significant differences in mortality or hatching success between control and exposed embryos. Exposed fish had pericardial edema and deformities of skeletal tissues (loss of tail, lordosis, scoliosis, and kyphosis). Other histological alterations were limited to dysplasia, hyperplasia and metaplasia of skeletal tissues in the deformed fish. This study showed that a short exposure of embryos during somite development has significant effects on the musculoskeletal development.     

1986-1987年E1 Nio期间南海北部的气候异常

本文根据南海北部的气象水文观测资料,比较系统地分析1986-1987年E1 Nino盛期,南海北部大气环流、台风活动、气温、雨量、蒸发量、水温、盐度以及海平面等的异常情况,并对异常原因作出初步分析。     

1980—2012年汕头市灰霾天气的气候特征

利用汕头市国家基准气候站1980—2012年的气象观测资料,对汕头市灰霾天气气候特征进行分析,找出灰霾天气出现时的主要气象影响因素。结果表明:近33年来,汕头市灰霾日数总体呈现上升趋势;灰霾天气具有明显的季节差异,呈现冬季>春季>秋季>夏季的季节特征;出现灰霾天气主要以轻微灰霾为主,轻度灰霾次之,没有出现重度灰霾;汕头市共出现176次灰霾天气过程,从20世纪90年代开始连续3 d或以上的灰霾天气过程明显增多,而连续灰霾过程大多持续3~5 d;偏东风向比较容易出现灰霾天气,在较小风速和较高相对湿度的条件下有利于灰霾天气的形成和维持,同时降水量与灰霾呈现明显的负相关性。     

灰色拓扑预测模型在初台预测中的应用

本文应用灰色系统理论，建立了南海初台的拓扑预测模型，并利用这些模型对南海初台未来十年出现日期作了预测分析，为南海台风的长期预测提供信息。