Effects of tributyltin at environmental levels on monooxygenase system of digestive gland in hard clam Meretrix meretrix

The effects on ethoxyresorufin O-deethylase （EROD）, NADPH-cytochrome c reductase and NADH cytochrorne b5 reductase activities of digestive gland in Meretrix meretrix exposed to tributyltin （TBT） at environmental levels （0.1,1.0,10.0 ng/dm as stannum concentration）,in experimental condition, were evaluated. The EROD, NADH cytochrorne b5 reductase activities were significantly inhibited after exposure to 10.0 ng/dm^3 TBT for 8 and 20 d, the NADPH cytochrorne c reductase activities were significantly inhibited after exposure to 0.1,1.0 and 10.0 ng/dm TBT for 8 d and to 1.0 and 10.0 ng/dm for 20 d, as compared with the matched control, while NADH cytochrorne b5 reductases and NADPH cytochrome c reductase activities were induced after exposure to 10.0 ng/dm^3 TBT for 2 d. The EROD activity in the 10 ng/dm^3 group,and the NADH cytochrome b5 reductases activities in 1.0 and 10.0 ng/dm groups, were significantly induced when transferred to clean recovery tanks for 7 d. The three enzymic activities in the clams exposed to TBT were recovered to the level corresponding to that of the control group after transfer to clean recovery tanks for 20 d. NADPH cytochrome c reductase activity in Meretrix meretrix seems to be more sensitive to exposure of TBT than that of the EROD and NADH cytochrome b5 reductases. The results suggest that induction and inhibition by TBT to the monooxygenase system enzymic activity in Meretrix meretrix would simultaneously exist. The enzymic activities were inhibited by exposure for a long time. The results suggest that inhibition of the monooxygenase system should be an indication of the exposure to environmentally relevant concentrations of TBT for a long time.     

一种基于BP算法学习的小波神经网络

为发展 Szu的基于信号表示的小波神经网络 ,提出一种多输入多输出的小波网络模型 ,网络隐层采用框架小波函数、输出层采用 Sigmoid激励函数 ,并选用“熵误差函数”以加速网络的学习速度。奇偶判别和混沌时间序列预测例子的实验结果表明了它具有良好的函数逼近能力和推广能力 ,收敛速度和均方误差均优于相同结构的多层感知器模型。     

琼州海峡铁路轮渡新海湾港区泥沙淤积问题

海南省拟建琼州海峡铁路轮渡。本文通过对海峡南岸新海湾轮渡港址附近自然条件、岸滩演变和输沙特征的分析研究，对不同类型港区布置方案港内开挖区和航道的淤积强度、淤积量等进行了计算，并对不同防护建筑物的有效拦沙时间等进行了探讨和计算，提出了港区类型推荐方案。     

鲁苏榴辉岩的地球化学

以微量元素、稀土元素、Ｓｒ和Ｎｄ同位素变异特征为依据，确定鲁苏榴辉岩为多成因、多来源和多阶段，指出主要是在印支期扬子陆块与华北陆块碰撞造山作用过程中，挤入的上地幔碎片以及不同原岩类型的壳内高压变质岩碎块。燕山晚期的区域构造热事件使得某些榴辉岩的同位素体系再平衡。     

Geochemical and hydrodynamic constraints on the distribution of trace metal concentrations in the lagoon of Nouméa, New Caledonia

Seawater samples were collected in the lagoon of Nouméa (southwest New Caledonia) along two transects from eutrophic coastal bays to the oligotrophic barrier reef. Land-based emissions to the lagoon were measured with dissolved and particulate concentrations of chromium (Cr) and nickel (Ni), used as tracers of both terrigenous and industrial (Ni ore treatment) activities, as well as dissolved and particulate concentrations of zinc (Zn), used as a tracer of urban effluents. The spatial variability of metal concentrations was related to geochemical and hydrodynamic conditions, i.e., respectively: (1) natural and anthropogenic emission sources, and chemical processes occurring in the water column; and (2) water residence times. The parameter used to describe the residence time of water masses was the local e-flushing time, i.e. the time required for a tracer mass contained within a given station to be reduced by a factor 1/e. High metal concentrations were found in coastal areas (up to 9000 ng dissolved Ni L⁻¹), and steeply decreased with distance from the coast (down to 101 ng dissolved Ni L⁻¹ near the barrier reef) to reach levels similar to those found in remote Pacific waters, suggesting a rapid renewal of waters close to the barrier. Distributions of metals in the lagoon are controlled upstream by land-based emission sources and later chemical processes. Then hydrodynamics constrain metal distributions, as shown by the observed relationship between local e-flushing times and the spatial variability of metal concentrations. In addition, a change in the direction of prevailing winds yielded a decrease of dissolved metal concentrations at the same site by a factor of 2.5 (Cr and Ni) and 2.9 (Zn). It is suggested that the residence time is a key parameter in the control of elemental concentrations in the lagoon waters, as much as land-based emission sources.     

近海工程环境应用中各种风资料的平均时间分析

本文从近海工程设计应用的需要出发，对于通常使用的不同来源的测风资料平均时间进行了分析，这些资料来源包括：岸边及近海探查与生产设施上的气象台站、天气观测船、浮标、商船气象报、从受灾情况估计出的极大风速以及动力诊断模型估计出的海面风速。     

Coupling of life cycles of the copepods Calanus chilensis and Centropages brachiatus to upwelling induced variability in the central-southern region of Chile

A time series of zooplankton sampling carried out at Station 18 off Concepción (36°S, 73°W) from August 2002 to December 2003 allowed the study of annual life cycles of the copepods Calanus chilensis and Centropages brachiatus in association with environmental variability in the coastal upwelling zone. Changes in the abundance of eggs, nauplii, and copepodids were assessed from samples taken at a mean time interval of ca. 20 days. Upwelling variability in near-surface waters was reflected in seasonal changes in salinity, water column stratification, and oxycline depth, as well as a weak seasonal signal in sea surface temperature (1-2 °C). Both copepods exhibited similar life cycles, characterized by continuous reproduction throughout the year. Estimates of generation times, as a function of temperature, were 25-30 days for C. chilensis and 27-35 days for C. brachiatus, predicting about 12 and 10 generations a year, respectively. These estimates were consistent with reproduction pulses observed in the field. It was thus suggested that copepods may grow under non-limiting food conditions in this upwelling area. However, despite continuous reproduction, there were abrupt changes in population sizes along with the disappearance of early naupliar and copepodid stages taking place even during the upwelling season (spring/summer). These changes were attributed to sudden increases in mortality taking place in spring or early summer, after which the populations remained at low levels through the fall and winter. It is thus suggested that, in addition to variability in the physical environment, biological interactions modulating changes in copepod mortality should be considered for understanding copepod life cycles in highly productive upwelling systems.     

威海地区高压岩石组合及其成因演化

利用矿物地质温压计估算变质高峰期温压条件、退变质作用温压条件。研究表明,本区为鲁苏构造带的北延部分,代表本区晚元古代华南陆块与华北陆块的碰撞及三叠纪华北陆块向华南陆块推覆事件的发生和演化。     

Toward a generic method for studying water renewal, with application to the epilimnion of Lake Tanganyika

We present a method, based on the concept of age and residence time, to study the water renewal in a semi-enclosed domain. We split the water of this domain into different water types. The initial water is the water initially present in the semi-enclosed domain. The renewing water is defined as the water entering the domain of interest. Several renewing water types may be considered depending on their origin. We present the equations for computing the age and the residence time of a certain water type. These timescales are of use to understand the rate at which the water renewal takes place. Computing these timescales can be achieved at an acceptable extra computer cost.The above-mentioned method is applied to study the renewal of epilimnion (i.e. the surface layer) water in Lake Tanganyika. We have built a finite element reduced-gravity model modified to take into account the water exchange between the epilimnion and the hypolimnion (i.e. the bottom layer), the water supply from precipitation and incoming rivers, and the water loss from evaporation and the only outgoing river. With our water renewal diagnoses, we show that the only significant process in the renewal of epilimnion water in Lake Tanganyika is the water exchange between the epilimnion and the hypolimnion, other phenomena being negligible.