Bacterioplankton dynamics along the gradient from highly eutrophic Pearl River Estuary to oligotrophic northern South China Sea in wet season: implication for anthropogenic inputs

Bacterioplankton abundance (BA) and biomass (BB) from the eutrophic Pearl River Estuary (PRE) to the oligotrophic northern South China Sea (NSCS) were studied in the wet season. BA was significantly higher (p < 0.05) in PRE (12.51 ± 3.52 × 10⁸ cells L⁻¹), than in the continental shelf neritic province (CSNP, 4.95 ± 2.21 × 10⁸ cells L⁻¹) and in the deep oceanic province (OP, 3.16 ± 1.56 × 10⁸ cells L⁻¹). Nutrient-replete PRE waters (DIN > 100 μM and PO₄ > 1 μM) resulted in high chl a and BB, whereas nutrient-depleted offshore waters (DIN <5 μM and PO₄ < 0.5 μM) had low biomass. Temperature (>26 °C) was not the controlling factor of BA. BB was significantly correlated with chl a biomass both in PRE and NSCS. The bacteria to phytoplankton biomass (BB/PB) ratio increased clearly along the gradient from near-shore PRE (0.15) to offshore CSNP (0.93) and deep OP (2.75), indicating the important role of small cells in the open ocean compared to estuarine and coastal zones.     

Diffuse pollution by persistent organic pollutants as measured in plastic pellets sampled from various beaches in Greece

Plastic pellets found stranded on beaches are hydrophobic organic materials and thus, they are a favourable medium for persistent organic pollutants to absorb to. In the present study, plastic pellets are used to determine the diffuse pollution of selected Greek beaches. Samples of pellets were taken from these beaches and were analyzed for PCBs, DDTs, HCHs, and PAHs. The observed differences among pellets from various sampling sites are related to the pollution occurring at each site. Plastic pellets collected in Saronikos Gulf beaches demonstrate much higher pollutant loading than the ones collected in a remote island or close to an agricultural area. Based on data collected in this study and the International Pellet Watch program, pollution in Saronikos Gulf, Greece, is comparable to other heavily industrialized places of the world. The present study demonstrates the potential of pellet watch to be utilized as a detailed-scale monitoring tool within a single country.     

Environmental response to sewage treatment strategies: Hong Kong's experience in long term water quality monitoring

In many coastal cities around the world, marine outfalls are used for disposal of partially treated wastewater effluent. The combined use of land-based treatment and marine discharge can be a cost-effective and environmentally acceptable sewage strategy. Before 2001, screened sewage was discharged into Victoria Harbour through many small outfalls. After 2001, the Hong Kong Harbour Area Treatment Scheme (HATS) was implemented to improve the water quality in Victoria Harbour and surrounding waters. Stage I of HATS involved the construction of a 24 km long deep tunnel sewerage system to collect sewage from the densely populated urban areas of Hong Kong to a centralized sewage treatment plant at Stonecutters Island. A sewage flow of 1.4 million m³ d⁻¹ receives Chemically Enhanced Primary Treatment (CEPT) followed by discharge via a 1.2 km long outfall 2 km west of the harbor. The ecosystem recovery in Victoria Harbour and the environmental response to sewage abatement after the implementation of HATS was studied using a 21-year data set from long term monthly water quality monitoring. Overall, the pollution control scheme has achieved the intended objectives. The sewage abatement has resulted in improved water quality in terms of a significant reduction in nutrients and an increase in bottom DO levels. Furthermore, due to the efficient tidal mixing and flushing, the impact of the HATS discharge on water quality in the vicinity of the outfall location is relatively limited. However, Chl a concentrations have not been reduced in Victoria Harbour where algal growth is limited by hydrodynamic mixing and water clarity rather than nutrient concentrations. Phosphorus removal in the summer is suggested to reduce the risk of algal blooms in the more weakly-flushed and stratified southern waters, while nutrient removal is less important in other seasons due to the pronounced role played by hydrodynamic mixing. The need for disinfection of the effluent to reduce bacterial (E. coli) concentrations to acceptable levels is also confirmed and has recently been implemented.     

Macroalgal diversity along the Baltic Sea salinity gradient challenges Remane's species-minimum concept

Remane’s species-minimum concept, which states that the lowest number of taxa occurs at the horohalinicum (5-8 psu), was tested by investigating macroalgal diversity on hard substrates along the natural salinity gradient in the Baltic Sea. Field data on species occurrence and abundance were collected by SCUBA diving along 10 transects of the Finnish, Swedish and German coasts, covering a salinity range from 3.9 to 27 psu. Macroalgal species numbers declined steadily with salinity, decreasing until 7.2 psu was reached, but in the horohalinicum, a marked reduction of species number and a change in diversity were indicated by the Shannon index and evenness values. The non-linear decrease in macroalgal diversity at 5-8 psu and the lack of increase in species numbers at salinities below 5 psu imply a restricted applicability of Remane’s species-minimum concept to macroalgae.     

Baseline heavy metals and metalloid values in blood of loggerhead turtles (Caretta caretta) from Baja California Sur, Mexico

Environmental pollution due to heavy metals is having an increased impact on marine wildlife accentuated by anthropogenic changes in the planet including overfishing, agricultural runoff and marine emerging infectious diseases. Sea turtles are considered sentinels of ecological health in marine ecosystems. The objective of this study was to determine baseline concentrations of zinc, cadmium, copper, nickel, selenium, manganese, mercury and lead in blood of 22 clinically healthy, loggerhead turtles (Caretta caretta), captured for several reasons in Puerto López Mateos, Baja California Sur, Mexico. Zinc was the most prevalent metal in blood (41.89 μg g⁻¹), followed by Selenium (10.92 μg g⁻¹). The mean concentration of toxic metal Cadmium was 6.12 μg g⁻¹ and 1.01 μg g⁻¹ respectively. Mean concentrations of metals followed this pattern: Zn > Se > Ni > Cu > Mn > Cd > Pb and Hg. We can conclude that blood is an excellent tissue to measure in relatively non-invasive way baseline values of heavy metals in Caretta caretta.     

渤海海洋石油平台设定地震反应谱的确定

以渤海海域内已兴建的BZ28-2石油平台为研究对象,综合确定性和概率地震危险性分析方法的优点,通过对渤海海域内地震活动时空分布特征、地震地质背景、发震断裂及其活动性、平台遭受破坏性地震震级与距离的可能组合、设定地震的实际发生概率等几个方面的研究,综合确定了平台不同超越慨率对应的设定地震参数,并基于以上研究结果,给出了B...     

考虑系统柔度影响的水压致裂法测量深部岩石应力

为了有效测量水压致裂方法中的重张压力,必须使用具有足够小柔度的试验设备,否则无法从重张压力估计垂直钻孔平面的最大水平应力.仅通过替换水压致裂系统中的某一部件来大幅度降低系统柔度是很难的.但如果流量计尽可能安装在靠近跨接式封隔器隔离出的钻孔测试区.那么系统柔度就会大大降低.为此,我们研制出配有井下流量计的试验系统,并在野...     

Radionuclides measurements and mineralogical studies on beach sands, East Rosetta Estuary, Egypt

Radiometric measurements were carried out for the beach sands from East Rosetta estuary to determine the activity concentrations of 238 U, 226 Ra, 232 Th, and 40 K, using a Hyper Pure Germanium spectrometer, to estimate the dose rates and radiation hazard indices. The average specific activities are 778.20 Bq/kg for 238 U; 646.89 Bq/kg for 226 Ra; 621.92 and 627.85 Bq/kg for the 222 Rn daughters 214 Pb and 214 Bi respectively. The average specific activity of 232 Th is 1510.25 Bq/kg, while the calculated specific activity for 40 K has an average of 8.41 Bq/kg. The average specific activity of 235 U is 38.61 Bq/kg. The average absorbed dose rate is 1211.36 nGy/h, 20 times higher than the estimated average global primordial radiation of 60 nGy/h and 6 times higher than that of the world range (10-200 nGy/h). The radium equivalent (Ra eq ) values are from 6 to 9 times the recommended value. The internal and external hazard indices (H int , H ex ) indicate that their values are from 6 to 11 times the permissible values of these indices. These higher values may be due to the presence of economic heavy minerals containing radionuclides as zircon and monazite as well as some trace minerals, thorite and uranothorite. The mineralogical study indicates the beach sands contain heavy minerals, zircon, monazite, rutile, ilmenite, leucoxene, magnetite and garnet. The average abundance of zircon is 0.175 wt% ranging from 0.125 wt% to 0.239 wt%, while it is 0.004wt% ranging from 0.001 wt% to 0.007 wt% for monazite. The average abundance is 0.087 wt% for rutile; 2.029 wt% for ilmenite; 1.084 wt% for magnetite; 0.384 wt% for leucoxene and 0.295 wt% for garnet.     

基于不同设定地震方法的长周期建筑设计反应谱的对比分析

现有的设定地震方法主要有两种：加权平均法和最大概率法。本文首先简要介绍了这两种方法,然后以烟台地区一高层建筑为研究对象,分别采用加权平均法和最大概率法进行地震危险性分析,确定出设定地震震级、震中距以及具体空间位置,给出了两种方法的设定地震反应谱,最后对这两种方法所得结果的差异进行了对比和分析。结果表明：加权平均法所得反应谱将长周期处的安全性考虑在内,适用于中长周期建（构）筑物;最大概率法由于其长周期处谱值偏低,会增加长周期工程的危险性,不宜用于长周期工程,但对短周期建（构）筑物应用合理;对于自振周期不同的建筑工程应选用不同的地震危险性分析方法进行设计反应谱的确定。     

对含厚软表层海域工程场地设计地震动参数确定的一点建议

工程上常用的等效线性化方法在处理常见的、含厚软表层的海域场地时,其计算结果往往产生较大的偏异.为了研究这些计算偏异产生的程度,本文利用等效线性化方法对典型海域工程钻孔进行了小震、中震和大震3种不同工况下保留和舍弃软表层情况下的土层计算.考虑到在大震作用下,土体可能进入大的非线性范围,等效线性化将不再适用,故引入了一种能更好地考虑土层大非线性效应的直接时域积分方法,并与等效线性化方法研究结果进行了对比分析.在此基础上,给出了确定含厚软表层海域工程场地设计地震动参数的处理建议.