Morphotaxonomy and seasonal distribution of planktonic and benthic Prorocentrales in Karachi waters, Pakistan Northern Arabian Sea     

Sonia MUNIR  Zaib-un-nisa BURHAN  Tahira NAZ  P.J.A.SIDDIQUI  Steve L.MORTON 《中国海洋湖沼学报》2013,31(2):267-281

Morphotaxonomy and seasonal abundance of dinoflagellates of the genera Prorocentrum and Mesoporos(Prorocentrales) were studied from nutrient-rich waters,Karachi Harbor and the mouth of the Manora Channel,Pakistan during May 2002-July 2003.Using both light and scanning electron microscopy,13 species of Prorocentrales were identified according to cell shape,size,ornamentation of thecal plates,and architecture of apical platelets,apical pore area,marginal pores,and intercalary bands.P.sigmoides,P.arcuatum,P.scutellum,P.donghaiense,P.balticum,P.minimum,P.emarginatum,P.lima,P.faustiae,and Mesoporos perforatus constitute new records for sindh coast of Pakistan.The most abundant species were P.minimum/P.balticum(4.5×103 cells/L),P.micans(1.1×103 cells/L),P.gracile/P.sigmoides(2.5×102 cells/L) and P.donghaiense(6.6×103 cells/L) at temperatures of 29-31℃ and salinities of 35-40.Maximum abundance was observed in winter and lower abundance in summer.There was no significant change in the distribution of species between stations except for the benthic species which occurred close to Karachi Harbor waters.Significant positive correlations were observed between Prorocentrum spp.and temperature(R 2 =0.27) and negative correlations with salinity(R 2 =-0.32) except for P.minimum and P.emarginatum which has negative correlation with temperature(R 2 =-0.24) and positive with salinity(R 2 =0.08,0.19).The finding of potential okadaic-acid producing species of benthic Prorocentrum call for monitoring for possible human health problems in this region.  相似文献   

Groundwater quality Management in China          下载免费PDF全文

Aizhong Ding  Lirong Cheng  Steve Thornton  Wei Huang  David Lerner 《地下水科学与工程》2013,1(1):54-59

Groundwater quality is of vital importance in groundwater safety especially for the purpose of water supply, its management becomes more and more necessary as groundwater contamination has threaten its safe use in China. The article analyzed the contamination sources of groundwater and impact of contamination on human health and water supply, the knowledge gaps were pointed and recommendations were made for groundwater quality management in China.  相似文献   

Isotopic investigation of runoff generation in a glacierized catchment in northern Sweden   总被引：2，自引：0，他引：2       下载免费PDF全文

Helen E. Dahlke  Steve W. Lyon  Peter Jansson  Torbjörn Karlin  Gunhild Rosqvist 《水文研究》2014,28(3):1383-1398

In this study, summer rainfall contributions to streamflow were quantified in the sub‐arctic, 30% glacierized Tarfala (21.7 km²) catchment in northern Sweden for two non‐consecutive summer sampling seasons (2004 and 2011). We used two‐component hydrograph separation along with isotope ratios (δ¹⁸O and δD) of rainwater and daily streamwater samplings to estimate relative fraction and uncertainties (because of laboratory instrumentation, temporal variability and spatial gradients) of source water contributions. We hypothesized that the glacier influence on how rainfall becomes runoff is temporally variable and largely dependent on a combination of the timing of decreasing snow cover on glaciers and the relative moisture storage condition within the catchment. The results indicate that the majority of storm runoff was dominated by pre‐event water. However, the average event water contribution during storm events differed slightly between both years with 11% reached in 2004 and 22% in 2011. Event water contributions to runoff generally increased over 2011 the sampling season in both the main stream of Tarfala catchment and in the two pro‐glacial streams that drain Storglaciären (the largest glacier in Tarfala catchment covering 2.9 km²). We credit both the inter‐annual and intra‐annual differences in event water contributions to large rainfall events late in the summer melt season, low glacier snow cover and elevated soil moisture due to large antecedent precipitation. Together amplification of these two mechanisms under a warming climate might influence the timing and magnitude of floods, the sediment budget and nutrient cycling in glacierized catchments. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Pump‐and‐Treat Groundwater Remediation Using Chlorine/Ultraviolet Advanced Oxidation Processes          下载免费PDF全文

Andrew K. Boal  Curtis Rhodes  Steve Garcia 《Ground Water Monitoring & Remediation》2015,35(2):93-100

Comparative studies of the use of chlorine/ultraviolet (Cl₂/UV) and hydrogen peroxide/ultraviolet (H₂O₂/UV) Advanced oxidation processes (AOPs) to remove trichloroethylene (TCE) from groundwater in a pump‐and‐treat application were conducted for the first time at the full‐scale operational level at two water treatment facilities in Northern California. In these studies, aqueous chlorine replaced hydrogen peroxide in the AOP treatment step, where the oxidant is exposed to UV light to produce highly reactive radical species that degrade groundwater contaminants. TCE removal rates as a function of initial chlorine dose and pH were then determined. At the site where the natural pH of the water was 7.1, TCE was removed (to a concentration of less than 0.5 µg/L) for nearly every chlorine dose point tested, and pH adjustment slightly enhanced the treatment process at this facility. The second site had a high natural pH of 7.7, and here, TCE was not completely removed for any chlorine dose up to 5.7 mg/L, although TCE removal did increase when the chlorine dose increased between 0.9 and 3.6 mg/L. Residual TCE remaining in the water post‐Cl₂/UV was readily removed using active carbon filtration, which is part of the overall treatment train at this facility. These studies also verified that Cl₂/UV AOP did not interfere with the photolysis of N‐nitrosodimethylamine or result in an effluent acutely toxic toward Ceriodaphnia dubia. Comparative economic analysis revealed that the chemical costs associated with Cl₂/UV AOP were 25 to 50% of the costs associated with in place H₂O₂/UV AOP treatment.  相似文献   

Oil spill modeling in the southeastern Mediterranean Sea in support of accelerated offshore oil and gas exploration     

Steve Brenner 《Ocean Dynamics》2015,65(12):1685-1697

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Climate change projections for the surface ocean around New Zealand     

Cliff S. Law  Graham J. Rickard  Sara E. Mikaloff-Fletcher  Matt H. Pinkerton  Erik Behrens  Steve M. Chiswell 《新西兰海洋与淡水研究杂志》2018,52(3):309-335

The future status of the surface ocean around New Zealand was projected using two Earth System Models and four emission scenarios. By 2100 mean changes are largest under Representative Concentration Pathway 8.5 (RCP8.5), with a +2.5°C increase in sea surface temperature, and decreases in surface mixed layer depth (15%), macronutrients (7.5–20%), primary production (4.5%) and particle flux (12%). Largest macronutrient declines occur in the eastern Chatham Rise and subantarctic waters to the south, whereas dissolved iron increases in subtropical waters. Surface pH projections, validated against subantarctic time-series data, indicate a 0.335 decline to ～7.77 by 2100. However, projected pH is sensitive to future CO₂ emissions, remaining within the current range under RCP2.6, but decreasing below it by 2040 with all other scenarios. Sub-regions vulnerable to climate change include the Chatham Rise, polar waters south of 50°S, and subtropical waters north of New Zealand, whereas the central Tasman Sea is least affected.  相似文献   

Evaluating Uncertainties in Coronal Electron Temperature and Radial Speed Measurements Using a Simulation of the Bastille Day Eruption     

Nelson Reginald  Orville St. Cyr  Joseph Davila  Lutz Rastaetter  Tibor Török 《Solar physics》2018,293(5):82

Obtaining reliable measurements of plasma parameters in the Sun’s corona remains an important challenge for solar physics. We previously presented a method for producing maps of electron temperature and speed of the solar corona using K-corona brightness measurements made through four color filters in visible light, which were tested for their accuracies using models of a structured, yet steady corona. In this article we test the same technique using a coronal model of the Bastille Day (14 July 2000) coronal mass ejection, which also contains quiet areas and streamers. We use the coronal electron density, temperature, and flow speed contained in the model to determine two K-coronal brightness ratios at (410.3, 390.0 nm) and (423.3, 398.7 nm) along more than 4000 lines of sight. Now assuming that for real observations, the only information we have for each line of sight are these two K-coronal brightness ratios, we use a spherically symmetric model of the corona that contains no structures to interpret these two ratios for electron temperature and speed. We then compare the interpreted (or measured) values for each line of sight with the true values from the model at the plane of the sky for that same line of sight to determine the magnitude of the errors. We show that the measured values closely match the true values in quiet areas. However, in locations of coronal structures, the measured values are predictably underestimated or overestimated compared to the true values, but can nevertheless be used to determine the positions of the structures with respect to the plane of the sky, in front or behind. Based on our results, we propose that future white-light coronagraphs be equipped to image the corona using four color filters in order to routinely create coronal maps of electron density, temperature, and flow speed.  相似文献   

印度板块俯冲到藏南之下的深反射证据   总被引：11，自引：1，他引：11  

赵文津  K·D·纳尔 《地球学报》1996,17(2):131-137

喜马拉雅和相邻的西藏高原，构成了地球上最大的高原和异常厚地壳的地区，是作为印度板块和亚洲板块新生代碰撞的结果，并被认作是典型的陆－陆碰撞［１．２．３．］地带。在此，我们报道了用深地震反射剖面方法进行本区地壳成像的第一个结果，试验的１００ｋｍ长剖面，布置在特提斯喜马拉雅（ＴｅｔｈｙａｎＨｉｍａｌａｙａ）最南端，且跨过了喜马拉雅山脊，接近高喜马拉雅（ＨｉｇｈＨｉｍａｌａｙａ）地带，剖面显示了在地壳中部有一强反射带。它可能代表了一个活动的道冲断裂，印度板块是沿此断裂俯冲到藏南之下；上地壳反射使人们联想到上地壳存在着大规模的叠瓦状结构；莫霍反射来自本区双倍正常地壳厚度的巨厚地壳的底部。这些结果对西藏南端地壳增厚，是由于印度大陆地壳整体俯冲到包括特提斯喜马拉雅地区地壳之下的观点，给予了实质性的支持。  相似文献   

Changes in water quality following tidal inundation of coastal lowland acid sulfate soil landscapes     

Scott G. Johnston  Richard T. Bush  Leigh A. Sullivan  Edward D. Burton  Douglas Smith  Michelle A. Martens  Angus E. McElnea  Col R. Ahern  Bernard Powell  Luisa P. Stephens  Steve T. Wilbraham  Simon van Heel 《Estuarine, Coastal and Shelf Science》2009

This study examines the remediation of surface water quality in a severely degraded coastal acid sulfate soil landscape. The remediation strategy consisted of partial restoration of marine tidal exchange within estuarine creeks and incremental tidal inundation of acidified soils, plus strategic liming of drainage waters. Time-series water quality and climatic data collected over 5 years were analysed to assess changes in water quality due to this remediation strategy. A time-weighted rainfall function (TWR) was generated from daily rainfall data to integrate the effects of antecedent rainfall on shallow groundwater levels in a way that was relevant to acid export dynamics. Significant increases in mean pH were evident over time at multiple monitoring sites. Regression analysis at multiple sites revealed a temporal progression of change in significant relationships between mean daily electrical conductivity (EC) vs. mean daily pH, and TWR vs. mean daily pH. These data demonstrate a substantial decrease over time in the magnitude of creek acidification per given quantity of antecedent rainfall. Data also show considerable increase in soil pH (2–3 units) in formerly acidified areas subject to tidal inundation. This coincides with a decrease in soil pe, indicating stronger reducing conditions. These observations suggest a fundamental shift has occurred in sediment geochemistry in favour of proton-consuming reductive processes. Combined, these data highlight the potential effectiveness of marine tidal inundation as a landscape-scale acid sulfate soil remediation strategy.  相似文献   

A tool to navigate overlaps in fragmented ocean governance     

Julia A. Ekstrom  Oran R. Young  Steve D. Gaines  Maria Gordon  Bonnie J. McCay 《Marine Policy》2009

Implementation of marine ecosystem-based management requires improved understanding of existing governance, including gaps and overlaps resulting from fragmented management. Focusing on overlaps, this paper presents a technique using text analysis to assist in the identification of agencies and laws involved in overlaps from a system perspective. The overlaps analysis uses term frequency counts on ocean laws and regulations in conjunction with relevant agency authority. Such information delivered in a transparent user-friendly presentation can help policymakers and other constituents of ecosystem-based management to find existing overlaps as a step to facilitate improved coordination.  相似文献