Spatial analysis of water quality and its suitability in farming giant freshwater prawn (Macrobrachium rosenbergii) in Negeri Sembilan region,Peninsular Malaysia     

Benjamin Ezekiel Bwadi  Firuza Begham Mustafa  Mohammad Lokman Ali  Subha Bhassu 《Singapore journal of tropical geography》2019,40(1):71-91

Finding potential sites for resilient prawn production in the tropical environment that also prevents wastage of natural resources is not an easy task. The purpose of this study is to evaluate water quality suitability for prawn farming in Negeri Sembilan of Peninsular Malaysia based on Geographic Information System (GIS). To achieve this goal, numerous criteria including sources of water, water temperature, water pH, sources of pollution, salinity, soil texture and availability of phytoplankton criteria were considered for the modelling process. Analytic Hierarchy Process (AHP) technique was performed to standardize the criteria and the weighting process. The weighted overlay of indicators and results were accomplished by applying the Multi‐Criteria Decision Analysis (MCDA) method in GIS. It was indicated that the Negeri Sembilan area has potential for prawn farming. The results showed that about 25 per cent (163 056.93 ha) of the area was most suitable for prawn farming, about 58 per cent (384 656.88 ha) was considered moderately suitable, while 18 per cent (117 633.49 ha) was regarded as least suitable. The study concluded that the multi‐criteria decision analysis of water quality for prawn farming is vital for regional economic planning in the Negeri Sembilan area and also significant when establishing a model for aquaculture development.  相似文献   

近岸海域大型水母来源与迁移路径分析——以红沿河电厂海域为例     

孙雪  魏皓  张海彦  王彦涛  张广跃  刘汉霖 《海洋与湖沼》2019,50(6):1281-1291

近岸海域水母暴发可导致滨海火/核电厂取水口堵塞,对电厂安全运行造成潜在威胁。寻找水母源地及其迁移路径是水母治理的基础。本文基于拉格朗日质点追踪方法(LTRANS)建立反向追踪模型,并结合水母生态学特性对2015年6—9月聚集在红沿河电厂海域的大型水母进行溯源,获得水母源地及迁移路径,可以为螅状体栖息地寻找和水母拦截打捞提供依据,对近岸海域水母灾害防治具有重要指导意义。溯源结果表明:(1)红沿河电厂及其邻近海域的水母可能来自多个不同源区,辽东湾西部、北部及电厂南北两侧等海域的水母均有可能迁移至电厂附近;(2)受水温和环流影响,6—9月期间到达电厂附近的水母主要源区及迁移路径不同,早期出现在电厂海域的水母很可能是局地产生的,而7—9月持续的高风险水母灾害则主要取决于渤海不同源区水母的物理聚集;(3)根据水母的主要迁移路径,建议在电厂取水口约15km的海域设置一条封闭监测断面,对水母进行实时监测;在距离取水口约30km的外侧海域设置一条调查断面,于7月初至8月中旬,每5天进行一次定点拖网调查。此外,在距离电厂取水口15—20km的西南方向上,对水母进行拦截打捞可大大降低水母入侵风险。  相似文献   

西藏知不拉和浪母家果矽卡岩铜矿地质特征及驱龙-知不拉-浪母家果成矿系统的确定   总被引：1，自引：0，他引：1  

王登芳 《地质与勘探》2015,51(4):619-633

西藏驱龙巨型斑岩铜钼矿床周围产出有知不拉与浪母家果矽卡岩铜矿。通过揭示知不拉和浪母家果的地质特征、成矿侵入体的地球化学特征和硫同位素特征,结合前人的年代学资料,确立两者与驱龙斑岩铜矿共同构成斑岩-矽卡岩成矿系统。结果显示知不拉与浪母家果矽卡岩矿床中的侵入岩地球化学特征与驱龙矿区的侵入岩地球化学特征相似,属于准铝质、钙碱性-高钾钙碱性岩石;稀土元素表现为强烈的LREE和HREE的分异,除知不拉的细晶岩有很强的Eu负异常,其他具有很弱的Eu负异常;明显富集大离子亲石元素(LILE)和高场强元素(HFSE),K、Pb的正异常,Ta、Nb、Ti的负异常。知不拉硫化物硫同位素与驱龙斑岩铜钼矿的硫同位素相比有明显的差异,这样的差异可能是由于成矿热液氧逸度的变化和晚期高δ34S值的天水加入造成的。研究确立驱龙-知不拉-浪母家果斑岩-矽卡岩成矿系统,主要基于:时代相近,空间毗邻;驱龙斑岩铜矿花岗闪长岩接触带发育有明显矽卡岩矿化;与矿化有关的侵入岩地球化学特征相似性;成矿物质演化趋势相似;矽卡岩连续演化的物理化学条件。而钙质围岩、多期次侵位且侵位较浅的岩浆与区域内构造活动及矿区内断裂、裂隙发育,共同决定了斑岩-矽卡岩系统的产出。  相似文献   

Caribbean hydrological variability during the Holocene as reconstructed from crater lakes on the island of Grenada     

Sherilyn C. Fritz  Svante Björck  Catherine A. Rigsby  Paul A. Baker  Amy Calder‐Church  Daniel J. Conley 《第四纪科学杂志》2011,26(8):829-838

Contemporary precipitation patterns in the Caribbean region are spatially variable, and the small number of Holocene paleoclimatic records may not adequately capture patterns of variation in the past. The hydrological history of Grenada was inferred from paleolimnological analyses of sediment cores from two crater lakes on the island. The basins were formed by volcanic activity some time during the Last Termination, but were dry between ca. 13 000 and ca. 7200 cal. a BP. After filling, the lakes were initially very shallow, and sedimentation was interrupted by a hiatus ca. 6300–5500 cal. a BP, followed by deposition of a thick tephra in both sites. After 5500 cal. a BP, lake level shows considerable multi‐centennial variability, superimposed upon a long‐term trend of generally higher lake level after 3200 cal. a BP. The pattern of lake‐level variation in Grenada shows some similarity with other Caribbean paleoclimatic records in terms of the timing of transitions, but differs from several classic studies in the sign of inferred precipitation change. The differences among records may reflect spatially variable precipitation patterns in the past in response to the position of the Intertropical Convergence Zone and to sea surface temperature influences on the trade winds and Caribbean low‐level jet. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Multi‐proxy study of Holocene environmental change and human activity in the Central Apennine Mountains,Italy     

A. G. Brown  J. Hatton  K. A. Selby  M. J. Leng  N. Christie 《第四纪科学杂志》2013,28(1):71-82

This paper describes a multi‐proxy palaeoecological investigation undertaken in conjunction with an archaeological survey of the Upper Sangro Valley in the Abruzzo National Park, Central Italy. Despite being a biodiversity hotspot and regarded as a near‐pristine area, the pollen, spore and diatom data all show major changes in the vegetation extending to over 2000 m a.s.l. during the mid to late Holocene. Although there are changes in ecological composition earlier in the Holocene they are different in type and magnitude from the changes which began about 800 cal a BC. The pollen and diatom evidence do not correlate well with regional palaeoclimate data, or on‐site isotopic evidence, but do appear to be related to Samnite (later Iron Age) clearance and upland grazing associated with transhumance and later annexation (and centuriation) of the lower slopes by Roman surveyors. The greatest change in vegetation was during the period c. AD 500–600 and corresponds with the Byzantine–Gothic Wars, and Lombard–Carolingian settlement reorganization into nucleated hilltop settlements which managed upland grazing. This pattern of intensive land use at all altitudes persisted until the early 20th century and only changed following rural depopulation after World War II. These data illustrate how cultural factors had a profound effect on this mountainous region which, in this case, far outweighed the effects of climatic fluctuations which are known to have occurred from both this study area and the region. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

南海晚第四纪硅藻遗体及其地质意义Ⅵ.硅藻的2个新种和7个新记录     

程兆第  蓝东兆 《台湾海峡》1995,14(1):40-43

本文记述了南海晚第四纪沉积物中发现的两个新种[线形辐环藻（Actinocyclus lineatus Liu,Cheng et Lan sp.nov.）、星圆筛藻（Coscinodiscus aster-aeus Cheng,Liu et Lan sp.nov.）]以及在我国首次记录的圆筛藻的7个种。  相似文献   

Multi-proxy evidence of long-term changes in ecosystem structure in a Danish marine estuary, linked to increased nutrient loading   总被引：3，自引：0，他引：3  

Marianne Ellegaard  Annemarie L. Clarke  Nina Reuss  Simon Drew  Kaarina Weckstrm  Stephen Juggins  N. John Anderson  Daniel J. Conley 《Estuarine, Coastal and Shelf Science》2006,68(3-4):567

This paper presents a study of changes in eutrophication over the past 100 years in a fertile estuary. The Danish estuary Mariager Fjord is a long, narrow sill-fjord with a permanently anoxic basin. In 1997 anoxia spread from the basin to the entire inner estuary, killing almost all eukaryotes and prompting debate on the causes. This paper reports a multi-proxy survey of ²¹⁰Pb-dated sediment cores from the anoxic basin. Analyses of diatoms, dinoflagellates, pigments and geochemical proxies were used to determine changes in ecosystem structure over the past 100 years. The aim was to establish ‘base-line conditions’, for management purposes, of the biological structure prior to 1900, and to examine possible causes of changes observed. Geochemical proxies total nitrogen (TN), total carbon (TC) and biogenic silica (BSi) were consistently high throughout the sediment record. Increased concentrations of pigments and natural isotopes (δ¹³C, δ¹⁵N) suggested increasing production and nutrient loading. The main changes in the biological proxies occurred between 1915 and the 1940s, and indicated that the estuary has been somewhat eutrophic since 1900, but that the eutrophication process increased over the past 100 years. A reconstruction of TN concentration by a diatom-based transfer function supports this interpretation, with inferred TN ca. 1900 around 60 μmol l⁻¹, and an increase in TN concentration over the past century to ca. 130 μmol l⁻¹ by 1995. Inferred TN decreased to ca. 100 μmol l⁻¹ by 2001, similar to present day monitoring data.  相似文献   

Laboratory Culture and Preliminary Characterization of the Nitrogen-Fixing Rhizosolenia-Richelia Symbiosis     

Tracy A.  Villareal 《Marine Ecology》1990,11(2):117-132

Abstract. The oceanic diatom Rhizosolenia clevei and its cyanobactcrial symbiont Richelia intracel-luluris were isolated into laboratory culture and their biology and growth dynamics examined. Nitrogen-fixation by the symbiont could sustain the symbiosis. Growth and nitrogenase activity demonstrated light saturation kinetics, with no photoinhibition up to 315 μE m^-1 s^-1 for growth and 780μE m^-1 s^-1 for nitrogen fixation. The symbiosis is not obligate for Rhizosolenia , which is capable of growth independent of the symbiont if a nitrogen source is available. The symbiont is contained in the pcriplasmic space between the Rhizosolenia plasmalcmma and frustulc, and preliminary evidence suggests excretion of fixed nitrogen into the medium may be occurring.  相似文献   

An Annotated Check-List of Planktonic Diatoms from the Gulf of Naples     

D. Marino  M. Modigh 《Marine Ecology》1981,2(4):317-333

Abstract. New data on the planktonic diatoms from the Gulf of Naples are presented together with those from the literature. Information is given on abundances, seasonal cycles and distributions of 183 taxa, including species, varieties and forms.  相似文献   

南海东北部末次冰期以来的沉积环境演变   总被引：1，自引：0，他引：1  

黄元辉  蓝东兆 《海洋地质与第四纪地质》2005,25(4):9-14

利用南海东北部上陆坡处所取的D孔柱样进行硅藻分析,结合粒度与碎屑矿物分析结果,探讨该海域末次冰期以来沉积环境演变过程.结果表明：粒度与硅藻分析结果较为吻合,共同显示D孔柱样可分为上下两层.上表层（0～2 cm）的砂质沉积层为冰后期海进过程改造的晚更新世残留沉积层,即变余沉积;下层（2～130 cm）主要是末次冰期形成的浅海沉积.整个柱样可反映出海洋同位素MIS 4期海退至MIS 3期海进与MIS 2期海退至冰后期海进的沉积变化韵律.  相似文献