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1.
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   
2.
【目的】针对跑道池光生物反应器光照比表面积小、产率低、耗水量大等问题,设计一种新型薄层自流式光生物反应器。【方法】使用Solidworks软件进行三维建模设计,建立该新型反应器的微藻培养系统,并与跑道池光生物反应器进行微藻培养中试对比评价试验;建造一套薄层自流式反应器的微藻大规模培养系统,并以同株栅藻(Scenedesmus sp.)为培养藻种,进行4批次的培养试验,评价该反应器的微藻培养效果。【结果】所设计薄层自流式反应器光径减小,光照比表面积,藻液混合程度提高;中试试验结果表明,薄层自流式反应器中栅藻的生长速率明显高于同期跑道池光生物反应器,生物质浓度显著高于跑道池反应器,单位面积产率(每天单位占地面积的产量)升高13%,薄层式反应器的耗水量约低于跑道池反应器6倍。大规模培养试验表明,薄层自流式反应器的微藻生物质产率明显高于跑道池反应器,微藻生物质产率单日高达0.86 g·L-1·d-1,占地面积产率达43.5 g·m-2·d-1,最终生物质浓度达2.31 g·L-1,远高于跑道池光生物反应器最高生物质质量浓度(约0.01~0.6 g·L-1)。【结论】薄层自流式光生物反应器一定程度上克服了跑道池光生物反应器的缺点,收获微藻的生物质产率和浓度高。  相似文献   
3.
Partitioning beta diversity into its two components of spatial turnover and nestedness is a more robust method for checking spatial variability in biological communities than calculating the total beta diversity alone. The relative contribution of spatial turnover and nestedness has been used to test the effects of climatic, environmental, spatial and temporal variables on community composition. In this study, we tested the effects of environmental factors and microhabitat features on total beta diversity and its spatial turnover and nestedness components using a comprehensive dataset of aquatic Heteroptera collected from four types of permanent freshwater habitats (i.e. streams, ponds, rock tanks and reservoirs) in the Western Ghats of India. We observed that communities in all four types of habitats were predominantly shaped by dissimilarity caused due to spatial turnover (>85 %). Each type of habitat showed the presence of one or more species uniquely associated with it, which might contribute to the turnover between communities. The abiotic environment (climatic factors, topological factors, soil characteristics and microhabitat features) as well as assemblage structure differed significantly between habitat types. Communities in each type of habitat were affected by different environmental factors, such as precipitation and temperature patterns for streams, altitude and rocky substrate for rock tanks, and soil characteristics and the presence of aquatic macrophytes for ponds and reservoirs. Assemblages observed in the four types of permanent habitats are thus compositionally distinct due to species replacements between local communities, which in turn are strongly influenced by environmental variables. Similar to previous studies, our results show that spatial turnover largely measures the same phenomenon as total beta diversity on a regional scale.  相似文献   
4.
ABSTRACT

Environmental sustainability and the long-term wellbeing of Māori (the indigenous people of New Zealand) are interdependent and degradation of landscapes risks the progressive degradation of Māori wellbeing. The present study developed an analysis framework based on Ki Uta Ki Tai (holistic-mountains to the sea- management philosophy advocated by Ngāi Tahu) for exploring relationships between landcover and Māori values to enable predictions of cultural values through space and time. We used this framework to predict how two Māori values (Overall Health and Cultural Land Use) have been altered as a result of landcover change between 2001–2012 in three Canterbury catchments. The area of native vegetation declined while exotic pasture increased between 2001–2012, and there were corresponding declines in both cultural health scores. These results suggest that the change in landcover has reduced the ability of the landscape to support Māori values. This framework for assessing changes in Māori values with respect to changing environmental conditions may identify opportunities for Māori to better engage in land use management decisions.  相似文献   
5.
The formation of subsurface freshwater lenses on top of brackish groundwater is a fascinating hydrologic phenomenon that creates groundwater supplies of great potential value in arid regions. Information on the recharge quantity and mechanism of these lenses is both scarce and uncertain. This study examines the formation and macroscale stability of the Rawdatain freshwater lens in Kuwait, for which significant pre-development data are available. The Rawdatain is a large (150 million m3) subsurface freshwater lens overlying brackish groundwater compared to the other freshwater lenses in the Arabian Peninsula. In this study, a three-dimensional (3D) density-dependent groundwater flow model is tested against the following data targets to estimate long-term diffuse and focused groundwater recharge: (i) groundwater head, (ii) total dissolved solids (TDS) groundwater concentration, (iii) volume and vertical thickness of stored groundwater of three different water quality TDS ranges (0–700, 700–1000 and 1000–2000 mg/L) and (iv) geometrical shape features of the lens along cross-sections. To better represent the spatial variation in TDS, six different recharge zones were assigned to allocate diffuse and focused recharge conditions. Twelve recharge rate scenarios, encompassing a wide range of feasible long-term average annual recharge values (200,000–5,000,000 m3/year), were tested against the multiple targets and compared with the groundwater age of the Rawdatain lens. Based on comparison with data targets, the long-term average annual recharge is estimated to be 500,000 m3/year. Scenarios of reduced recharge, which may occur due to changes in land-use or climate, demonstrate the extremely slow response of the lens, which is in agreement with the slow development and formation of the lens (>2,000 years). Within a 100-year time frame, a 50% reduction in annual recharge reduces the lens volumes by 21, 17 and 9% for the three water quality categories, respectively. This study demonstrates the stability of freshwater lenses in arid regions and also provides methodology for similar focused rainfall recharge freshwater lenses.  相似文献   
6.
土地质量地球化学调查计划是我国继区域化探全国扫面计划之后一个新的国家地球化学填图计划,该计划实施20年来,在支撑土壤环境污染防控、土地资源管理、国家重大立法、精准扶贫等方面做出了重大贡献,显著拓展了地质工作服务链。本文从计划的提出背景、项目的组织实施、主要进展、调查技术的进步和分析测试技术的提高与质量控制方案的完善等方面回顾了该计划的发展历程。从全国耕地地球化学状况、全国省会城市土壤环境质量状况、中国主要淡水湖泊沉积物环境质量状况、中国主要农耕区20年来土壤碳库变化4个方面对调查成果做了全面总结。全方位介绍了调查应用成果在土地管理、土壤污染防治、农业种植结构调整、脱贫攻坚、地方病防治、油气勘查、固体矿产勘查等7个领域中的应用。并在调查技术革新、评价方法创新和调查与研究融合三个方面对土地质量地球化学调查工作的未来发展趋势做了展望。  相似文献   
7.
舟山北部海域海底第四系淡水资源赋存潜力   总被引:1,自引:1,他引:0  
为了解东海舟山北部海域海底第四系淡水资源赋存情况,本文在系统分析舟山北部海域地质钻孔和单道地震资料基础上,分析了研究海域海底第四纪地层结构与沉积环境,阐述了研究海域海底松散沉积物分布规律,探讨了上海陆地地区早更新世中、晚期和早期古河道在研究海域的延伸和分布状况,分析了研究海域海底第四系含水层赋存状况。研究海域第四系可供开发利用的主要含水层为早更新世中、晚期的第四承压含水层(Ⅳ)和早更新世早期的第五承压含水层(Ⅴ);第四承压含水层古河道分布区富水性最佳,含水层顶部发育厚层黏性土隔水层区域赋存淡水资源的可能性很大,含水层开发利用潜力可分为开发前景良好A区、开发前景较好B区和开发前景一般C区3类;第五承压含水层在古河道分布区富水性强,具有很好的淡水赋存潜力和良好的开发利用前景。  相似文献   
8.
Subsurface dams are rather effective and used for the prevention of saltwater intrusion in coastal regions around the world. We carried out the laboratory experiments to investigate the elevation of saltwater wedge after the construction of subsurface dams. The elevation of saltwater wedge refers to the upward movement of the downstream saltwater wedge because the subsurface dams obstruct the regional groundwater flow and reduce the freshwater discharge. Consequently, the saltwater wedge cannot further extend in the longitudinal direction but rises in the vertical profile resulting in significant downstream aquifer salinization. In order to quantitatively address this issue, field-scale numerical simulations were conducted to explore the influence of various dam heights, distances, and hydraulic gradients on the elevation of saltwater wedge. Our investigation shows that the upward movement of the saltwater wedge and its areal extension in the vertical domain of the downstream aquifer become more severe with a higher dam and performed a great dependence on the freshwater discharge. Furthermore, the increase of the hydraulic gradient and the dam distance from the sea boundary leads to a more pronounced wedge elevation. This phenomenon comes from the variation of the freshwater discharge due to the modification of dam height, location, and hydraulic gradient. Large freshwater discharge can generate greater repulsive force to restrain the elevation of saltwater wedge. These conclusions provide theoretical references for the behaviour of the freshwater–seawater interface after the construction of subsurface dams and help optimize the design strategy to better utilize the coastal groundwater resources.  相似文献   
9.
Freshwater flux (FWF) directly affects sea surface salinity (SSS) and hence modulates sea surface temperature (SST) in the tropical Pacific. This paper quantifies a positive correlation between FWF and SST using observations and simulations of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) to analyze the interannual variability in the tropical Pacific. Comparisons among the displacements of FWF, SSS and SST interannual variabilities illustrate that a large FWF variability is located in the west-central equatorial Pacific, covarying with a large SSS variability, whereas a large SST variability is located in the eastern equatorial Pacific. Most CMIP5 models can reproduce the fact that FWF leads to positive feedback to SST through an SSS anomaly as observed. However, the difference in each model's performance results from different simulation capabilities of the CMIP5 models in the magnitudes and positions of the interannual variabilities, including the mixed layer depth and the buoyancy flux in the equatorial Pacific. SSS anomalies simulated from the CMIP5 multi-model are sensitive to FWF interannual anomalies, which can lead to differences in feedback to interannual SST variabilities. The relationships among the FWF, SSS and SST interannual variabilities can be derived using linear quantitative measures from observations and the CMIP5 multi-model simulations. A 1 mm d-1 FWF anomaly corresponds to an SSS anomaly of nearly 0.12 psu in the western tropical Pacific and a 0.11°C SST anomaly in the eastern tropical Pacific.  相似文献   
10.
本文采用多源卫星遥感数据通过统计分析的方法研究了17年间(2000—2016年)南海夏季(6—9月)台风对该海域降水、淡水通量的贡献及其可能导致的环流异常。主要结论如下: 1) 台风是南海中北部降水的重要影响因子, 可导致日平均降水量增加12mm, 约占南海夏季日平均降水(25mm·d -1)的一半, 且西北太平洋台风和南海“土台风”产生的降水分布存在显著的区域和强度差异; 2) 夏季, 南海由淡水通量引起的盐致环流表现为以海南岛东南部海域为中心的弱气旋式, 其流量量级约为-0.15Sv, 约占同期风生环流流量(约为-1.5Sv)的10%; 3) 夏季, 台风带来的降水使得南海中北部的气旋式盐致环流增强, 且西北太平洋台风降水导致的淡水通量变化引起的盐致环流强度要强于南海“土台风”。  相似文献   
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