Fractionation of trace metals (Mn,Zn, Cu,Pb) in Red Sea sediments,Gulf of Aden,Yemen

A sequential extraction technique was applied to estimate the chemical association of Mn, Zn, Cu and Pb in five chemical phases (exchangeable, carbonate, Fe–Mn oxides, organic matter and residual) in sediments of the Gulf of Aden, Yemen. The results indicated that a higher level of Mn was associated with the residual fraction (natural sources) than the non-residual fraction (anthropogenic sources). Zn fractionations revealed that it was associated more with Fe–Mn oxides and organic fractions than exchangeable and carbonate fractions. Most of the Cu was present in the residual form (60–72%) except for in the main port area (zone III), where it was associated with the organic phase (77% of the total Cu content, the organic matter content was 5%). Similarly, most Pb was bound in the residual fraction (56–71%) except the main port area where ～ 62% of the total Pb was bound in non-residual fractions. It was also found that the Pb concentration in the exchangeable fraction was very high compared with other metals. The risk assessment code for the metals showed a low risk for Zn and Cu, but low to medium risk for Mn. Fractionation of Pb showed medium risk at most of the regions except at the eastern area, which revealed a high risk for the aquatic environment.     

Experimental degradation of oil in permeable sand from the Gulf of Aqaba,Red Sea

Degradation rates of light and heavy oil in permeable carbonate sands from the Gulf of Aqaba were investigated to evaluate the ability of sediments to degrade oil compounds. Silicate sands that are less permeable and different properties from carbonate sands were used for comparison. Estimates of oil degradation rates were based on oxygen consumption rates, calculated by incubating natural carbonate sands with oil. The degradation rates of light oil were twofold higher than those of heavy oil, which may be attributed to the presence of a higher carbon number in heavy oil compared with light oil. Degradation rates of light oil in carbonate sands were twofold higher than in silicate sands. Oil degradation rates calculated using the bottle incubation technique were three- to fourfold higher than rates from chamber incubations, indicating the importance of adequate mixing between oil particles and sediments during degradation processes. This study suggests that permeable sands, through their chemical and physical properties, increase oil biodegradation rates by enhancing flow through sediment particles and positively impacting bioturbation processes.     

北部湾沿海地区植被覆盖对气温和降水的旬响应特征

论文分析北部湾沿海地区植被覆盖对气候变化的响应,为该区域植被恢复和植被生产力研究提供依据.基于研究区2000--2011年423景SPOT-VEGETATION逐旬NDVI数据及逐日气温和降水数据,利用像元二分模型,相关分析,偏相关分析和时滞偏相关分析等数理统计方法,对研究区植被覆盖时空变化特征及与旬降水和旬均温的相关性及滞后性进行分析.结果表明:1)近12 a来,北部湾沿海地区植被覆盖度平均值呈增长趋势,由2000年的65.23%增加到2011年的72.02%,增加了6.79%;2)研究区植被生长季旬NDVI均值介于0.21~0.67之间,在不同时期变化是不同的,其值呈现出"降低--增长--降低"3种变化过程;3)各种植被类型与温度具有显著的相关关系,全部通过了0.01的显著性水平,且NDVI与温度的显著性水平高于NDVI与降水的显著性水平,说明北部湾沿海地区植被覆盖NDVI对气象因子中的温度更为敏感;4)NDVI与气温的时滞偏相关系数显著高于NDVI与降水的时滞偏相关系数,旬NDVI与旬降水的滞后时间多集中于6~9旬之间,而旬NDVI与旬气温的滞后时间多以0~5旬为主;5)不同类型植被的生长对气温和降水的响应时间不一致,但与水热条件时滞偏相关系数越高的植被类型响应时间越短.上述研究结果表明,近12 a来北部湾沿海地区植被处于恢复状态,且植被对降水和气温具有明显的阈值和滞后性.     

Effects of brine injection wells, dry holes, and plugged oil/gas wells on chloride, bromide, and barium concentrations in the Gulf Coast Aquifer, southeast Texas, USA

Data from 1,122 brine injection wells, 24,515 dry holes, 20,877 plugged oil/gas wells, and 256 water wells were mapped with a geographic information system (GIS) and statistically analyzed. There were 9, 107, and 58 water wells within 750 m of a brine injection well, dry hole, or plugged oil/gas well, respectively. Computed median concentrations were 157 mg/l for chloride, 0.8 mg/l for bromide, and 169 microg/l for barium. The maximum chloride concentration was 2,384 mg/l, close to 10 times the secondary drinking water standard. Shallow water wells and water wells near plugged oil/gas wells had significantly higher chloride and bromide levels.     

VARIABILITY IN ADJUSTMENT PREFERENCES TO GROUNDWATER DEPLETION IN THE AMERICAN HIGH PLAINS1

ABSTRACT: This paper explores the adjustments and institutions that residents of the American High Plains prefer in coping with the depletion of the High Plains (Ogallaia) aquifer. The authors identify 48 possible adjustments and report on public preferences for them as determined from a mail survey of 956 respondents in 14 counties. For purposes of analysis, the adjustments are categorized into five groups: user practices, management policies, financial incentives and disincentives, technological fixes, and other. Preferences were also determined among five levels of government to enforce each of the adjustments. Adjustments associated with user conservation practices were generally most preferred while financial incentives and disincentives were least favored. Local groundwater management agencies were the most favored level of institution to administer conservation adjustments followed by the state, county, and federal levels. The most preferred option for 20 adjustments was that no agency should be involved. Respondents in agriculturally related occupations showed less support for water conservation laws and gave greater acceptance to the continuance of existing methods. Irrigators viewed the increasing cost of lifting water as a more serious problem than the depletion of groundwater.     

MONITORING AND CONTROL OF CENTER PIVOT SYSTEMS WITH MICROCOMPUTERS1

A computerized water-energy-management system (WEMS) can be used by center pivot operators to reduce pumping fuel costs and monitoring expenses. Irrigation costs are lowered primarily because the system used climatic data and plant growth models to derive water schedules that considerably lowers the use of water compared with conventional irrigation practices. A capital budget analysis of a hypothetical, but representative farm growing corn, shows that cost savings are from three sources: 61 percent from pumping less water, 28 percent from labor savings, and 11 percent from savings on truck fuel, maintenance, and oiL The analysis illustrates that only a 4 percent water savings from irrigation scheduling over a 10-year period is required for the investment to be profitable for many central High Plains’ irrigators. The water savings required are relatively small compared with the potentials shown by irrigation scheduling research. WEMS is cost effective and can extend the life of the ground water source.     

渤海湾风暴潮灾害及对策

较详细地分析了天津、河北沿海地区风暴潮时空分布规律、灾情、产生的原因, 指出近年来本区风暴潮发生频率和强度有明显增加的趋势, 而且造成的经济损失增长更快。在过去４０ ａ中, 每过１０ ａ 灾损约增加１０ 倍。并提出了防潮减灾对策     

Cadmium bioaccumulation in three benthic fish species, Salaria basilisca,Zosterisessor ophiocephalus and Solea vulgaris collected from the Guff of Gabes in Tunisia

To select a marine teleost fish which can be used as a bioindicator of cadmium (Cd) pollution in the Gulf of Gabes in Tunisia, Cd concentrations in liver and gill were compared in three benthic fish species including Salaria basilisca, Zosterisessor ophiocephalus and Solea vulgaris. Fish samples were collected from three selected sites in the Gulf of Gabes, with different degrees of Cd contamination: the industrialized coast of Sfax (S1), the coast of Douar Chart (S2) and the coast of Luza ($3). The results shows that Cd concentrations in both sediment and water collected from S1 were significantly higher (p<0.0001) than those from S2 and $3. For each species, Cd concentrations, in both liver and gill, showed the decreasing order: S1>S2>S3. The highest concentration of Cd was detected in the liver of S. basilisca, and only S. basilisca showed bioaccumulation factors (BAF) greater than 1 in all studied sites. In S1 and S2, BAF values respect the following order: S. basilisca>Z. ophiocephalus>S. vulgaris. These results of significant bioaccumulation of Cd, in terms of hepatic concentrations and bioaccamulation factors, indicated that S. basilisca can be used as bioindicator to evaluate the evolution of Cd pollution in the Gulf of Gahes.     

福建深沪湾旅游资源评价及SWOT分析

在综合考察福建深沪湾地区旅游资源的基础上,对其进行了系统分类和评价,同时引入现代营销学中常用的SWOT分析法对福建深沪湾旅游资源的开发建设条件进行了系统分析,从而为该旅游资源的开发利用和申报国家地质公园提供战略性的决策支持.     

Batch-test study on the dechlorination of 1,1,1-trichloroethane in contaminated aquifer material by zero-valent iron

Chlorinated aliphatic hydrocarbons are common groundwater contaminants. One possible remediation option is in-situ reductive dechlorination by zero-valent iron, either by direct injection or as reactive barriers. Chlorinated ethenes (tetrachloroethene: PCE; trichloroethene: TCE) have received extensive attention in this context. However, another common groundwater pollutant, 1,1,1-trichlorethane (TCA), has attracted much less attention. We studied TCA reduction by three types of granular zero-valent irons in a series of batch experiments using polluted groundwater, with and without added aquifer material. Two types of iron were able to reduce TCA completely with no daughter product concentration increases (1,1-dichloroethane: DCA; chloroethane: CA). One type of iron showed slower reduction, with intermediate rise of DCA and CA concentrations. When evaluating the formation of daughter products, the tests on the groundwater alone showed different results than the groundwater plus aquifer batches: DCA did not temporarily accumulate in the batches with added aquifer material, contrary to the batches without added aquifer material. 1,1-dichloroethene (DCE, also present in the groundwater as an abiotic degradation product of TCA) was also reduced slower in the batches without added aquifer material than in the batches with aquifer material. Redox potentials gradually decreased to low values in batches with aquifer material without iron, while the batches with groundwater alone maintained a constant higher redox potential. Either adsorption processes or microbiological activity in the samples could explain these phenomena. Polymerase Chain Reaction (PCR: a targeted gene probe technique) for chlorinated aliphatic compound (CAH)-degrading bacteria confirmed the presence of Dehalococcoides sp. (chloroethene-degraders) but was negative for Desulfobacterium autotrophicum (a known co-metabolic TCA degrader). DCA reduction was rate determining: first-order half-lives of 300-350 h were observed. TCA was fully removed within hours. CA is resistant to reduction by zero-valent iron but it is known to hydrolyze easily. Since CA did not accumulate in our batches, it may have disappeared by the latter mechanism or it may not have formed as a major daughter product.