Porosity and permeability in sediment mixtures

Porosity in sediments that contain a mix of coarser- and finer-grained components varies as a function of the porosity and volume fraction of each component. We considered sediment mixtures representing poorly sorted sands and gravely sands. We expanded an existing fractional-packing model for porosity to represent mixtures in which finer grains approach the size of the pores that would exist among the coarser grains alone. The model well represents the porosity measured in laboratory experiments in which grain sizes and volume fractions were systematically changed within sediment mixtures. Permeability values were determined for these sediment mixtures using a model based on grain-size statistics and the expanded fractional-packing porosity model. The permeability model well represents permeability measured in laboratory experiments using air- and water-based permeametry on the model sediment mixtures.     

Biomarker responses as indication of contaminant effects in blue mussel (Mytilus edulis) and female eelpout (Zoarces viviparus) from the southwestern Baltic Sea

During a field study performed in spring and autumn 2001 and 2002, blue mussels (Mytilus edulis) and female eelpout (Zoarces viviparus) were collected at three locations in the Wismar Bay (Baltic Sea), and several biomarkers of contaminant effects were analysed. Besides seasonal and inter-annual variations, biomarker signals were most pronounced at the location closest to Wismar Harbour (Wendorf) in both species. Lysosomal membrane stability (LMS) was lowest and acetylcholinesterase activity (AChE) was significantly reduced. Frequency of micronuclei (MN) was significantly higher (in blue mussels), indicating mutagenic effects. In eelpout elevated levels of DNA adducts, EROD induction and PAH-metabolites were measured. Metallothionein (MT), biomarker for trace metal exposure, showed a gradient only in spring. Organochlorine contaminant analyses (PCBs, DDTs) corresponded to the observed biomarker levels. The results obtained clearly demonstrate pollution effects in the southwestern Baltic Sea. Moreover, they show that a multibiomarker approach is also applicable in a brackish water environment.     

Legal aspects of conserving native oysters in Scotland

Native oysters (Ostrea edulis) historically supported valuable fisheries in Scotland, but are now absent from areas of former abundance on the east coast and occur mainly in isolated populations in west coast sea lochs. The main contemporary threat is from unauthorized gathering. In most places, the exclusive right to gather is retained by the Crown, as a remnant of the feudal system, but in some areas the right has been acquired by individuals or institutions. A temporary right to gather oysters may be obtained by permit from the proprietor, or through a Several or Regulating Order made under shellfish fisheries legislation. The right to gather oysters is separate from ownership of the foreshore or sea bed on which they are located. To receive the maximum legal protection, oyster beds must be marked out, or the rights to them otherwise adequately made known. Wild or formerly-cultivated oyster beds may not meet this criterion and, in any case, enforcement is difficult in remote locations. It has been proposed that there should be a statutory public right to gather oysters. Were this to be created, then strong conservation measures would need to be implemented to protect native oysters from eradication by uncontrolled gathering.     

试论矿产勘查工作的改革方向

随着地质找矿改革发展大讨论的深入,必然涉及一些地质工作改革深层次的问题。本文拟从市场化改革角度,探讨地质勘查工作改革方向和思路。     

公益性地学数据的功效：拉动商业性矿产勘查

通过分析商业性矿产勘查业对公益性地学数据的需求、公益性地学数据对商业性矿产勘查的短期和长期影响,探讨了公益性地学数据和商业性矿产勘查的关系,肯定了公益性地学数据在促进矿产勘查中的积极作用,提出了利用公益性地学数据拉动商业性矿产勘查、服务于商业性矿产勘查的基本思路。     

金融危机对矿业的影响及分析预测

席卷全球的金融危机正在疯狂肆虐,矿业也难以独善其身。金融危机导致矿产品价格全线跳水、矿业公司股价大幅下跌、矿产品需求下降。矿产品价格大幅下跌是矿产品价格在挤出泡沫之后的一种理性回归。矿业发展自身的规律与百年不遇的金融危机的相互叠加、相互影响,加速了此轮矿业繁荣周期的终结并开始了走向下行期的步伐。金融危机给矿业带来了挑战与机遇,但机遇远大于挑战。对此提出如下建议：改善中国矿业投资环境,调整矿产品进出口政策;培育大型跨国矿业公司,提高竞争力;建立国外资源储备基地,吸引海外地质勘查人才;重新审视和再认识地勘基金的定位;抓住有利时机整合资源,促进矿业结构调整。     

Systematic study of effects of pH and ionic strength on attachment of phage PRD1

Objectives of this work are to investigate effects of pH and ionic strength (IS) on virus transport in saturated soil and to develop a quantitative relationship for these effects. A series of 50-cm column experiments with clean quartz sand under saturated conditions and with pH values of 5, 6, 7, 8, and IS values of 1, 10, and 20 mM were conducted. Bacteriophage PRD1 was used as a model virus. Applying a one-site kinetic model, attachment, detachment, and inactivation rate coefficients were determined from fitting breakthrough curves using the software package Hydrus-1D. Attachment rate coefficients increased with decreasing pH and increasing IS, in agreement with DLVO theory. Sticking efficiencies were calculated from the attachment rate coefficients and used to develop an empirical formula for sticking efficiency as a function of pH and IS. This relationship is applicable under unfavorable conditions for virus attachment. We compared sticking efficiencies predicted by the empirical formula with those from field and column experiments. Within the calibrated range of pH and IS, the predicted and observed sticking efficiencies are in reasonable agreement for bacteriophages PRD1 and MS2. However, the formula significantly overestimates sticking efficiencies for IS higher than 100 mM. In addition, it performs less well for viruses with different surface reactivity than PRD1 and MS2. Effects of pH and IS on detachment and inactivation rate coefficients were also investigated but the experimental results do not allow constraining these parameters with sufficient certainty.     

Measuring ignitability for in situ burning of oil spills weathered under Arctic conditions: from laboratory studies to large-scale field experiments

This paper compares the ignitability of Troll B crude oil weathered under simulated Arctic conditions (0%, 50% and 90% ice cover). The experiments were performed in different scales at SINTEF’s laboratories in Trondheim, field research station on Svalbard and in broken ice (70-90% ice cover) in the Barents Sea. Samples from the weathering experiments were tested for ignitability using the same laboratory burning cell. The measured ignitability from the experiments in these different scales showed a good agreement for samples with similar weathering. The ice conditions clearly affected the weathering process, and 70% ice or more reduces the weathering and allows a longer time window for in situ burning. The results from the Barents Sea revealed that weathering and ignitability can vary within an oil slick. This field use of the burning cell demonstrated that it can be used as an operational tool to monitor the ignitability of oil spills.     

Metal speciation and toxicity of Tamar Estuary water to larvae of the Pacific oyster, Crassostrea gigas

As part of the PREDICT Tamar Workshop, the toxicity of estuarine waters in the Tamar Estuary (southwest England) was assessed by integration of metal speciation determination with bioassays. High temporal resolution metal speciation analysis was undertaken in situ by deployment of a Voltammetric In situ Profiling (VIP) system. The VIP detects Cd (cadmium), Pb (lead) and Cu (copper) species smaller than 4?nm in size and this fraction is termed 'dynamic' and considered biologically available. Cadmium was mainly present in the dynamic form and constituted between 56% and 100% of the total dissolved concentration, which was determined subsequently in the laboratory in filtered discrete samples. In contrast, the dynamic Pb and Cu fractions were less important, with a much larger proportion of these metals associated with organic ligands and/or colloids (45-90% Pb and 46-85% Cu), which probably reduced the toxicological impact of these elements in this system. Static toxicity tests, based on the response of Crassostrea gigas larva exposed to discrete water samples showed a high level of toxicity (up to 100% abnormal development) at two stations in the Tamar, particularly during periods of the tidal cycle when the influence of more pristine coastal water was at its lowest. Competitive ligand-exchange Cu titrations showed that natural organic ligands reduced the free cupric ion concentration to levels that were unlikely to have been the sole cause of the observed toxicity. Nonetheless, it is probable that the combined effect of the metals determined in this work contributed significantly to the bioassay response.     

关于找矿模型的探讨

矿床类型是建立各类矿床模型的地质前提,矿床模型的应用方向是建立模型的关键,经验模型与理论模型交叉与融合是建立矿床模型的核心.这3条是矿床模型研究中必须坚持的原则,也是建立找矿模型的重要原则.它基本明确了找矿模型的定位和建设方向.所谓找矿模型,不管其成熟度如何,均以经验模型与理论模型的各类信息的兼收并蓄为基础,以找矿为目...