金属矿电法勘探中化探资料的利用

电法是寻找金属矿产的重要手段,无论是五十年代就开始应用的“自电”(以及电阻率法),还是六十年代以后广泛开展的“激电”,以及七十年代开始推广的电磁法,在新、老矿区,在地质工作的不同阶段,曾取得了一定的直接或间接的找矿效果。     

Use of composite data sets for source-tracking enterococci in the water column and shoreline interstitial waters on Pensacola Beach, Florida

Sources of Enterococcus faecalis isolates from Pensacola Beach, FL. were identified using a library-based approach by applying the statistical method of average similarity to single and composite data sets generated from separate analyses. Data sets included antibiotic resistance analysis (ARA), rep-fingerprints, and fatty acid methyl ester (FAME) profiles. Use of a composite data set composed of ARA and rep-fingerprints, added to the confidence of the identifications. The addition of FAME data to composite data sets did not add to the confidence of identifications. Source identification was performed to better understand risk associated with higher densities of enterococci found in swash zone interstitial water (SZIW) as compared to adjacent bathing water on Pensacola Beach, FL. The "swash zone" is that area of the beach continually washed over by waves. As the potential sources of enterococci were limited in this environment, only two library units, sea gull and human, were constructed. Identification of the beach isolates using a composite data set indicated a sea gull origin. The clonality of the beach isolates suggested that the beach environment selects certain subspecies of E. faecalis.     

Air-based measurements of permeability in pebbly sands

We considered small-scale measurement of permeability in pebbly sands having coarser grains supported in a finer grained matrix (fine packing). Our central question was whether air-based measurements are representative if made with a permeameter tip seal pressed in the sand matrix. We created pebbly sands and variably sorted sands, with systematic variation in aspects of their fine packing. We made permeability measurements by inserting the tip seal of an air permeameter in the matrix of these samples and compared them to the permeability of the composite sample determined by both water-based methods and theory. The air-permeameter measurements made in this way represent the permeability of the composite mixtures of coarser and finer grains and allow for the discernment of permeability between samples with different matrix compositions, ranging from fine to coarse sand. Furthermore, the collective results show that permeability differences in the pebbly sands and variably sorted sands with fine packing, however measured, are primarily due to differences in matrix permeability and not due to differences in the size or the percentage of the coarser grains.     

金矿矿源层与矿源层中金的丰度和活度

矿源层中金的原始丰度高。岩石中金的活度与丰度有关。矿源层与非矿源层的同类岩石,除均含有数量大致相当的造岩矿物中背景量级的金外,矿源层比非矿源层多含了一部分活化金。矿源层是某些类型金矿成矿的必要条件之一。     

Cypermethrin induces glutathione S-transferase activity in the shore crab,Carcinus maenas

Cypermethrin is a synthetic pyrethroid that is particularly toxic to crustacea. It is therefore applied as a chemotherapeutant in the salmonid aquaculture industry for the treatment of sea lice infestations. After use, cypermethrin is released directly into the marine environment, to be diluted by fresh seawater. The shore crab, Carcinus maenas is found in the vicinity of fish farms, and may come into contact with released cypermethrin. The detoxification enzyme, glutathione S-transferase (GST) has been implicated in cypermethrin metabolism in terrestrial arthropods, but this has not yet been demonstrated in crustacea. In this paper we investigate the response of GST activity in Carcinus to cypermethrin exposure, and also the time course of the induction process. GST activity is significantly increased in Carcinus exposed to nominal concentrations of 50 and 500 ng/l of water-borne cypermethrin. Carcinus demonstrate a significant elevation in GST activity following intra-cephalothoracic injection with 10 ng of cypermethrin. GST activity returns to basal levels after 36 h. The potential application of GST activity in Carcinus as a biomarker of cypermethrin exposure is discussed.