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The practice of exploration and development in recent years shows that the reservoir lithology changes rapidly in the large-scale bedrock gas field in Altun forelands. in the Qaidam Basin. The PX bedrock gas reservoir is located in the gas field of the Altun forelands, and the drilling reveals that the main lithology is epimetamorphic limestone, slate and calcareous slate. It’s very important to identify and predict lithology for studying the main controlling factors of development productivity and the overall distribution of lithology space of bedrock reservoirs. But the conventional impedance inversion method for sand-shale lithology hard to apply in this area, it’s has very limited or almost no effect. In this study, firstly, the main lithology distribution of well was determined from core observation, analysis of thin sections and X-ray diffraction mineral analysis. Then the well logging characteristics of different bedrock lithology were analyzed by logging charts. Based on this, logging attribute inversion was applied to predict the spatial distribution characteristics of bedrock lithology in PX area. Further, using the geostatistical modeling method the three-dimensional lithofacies model for this area was established. The results show that the spatial distribution structure of lithology in PX area is obvious. The upper part is mainly epimetamorphic limestone, the lower part is mainly slate, and calcareous slate distributes locally. The metamorphic limestone is the dominant lithology for productivity, and the gas in the lower slate is mainly confined to the local fracture zone near the fault. The method of comprehensive identification and prediction of lithology formed by this study is very significant especially for revealing the lithology distribution and variation law of bedrock gas reservoirs in Altun forelands.

Arsenic (As) contamination poses a high risk to human health. Phytoremediation based on As hyperaccumulator Pteris vittata has been utilized on large areas of contaminated farmland in southern China. However, the reason for the observed differences in As removal among P. vittata populations remains unclear. In this study, spores of four P. vittata populations were collected from four neighboring sites with varying soil As concentration (from 108mgkg-1 to 7527mgkg-1) and then cultured in a controlled environment to analyze their differing abilities in terms of As accumulation and tolerance. The results indicate that populations from low-As habitats exhibited 80% greater shoot As concentrations compared with those from high-As habitats. On the other hand, populations from high-As habitats exhibited approximately five times greater biomass compared with those from low-As habitats when exposed to the same As stress. Thus, the As accumulation and tolerance of P. vittata were suggested to be two independent processes. Further investigations reveal that the As absorption and As species conversion occurring in roots are two essential activities that bridge the soil As concentration and the responses of P. vittata to As. Depending on the As concentration of the target soil, the selection of different P. vittata populations can result in approximately an eight-fold difference in terms of remediation efficiency. 2012 Elsevier B.V.

The impacts of the regulation of sulfur (S) metabolism in vivo on arsenic (As) and S species and on As accumulation by Pteris vittata L were investigated using a synchrotron-based X-ray-absorption fine structure method. The S assimilation inhibitor L-buthionine-sulfoximine (BSO) markedly inhibited As reduction, doubling arsenate (As(V)) content in P. vittata rhizoids. The resulting As transport blockage in rhizoids, decreased As movement to aboveground tissues by 47%. The significant impact of BSO demonstrated the vital role of sulfhydryl groups (-SH) as reductants in As(V) reduction and confirmed the importance of As(V) reduction in As accumulation in this fern. The S metabolism accelerant O-acetyl-L-serine resulted in the appearance of large amounts of As-SH in rhizoids and had no obvious impact on As accumulation, but with As stress conditions, effectively increased plant biomass, possibly through chelation of excess As with -SH. Thus, -SH appeared able to act as both a reductant and a chelator of As in P. vittata, and the ratio of -SH to As may have been a factor that determined the specific role of -SH in P. vittata under these conditions. (C) 2012 Elsevier B.V. All rights reserved.

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We aimed to optimize germination and growth conditions of the arsenic hyperaccumulating fern, Pteris vittata L. Pot experiments were carried out to investigate the effects of soil pH, soil calcium (Ca) concentration, and temperature on the sexual propagation of P. vittata. At 25 degrees C, germination was both accelerated and increased by high soil pH and Ca concentration. Spores of P. vittata did not germinate on medium with a pH of 4.6. Amending strongly acid soils with 27.5 or 40 micromol/g Ca(OH)2 significantly improved the growth rate during both the germination phase and the gametophyte phase. Amending strongly acid soils with NaOH (55 micromol/g) promoted germination, but did not affect subsequent growth. Among the different temperature, germination and growth rates were higher at 25 degrees C than at 20 degrees C or 30 degrees C. The distribution of P. vittata in China might be influenced by its requirement for high pH and high Ca concentration in the soil and appropriate growth temperature to complete sexual propagation. These results provided important information for improving breeding conditions of P. vitatta and will be helpful for extending the range of areas in which P. vittata can be used for phytoremediation.

Because of the strong tectonic movement during the formation of limestone buried hills, lots of fractures came into being. The early formed structural fractures have undergone denudation, demorphism, leaching, dissolution from atmosphere precipitation, and surface runoff, which make some of the initial structural fractures enlarged and some half-filled or fully filled with calcite. The fractures formed in the later tectonic movement are not often filled and become the main channel connecting dissolution pores with cavities. This paper calculates the strain magnitude of buried hill formation resulting from every stage tectonic movement using the strain analysis methods such as inversion and forward modeling of structural evolution history of formations. The paper also predicts the 3D fracture network formed during every tectonic movement from the geological genesis standpoint, and therefore, distinguishes the early filled fractures formed during the period of buried hill formation from the unfilled fractures formed later, achieving the goal of predicting fracture reservoirs in the limestone buried hills. Key words: limestone, buried hill, multi-period fracture, effective fracture

Field investigation and greenhouse experiments were conducted to study the tolerance of Pteris vittata L. (Chinese brake) to cadmium (Cd) and its feasibility for remediating sites co-contaminated with Cd and arsenic (As). The results showed that P. vittata could survive in pot soils spiked with 80 mg/kg of Cd and tolerated as great as 301 mg/kg of total Cd and 26.8 mg/kg of diethyltriaminepenta acetic acid (DTPA)-extractable Cd under field conditions. The highest concentration of Cd in fronds was 186 mg/kg under a total soil concentration of 920 mg As/kg and 98.6 mg Cd/kg in the field, whereas just 2.6 mg/kg under greenhouse conditions. Ecotypes of P. vittata were differentiated in tolerance and accumulation of Cd, and some of them could not only tolerate high concentrations of soil Cd, but also accumulated high concentrations of Cd in their fronds. Arsenic uptake and transportation by P. vittata was not inhibited at lower levels (< or = 20 mg/kg) of Cd addition. Compared to the treatment without addition of Cd, the frond As concentration was increased by 103.8% at 20 mg Cd/kg, with the highest level of 6434 mg/kg. The results suggested that the Cd-tolerant ecotype of P. vittata extracted effectively As and Cd from the site co-contaminated with Cd and As, and might be used to remediate and revegetate this type of site.

Synchrotron radiation X-ray absorption near edge structure was employed to study the arsenic (As) speciation in 13 Pteris vittata L. populations collected from 7 provinces, cities, and autonomous regions in China. As in roots of P. vittata was mainly combined with oxygen (O), with a small amount of As combined with glutathione (GSH). Populations from Hunan and Guangxi provinces showed higher percentages of As-GSH in soots. As in roots of P. vittata was predominated with As(V), with the percentage of As(V) to the total As being 59.6±0.6%~83.8±3.8%. The As(V) percentage was in the order of HN5GX2HN1CQGX1GDHN3HN4GX3HN2TWAHFJ. Similar with that in roots, As in shoots was also mainly combined with O, with few combined with GSH. The percentage of As-GSH to the total As was in the order of GDHN3HN1TWCQAHFJHN5HN2GX2GX3HN4GX1, within the range of 2.4%~12.9%. Different from that in roots, As in shoots was predominated with As(III), with no As(V) detected. The disclosure of As speciation in the roots and shoots of P. vittata contributes to the future research on As accumulation mechanism.

Arsenic (As) reduction and translocation are key processes for As hyperaccumulation by the hyperaccumulator Pteris vittata L. Micro-X-ray adsorption spectroscopy of P. vittata’s rhizoid tissues revealed that As reduction mainly occurred in endodermis during translocation from epidermis to vascular bundle. Prior to reduction, arsenate (As (V)) translocation was an active process requiring energy and employing a phosphate (P) transporter. Use of a synchrotron X-ray microprobe showed that As (V) and P were cotransported and that this process could be enhanced by As (V) exposure or P deficiency but restrained by energy release inhibition caused by 2,4-dinitrophenol or sodium orthovanadate. In contrast, after As reduction, As(III) translocation differed from P translocation and was more efficient, appearing free from the apparent endodermal blockage. The results here revealed the role of the P transporter on As translocation as well as the key role of As reduction in As hyperaccumulation by P. vittata.

The arsenic (As) hyperaccumulators, Pteris vittata and Pteris cretica and an As-tolerant plant Boehmeria nivea, were selected to compare the toxicity, uptake, and transportation of inorganic arsenate (As(V)) and its methylated counterpart dimethylarsinic acid (DMA). The XANES method was used to elucidate the effect of As species transformation on As toxicity and accumulation characteristics. Significantly higher toxicity and lower accumulation of DMA than inorganic As V) was shown in the As hyperaccumulators and the As-tolerant plant. Reduction of As(V) was commonly found in the plants. Arsenic complexation with thiols, which have less mobility in plants and usually occur in As-tolerant plants, was also found in rhizoids of P. cretica. Plants with greater ability to form As-thiolate have lower ability for upward transport of As. Demethylation of DMA occurred in the three plants. The DMA component decreased from the rhizoids to the fronds in both hyperaccumulators, while this tendency is reverse in B. nivea.

As soil arsenic concentration might have great effect on arsenic accumulation of hyperaccumulator Pteris vittata L. , three sample areas with different As pollution level in the soils are investigated in Chenzhou, Hunan Province, where Pteris vittata L. grows broadly. Great variation of As concentrations is found to be not only among different samples in the same sampling areas but also between rhizosphere and bulk soil of P. vittata L. So it is suggested that rhizosphere soil should be sampled to study the effect of soil contamination on plant accumulation. The As concentration in frond of P. vittata L. increased dramatically at lower As level but decreased slowly when As concentration higher than 1 000 mg/kg. Arsenic translocation factors of P. vittata L. were greater than 1 in all samples in this study, whereas As concentration in shoots in lower As contaminated soil and bioaccumulation factors in higher As contaminated soil are fail to meet the definition of As hyperaccumulator.

In order to assess soil As contamination and potential risk for human, soil, paddy rice, vegetable and human hair samples from the areas near the industrial districts in Chenzhou, southern China were sampled and analyzed. The results showed that the anthropogenic industrial activities have caused in local agricultural soils to be contaminated with As in a range of 11.0–1217 mg/kg. The GIS-based map shows that soil contamination with As occurred on a large scale, which probably accounted for up to 30% of the total area investigated. Soil As concentration abruptly decreased with an increase in the distance from the polluting source. High As concentrations were found in the rice grain that ranged from 0.5 to 7.5 mg/kg, most of which exceed the maximal permissible limit of 1.0 mg/kg dry matter. Arsenic accumulated in significantly different levels between leafy vegetables and non-leafy vegetables. Non-leafy vegetables should be recommended in As-contaminated soils, as their edible parts were found in relatively low As level. Arsenic concentrations in 95% of the total human hair samples in the contaminated districts were above the critical value, 1.0 mg/kg, set by the World Health Organization. Arsenic could be enriched in human hair to very high levels without being affected by As containing water. The results revealed that the soils and plants grown on them are major contributors to elevate hair As in the industrial population. Therefore, the potential impact on human health of ingestion/inhalation of soil As around the industrial districts seems to be rather serious. Hence proper treatments for As contaminated soils are urgently needed to reduce the contamination. Keywords: Arsenic, Contamination, Hair, Industrial district, Rice, Soil, Vegetable