The origin of high hydrocarbon groundwater in shallow Triassic aquifer in Northwest Guizhou,China

Original high hydrocarbon groundwater represents a kind of groundwater in which hydrocarbon concentration exceeds 0.05 mg/L. The original high hydrocarbon will significantly reduce the environment capacity of hydrocarbon and lead environmental problems. For the past 5 years, we have carried out for a long-term monitoring of groundwater in shallow Triassic aquifer in Northwest Guizhou, China. We found the concentration of petroleum hydrocarbon was always above 0.05 mg/L. The low-level anthropogenic contamination cannot produce high hydrocarbon groundwater in the area. By using hydrocarbon potential, geochemistry and biomarker characteristic in rocks and shallow groundwater, we carried out a comprehensive study in Dalongjing (DLJ) groundwater system to determine the hydrocarbon source. We found a simplex hydrogeology setting, high-level water–rock–hydrocarbon interaction and obviously original hydrocarbon groundwater in DLJ system. The concentration of petroleum hydrocarbon in shallow aquifer was found to increase with the strong water–rock interaction. Higher hydrocarbon potential was found in the upper of Guanling formation (T₂g³) and upper of Yongningzhen formation (T₁yn⁴). Heavily saturated carbon was observed from shallow groundwater, which presented similar distribution to those from rocks, especially from the deeper groundwater. These results indicated that the high concentrations of original hydrocarbon in groundwater could be due to the hydrocarbon release from corrosion and extraction out of strata over time.

     

Changes in CO2 flux for different recovery processes of desertification in the alpine meadows of Northwest Sichuan北大核心CSCD

Desertification has emerged as a serious threat to the alpine meadows of Northwest Sichuan in recent decades. Artificial vegetation had certain effects on desertification recovery, while how the CO2 flux changed and its reasons are still unclear. During the growing season in 2016 (i.e., from July to September), we selected the desertified alpine meadows with different recovery degrees, including the early stage of restoration, the middle stage of restoration, the late stage of restoration, and control (the unrecovered desertification meadow) as four transects. CO2 flux was measured by the instrument LI-8100, and the microenvironment factors that affected CO2 flux changes were analyzed. The results showed that the carbon sequestration function of desertified alpine meadows gradually increased with the degree of recovery. Net ecosystem exchange (NEE) were -1.61, -3.55, and -4.38 μmol m-2 s-1 in the early, mid-term, and late transects, respectively, and the most dramatic changes occurred from the early stage to mid-term stage, increasing by 120.50%. Both ecosystem respiration (ER) and soil respiration (SR) were enhanced significantly with restoration (P < 0.05). In mid or late July, NEE, ER, and SR reached their maximum values, and thereafter, the indicators varied to near zero (P < 0.05). During the whole growing season, the daily dynamic in CO2 flux for the control alpine meadow was mild and retained the trend of continuous release all day, but that in the desertified alpine meadow was a single peak pattern. Moreover, with restoration process, the peak of CO2 flux increased and reached a peak in the late stage of the recovery process. The regression analysis showed that there was a significant positive correlation between CO2 flux and vegetation coverage, aboveground biomass, and soil moisture (0-5 cm) (P < 0.01), and a weak correlation with 0-5-cm soil temperature (P < 0.01). This indicates that topsoil moisture (5 cm) is a more significant factor for CO2 flux than topsoil temperature during the growing season in the restoration of desertified alpine meadows in Northwest Sichuan. In general, the vegetation recovery significantly improved the carbon-sequestration ability of the desertified alpine meadows during the growing season in Northwest Sichuan, and at the middle stage of restoration, the carbon-sequestration ability improved significantly due to vegetation restoration and increase in topsoil (0-5 cm) moisture. © 2018 Science Press. All rights reserved.     

Interspecific association among main plant species in the unstable slope with high-frequency debris flow北大核心CSCD

To determine the characteristics of vegetation community structure and the relationship between species in the frequent watersheds of debris flow in fragile ecological environments, based on sample survey and 2 × 2 joint table techniques, we used analysis of variance test, χ2 test, Jaccard index, Pearson correlation coefficient, and Spearman's rank correlation coefficient test to study the main plant species correlations in the stable zone, instable zone, and deposit zone of the unstable slope. The analysis of variance test showed that all 45 species pairs had a significant negative correlation in the stable zone and instable zone, whereas there was no significant negative correlation in the deposit zone, which showed that the species had an independent distribution trend. The results from the different tests showed that there were 1 pair, 4 pairs, and 4 pairs from the stable zone, instable zone, and deposit zone, respectively, which had significant interspecific association under the χ2 test and the ratios of positive correlation pairs to negative correlation pairs were 0.55, 0.67, and 0.67 in the stable zone, instable zone, and deposit zone, respectively. There were 8 pairs, 5 pairs, and 5 pairs from the stable zone, instable zone, and deposit zone, respectively, which had significant interspecific association from the Pearson correlation analysis test, and the ratios of positive correlation pairs to negative correlation pairs were 0.36, 0.45, and 0.45 in the stable zone, instable zone, and deposit zone, respectively. There were 10 pairs, 6 pairs, and 9 pairs from the stable zone, instable zone, and deposit zone, respectively, which had significant interspecific association from the Spearman's rank correlation analysis test and the ratios of positive correlation pairs to negative correlation pairs were 0.5, 0.55, and 0.6 in the stable zone, instable zone, and deposit zone, respectively. The three test results showed general similarities but there were some differences. Most species pairs did not reach a significant level in the three zones and the number of negatively related species was more than the number of positively related species. In brief, this loose interspecific relationship indicates that the entire plant community was not stable, and the interspecific relationships among species are susceptible to environmental interference in the ecologically fragile areas of the debris flow basin. Therefore, rational selection and configuration of species should be applied to promote community structure development and ecological environmental improvement in vegetation restoration process areas with high-frequency debris flow. © 2018 Science Press. All rights reserved.     

我国地表水中磷酸三苯酯的多层次生态风险评估

磷酸三苯酯(triphenyl phosphate,TPP)在电缆材料、塑料制品中被大量使用,是地表水中检出频率最高的有机磷酸酯类阻燃剂之一,近年来受到广泛关注。本文通过文献检索TPP的地表水环境暴露浓度以及对水生生物的毒性效应浓度,利用风险商(hazard quotient,HQ)和概率生态风险评价法(probabilistic ecological risk assessments,PERA)对我国主要地表水中的TPP进行多层次生态风险评价。结果显示,TPP在我国地表水中的浓度为0.2～96.3 ng·L~(-1),以生存为测试终点的急性毒性数据推导出的预测无效应浓度(predicted no effect concentration,PNEC)为36.49μg·L~(-1),而以繁殖、发育和生长等为测试终点的慢性毒性数据推导出的PNEC值为1.30μg·L~(-1)。基于急、慢性毒性数据计算的风险商均小于0.1。我国地表水中TPP对0.1%到1%的水生生物造成繁殖、发育和生长等慢性毒性影响的概率分别为1.40%和0.04%,存在较低的潜在生态风险。     

2种类型多壁碳纳米管对蛋白核小球藻的毒理研究

碳纳米材料由于其具有优异的性能,得以广泛生产和使用,其不可避免会进入水环境中,对水生生态系统造成潜在影响。多壁碳纳米管(P-MWCNTs)和羟基化多壁碳纳米管(MWCNTs-OH)作为纳米材料的典型代表,应用非常广泛,其潜在的环境效应受到人们越来越多的关注。为此,本文以蛋白核小球藻(Chlorella pyrenoidosa)作为受试生物,通过暴露实验,研究了P-MWCNTs和MWCNTs-OH对蛋白核小球藻的生物学效应。研究结果表明：1)当P-MWCNTs浓度≤10 mg·L-1、MWCNTs-OH≤20 mg·L-1浓度时对蛋白核小球藻生长未造成影响;2)暴露96 h后,当P-MWCNTs≤10 mg·L-1、MWCNTs-OH浓度≤20 mg·L-1时,蛋白核小球藻细胞可溶性蛋白质含量增加,当P-MWCNTs浓度≥20 mg·L-1、MWCNTs-OH浓度≥40 mg·L-1时,2种类型MWCNTs均对蛋白核小球藻造成毒性效应;3)随着2种类型MWCNTs浓度的增加,蛋白核小球藻细胞总抗氧化能力(T-AOC)值减少,蛋白核小球藻细胞丙二醛(MDA)含量显著增加,细胞的健康程度逐渐恶化,细胞结构受到严重损伤;4)MWCNTs-OH比P-MWCNTs具有更好的生物相容性。     

考虑偏应力比影响的主应力轴旋转下重塑黄土变形研究

采用浙江大学空心圆柱扭剪仪对重塑黄土试样进行了3种复杂应力路径下的试验,研究了主应力轴旋转条件下偏应力比η对重塑黄土变形特性的影响。试验结果表明,不同偏应力比下重塑黄土的强度差异较大,η=0.133时归一化强度最小,而η=0.433时强度最大,偏应力比η从0.133到0.5时归一化强度呈现增大—减小—增大—减小的规律。主应力轴旋转对重塑黄土的各应变增量均有影响,并且对中间主应变增量的影响最大,其中大主应变和小主应变在ε-q平面内对称开展,且总体表现出Δεz0,Δεθ0的趋势,中间主应变整体呈现Δεr0的发展趋势,当应力主轴旋转目标角度α45°时,中间主应变呈现出不同的开展形式,重塑黄土在应力主轴旋转下向异性较为显著。     

Application and mechanism of polysaccharide extracted from Enteromorpha to remove nano-ZnO and humic acid in coagulation process

Green source Ep was extracted from marine alga waste. The molecule model structure of Ep was studied and constructed. PAC-Ep coagulation system improves the efficiency of removal efficiency. Synergistic effects between NPs and HA make a big difference to enhance efficiency. Mechanism is charge neutralization, hydrogen bonding and adsorbing-complexing Enteromorpha polysaccharide (Ep) extracted from alga a novel green coagulant aid for nanoparticles (NPs) and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration of Ep with polyaluminum chloride (PAC-Ep) coagulants exhibited higher coagulation performance than that of the polyaluminum chloride (PAC) because of the negatively charged NPs suspension and humic aid (HA) solution. Significant high removal efficiencies of dissolved organic matter (94.1%), turbidity (99.3%) and Zn ions (69.3%) were achieved by the PAC-Ep coagulants. The dual-coagulation properties of PAC-Ep for different pollutants was based on multiple mechanisms, including (i) Al³⁺ charge neutralization; (ii) hydroxy aluminum hydroxyl bridging formed polynuclearhydroxy complexes bridge and sweep colloidal particles; (iii) adsorption and bridging of Ep chain for the NPs and heavy metal ions. Results indicated that the destabilization of colloid was induced by the coexisting HA and higher removal was achieved as ions adsorption was enhance in the presence of HA complexation. On the basis of that, the extraction of polysaccharide is a promising candidate for its high coagulation performance in water treatment.     

基于超声空化原理的废旧线缆回收方法

废旧线缆是一种可以回收利用的资源。目前普遍使用机械破碎方法回收废旧线缆,具体工艺是采用机械磨削的方法分离铜和绝缘皮,然后用筛分法获得。由于此工艺中包含有磨削过程,因此会损失很大一部分铜,从而造成资源浪费。为此,研究使用超声波工艺回收电线,并探讨一些因素对分离率的影响。研究结果表明:利用超声波的空化效应分离电线中的金属和塑料,能有效避免铜的大量损失。当水温为60℃,分离率达到最高值;电线长度与分离率之间基本成反比关系;电线总量的大小对分离率也有一定的影响。     

Modified explosive diagram for determining gas-mixture explosibility

Determination of mine gas explosibility is definitely a significant work for mine safety especially when any mine rescue strategies are under planning or implementing. In detail, its importance can be well understood by the following two aspects: First, if a coal mine's production is under the normal conditions, the underground mine atmosphere must be monitored as a timely matter and its explosibility should also be determined shortly due to the continuous emission of methane or other combustible gases. Thus, the critical time which means a time period that combustible gases could build up to reach the lower flammable limit and then pass the upper flammable limit can be effectively watched and controlled. Second, when facing a mine rescue work or mitigating a hazard of mine accidents (gas explosion, coal fire, etc.), the explosibility determination is also very critical for miners' lives. In this paper, a widely used mine gas explosibility determination method, the Coward diagram, is going to be modified to improve its accuracy. The improvements made in this research effort include: (1) expanding the original Coward diagram; (2) correcting flammable limits; (3) redefining the nose limit for each combustible gas; (4) developing an equation to predict the excess amount of inert gas for individual combustible gas. Finally, the flowchart of the modified Coward explosibility diagram method is listed. By a cross-verification study, it shows that the modified Coward method has better accuracy and reliability and could be applied in practices.     

让纳若尔油田采出水处理汽提脱硫阻垢技术

让纳若尔油田采出水处理汽提脱硫工艺,高温工况下结垢严重,筛选合适的阻垢剂并对其进行应用评价,使脱硫塔达到良好的运行效果。文章分析了汽提脱硫装置结垢原因,进行了常规阻垢剂筛选评价、新型合成阻垢剂性能评价、化学平衡防垢技术的研究。结果表明：现场试运行实验投加有机复合酸离子调整剂A40mg／L、新型合成阻垢剂G－3为30mg／L,作为适合本工程的阻垢剂。