Effects of medium-pressure UV lamps radiation on water quality in a chlorinated indoor swimming pool

The aim of our study was to determine the impact of medium-pressure UV lamps radiation on water quality in a chlorinated indoor swimming pool. An indoor swimming pool was equipped with two medium-pressure UV lamps. We collected eight samples of water daily over a four-weeks period and measured total and free chlorine, pH, water temperature, bacteriological parameters, total organic carbon and trihalomethanes. During the first week, which served as control, medium-pressure UV lamps were turned off. During the next three weeks, medium-pressure UV lamps were kept on 24 h per day. The third week, we reduced the level of the injected chlorine into water, and the last week we also reduced the water renewal volume by 27%. Our results showed that bacteriological parameters remained within allowable french limits. When medium-pressure UV lamps were kept on, total, free and active chlorine levels were significantly increased (P<0.001), whereas combined chlorine level were significantly decreased (P<0.001 and P<0.05, respectively). The levels of chloroform and bromodichloromethane were significantly increased when medium-pressure UV lamps were kept on (P<0.001), whereas chlorodibromomethane and bromoform levels significantly decreased (P<0.05 and P<0.001, respectively). The additional formation of chloroform and bromodichloromethane may be explained by the increase in active chlorine and by radicalizing mechanisms initiated by UV radiation.     

Bioaccumulation and physiological effects of mercury in Sesbania drummondii

The accumulation of mercury and its effect on growth, photosynthesis and antioxidative responses were studied in Sesbania drummondii seedlings. Mercury concentration in shoots as well as in the roots increased with increasing Hg concentrations in the growth solution. The accumulation of Hg was more in roots than shoots. At 100 mg l-1 Hg concentration, shoots accumulated 998 mg Hg kg -1 dry weight (dw) while roots accumulated 41,403 mg Hg kg-1 dw. Seedlings growth was not significantly affected at lower concentrations of Hg. A concentration of 100 mg l-1 Hg inhibited growth by 36.8%, with respect to control. Photosynthetic activity was assessed by measuring chlorophyll a fluorescence by determination of Fv/Fm and Fv/Fo values. Photosynthetic integrity was not affected up to 50 mg l-1 Hg concentration, however, concentrations higher than 50 mg l-1 affected photosynthetic integrity. Sesbania responded to Hg induced oxidative stress by modulating non-enzymatic antioxidants [glutathione (GSH) and non-protein thiols (NPSH)] and enzymatic antioxidants: superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR). Glutathione content and GSH/GSSG ratio increased up to a concentration of 50 mg l-1 while slight down at 100 mg l-1 Hg. The content of NPSH significantly increased with increasing Hg concentrations in the growth medium. The activities of antioxidative enzymes, SOD, APX and GR followed the same trends as antioxidants first increased up to a concentration of 50 mg l-1 Hg and then slight decreased. The results of present study suggest that Sesbania plants were able to accumulate and tolerate Hg induced stress using an effective antioxidative defense mechanisms.     

应用选择性萃取法和感耦等离子体(ICP)光源测定地质样品中的Ag、Au、Bi、Cd、Cu、Pb和Zn元素的初步研究

<正> 前言在现有的分析技术中,作为一种分析方法,只有等离子体光谱具有检测极限低,线性含量范围宽,工作温度高,对多元素同时测定的能力,同时具有极好的精度和准确度等优点。ICP 发射光谱是一种相当新的分析方法,实际用来分析各种类型的样品。特别     

Predictive models of turbidity and water depth in the Doñana marshes using Landsat TM and ETM+ images

We have used Landsat-5 TM and Landsat-7 ETM+ images together with simultaneous ground-truth data at sample points in the Doñana marshes to predict water turbidity and depth from band reflectance using Generalized Additive Models. We have point samples for 12 different dates simultaneous with 7 Landsat-5 and 5 Landsat-7 overpasses. The best model for water turbidity in the marsh explained 38% of variance in ground-truth data and included as predictors band 3 (630–690 nm), band 5 (1550–1750 nm) and the ratio between bands 1 (450–520 nm) and 4 (760–900 nm). Water turbidity is easier to predict for water bodies like the Guadalquivir River and artificial ponds that are deep and not affected by bottom soil reflectance and aquatic vegetation. For the latter, a simple model using band 3 reflectance explains 78.6% of the variance. Water depth is easier to predict than turbidity. The best model for water depth in the marsh explains 78% of the variance and includes as predictors band 1, band 5, the ratio between band 2 (520–600 nm) and band 4, and bottom soil reflectance in band 4 in September, when the marsh is dry. The water turbidity and water depth models have been developed in order to reconstruct historical changes in Doñana wetlands during the last 30 years using the Landsat satellite images time series.     

德意志联邦共和国五座城市的大气悬浮物中的135种多环芳烃

多环芳烃(PAH)产生于有机物的未完全燃烧过程,并以气态或附于液态和固态颗粒上散发到大气中去。PAH的数量以及各种PAH之间的数量比例,也就是PAH的分布情况,在很大程度上与燃烧过程有关,甚至于可以说不同的散发情况会有各自典型的分布。 然而我们主要感兴趣的不是排放的PAH分布与人体负荷的关系,而更多的是关心实际吸入的PAH情况。这一点既和各项排放有关也与PAH从排放到被大气吸收的变化有关。     

The hierarchy and spatial characteristics of ecosystems: A reconsideration of the ecosystem concept (II)

This paper, based on the autonomy concept, continues to investigate hierarchical forms and spatial structure of ecosystems. The former can lead to limits for the selection of the component parts of an ecosystem and a distinction between its endogenous and exogenous variables; and the latter can be lead to a hypothesis of the space of an ecosystem: the space of an ecosystem = its habitat area + supporting area + impact area, and two characteristics of ecosystems, space-overlapping and the area of ecosystem space, have been further studied referring to human activities.     

石油成分是预测新区含油气性的标准

在普查勘探工作中采集到的石油,其化学成分可为区域勘探阶段中一些地区含油气远景评价的地球化学标准。在这种情况下,石油显示的本身并不是解决地区远景问题的明确标志。只有全面的地球化学分析才能判断,是象世界大多数油田那样的“正常石油”     

Influence of x-ray diffraction sample preparation on quantitative mineralogy: implications for chromate waste treatment

Powders of chromite ore processing residue (COPR) were mineralogically evaluated using quantitative X-ray powder diffraction (XRPD) to illustrate the impacts of sample preparation procedures. Chromite ore processing residue is strongly alkaline, reactive, contains minerals of varying hardness and absorption coefficients, and exhibits significant amorphicity. This poses a challenge to produce powders for XRPD analysis that are sufficiently fine and of uniform particle size while avoiding mineral reactions and overgrinding effects. Dry, hand pulverization to different grain sizes, and wet, mechanical pulverization (micromilling) using four milling liquids (cyclohexane, isopropanol, ethanol, and water), and variable milling durations (up to 15 min) were evaluated. Micromilling with a light, nonpolar, highly evaporative liquid such as cyclohexane with a milling time of 5 min mitigated systematic errors such as microabsorption and preferred orientation as it produced finer and more uniform particle size distributions than the hand-pulverized powders, while simultaneously affording the least time for sample preparation. Conversely, the use of water as milling liquid resulted in extensive hydration reactions during sample preparation, causing mischaracterization and significant underestimation of its reactive brownmillerite content, which can complicate the remediation design process for COPR. Hand pulverization emerged as a necessary complement to quantify Cr(VI)-containing, softer minerals destroyed during mechanical milling, the quantification of which has also important implications for COPR treatment design. The findings of this study may be applicable in a variety of geochemically complicated and reactive environmental media (metal-contaminated soils, stabilized/solidified media, inorganic waste), and points to the importance of the sample preparation method to obtain reliable quantitative XRPD results.     

A preliminary in vitro assessment of GroBiotic-A, brewer's yeast and fructooligosaccharide as prebiotics for the red drum Sciaenops ocellatus

This study examined the effects of brewers yeast, fructooligosaccharide (FOS), and GroBiotic-A, a mixture of partially autolyzed brewers yeast, dairy components and dried fermentation products, on the intestinal microbial community of red drum, Sciaenops ocellatus. Gastrointestinal (GI) tracts were aseptically removed from three sub-adult red drum previously maintained on a commercial diet and placed in an anaerobic chamber. Intestinal contents were removed, diluted and incubated in vitro in one of four liquid media: normal diet alone, diet + 2% (w/w) GroBiotic-A, diet + 2% brewers yeast, and diet + 2% FOS. After 24 and 48 h of incubation at 25 degrees C, supernatants were removed for volatile fatty acid (VFA) analysis and DNA was extracted for denaturing gradient gel electrophoresis (DGGE) analysis. Polymerase chain reaction (PCR) was performed on a highly conserved region of M 16S rDNA and the amplicons were subjected to DGGE. The microbial community (MC) fingerprint was used to distinguish microbial populations. The intestinal contents incubated with GroBiotic-A had significantly (P<0.05) higher acetate and total VFA concentrations at 48 h compared to the other treatments. DGGE analysis demonstrated that the microbial community was significantly altered by Grobiotic-A and brewers yeast.