Assessment of heavy metals in sediments from a typical catchment of the Yangtze River, China

An intensive investigation was conducted to study the accumulation, speciation, and distribution of various heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in sediments from the Yangtze River catchment of Wuhan, China. The potential ecological risks posed by these heavy metals also were estimated. The median concentrations of most heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) were higher than the background values of soils in Wuhan and were beyond the threshold effect level (TEL), implying heavy metal contamination of the sediments. Carbonate-bound Cd and exchangeable Cd, both of which had high bioavailability, were 40.2% and 30.5% of the total for Cd, respectively, demonstrating that Cd poses a high ecological risk in the sediments. The coefficients of the relationship among Pb, Hg, and Cu were greater than 0.797 using correlation analysis, indicating the highly positive correlation among these three elements. Besides, total organic carbon content played an important role in determining the behaviors of heavy metals in sediments. Principal component analysis was used to study the distribution and potential origin of heavy metals. The result suggested three principal components controlling their variability in sediments, which accounted for 36.72% (factor 1: Hg, Cu, and Pb), 28.69% (factor 2: Cr, Zn, and Ni), and 19.45% (factor 3: As and Cd) of the total variance. Overall, 75% of the studied sediment samples afforded relatively low potential ecological risk despite the fact that generally higher concentrations of heavy metals relative to TEL were detected in the sediments.     

Spatial heterogeneity of stream environmental conditions and macroinvertebrates community in an agriculture dominated watershed and management implications for a large river (the Liao River,China) basin

Understanding the effects of watershed land uses (e.g., agriculture, urban industry) on stream ecological conditions is important for the management of large river basins. A total of 41 and 56 stream sites (from first to fourth order) that were under a gradient of watershed land uses were monitored in 2009 and 2010, respectively, in the Liao River Basin, Northeast China. The monitoring results showed that a total of 192 taxa belonging to four phyla, seven classes, 21 orders and 91 families were identified. The composition of macroinvertebrate community in the Liao River Basin was dominated by aquatic insect taxa (Ephemeroptera and Diptera), Oligochaeta and Molluscs. The functional feeding group GC (Gatherer/Collector) was dominant in the whole basin. Statistical results showed that sites with less watershed impacts (lower order sites) were characterized by higher current velocity and habitat score, more sensitive taxa (e.g., Ephemeroptera), and the substrate was dominated by high percentage of cobble and pebble. The sites with more impacts from agriculture and urban industry (higher order sites) were characterized by higher biochemical (BOD₅) and chemical oxygen demand (COD), more tolerant taxa (e.g., Chironominae), and the substrate was dominated by silt and sand. Agriculture and urban-industry activities have reduced habitat condition, increased organic pollutants, reduced macroinvertebrate abundance, diversity, and sensitive taxa in streams of the lower Liao River Basin. Restoration of degraded habitat condition and control of watershed organic pollutants could be potential management priorities for the Basin.     

双酚A替代品与双酚A对非洲爪蛙急性毒性及其应激响应的比较

双酚F(bisphenol F, BPF)和双酚AF(bisphenol AF, BPAF)作为双酚A(bisphenol A, BPA)的替代品已被投入生产和使用,然而目前有关BPA替代品毒性的数据还很缺乏。本文从急性毒性和应激响应2个方面比较了BPF、BPAF与BPA对非洲爪蛙蝌蚪的毒性。结果表明,48 h的半致死浓度(LC_(50))顺序为BPF(11.01 mg·L~(-1))>BPA(7.54 mg·L~(-1))>BPAF(2.87 mg·L~(-1));对氧化应激水平的影响BPAF强于BPA,BPF与BPA相近;BPA和BPAF对热休克蛋白基因表达水平有影响,BPF没有影响。本研究提示,BPAF作为BPA的替代品,其毒性强于BPA,而BPF与BPA类似。     

Utilizing transparent and conductive SnO2 as electron mediator to enhance the photocatalytic performance of Z-scheme Si-SnO2-TiOx

• A novel Z-scheme Si-SnO₂-TiO_x with SnO₂ as electron mediator is first constructed. • Transparent and conductive SnO₂ can pass light through and promote charge transport. • V_O from SnO₂ and TiO_x improve photoelectrochemical performances. • Efficient photocatalytic degradations originate from the Z scheme construction. Z-scheme photocatalysts, with strong redox ability, have a great potential for pollutants degradation. However, it is challenging to construct efficient Z-scheme photocatalysts because of their poor interfacial charge separation. Herein, by employing transparent and conductive SnO₂ as electron mediator to pass light through and promote interfacial charge transportation, a novel Z-scheme photocatalyst Si-SnO₂-TiO_{x (1<x<2)} was constructed. The Z-scheme photocatalyst displayed an order of magnitude higher photocurrent density and a 4-fold increase in open-circuit potential compared to those of Si. Moreover, the onset potential shifted negatively for approximately 2.2 V. Benefiting from these advantages, this Z-scheme Si-SnO₂-TiO_x exhibited efficient photocatalytic performance toward phenol degradation and mineralization. 75% of the phenol was degraded without bias potential and 70% of the TOC was removed during phenol degradation. Other typical pollutants such as bisphenol A and atrazine could also be degraded without bias potential. Introducing a transparent and conductive electron mediator to construct Z-scheme photocatalyst gives a new sight to the improvement of photocatalytic performance in Z scheme.     

Land Degradation Evaluation in North Hebei Province Based on Remote Sensing and GIS

Land degradation is one of the serious environmental problems that can lead to poverty, and is especially prominent in eco-fragile areas in developing countries and increases the risk of environmental safety. North Hebei Province belongs to an ecologically fragile region in North China, which has great impact on the eco-safety of Beijing and Tianjin. Using Landsat TM data and GIS, this paper evaluates land degradation in North Hebei province of China from the the 1960＇s to 1987 and 2000. Land use/cover change pattern from 1987 to 2000, its regional difference and forest change characteristics will also be analyzed; soil erosion intensity and arable land suitability were also evaluated. Results revealed that land use/cover pattern in this study area did not change greatly from 1987 to 2000. The structure and function of regional land ecosystem was at a level of local improvement and integral deterioration. Land above medium soil erosion intensity reached 21 percent, which was also the area with a serious soil erosion and land degradation problem. Soil erosion and land degradation intensity of grassland was the biggest. For the present arable land, the proportion of high suitability was 13 percent.     

麻质活性炭的制备及其对Cu2＋的吸附研究

以废麻为原料,KOH为活化剂制备粉状活性炭,通过静态吸附实验研究了活性炭对Cu2＋的吸附性能,探讨了溶液起始pH值、活性炭投加量、吸附时间、起始Cu2＋质量浓度等对Cu2＋吸附效果的影响。结果表明,溶液pH和活性炭投加量对吸附效果有较大影响,活性炭对Cu2＋的吸附率在60 min内超过50%,初始浓度在10~50 mg/L时,活性炭对Cu2＋的吸附量与起始浓度近似成正比。采用Langmuir、Freundlich吸附等温式对吸附平衡数据进行了拟合,结果表明吸附等温线符合Frenudlich模型。采用傅立叶红外光谱法（FT-IR）分析了活性炭的表面官能团,分析表明活性炭表面酸性官能团可能是吸附Cu2＋的活性中心。     

天祝县地震监测网点建设及地质构造断层划分的探讨

地震监测网点建设与地质构造断层划分是地震观测和预报技术的一个重要组成部分。必须按照中国地震局地震台网前兆标准和甘肃省地震局台网建设规定，统一布设网点，打破行政区域界线，根据地震活动背景，从地震活动性、灵敏性、密集性，重要性构造差异，人口密度等因素布局设立地震监测网点。地震监测网点布局必须服从地震科研和预报的需要，有目地、有组织、有限度、有预测。本文以天祝县地震监测网点建设为实例，探讨了以上问题。     

城市生活垃圾卫生填埋场恶臭的防治技术进展

恶臭污染已成为垃圾处理和处置过程中的严重公害。在分析中,介绍了填埋场各区域恶臭的控制措施,综述了卫生填埋场恶臭的常规防治技术,重点讨论了生物技术在填埋场脱臭中的应用,这些防治技术对各类环境卫生设施,如垃圾收集站、中转站、焚烧场、堆肥厂及粪便处理厂的臭气治理均有借鉴意义。     

Identification of rice cultivar with exclusive characteristic to Cd using a field-polluted soil and its foreground application

Using low-accumulative plant, especially excluder crop, to safely produce food is one of the very important technologies of phytoremediation, which is practical to safe production and long-term remediation of heavy metal-contaminated soil. A pot experiment using field cadmium (Cd)-contaminated soil (Cd concentration was 0.75 mg?kg^?1) was conducted to compare Cd accumulation differences among 39 normal rice cultivars (Japonica) in Shenyang region of China for food safety and high grain yield aim. The results showed that brown grain Cd concentration in 12 rice cultivars of a total of 39 tested cultivars was lower than 0.2 mg?kg^?1 (Agricultural Trade Standard of Nonpollution Food for Rice of China, NY 5115–2008). In these 12 cultivars, Cd enrichment factors (Cd concentration ratio in shoot to that in soil) of nine cultivars were lower than 1. Likewise, Cd translocation factors (Cd concentration ratio in shoot to that in root) of eight cultivars were lower than the 0.28 average. Furthermore, grain yield per pot of seven cultivars were higher than the average 18.4 g?pot^?1. Four cultivars, i.e., Shendao 5, Tianfu 1, Fuhe 90, and Yanfeng 47 showed Cd-exclusive characteristic and better foreground application.     

美人蕉对西安护城河水体净化功能的初步研究

以西安护城河污染较严重的北门段水体为研究对象,利用浮床技术种植美人蕉净化重污染水体。研究表明,美人蕉对西安护城河北门段河水TN、TP、COD、NH3-N等的去除率分别为77.4%、89%、93%、97%;这为利用美人蕉浮床系统对西安市护城河水体修复提供了科学依据。