天津水产业磺胺类耐药细菌及其分布

水产养殖中抗生素的滥用可能会诱导水产品和周围环境中的耐药菌.针对天津市北辰区、西青区、东丽区和津南区的6个水产养殖场的底泥和水样,采用抗性平板筛选耐药细菌,通过对磺胺甲恶唑的耐药率分析,发现底泥中的耐药率要大大高于水中的耐药率,并且与国外的某些研究相比,底泥的细菌耐药率呈现较高的趋势.另外,利用16S-rDNA鉴定出8...     

Temporal-spatial variability and fractal characteristics of soil nitrogen and phosphorus in Xinji District, Hebei Province, China

Traditional statistics, geostatistics, fractal dimensions, and geographic information systems (GIS) were employed to study the temporal?Cspatial variability of soil total nitrogen (TN) and total phosphorus (TP) levels in Xinji District, Hebei Province area of the North China Plain from 1980 to 2007. The results indicate that nutrient levels follow normal or lognormal distributions. The TN content was 0.59 ±0.155 g kg^???1 in 2007, an increase of 0.44 g kg^???1 compared with that of 1980. In 2007, the TP content was 1.21 ±0.227 g kg^???1, an increase of 0.01 g kg^???1 from 1980. The geostatistical analysis showed that the distribution of these soil nutrients in the study area exhibits a trend and anisotropy. The range and [C ₀/(C ₀?+?C)] of TN and TP in 1980 were all less than in 2007. The ordinary kriging interpolation method was used to analyze the nutrient contents differences between 1980 and 2007. The results indicate that soil TN levels have increased over the 27-year period, and the area where the TN level had increased by at least 0.4 g kg^???1 was about 61.7% of the district. The area where the TP content increased covered about 58.4% of the district. The variance analysis indicated that land-use type had a clear influence on the distribution and change in TN and TP content. Using the 3-D box-counting dimension method combined with GIS, the fractal dimension of soil nutrient spatial distribution over the two periods showed that in 27 years, the fractal dimension of TN increased from 1.95 to 2.02, and the fractal dimension of TP increased from 1.89 to 2.01, indicating that the complexity of the spatial distribution of all nutrient contents had increased. This study can provide a basis for accurate fertilizing and to enhance the conversion of soil characteristics under different spatial scales.     

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.     

Test of Firefighter’s Turnout Gear in Hot and Humid Air Exposure

Five students of a rescue training school cycled at 50 W for 20 min at 20 °C before walking at 5 km/hr up to 30 min in a climatic chamber at 55 °C and 30% relative humidity. 4 different types of clothing ensembles differing in terms of thickness and thermal insulation value were tested on separate days. All subjects completed 28–30 min in light clothing, but quit after 20–27 min in 3 firefighter ensembles due to a rectal temperature of 39 °C or subjective fatigue. No difference in the evolution of mean skin or rectal temperature was seen for the 3 turnout ensembles. Sweat production amounted to about 1000 g in the turnout gears of which less than 20% evaporated. It was concluded that the small differences between the turnout gears in terms of design, thickness and insulation value had no effect on the resulting heat physiological strain for the given experimental conditions.     

Woody Vegetation Composition and Structure in Peri-urban Chongming Island, China

Chongming, the world’s largest alluvial island, is located within the municipality of Shanghai, China. Recent projects have now linked peri-urban Chongming to Shanghai’s urban core and as a result will soon undergo substantial changes from urbanization. We quantitatively analyzed the structure and composition of woody vegetation across subtropical, peri-urban Chongming as a basis for sustainable management of these rapidly urbanizing subtropical ecosystems elsewhere. We used 178 permanent, random plots to statistically and spatially analyze woody plant composition and tree structure across the 1,041 km² of Chongming. A total of 2,251 woody plants were measured comprising 42 species in 37 genera. We statistically and geospatially analyzed field data according to land uses and modeled air pollution removal by trees. Average tree diameter at breast height, total height, and crown widths on transportation land uses were greater than other land uses. These same values were lowest on forest land use and greater tree cover was associated with areas of increased anthropogenic activity. Less than 20 % of the woody vegetation was exotic and a species richness index was significantly different between land uses due to legacy effects. Composition of agriculture and forest land uses were similar to residential and transportation. Tree cover across Chongming was also estimated to annually remove 1,400 tons of air pollutants. We propose that this integrated and quantitative method can be used in other subtropical, peri-urban areas in developing countries to establish baseline trends for future sustainability objectives and to monitor the effects of urbanization and climate change.     

要强化减灾的非工程性措施

本文对我国目前在防减灾工程性措施方面存在的问题进行了分析探讨,阐述了在目前国情下强化减灾的非工程性措施的必要性和重要性,并对减灾的非工程性措施的具体作法进行了论述。     

发展家庭经济与区域资源的关系

家庭经济是农村经济的重要组成部分,它适应了区域资源的固有特征,因而在较长时期内仍将在我国农村广泛存在。但是,由于经营权的自主性和决策能力的先天不足,使家庭经济在其发展的每个阶段和生产经营的各个过程都暴露出种种矛盾,制约着家庭经济的发展,这就要求我们必须通过各种途径,引导自发的家庭经济向立足本地资源的产业模式集结,逐步形成各具特色的家庭经济小区。     

含铁废料综合利用及污染防治措施

钢铁行业含铁泥浆的治理一直是个难题，文中就此给出了应用范例，即利用泥浆生产酸性炉料，用于高炉炼铁。并且对可能产生的污染进行了预测，提出了防治措施。