Enhancement of semi-theoretical models for predicting peak discharges in breached embankment dams

Environmental Fluid Mechanics - During the application of semi-theoretical models to predict peak discharges for breached embankment dams, it is often encountered to be lack of necessary model...     

雄激素1,4-雄烯二酮和雄烯二酮对斑马鱼胚胎昼夜节律和下丘脑-垂体-性腺轴通路中基因转录表达的影响

雄激素1,4-雄烯二酮(androstadienedione, ADD)和雄烯二酮(androstenedione, AED)主要用于人类和牲畜疾病的预防和治疗。近年来,ADD和AED的大量使用导致其在河流中广泛检出,甚至在多种鱼类体内亦有检出,且浓度较高。ADD和AED已被证实对鱼类具有生殖毒性和发育毒性,但ADD和AED在转录水平上对鱼类的影响鲜有报道。为探究ADD和AED分子水平毒性,本研究考察了斑马鱼胚胎暴露于ADD(4.48、30.0和231 ng·L~(-1))和AED(3.64、21.7和230 ng·L~(-1))144 h后,对其昼夜节律和下丘脑-垂体-性腺轴(hypothalamic-pituitary-gonadal axis, HPG axis)通路中基因转录表达的影响。结果表明,所有浓度的ADD都显著上调了昼夜节律通路中生物钟基因(per1b)、核受体亚族1的D群基因(nr1d2b)、隐花色素基因(cry5)和si:ch211-132b12.7的转录水平,30.0和231 ng·L~(-1)的ADD下调了时钟节律调节因子基因(clocka)和芳香烃受体核转录蛋白样基因(arntl2)的转录水平。3.64 ng·L~(-1)AED显著增强了per1b和nr1d2b的转录表达。此外在HPG轴中,30.0 ng·L~(-1)ADD显著降低了促黄体生成素V亚基基因(lhb)的转录表达水平,而3.64 ng·L~(-1)AED显著上调了lhb的转录表达水平。值得注意的是,4.48ng·L~(-1)ADD和3.64 ng·L~(-1)AED均显著降低了细胞色素P450的11亚族基因(cyp11b)的转录表达水平。上述研究表明,ADD和AED对昼夜节律和HPG轴中相关基因的转录表达有显著性影响,对斑马鱼具有潜在的内分泌干扰风险。     

Impact of land use and land cover changes on ecosystem services in Menglun, Xishuangbanna, Southwest China

Changing the landscape has serious environmental impacts affecting the ecosystem services, particularly in the tropics. In this paper, we report changes in ecosystem services in relation to land use and land cover over an 18-year period (1988--2006) in the Menglun Township, Xishuangbanna, Southwest China. We used Landsat TM/ETM and Quickbird data sets to estimate changes in ten land use and land cover categories, and generalized value coefficients to estimate changes in the ecosystem services provided by each land category. The results showed that over the 18-year period, the land use and land cover in the study area experienced significant changes. Rubber plantations increased from 12.10% of total land cover to 45.63%, while forested area and swidden field decreased from 48.73 and 13.14 to 27.57 and 0.46%, respectively. During this period, the estimated value of ecosystem services dropped by US $11.427 million (approximately 27.73%). Further analysis showed that there were significant changes in ecological functions such as nutrient cycling, erosion control, climate regulation and water treatment as well as recreation; the obvious increase in the ecological function is provision of raw material (natural rubber). Our findings conclude that an abrupt shift in land use from ecologically important tropical forests and traditionally managed swidden fields to large-scale rubber plantations result in a great loss of ecosystem services in this area. Further, the study suggests that provision of alternative economic opportunities would help in maintaining ecosystem services and for an appropriate compensation mechanisms need to be established based on rigorous valuation.     

Seasonal variation, source, and regional representativeness of the background aerosol from two remote sites in western China

Using observations from two remote sites during July 2004 to March 2005, we show that at Akdala (AKD, 47° 06′ N, 87° 58′ E, 562 m asl) in northern Xinjiang Province, there were high wintertime loadings of organic carbon (OC), elemental carbon (EC), and water-soluble (WS) ${\rm SO}_{4}^{2-}$ , ${\rm NO}_{3}^{2-}$ , and ${\rm NH}_{4}^{+}$ , which is similar to the general pattern in most areas of China and East Asia. However, at Zhuzhang (ZUZ, 28° 00′ N, 99° 43′ E, 3,583 m asl) in northwestern Yunnan Province, the aerosol concentrations and compositions showed little seasonal variation except for a decreasing trend of OC from August to autumn–winter. Additionally, the OC variations dominated the seasonal variation of PM₁₀ (particles ≤10 μm diameter) level. Chemical characteristics combined with transport information suggested sea salt origin of ionic Na^?+?, Mg^2?+?, and Cl^??? at ZUZ. At AKD, ionic Ca^2?+?, Mg^2?+?, Na^?+?, and Cl^??? primarily originated from salinized soil. Furthermore, the WS Ca^2?+? contributions (5.4–6%) to the PM₁₀ mass during autumn, winter, and early spring reflected a constant dust component. The results of this study indicated that both sites were regionally representative. However, the representative regions and scales of these background sites may vary seasonally as the regional atmospheric transport patterns change. Seasonal variations in the background aerosol levels from these two areas need to be considered when evaluating the regional climate effects of the aerosols.     

某市饮用水水质生物稳定性研究

研究某市的几个典型水厂的ＡＯＣ和ＢＤＯＣ含量和其在处理工艺和管 的变化规律,以及对爆管管道取样作扫描电镜分析,得到初步结论：（１）水源水质较好的水厂其出厂水和管网水中ＡＯＣ含量相对较低,反之则高,（２）在饮用水中ＡＯＣ与ＢＤＯＣ之比变化较大,但大量数据统计结果表明平均约为３０－４０％,因此如果以ＢＤＯＣ作为饮用水生物稳定性的评价指标也是可以的,（３）常规给水处理工艺对ＡＯＣ的支 动较大,大多数情况     

UV/H2O2联合氧化法去除畜禽养殖废水中抗生素

随着畜禽养殖业的迅猛发展,畜禽养殖废水污染问题日益突出,尤其是养殖过程中大量使用抗生素,致使畜禽养殖废水含有抗生素,成为一类新型环境危害污染物.如何有效去除畜禽养殖废水中的抗生素,成为国内外研究热点.采用UV/H2O2联合氧化法去除畜禽养殖废水中抗生素(磺胺甲恶唑、磺胺噻唑、磺胺甲噻二唑、磺胺二甲氧嘧啶、磺胺二甲嘧啶)...     

几种烟气脱硫剂的脱硫性能试验

用添加Ｃａ（ＯＨ）２的碱性水,含炉灰渣、赤泥的碱性工业废水及含有Ｆｅ２＋、Ｍｎ２＋催化剂的水溶液作为吸收液;以冷态模拟脱硫洗涤塔为吸收设备,研究了多种脱硫剂的脱硫效果。结果显示,Ｃａ（ＯＨ）２、Ｆｅ２＋、Ｍｎ２＋催化剂对浓度为１０００～２０００ｐｐｍ的ＳＯ２气体有较高脱硫效率;炉灰水、赤泥水对浓度为１０００ｐｐｍ左右的ＳＯ２气体有明显的脱硫效果     

挥发性有机物低温等离子体降解的影响参数研究

作为一类重要的有机污染物,挥发性有机物的危害已引起了世界各国的广泛关注。以挥发性有机物代表物质苯为研究对象,考察了多种实验参数对苯降解特性的影响。在高频电源条件下,对于施加电压、电源频率及反应器参数（包括管径、有效长度、电极材料和电极直径）与苯去除率的关系进行了研究。结果表明,高施加电压、高电源频率有利于苯的降解。管径较小、有效长度较长、内电极直径较大、内电极材料为钨的反应器对于苯的去除效果明显。反应器参数与电源的匹配问题对于提高污染物去除率及节能降耗方面十分重要。     

4种重金属离子对间接火焰原子吸收光谱法测定铝的干扰

空气-乙炔间接火焰原子吸收法是我国目前运用较多且易于推广的铝检测方法,研究了Mg2+、Ca2+、Zn2+和Ni2+4种离子对此法测定0.40 mg/L Al3+的干扰情况。得出如下结论:(1)在±5%误差范围内,15.10 mg/L Mg2+、105.00mg/L Ca2+、0.23 mg/L Zn2+、0.88 mg/L Ni2+对0.40 mg/L Al3+无干扰。(2)本方法虽然操作复杂,但成本较低、灵敏度高,检测的浓度范围宽、稳定性好,加标回收率为96%~99%,检出限为0.04 mg/L,适宜测定范围为0.05~100.00 mg/L,适用于饮用水、河水及地下水中Al3+的测定。     

Development of Instrumentation for Continuous On-line Monitoring of Non-Methane Organic Carbon in Air Emissions

ABSTRACT

Non-methane organic carbon (NMOC) is a measure of total organic carbon in an air emission, excluding that from methane. Thus, it measures the total amount of carbon, irrespective of the structure and functional groups in the molecule. The U.S. Environmental Protection Agency (EPA) Method 25 is used for quantification of NMOC in emission sources and in ambient air. This method involves laboratory analysis of collected air samples and cannot be used for real-time measurements. It is prone to interferences from CO₂, CH₄, and CO, as well as moisture. In this paper, a novel method for continuous, on-line monitoring of NMOC in air emissions and ambient air is presented. Detection limits are at ppb levels, and interference of permanent gases have been eliminated.