Biological elimination of H2S and NH3 from wastegases by biofilter packed with immobilized heterotrophic bacteria

Biotreatment of various ratios of H₂S and NH₃ gas mixtures was studied using the biofilters, packed with co-immobilized cells (Arthrobacter oxydans CH8 for NH₃ and Pseudomonas putida CH11 for H₂S). Extensive tests to determine removal characteristics, removal efficiency, removal kinetics, and pressure drops of the biofilters were performed. To estimate the largest allowable inlet concentration, a prediction model was also employed. Greater than 95% and 90% removal efficiencies were observed for NH₃ and H₂S, respectively, irrespective of the ratios of H₂S and NH₃ gas mixtures. The results showed that H₂S removal of the biofilter was significantly affected by high inlet concentrations of H₂S and NH₃. As high H₂S concentration was an inhibitory substrate for the growth of heterotrophic sulfur-oxidizing bacteria, the activity of H₂S oxidation was thus inhibited. In the case of high NH₃ concentration, the poor H₂S removal efficiency might be attributed to the acidification of the biofilter. The phenomenon was caused by acidic metabolite accumulation of NH₃. Through kinetic analysis, the presence of NH₃ did not hinder the NH₃ removal, but a high H₂S concentration would result in low removal efficiency. Conversely, H₂S of adequate concentrations would favor the removal of incoming NH₃. The results also indicated that maximum inlet concentrations (model-estimated) agreed well with the experimental values for space velocities of 50–150 h⁻¹. Hence, the results would be used as the guideline for the design and operation of biofilters.     

The perpetual state of emergency that sacrifices protected areas in a changing climate

A modern challenge for conservation biology is to assess the consequences of policies that adhere to assumptions of stationarity (e.g., historic norms) in an era of global environmental change. Such policies may result in unexpected and surprising levels of mitigation given future climate‐change trajectories, especially as agriculture looks to protected areas to buffer against production losses during periods of environmental extremes. We assessed the potential impact of climate‐change scenarios on the rates at which grasslands enrolled in the Conservation Reserve Program (CRP) are authorized for emergency harvesting (i.e., biomass removal) for agricultural use, which can occur when precipitation for the previous 4 months is below 40% of the normal or historical mean precipitation for that 4‐month period. We developed and analyzed scenarios under the condition that policy will continue to operate under assumptions of stationarity, thereby authorizing emergency biomass harvesting solely as a function of precipitation departure from historic norms. Model projections showed the historical likelihood of authorizing emergency biomass harvesting in any given year in the northern Great Plains was 33.28% based on long‐term weather records. Emergency biomass harvesting became the norm (>50% of years) in the scenario that reflected continued increases in emissions and a decrease in growing‐season precipitation, and areas in the Great Plains with higher historical mean annual rainfall were disproportionately affected and were subject to a greater increase in emergency biomass removal. Emergency biomass harvesting decreased only in the scenario with rapid reductions in emissions. Our scenario‐impact analysis indicated that biomass from lands enrolled in the CRP would be used primarily as a buffer for agriculture in an era of climatic change unless policy guidelines are adapted or climate‐change projections significantly depart from the current consensus.     

江苏省自然资源利用时空变化特征及驱动力分析

基于改进的三维生态足迹模型测度江苏省2009—2016年的人均生态足迹、足迹深度与足迹广度,定量分析江苏省自然资源利用状况的时空变化特征;用改进的T型关联分析探讨江苏省人均生态足迹的驱动因子,并利用灰色预测模型GM(1,1)预测江苏省2019—2022年生态足迹与生态承载力的演变趋势。结果表明:1)2009—2016年,江苏省人均生态足迹、人均生态赤字、足迹深度与足迹广度均呈上升趋势,人均生态承载力略有下降。除建设用地外,耕地、林地、牧草地、水域与化石能源用地均处于生态赤字状态,其中,化石能源用地的生态足迹占全省生态足迹的主要部分;牧草地与水域的足迹深度较高,资源存量透支较为严重;耕地的足迹广度占全省足迹广度的主要部分,其在研究期内略有下降。省内各城市间足迹深度与足迹广度的差异较大,足迹深度表现为苏南＞苏中＞苏北,足迹广度为苏北＞苏中＞苏南。2)引导第三产业发展,提高能源利用效率,增强区域贸易交流能够缓解人均生态足迹的增长;人均GDP的增长、城市化水平以及人口规模的提高促进了生态足迹的增长。3)2019—2022年,江苏省人均生态足迹将进一步增加,人均生态承载力将小幅下降,生态赤字现象将继续存在且总量不断增加,生态环境压力进一步加剧。     

基于MIKE 11模型的引江济淮工程涡河段动态水环境容量研究

为探索分析水体环境容量的动态特性,论文以引江济淮工程涡河段为例,首次提出MIKE 11模型结合稀释流量比m值法计算河流水环境容量。计算结果表明:1)基于MIKE 11模型的m值法计算环境容量来分析河流水体环境容量的动态特性是可行的,它综合了环境管理中的总量控制和质量控制思想。2)通过对参数的合理取值,可建立客观反映模拟河段水动力、水质时空演变规律的模型;MIKE 11模型综合考虑河床糙度、纵向扩散系数、综合衰减系数、地表储水层最大含水量、土壤或根区储水层最大含水量等因素,水深的绝对误差(Re)、确定性系数(R2)和Nash-Suttcliffe系数Ens分别为3.30%、0.990和0.984;流量的Re、R2和Ens分别为9.8%、0.969和0.997;义门大桥断面COD模拟误差为13.7%,氨氮模拟误差为14.7%。3)基于MIKE 11模型的m值法计算谯城区COD的月均环境容量为-220.48 g/s、氨氮的月均环境容量为-10.97 g/s;涡阳县COD的月均环境容量为-17.05 g/s、氨氮的月均环境容量为2.56 g/s;蒙城县COD的月均环境容量为30.58 g/s、氨氮的月均环境容量为4.47 g/s;怀远县COD的月均环境容量为176.59 g/s、氨氮的月均环境容量为10.67 g/s;与传统的一维模型计算值相比,计算精度更高。结论认为,此方法可为MIKE 11模型的应用拓宽新思路,为引江济淮工程中河流水体的动态水环境容量计算提供依据,为污染物在横断面均匀混合的非感潮河流水体的环境容量计算和流域水污染治理提供一种新的技术方法。     

废弃聚氨酯硬泡中CFC-11的释放机理

将聚氨酯硬泡在密闭室中切割破碎,破碎后的颗粒置于密闭瓶中并对其加热及常温下长期放置,用GC/MS测量切割破碎和加热时CFC-11的释放量,以及长期放置时CFC-11释放量。结果表明:破碎处理PUR泡沫时,CFC-11的释放分为瞬间释放、短期释放和长期释放三个阶段。将硬泡破碎至<8 mm、<4 mm、<1 mm和<0.5 mm时,CFC-11瞬间释放量分别占CFC-11总量的40.72%、65.24%、70.79%和75.16%;当破碎粒径<0.5 mm时,包裹于硬泡泡孔中的CFC-11全部释放;PUR泡沫破碎后,短期释放和长期释放同时发生;根据理想数学扩散模型和实验所得扩散系数估算,1~10 mm颗粒中残留的CFC-11长期释放时间为2.4~120年。     

壬基酚对斑马鱼精巢组织及性激素合成酶基因表达的影响

壬基酚（NP）是广泛存在于水体中的环境内分泌干扰物,会影响鱼类的生殖和发育.为了解NP影响鱼类精巢发育的分子机制,将成年雄性斑马鱼（Danio rerio）暴露于不同浓度（0、125、250、500μg·L-1）NP下21d,用常规组织学方法研究试验鱼精巢组织结构的变化,并用荧光定量PCR（QRT-PCR）方法检测试验...     

Congenital heart disease and aneuploidy

Congenital heart disease (CHD) is one of the commonest prenatal diagnoses made on routine ultrasound screening. Overall, up to 33% of CHD are associated with fetal aneuploidy. However, some specific cardiac lesions have a significantly greater association with particular chromosomal abnormalities. The majority of fetuses with CHD and aneuploidy also have extra-cardiac anomalies and are best managed by a multidisciplinary team where the management and prognosis of the cardiac defect can be discussed in the context of the baby as a whole. It is therefore important for clinicians involved in the management of fetuses with CHD to be aware of the association of aneuploidy as well as the prognosis and management of these cases, so that they can appropriately counsel the parents. In this chapter, we review the frequency and types of aneuploidy associated with the commonly diagnosed CHD and discuss their management. Copyright © 2004 John Wiley & Sons, Ltd.     

基于MIKE11模型提高污染河流水质改善效果的方法

为寻求提高污染河流水质改善效果的方法,本研究选择中国多坝闸重污染河流颍河为研究对象,针对引江济淮工程颍河段的水质改善要求,以颍河主要的污染物高锰酸盐指数、氨氮为指标,提出了应用MIKE11建立试验河流一维河网水动力和水质模型,采用数值模拟的方法,试验研究河流水质改善的最优技术方法,模拟试验主要进行了补水流量、补水水质、补水位置和补水方式等措施对改善颍河水质效果的影响.模拟结果表明:用MIKE11模型中水动力模块(HD)和对流扩散模块(AD)并结合降雨径流模块(NAM)来进行污染河流水质改善是可行的,即补水流量为河流本底流量的10%,分别对补水点1采用Ⅲ类水,补水点2和补水点3采用Ⅳ类水进行补给,补给效果最佳,高锰酸盐指数和氨氮的去除率分别为72.3%和55.7%,使研究区颍河85%以上的河段达到Ⅳ类水水质标准,为河流污染控制提供了一种新方法.     

Multiscale Plume Transport from the Collapse of the World Trade Center on September 11, 2001

The collapse of the world trade center (WTC) produced enhanced levels of airborne contaminants in New York City and nearby areas on September 11, 2001 through December, 2001. This catastrophic event revealed the vulnerability of the urban environment, and the inability of many existing air monitoring systems to operate efficiently in a crisis. The contaminants released circulated within the street canyons, but were also lifted above the urban canopy and transported over large distances, reflecting the fact that pollutant transport affects multiple scales, from single buildings through city blocks to mesoscales. In this study, ground-and space-based observations were combined with numerical weather forecast fields to initialize fine-scale numerical simulations. The effort is aimed at reconstructing pollutant dispersion from the WTC in New York City to surrounding areas, to provide means for eventually evaluating its effect on population and environment. Atmospheric dynamics were calculated with the multi-grid Regional Atmospheric Modeling System (RAMS), covering scales from 250 m to 300 km and contaminant transport was studied using the Hybrid Particle and Concentration Transport (HYPACT) model that accepts RAMS meteorological output. The RAMS/HYPACT results were tested against PM2.5 observations from the roofs of public schools in New York City (NYC), Landsat images, and Multi-angle Imaging SpectroRadiometer (MISR) retrievals. Calculations accurately reproduced locations and timing of PM2.5 peak aerosol concentrations, as well as plume directionality. By comparing calculated and observed concentrations, the effective magnitude of the aerosol source was estimated. The simulated pollutant distributions are being used to characterize levels of human exposure and associated environmental health impacts.     

基于MIKE11模型入河水污染源处理措施的控制效能分析

为分析入河水污染源不同处理措施的控制效能,以中国多闸坝重污染河流的典型代表—涡河为例,针对"引江济淮"工程涡河段的水质改善需求,以涡河主要污染物COD、氨氮为指标,应用MIKE 11模型建立能客观反映模拟河段水动力、水质时空演变规律的模型;结合情景分析方法对涡河流域入河水污染源不同处理措施的控制效能进行量化评估.模拟结果表明:截污是改善"引江济淮"工程涡河段水质的关键,可降低约18.9%~36.8%的COD入河负荷,以及13.9%~26.3%的氨氮入河负荷;提高污水厂的处理量是改善"引江济淮"工程涡河段水质的有效措施,可削减15.0%的COD和10.8%的氨氮污染;综合处理措施优于单一措施,通过截污、提高污水厂的处理量和排放标准可以使86%以上的河段达到IV类水体要求.本研究结果可为"引江济淮"工程沿线的水污染防治提供技术支持,同时为河流综合治理工程决策提供借鉴和依据.