极端严寒地区湿法烟气脱硫系统的设计

通过实例,介绍了如何通过设计优化,使湿法烟气脱硫系统(FGD)在我国北方极端严寒地区的脱硫工程中得到稳定、可靠的运行.     

“烟塔合一”脱硫技术应用中应注意的问题

以山阴电厂2×300MW机组烟气排放系统采用的烟囱、间冷塔、吸收塔"三塔合一"项目为例,分析了湿法脱硫技术运用在烟塔合一项目中的特点及所需要注意的问题。     

模拟氮沉降对内蒙古克氏针茅草原N2O排放的影响

随着工农业和社会的快速发展,我国成为全世界氮沉降最高的国家之一,温带草原地区的氮沉降水平局部可能超过3g·(m~2·a)~(-1).为研究氮沉降对我国典型草原生态系统氮循环的影响,在内蒙古太仆寺旗的克氏针茅草原,对土壤氧化亚氮(N_2O)的排放进行了为期1 a测定;同时,对该天然草地施加Na NO_3~-N以模拟氮沉降增加,进行了6个水平:CK(对照)、N_2[2g·(m~2·a)~(-1)]、N5[5 g·(m~2·a)~(-1)]、N10[10 g·(m~2·a)~(-1)]、N_25[25 g·(m~2·a)~(-1)]和N50[50 g·(m~2·a)~(-1)]的野外控制实验.结果表明,在自然氮沉降条件下,该生态系统N_2O的排放主要取决于土壤含水量和土壤温度,通过参数拟合估计全年N_2O-N排放量为0.10 g·(m~2·a)~(-1),约为当地氮沉降量的3%.而提高氮沉降可以显著提高N_2O的排放,特别是在高氮处理下(N_25和N50),N_2O的年排放量与模拟氮沉降量呈线性关系.我国温带典型草原较高的温室气体N_2O排放值得关注.     

高炉煤气高效曲板脱水装置的试验研究

提出了一种降低机械水含量的新型脱水装置,针对曲板脱水装置内两相流动复杂的问题,在改变结构和运行参数的情况下对曲板脱水装置的性能进行了试验研究,探讨了各影响因素对脱水效率和压力损失的影响。试验结果表明:曲板脱水装置的最佳气流速度为1.75～2.25 m/s,曲板间距为5～7.5 mm,斜板长度为200～250 mm,液气比为0.2～0.25 L/m3,水雾粒径为100～500μm时,可以获得最高脱水效率和最小压力损失。     

The Effects of Acidity on Carbon Fluxes from Ombrotrophic Peat

Replicate intact peat/vegetation monoliths were collected along a pollution gradient in the UK and subjected over one year to 1200 mm of simulated rainfall of the same chemical composition as they received in the field. Drainage water was analysed periodically for DOC and pH, and the decomposition rates of Calluna vulgaris and Eriophorum angustifolium leaves were measured, as well as soil atmosphere CO₂ contents and peat matric potentials. the chemical characteristics of the peats as initially sampled from the field also were determined. the results suggest that acidic precipitation has induced chemical changes in ombrotrophic peats, lowering their pH and base status, when due account is taken of calcium deposition or any mineral content. Greater DOC fluxes were observed from the more acid peats, and litter decomposition rates from these peats were reduced.     

Foliar and root uptake of Cs, Sr and Zn in processing tomato plants (Lycopersicon esculentum Mill.)

The results of an experimental study on the behaviour of ¹³⁴Cs, ⁸⁵Sr and ⁶⁵Zn in processing tomato plants grown in peat substrate are presented. Plants were contaminated by wet deposition of ¹³⁴Cs, ⁸⁵Sr and ⁶⁵Zn, either by sprinkling the above ground part at two phenological stages or by administering ¹³⁴Cs, ⁸⁵Sr and ⁶⁵Zn to the soil. The plants contaminated at the second phenological stage intercepted 38.3% less than those contaminated at the first stage, although leaf area increased by more than double. Transfer coefficients from peat soil to ripe fruit for ¹³⁴Cs are significantly higher than those for ⁸⁵Sr and ⁶⁵Zn. Leaf to fruit transfer coefficients for ¹³⁴Cs are one order of magnitude higher than for ⁶⁵Zn and two orders higher than for ⁸⁵Sr. Only when deposition affects fruits, as at the second phenological stage, are transfer coefficients to fruits similar for the three radionuclides.     

A Chronology of Nitrogen Deposition in the UK Between 1900 and 2000

Measurements of the concentrations of nitrogen compounds in air and precipitation in the UK have been made since the mid-19th century, but no networks operating to common protocols and having traceable analytical procedures were established until the 1950s. From 1986 onwards, a high-quality network of sampling stations for precipitation chemistry was established across the UK. In the following decade, monitoring networks provided measurement of NO₂, NH₃, HNO₃ and a satisfactory understanding of the dry deposition process for these gases allowed dry deposition to be quantified. Maps of N deposition for oxidized and reduced compounds at a spatial scale of 5 km × 5 km are available from 1986 to 2000. Between 1950 and 1985, the more limited measurements, beginning with those of the European Air Chemistry Network (EACN) provide a reasonable basis to estimate wet deposition of NO ₃ ^– –N and NH ₄ ⁺ –N. For the first half of the century, estimates of deposition were scaled with emissions assuming a constant relationship between emission and deposition for each of the components of the wet and dry deposition budget at the country scale. Emissions of oxidized N, which dominated total nitrogen emissions throughout the century, increased from 312 kt N annually in 1900 to a peak of 787 kt for the decade 1980–1990 and then declined to 460 kt in 2000. Emissions of reduced N, largely from coal combustion were about 168 kt N in 1900, increasing to a peak of 263 kt N in 2000 and by now dominated by agricultural sources. Reduced N dominated the deposition budget at the country scale, increasing from 163 kt N in 1900 to 211 kt N in 2000, while deposition of oxidized N was 66 kt N in 1900 and 191 kt N in 2000. Over the century, 68 Mt (Tg) of fixed N was emitted within the UK, 78% as NO _x , while 29 Mt of nitrogen was deposited (43% of emissions), equivalent to 1.2 t N ha^–1, on average, with 60% in the reduced form. Deposition to semi-natural ecosystems is approximately 15 Tg N, equivalent to between 1 and 5 t N ha^–1, over the century and appears to be accumulating in soil. The N deposition over the century is similar in magnitude to the total soil N inventory in surface horizons.     

短期氮添加对黄土高原人工刺槐林土壤有机碳组分的影响

人类活动背景下,氮(N)沉降持续影响着生态系统的碳循环.氮沉降对土壤有机碳的影响与不同碳组分的差异性响应有关.为探究短期氮沉降背景下土壤有机碳组分变化及其影响因素,基于野外氮添加试验,以刺槐人工林为研究对象,共设置4个氮添加梯度：0(CK)、1.5(N1)、3(N2)和6(N3) g·(m²·a)^-1,分别在6月和9月进行取样,测定土壤理化性质、微生物生物量和酶活性.结果表明：(1)外源氮输入降低了土壤pH,促进可溶性有机碳含量的增加,增加了土壤氮素有效性.(2)短期氮添加显著降低了土壤有机碳含量,且有机碳各组分对氮添加响应不同.其中,易氧化有机碳含量显著降低,且在N2处理下达到最低,与对照相比分别降低了54.4%和48.2%,惰性有机碳含量增加,但增加不显著.氮添加降低了土壤碳库活度,提高了土壤碳库的稳定性.土壤碳库活度分别在N3和N2处理下达到最低,与对照相比分别降低了53.3%和52.80%.(3)随机森林模型表明,短期氮添加下土壤微生物生物量化学计量比、微生物生物量碳和AP是驱动土壤有机碳活度变化的关键因子,分别解释了易氧化有机碳和惰...     

湿法预处理对垃圾焚烧飞灰中重金属的形态及风险影响研究

以某典型城市生活垃圾焚烧飞灰为研究对象,采用X射线荧光光谱仪（XRF）、X射线衍射仪（XRD）和电感耦合等离子体光谱仪（ICP）测定了焚烧飞灰的主要成分、矿物学组成和重金属含量,探讨了湿法预处理工艺对飞灰的化学组成、矿物学形态、化学形态及风险水平的影响.结果表明,飞灰的主要化学组成为O、Ca、Cl、Na、K等,占飞灰总质量的93.54％,其次含有0.04％ ～0.68％的Zn、Pb、Cu、Cr等微量重金属元素;经过湿法预处理,飞灰中可溶性氯盐具有较好的去除效果,且几乎所有重金属元素的不稳定形态（弱酸提取态和可还原态）比例都有一定程度的减少,有效降低了重金属的毒性、生物有效性及环境风险水平.本研究有助于降低焚烧飞灰的环境风险和探寻其资源化的有效途径.     

渤海湾大气金属元素沉降和来源解析研究

干湿沉降是污染物从大气进入到地表生态环境的主要途径.渤海湾临近大气污染严重的京津冀地区,同时受航运交通排放影响,但渤海湾大气金属元素沉降量及其来源并不十分清楚.本研究于2016年11月—2017年10月在渤海西岸采集了大气沉降样品,利用电感耦合等离子体质谱仪(ICP-MS)对样品中25种金属元素的含量进行了测定分析,估算了大气金属沉降量并进行了源解析.结果表明:沉降样品中25种元素的浓度变化范围为2458.8μg·L~(-1)(Ca)～9.9 ng·L~(-1)(Th),年沉降量变化为1229.9 mg·m~(-2)·a~(-1)(Ca)～5.0μg·m~(-2)·a~(-1)(Th).受降水量季节分布的影响,多数金属元素的沉降量在夏季最高,春秋季较低.除Be、Fe、Ni、Cr、Al、Th和U等元素外,其余18种元素都有不同程度的富集,特别是Cd、Ag、Se和Sb等元素已高度富集.燃煤(12.8%)、扬尘(25.9%)、工业(33.1%)和航运(28.2%)是渤海湾沉降样品中金属元素的主要来源,尤其是航运排放对海湾大气Sb、Cd和Mo沉降具有显著贡献.研究结果可为京津冀区域海陆协同发展和环境质量改善提供科学参考.