Influences of adding easily degradable organic waste on the minimization and humification of organic matter during straw composting

To find a better composting process with low greenhouse gas emission and high humus production, the effect of adding kitchen waste on reduction and humification of organic matter during straw composting was studied. Three processes were compared, consisting of different ratios of straw and kitchen waste (1:2, 1:1, and 2:1). At four time points over a 62-d incubation, the reduction and humification of compost was evaluated by measuring the total mass, carbon content, and humic material content of the compost. Treatment 1 (straw/kitchen waste ratio of 1:2) reduced the total mass of compost the most. Treatment 2 (straw/kitchen waste ratio of 1:1) reduced the total carbon content the most, reflecting the highest emission of greenhouse gas. Treatment 3 produced the most humic acid material and released the lowest amount of carbon. Hence, from the point of view of reducing greenhouse gas emissions and increasing stable organic matter such as humus and humic acid during composting, treatment #3 was optimal. The three treatments resulted in significant differences in microbial biomass and enzyme activity during composting. The highest amount of active microbial biomass was associated with the largest reduction in compost mass (treatment 1). Higher proportions of straw (treatments 2 and 3), which contains more lignin, were associated with greater β-glycosidase activity, which may generate more humus that can improve soil quality. Dehydrogenase activity seemed to be the most important microbial factor in organic carbon catabolism or humification.     

秸秆焚烧对北京市空气质量的影响

用火焰原子吸收光谱法测试了北京市两个采样点 1 #站 (十三陵站 ,清洁对照点 )和 5#站 (天坛站 ,居民生活区 )1 1 0个大气颗粒物样品中的水溶性钾 ,以表征秸秆焚烧颗粒物。 1 #站水溶性钾的质量浓度年均值为 1 .2 1 μg/m3,其中以1 998年 6月份浓度 (3 .0 7μg/m3)最高 ,是 5月份 (1 .0 2μg/m3)的 3倍 ;5#站水溶性钾的质量浓度年均值为 1 .94μg/m3,6月份 (4 .2 2 μg/m3)最高 ,是 5月份 (1 .97μg/m3)的 2 .1倍。数据分析结果表明 1 998年 6月份麦收季节存在以秸秆焚烧为主的生物质燃烧现象 ,使大气颗粒物中有机碳浓度水平升高 ,并对北京市的空气质量带来负面影响     

Impact of anthropogenic emissions and open biomass burning on regional carbonaceous aerosols in South China

Carbonaceous aerosols were studied at three background sites in south and southwest China. Hok Tsui in Hong Kong had the highest concentrations of carbonaceous aerosols (OC = 8.7 ± 4.5 μg/m³, EC = 2.5 ± 1.9 μg/m³) among the three sites, and Jianfeng Mountains in Hainan Island (OC = 5.8 ± 2.6 μg/m³, EC = 0.8 ± 0.4 μg/m³) and Tengchong mountain over the east edge of the Tibetan Plateau (OC = 4.8 ± 4.0 μg/m³, EC = 0.5 ± 0.4 μg/m³) showed similar concentration levels. Distinct seasonal patterns with higher concentrations during the winter, and lower concentrations during the summertime were observed, which may be caused by the changes of the regional emissions, and monsoon effects. The industrial and vehicular emissions in East, Southeast and South China, and the regional open biomass burning in the Indo-Myanmar region of Asia were probably the two major potential sources for carbonaceous matters in this region.     

Implications of high altitude desert dust transport from Western Sahara to Nile Delta during biomass burning season

The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5-6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe.     

Size distributions of aerosol and water-soluble ions in Nanjing during a crop residual burning event

To investigate the impact on urban air pollution by crop residual burning outside Nanjing, aerosol concentration, pollution gas concentration, mass concentration, and water-soluble ion size distribution were observed during one event of November 4-9, 2010. Results show that the size distribution of aerosol concentration is bimodal on pollution days and normal days, with peak values at 60-70 and 200-300 nm, respectively. Aerosol concentration is 10⁴ cm^-3. nm^-1 on pollution days. The peak value of spectrum distribution of aerosol concentration on pollution days is 1.5-3.3 times higher than that on a normal day. Crop residual burning has a great impact on the concentration of fine particles. Diurnal variation of aerosol concentration is trimodal on pollution days and normal days, with peak values at 03:00, 09:00 and 19:00 local standard time. The first peak is impacted by meteorological elements, while the second and third peaks are due to human activities, such as rush hour traffic. Crop residual burning has the greatest impact on SO₂ concentration, followed by NO₂, O₃ is hardly affected. The impact of crop residual burning on fine particles (< 2.1 μm) is larger than on coarse particles (> 2.1 μm), thus ion concentration in fine particles is higher than that in coarse particles. Crop residual burning leads to similar increase in all ion components, thus it has a small impact on the water-soluble ions order. Crop residual burning has a strong impact on the size distribution of K⁺, Cl^-, Na⁺, and F^- and has a weak impact on the size distributions of NH₄⁺, Ca²⁺, NO₃^- and SO₄^2-.     

浙江2001—2016年露天生物质燃烧排放污染物时空格局

生物质露天燃烧排放烟气颗粒物对大气环境、生态系统和人类健康有重要影响. 该研究基于MODIS - MCD64A1数据提取2001—2016年浙江省森林、灌丛、草地火灾面积和作物秸秆火点数据,结合植被类型、生物质密度和燃烧效率,运用排放因子法,估算16年间浙江区域露天生物质燃烧排放污染物总量. 结果表明,2001—2016年浙江区域露天生物质燃烧总量为58.78 mt,其中乔木、灌木、草本、水稻、小麦、玉米、豆类和油菜燃烧总量分别为202.18 kt、10.43 kt、300.10 t、46.66 mt、1.94 mt、2.45 mt、3.45 mt和4.06 mt. 森林和秸秆火次数分别为1783次和23257次,森林火灾多集中在浙江南部区域,秸秆火多集中在浙江北部区域. 森林和草地火灾次数主要集中在3月和10月,作物秸秆火点主要集中在5、7和8月份,占全年75%以上. 各污染物CO₂、CO、NO_x、VOCs、PM_2.5、TC、OC和EC排放总量分别为667.20、26.40、1.13、4.92、5.12、2.85、2.59和0.23 mt. 该研究揭示了浙江地区生物质露天燃烧排放污染物的时空变化,为深入揭示生物质燃烧对区域环境影响提供数据支持.     

燃煤锅炉低温烟气余热利用探讨

针对燃煤锅炉燃烧产生的低温烟气仍具有一定温度的现象,提出通过增设超导热管空气预热器对这部分低温烟气余热加以回收的设想,对锅炉送风进行预热,探讨烟气余热利用可达到的送风温度、节能效果及可能产生的经济效益。     

插板对正庚烷油池火燃烧行为的影响研究

海上石油泄漏常规的处理方法是原位燃烧,加速其燃烧并使其燃尽是降低其对生态环境影响的重要措施之一。以正庚烷为燃料,在油池内插入竖直铝板,研究不同高度铝板对池火燃烧行为的影响。结果表明,插板对池火燃烧速率以及火焰高度具有明显的增强作用,随着板的高度的增加,增强作用先增大后减小,当H_p/D(板高与油池直径之比)为3.5时,增强作用最大。火焰高度、板的温度、热通量以及燃烧速率的变化趋势一致,它们的临界点均在H_p/D=3.5附近。插板后燃烧速率增大主要是因为插板自身的热传导导致了燃料的核态沸腾,使燃料接受的热反馈增大,从而加快了燃料的蒸发,增大了燃烧速率。     

氢气添加对乙醇/空气预混火焰燃烧特性影响的数值模拟研究

通过对不同混合比率的乙醇/氢气/空气燃烧特性进行数值模拟,研究氢气添加量对点火延迟时间、层流燃烧速度、火焰厚度、化学反应滞留时间及组分分布情况的影响。研究发现一定程度上氢气添加量的增加能够缩短混合气体的点火延迟时间,并且氢气对点火延迟时间的影响随着温度的升高而逐渐减小。随着混合比率的增大,层流燃烧速度增大,并且在混合比率大于0.4时显著增大。火焰厚度及化学反应滞留时间随氢气增加而逐渐减小。此外,进一步分析组分分布情况得知氢气添加使火焰中H*、O*、OH*自由基摩尔分数峰值增大,并且H+O+OH摩尔分数峰值与层流燃烧速度存在线性关系。     

生物质燃烧释放N2O的测定及其分布

本文报导了实验室规模的生物质封闭燃烧系统及稻草、玉米秸、麦杆燃烧过程中Ｎ２Ｏ排放因子的测定结果，测定结果表明：稻草、麦杆及玉米秸燃烧排气中Ｎ２Ｏ的排放因子分析是８４．４ｇ／ｔ，２７．３ｇ／ｔ，１３２ｇ／ｔ。用Ｎ２Ｏ－Ｎ占生物全氮的百分含量表示，稻草及玉米秸分别上０．５９％，０．８７％。用实验得到的Ｎ２Ｏ的排放因子计算出了生物质燃烧产生Ｎ２Ｏ在全国各省、直辖市、县的年排放量，并作出了全国年排放的分布