马尾松林地与玉米地土壤有机碳的分异研究

林农生态系统转化对土壤有机碳(SOC)组成和来源产生了较大的影响,但不同学者的结论仍然存在一定差异,且这一转化过程对土壤溶解性有机碳(DOC)的影响鲜有报道.基于这一背景,该研究在贵州中部区域选择马尾松(Pinus massoniana)林地和玉米(Zea mays L.)地土壤作为研究对象,通过对SOC和DOC含量和同位素组成的测定,分析林农生态系统转化前后土壤有机碳的分异.结果表明,在马尾松林地剖面中,SOC和DOC含量随剖面深度的变化幅度均大于玉米地土壤,DOC含量最大值出现在5～10 cm处;銼O13C和銬O13C随着土壤深度的加深有所偏正,但銬O13C在剖面中的变异远大于銼O13C,其极差分别为5.015‰和2.431‰;通过对比銬O13C和銼O13C的差异,说明其0～5 cm的DOC主要来源于新成枯枝落叶,而土体内部DOC则主要来自土壤腐殖类物质的转化.在玉米地剖面中,銼O13C和銬O13C随着土壤深度的加深有所偏负,但整个剖面中两值的差异较小,DOC主要来源于土壤腐殖类物质的转化;SOC来源于玉米植物体有机碳(C4-C)的比例介于2.55%～20.80%之间,随剖面层次的加深有降低趋势,但出现"之"字形反复;DOC中C4-C的比例在剖面0～40 cm间较为相近(25.94%～34.54%),40 cm以下则急剧下降(3.18%～15.65%).     

Ammonia emissions from different pig production scales and their temporal variations in the North China Plain

ABSTRACT

Pig production systems in China are shifting from small to industrial scale. Significant variation in housing ammonia (NH₃) emissions can exist due to differences in diet, housing design, and management practices. However, there is a knowledge gap regarding the impacts of farm-scale in China, which may be critical in identifying hotspots and mitigation targets. Here, continuous in-situ NH₃ concentration measurements were made at pig farms of different scales for sows and fattening pigs over periods of 3–6 days during two different seasons (summer vs. winter). For the sow farms, NH₃ emission rates were greater at the small farm (summer: 0.52 g pig^?1 hr^?1; winter: 0.21 g pig^?1 hr^?1) than at the large farm (summer: 0.34 g pig^?1 hr^?1; winter: 0.12 g pig^?1 hr^?1). For the fattening pig farms, NH₃ emission rates were greater at the large farm (summer: 0.22 g pig^?1 hr^?1; winter: 0.16 g pig^?1 hr^?1) than at the small farm (summer: 0.19 g pig^?1 hr^?1; winter: 0.07 g pig^?1 hr^?1). Regardless of farm scale, the NH₃ emission rates measured in summer were greater than those in winter; the NH₃ emission rates were greater in the daytime than at the nighttime; a positive relationship (R² = 0.06–0.68) was established between temperature and NH₃ emission rate, whereas a negative relationship (R² = 0.10–0.47) was found between relative humidity and NH₃ emission rate. The effect of farm-scale on indoor NH₃ concentration could mostly be explained by the differences in ventilation rates between farms. The diurnal variation in NH₃ concentration could be partly explained by ventilation rate (R² = 0.48–0.78) in the small traditional farms and by emission rate (R² = 0.26–0.85) in the large industrial farms, except for the large fattening pig farm in summer. Overall, mitigation of NH₃ emissions from sow farms should be a top priority in the North China Plain.

Implications: The present study firstly examined the farm-scale effect of ammonia emissions in the North China Plain. Of all farms, the sow farm was identified as the greatest source of ammonia emission. Regardless of farm scale, ammonia emission rates were observed to be higher in summer. Ammonia concentrations were mostly higher in the large industrial farms partly due to lower ventilation rates than in the small traditional farms.     

对美国FHWA公路噪声预测模式的深入讨论

美国ＦＨＷＡ公路噪声预测模式在我国被广为应用，甚至有各种修正模式，但因对原模式的理论依据仍缺少了解，以至在实际应用过程中或对原模式进行修正时诸如参数的选择及计算、模式适用范围等出现了不当或错误现象。本文从理论上对ＦＨＷＡ公路噪声预测模式进行了深入分析、进而讨论了各参数的物理意义、模式的适用范围，并提供了二种特殊情况下公路噪声的预测模式。     

微电解+Fenton氧化+二级A/O组合工艺处理农药杀菌剂废水

杀菌剂生产废水含有大量三环唑、无机盐、高毒性物质和难生物降解有机物,对生化细菌有较强的抑制和毒害作用,且BOD5/COD值较小,采用传统生化处理工艺无法进行。现采用微电解、Fenton氧化和二级A/O组合工艺建成的废水处理工程,运行良好,出水各项指标达到环太湖流域排放标准DB 32/1072—2007。     

Removal of phosphate from wastewater using alkaline residue

Alkaline residue(AR) was found to be an efficient adsorbent for phosphate removal from wastewater. The kinetic and equilibrium of phosphate removal were investigated to evaluate the performance of modified alkaline residue. After treatment by NaOH(AR-NaOH), removal performance was significantly improved, while removal performance was almost completely lost after treatment by HCl(AR-HCl). The kinetics of the removal process by all adsorbents was well characterized by the pseudo second-order model. The Langmuir model exhibited the best correlation for AR-HCl, while AR was effectively described by Freundlich model. Both models were well fitted to AR-NaOH. The maximum adsorption capacities calculated from Langmuir equation were in following manner: AR-NaOH AR AR-HCl. Phosphate removal by alkaline residue was pH dependent process. Mechanisms for phosphate removal mainly involved adsorption and precipitation, varied with equilibrium pH of solution. For AR-HCl, the acid equilibrium pH( 6.0) was unfavorable for the formation of Ca-P precipitate, with adsorption as the key mechanism for phosphate removal. In contrast, for AR and ARNaOH, precipitation was the dominant mechanism for phosphate removal, due to the incrase on pH( 8.0) after phosphate removal. The results of both XRD and SEM analysis confirmed CaHPO4·2H2O formation after phosphate removal by AR and AR-NaOH.     

粉状活性焦在双层滤料颗粒床中的脱硫试验研究

在双层滤料颗粒床模型试验台上对粒径为300～400目的粉状活性焦进行了脱硫试验,研究了温度、O2和水蒸气体积分数、气体流速、再生次数对脱硫效果的影响.试验结果表明.温度为120℃、O2体积分数为8%、水蒸气体积分数为10%条件下,脱硫效果最好;粉状活性焦在双层滤料颗粒床中经过7次重复吸附.达到硫饱和吸附量为66.2 mg/g.粉状活性焦再生试验表明,随着再生次数的增加.粉状活性焦的脱硫性能呈下降趋势.     

Effect of applying chemical fertilizers on forms of lead and cadmium in red soil

A three-month incubation study was undertaken to examine the influence of N, P and K on the various forms (soluble plus exchangeable (SE), weakly specifically adsorbed (WSA), Fe-Mn oxides bound (OX), organic matter complexed (OM) and residual fractions (RES)) of lead (Pb) and cadmium (Cd) in a red soil. Application of urea at the rate of 200 mg N/kg significantly lowered the SE fraction, but raised the WSA or OX fraction of both metals. Supply of 80 mg P/kg caused a decrease in the SE fraction of the two metals. The WSA fraction of Pb was reduced, whereas that of Cd increased by adding P. However, addition of 100 mg K/kg led to an increase in the SE fraction, but a decrease in the WSA fraction of Pb and Cd. Applying chemical fertilizers had no significant consistent influences on the other fractions of metals. These findings suggest that in heavy metal contaminated red soil, applying fertilizers does not only provide plant nutrients, but may also change the speciations and thus biovailability of heavy metals.     

环境监测中生物传感器技术的应用研究

随着工业、农业迅速发展,环境污染问题已经越来越严重,人们已经逐渐认识到环境保护的重要性.生物传感器在环境监测中的应用也越来越广泛,其不但具有选择性好、稳定性高、响应时间短的优点,同时还不需要对样品实时预处理,携带方便,可进行连续、实时、原位监测.本文就对生物传感器技术在环境监测中的应用进行研究.     

深入认识生态承载力的空间构成发展节约化畜牧业的初探

内蒙古自治区位于祖国北部边疆，地域辽阔，是我国北疆的绿色屏障，由于自然条件的制约，草场保护与草地资源利用间的矛盾比较突出。近几年我区的过度放牧和养殖，使草地面积退化，而且草地建设严重滞后。我区有得天独厚的风能和水资源，但资源分布不均，东部地区水资源和草地资源丰富，而中西部地区风能资源丰富，如何充分认识与利用资源空间有机组成，充分利用生态承载力，实现生存与生态良性发展，则显得十分重要。本文要结合我区的风、水、土、草等资源的分布条件，探讨我区走协调发展的道路。     

Ambient volatile organic compounds at a receptor site in the Pearl River Delta region: Variations, source apportionment and effects on ozone formation

We present the continuously measurements of volatile organic compounds（VOCs） at a receptor site（Wan Qing Sha, WQS） in the Pearl River Delta（PRD） region from September to November of 2017. The average mixing ratios of total VOCs（TVOCs） was 36.3 ± 27.9 ppbv with the dominant contribution from alkanes（55.5%）, followed by aromatics（33.3%）. The diurnal variation of TVOCs showed a strong photochemical consumption during daytime,resulting in the formation of ozone（O₃）. Five VOC sources were ...