Influence of Particle Size of Municipal Solid Waste Amendments and Presence or Absence of Eisenia fetida on Soil Greenhouse Gases Emission

We investigated in the laboratory the influence of a municipal solid waste applied to soil at two different particle sizes (<2 and <0.5 mm) and the presence or absence of the Eisenia fetida earthworm on soil carbon dioxide (CO₂) and nitrous oxide (N₂O) fluxes, as well as on the changes in chemical [ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^—N), soluble carbon (C), and soluble carbohydrates] and biochemical (dehydrogenase activity) properties of the soil. The presence of Eisenia fetida caused an increase in the emission of both gases (CO₂ and N₂O) in municipal solid waste (MSW)–amended soils due to the enhanced soil microbial activity and the degradation of the exogenous organic matter. Soil gas fluxes were influenced by the particle size of the organic waste added. The lowest particle size (<0.5 mm) increased the contact surface of the organic amendment, facilitating the accessibility to the microorganisms, enhancing soil biological activity, and the mineralization of the organic matter.     

Diurnal and seasonal variations on soil CO2 fluxes in tropical silvopastoral systems

This study aimed to quantify the dynamics of soil CO₂ fluxes in two silvopastoral systems based on Leucaena leucocephala, one associated with Panicum maximum (L + P) and another with Cynodon plectostachyus (L + C). We measured CO₂ fluxes fortnightly during the dry and rainy seasons in the morning and the afternoon, with an infrared gas analyzer. Simultaneously, we measured soil temperature, soil moisture, ambient temperature, and relative humidity. Soil CO₂ fluxes ranged from 6.0 ± 0.14 to 6.1 ± 0.12 µmol CO₂/m²/s but no statistical differences were observed between systems. Soil CO₂ flux in the L + P was 12.5% higher in the rainy season compared with the dry season but the season did not affect the fluxes in L + C. Regarding the diurnal variation, CO₂ fluxes were 17.6%–34.8% higher in the morning compared with afternoon measurements. Soil moisture and temperature were higher in L + C, but the ambient temperature and relative humidity showed no statistical differences between systems. In both systems, soil temperature was greater in the afternoon, while the soil moisture and relative humidity were greater in the morning. The diurnal variation of soil CO₂ fluxes in silvopastoral systems correlated positively with soil temperature and ambient temperature, but negatively with relative humidity. We concluded that soil CO₂ fluxes did not vary between silvopastoral systems but respond differently to the seasons. The results have important implications on the establishment and management of Leucaena-based silvopastoral systems for the mitigation of soil CO₂ fluxes from extensive livestock production lands.     

海峡两岸（厦门）碳权交易平台构建及推动策略

该文概述了碳交易市场的发展现状，指出国际我国两岸碳交易市场的特点，分析了厦门碳权交易平台构建在政策、经济、区位、交通、金融、资讯、基础研究方面的有利条件，从建设原则、框架设计、制度建设、交易流程、组织构架方面提出构建方案，并就此提出推动策略。     

Effect of ventilation on distributions,concentrations, and emissions of air pollutants in a manure-belt layer house

Air pollutants from poultry operations pose a potential threat not only for bird health, but also for the environment outside. Ventilation is believed to be an effective way of regulating house environment. To improve understanding of ventilation effects on house environment, distributions, concentrations and emissions of ammonia, carbon dioxide, total suspended particulates, and particulate matter 2.5 (fine particles with a diameter of 2.5 μm or less) were investigated in a manure-belt layer house using 9 ventilation stages (VS) with different ventilation rates (VT). Distributions of pollutants were assessed visually using contour plots and coefficient of variation. Emission rates of pollutants were estimated by multiplying VT by concentration. Spatial distributions of 4 pollutants were not homogeneous throughout the house, regardless of VS, and increased VT aggravated the spatial disparity. In the house, pollutant concentrations were controlled under harmful levels during the 9 VS. Ventilation, as expected, can decrease pollutant concentrations. However concentrations of ammonia and carbon dioxide did not decrease proportionately to increased VT. The highest emission rates of 4 pollutants were observed during VS1, a stage with maximum ventilation, which reflected VT as a key factor determining emission rate. The study indicated that it is difficult to balance house environment and control pollutant concentrations depending only on ventilation. Several additional factors, such as temperature, humidity, manure handling, bird management, and ventilation system design, should be comprehensively considered to control air pollutants from poultry operations.     

季节对育成母牛产粪量及粪N、P、Cu、Zn等污染物排放量的影响

选择健康状况良好、体重相似、出生日期相近的中国荷斯坦育成母牛5只,采用全收粪法研究育成母牛在一年四季中产粪量及粪污染物(N、P、Cu、Zn和有机质)排放量的变化情况及规律。结果表明,季节对育成母牛产粪量与粪样中有机质及N、P、Cu、Zn污染物的排放量均存在着极显著(P0.01)或显著(P0.05)的差别,因此,根据不同季节产粪量及粪中污染物排泄规律来研究配制符合育成母牛的饲料配方,可达到既满足育成母牛的生产需要,又能最大限度地降低污染物排放量,减少奶牛场的污染。     

中国木结构产业的现状及发展(二)

上篇回顾了我国木结构的发展历程,总结我国木结构产业的现状和宏观特征,本篇重点分析目前我国木结构产业的产业链不完整、企业规模小、产品技术含量低、社会化分工不发达等问题,提出木结构相关企业的生态-木结构-地产的互动经营模式和企业经营向资本经营转变的发展战略,指出未来我国木结构产业应结合新能源新技术并传承文化的发展方向。     

近红外土壤含水率传感器设计与试验

设计了一种适用于快速测量土壤含水率的近红外传感器。发光二极管(LED)作为传感器的光源,中心波长为1 940 nm的光为测量光,1 800 nm为参考光,土壤含水率对这2个波长的光有不同的吸收特性。光源发出的光照射到土壤表面,经反射后进入光电转换器,将光信号转换为电信号,送至两级放大电路、模数转换器(A/D)、显示和存储设备,输出的反射光强与土壤含水率存在一定的关系。仪器性能试验表明:光源传感器到土壤表面的距离对采集信号的强度有一定影响,根据传感器的结构,可以选择一定的距离使反射信号的强度和稳定性最好。两波长光的反射光强随着土壤粒径的增大而减小;土壤含水率与相对吸收深度之间具有很好的线性相关性,回归分析的决定系数为0.863。     

Soil Carbon Dioxide Emissions from Sorghum–Sunflower Rotation in Rainfed Semi-arid Tropical Alfisols: Effects of Fertilization Rate and Legume Biomass Incorporation

The long-term effects of plant legume [horse gram (Macrotyloma uniflorum)] biomass incorporations were assessed in terms of carbon dioxide (CO₂) emissions, soil quality parameters, and climatically influenced soil parameters in a dryland Alfisol under varying soil fertility conditions. Six selected treatments consisted of off-season legume incorporation (I) and no incorporation?/?fallow (F), each under three varying nitrogen and phosphorus fertilizer levels (viz., N₀P₀, N₂₅P₃₀, and N₅₀P₃₀). Soil moisture, soil temperature, soil surface carbon dioxide emission, soil dehydrogenases, and microbial biomass carbon (MBC) were monitored at three different crop situations [viz., Kharif period (KP), legume/fallow period (LP), and no crop period (NP)] at 14 different periods of the year. Incorporation practices resulted in greater rates of CO₂ emission over fallow conditions during the Kharif and legume periods, whereas the emission rate was greater in fallow soils during the end of the legume and no crop periods. The increased rates of fertilizer doses also significantly increased the soil CO₂ flux during the majority of the measurements. Beneficial effects of incorporation practices were observed in terms of high soil moisture (5–11%), low soil temperature (3–7%), and high content of MBC over without incorporations. Correlation studies indicated that the soil property MBC was found to be the greatest significant variable with CO₂ emission in all the fertilizer treatments under biomass-incorporated soils. These results indicated the undesirable (in terms of CO₂ fluxes) and desirable (soil biological and other parameters) effects of legume biomass incorporation and fertilizer application and their significance in improving soil quality and greenhouse gas (GHG) emissions in dryland Alfisols of semi-arid tropics.     

Comparison of analytical results from plant analysis laboratories

Abstract

Analyses of 6 reference plant tissue samples were completed by 22 commercial and university laboratories across the U.S and compared. Cooperators were requested to analyze samples of apple leaf (Malus domestica Borkh.), grape petiole (Vitis labrusea L.), pecan leaf (Carya illinoensis (Wangenh.)K. Koch), snapbean leaf (Phaseolus vulgaris L.). eweet corn leaf (Zea mays L.), and rose leaf (Rosa hybrida) for the elements comprising a routine analysis. Each laboratory was requested to use their routine analytical procedures, with no attempt to standardize these methods. Close agreement between laboratories occurred with analyses of N, P, and Mg in which 80%, 69%, and 68% of the laboratories reported values within ± 5 % of the mean, respectively. Close agreement was also found for Mn and Zn, with 81% of laboratories reporting Mn and 73% reporting Zn values within ± 10% of the mean. Variation between laboratories was greater for K and S, in which 46% and 30% of the laboratories reported values within ± 5% of the mean, respectively. Values for Fe, Cu, and B were also variable, with 46%, 48%, and 46% being within ± 10% of the mean, respectively. Similiar values were reported for Ca, Mg, Mn, and Zn by laboratories using either AA spectrophotometer (AA) or ICP emisssion spectrometer (ICP) as the primary instrument. Lower values were reported by those using ICP versus AA for determination of Cu and Fe.     

我国河流N_2O饱和度与释放系数变化及其与河流氮水平的关系研究

通过选择我国3个不同流域的河流,研究了河流N2O饱和度与释放量的时空变化及其与河流氮水平的关系,并评估了IPCC关于河流N2O的释放系数。结果显示,河流硝态氮和氨氮的浓度变化范围分别为0.023～5.24（均值1.29±0.822）mg N.L-1和0.020～40.3（均值2.54±5.47）mg N·L-1;相应地,河流N2O饱和度和释放量的变化范围分别为90%～8213%（均值407%±1010%）及0.250～1960（均值58.3±221）μg N.m-2·h-1。不同河流N2O饱和度均呈现明显的季节变化特征,N2O饱和度几乎持续处于过饱和状态,表明河流N2O是大气N2O的源。不同类型的河流,其氮浓度水平、N2O饱和度与释放量均有显著差异,城市纳污型河流——南淝河,其氨氮浓度、N2O饱和度和释放量显著高于其他河流,均值分别达（12.5±6.10）mg N·L-1、1760%±2620%及（363±548）μg N m-2·h-1。研究发现,除南淝河外,所有径流主导型的河流,其N2O饱和度与NO3-含量存在显著线性正相关关系,说明高NO3-含量的河流能增加N2O的表观产量。除南淝河以外的河流N2O释放系数变化范围为0.05%～0.87%,均值为0.20%,较为接近IPCC的参考值0.25%。但我们的研究建议采用修正后的河流N2O释放系数（均值为0.10%）,该系数更能体现河流释放N2O的实际情况。