黑土有机碳、氮及其活性对长期施肥的响应

以长期定位试验为基础,研究不同长期施肥模式对中国东北黑土表层(0～20 cm)及亚表层(20～40 cm)土壤碳、氮的影响.结果表明,有机肥的施入显著提高了表层土壤有机碳(SOC)和全氮(TN)含量,其中以有机无机配施处理最为显著.与不施肥相比,常量和高量有机无机配施分别增加了表层SOC含量24.6%和25.1%,分别增加了表层土壤TN含量29.5%和32.8%,亚表层土壤SOC和TN含量对施肥无响应.尽管常量及高量有机无机配施分别增加了黑土0～40 cm土壤碳储量11.6%和7.6%、氮储量17.3%和12.7%,但各处理之间无显著差异,仅增加了黑土碳、氮储量的变异性.与不施肥相比,有机肥的施用不仅显著增加了表层和亚表层土壤微生物生物量碳、氮(SMBC、SMBN)及可溶性碳、氮(DOC、DN)的含量,且显著提高了这些组分在总有机碳、全氮中所占的比例.有机无机配施处理能使表层土壤SMBC/SOC、SMBN/TN值分别提高0.36～0.59和1.21～1.95个百分点,而DOC/SOC、DN/TN也分别达到0.53%～0.72%和1.41%～1.78%.土壤微生物生物量碳氮、可溶性碳氮及其在总有机碳、氮中所占的比例对于施肥的响应在土壤剖面上表现更为敏感,更能反映土壤肥力对于长期施肥的响应.有机肥的施入尤其是有机无机配施能显著提高黑土表层和亚表层土壤有机碳、氮活性,有利于提升土壤肥力和养分供应能力,但同时也导致了农田系统碳、氮的大量损失,容易引起潜在的环境污染.     

溪源宫水源保护区浮游植物群落结构分析研究

文章主要对2011年8月至12月溪源宫水源保护区浮游植物群落结构进行调查分析。溪源宫水体共鉴定出浮游植物6门51属137种,主要都是以绿藻门、硅藻门、蓝藻门为主。通过采用浮游植物生物量以及多样性指数对研究区域水体进行了评价,结果表明溪源宫水源保护区水质状况较好。同时还将溪源宫水源保护区、闽江、山仔水库等不同水源地的浮游植物群落结构进行对比分析,发现不同营养状态下,水体中浮游植物群落结构有显著的不同。     

蚂蚁扰动对青海湖北岸高寒草甸草原群落结构影响

蚂蚁的筑丘活动是草地生态系统中不可忽视的生物干扰因子。本文针对青海湖北岸高 寒草甸草原,调查了不同大小的蚁丘及其周围对照草地的土壤理化性质和植被状况。结果表明： 蚂蚁筑丘活动显著地降低了土壤容重和土壤湿度,增加土壤温度,但对土壤pH 值的影响较小。 蚂蚁扰动改变了群落组成,增加了大部分禾本科和豆科物种的重要值而降低了杂类草的重要值。 以莎草科的矮嵩草（Kobresia humilis）和禾本科的异针茅（Stipa aliena Keng）、赖草（Leymus secalinus）、溚草（Koeleria cristata）等为主的群落逐步演替为以禾本科的异针茅和赖草为主的 群落。植物群落的盖度降低但其地上、地下生物量增加;植物群落丰富度指数降低但均匀度指 数增加。     

Glucose production from hydrolysis of cellulose over a novel silica catalyst under hydrothermal conditions

A novel silica catalyst was synthesized by evaporation-induced self-assembly (EISA) method and tested for the catalytic selective hydrolysis of cellulose to glucose. This silica catalyst exhibited a higher catalytic activity than other oxides prepared by the same method, such as ZrO₂, TiO₂, and Al₂O₃. Using silica as a catalyst, cellulose was selectively hydrolyzed into glucose with a glucose yield as high as 50% under hydrothermal conditions without hydrogen gas. The silica catalyst was characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results of temperature-programmed desorption of ammonia (NH₃-TPD) and textural properties indicated that the synergistic effect between strong acidity and a suitable pore diameter of the silica catalyst may be responsible for its high activity. In addition, the catalyst was recyclable and showed excellent stability during the recycle catalytic runs.     

Responses of protists with different feeding habits to the changes of activated sludge conditions: A study based on biomass data

Changes of protists, which were categorized into different functional groups primarily according to their feeding habits, in two full-scale municipal wastewater treatment systems experiencing sludge bulking were investigated over a period of 14 months. Protist biomass represented 3.7% to 5.2% of total biomass on average under normal sludge conditions, and the percentage increased significantly (p < 0.05) under sludge bulking conditions. The biomass of Chilodonella spp., capable of eating filamentous bacteria, tended to decrease in both systems when sludge bulking occurred, showing that the abnormal growth of filamentous bacteria did not lead to a biomass bloom of this group of protists. On the other hand, the bactivorous protists represented more than 96% of total protist biomass, and the biomass of this group, particularly the attached ciliates, increased significantly (p < 0.05) when sludge bulking occurred. The significant increase of the attached ciliates may have possibly facilitated the growth of filamentous bacteria through selectively preying on non-filamentous bacteria and further exacerbated sludge bulking. The redundancy analysis and correlation analysis results showed that the biomass changes of the attached ciliates were primarily related to the sludge volume index and to some extent related to five-day biochemical oxygen demand loading and hydraulic retention time.     

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-.     

Differences in nitrous oxide fluxes from red soil under different land uses in mid-subtropical China

Red soil may play an important role in nitrous oxide (N₂O) emissions due to its recent land use change pattern. To predict the land use change effect on N₂O emissions, we examined the relationship between soil N₂O flux and environmental determinants in four different types of land uses in subtropical red soil. During two years of study (January 2005-January 2007), biweekly N₂O fluxes were measured from 09:00 to 11:00 a.m. using static closed chamber method. Objectives were to estimate the seasonal and annual N₂O flux differences from land use change and, reveal the controlling factors of soil N₂O emission by studying the relationship of dissolved organic carbon (DOC), microbial biomass carbon (MBC), water filled pore space (WFPS) and soil temperature with soil N₂O flux. Nitrous oxide fluxes were significantly higher in hot-humid season than in the cool-dry season. Significant differences in soil N₂O fluxes were observed among four land uses; 2.9, 1.9 and 1.7 times increased N₂O emissions were observed after conventional land use conversion from woodland to paddy, orchard and upland, respectively. The mean annual budgets of N₂O emission were 0.71-2.21 kg N₂O-N ha⁻¹ year⁻¹ from four land use types. The differences were partly attributed to increased fertilizer use in agriculture land uses. In all land uses, N₂O fluxes were positively related to soil temperature and DOC accounting for 22-48% and 30-46% of the seasonal N₂O flux variability, respectively. Nitrous oxide fluxes did significantly correlate with WFPS in orchard and upland only. Nitrous oxide fluxes responded positively to MBC in all land use types except orchard which had the lowest WFPS. We conclude that (1) land use conversion from woodland to agriculture land uses leads to increased soil N₂O fluxes, partly due increased fertilizer use, and (2) irrespective of land use, soil N₂O fluxes are under environmental controls, the main variables being soil temperature and DOC, both of which control the supply of nitrification and denitrification substrates.     

Effect of land management on soil microbial N supply to crop N uptake in a dry tropical cropland in Tanzania

In Sub-Saharan Africa, conservation of available soil N during early crop growth, when N loss by leaching generally occurs, is important to improve crop productivity. In a dry tropical cropland in Tanzania, we assessed the potential role of soil microbes as a temporal N sink-source to conserve the available soil N until later crop growth, which generally requires substantial crop N uptake. We evaluated the effect of land management [i.e., no input, plant residue application before planting (P plot) with or without fertilizer application, fertilizer application alone, and non-cultivated plots] on the relationship between soil N pool [microbial biomass N (MBN) and inorganic N] and crop N uptake throughout the ∼120-d crop growth period in two consecutive years. In the P plot, MBN clearly increased (∼14.6-29.6 kg N ha⁻¹) early in the crop growth period in both years because of immobilization of potentially leachable N, and it conserved a larger soil N pool (∼10.5-21.2 kg N ha⁻¹) than in the control plot. Especially in one year in which N leaching was critical, increased MBN maintained a larger soil N pool in the P plot throughout the experimental period, and a delay of increased MB C:N ratio and a substantial decrease in MBN was observed, indicating better soil microbial N supply for crop N uptake during later crop growth. Therefore, plant residue application before planting should enhance the role of soil microbes as a temporal N sink-source, leading to the conservation of potentially leachable N until later phase of crop growth, especially in years in which N leaching is relatively severe. Although further studies are necessary, our results suggest that plant residue application before planting is a promising option to achieve better N synchronization.     

生物质发电项目碳排放计算方法应用研究

生物质发电是将废弃生物质变成可再生能源得以充分利用,这些工程将减少来自于生物质自然腐烂和无控燃烧产生的温室效应,这不仅节约了煤炭的同时也减少了二氧化碳的排放。本文中以某生物质项目发电为例,根据CDM方法学ACM0006计算了该项目的减排量。结果表明,该项目10年间共减少了二氧化碳排放量2,075,140 t,给我国带来了可观的经济效益和环境效益。     

污泥焚烧中二氧化硫检测新方法及污泥处理探讨

对新乡市9个污水处理场污泥预处理后,用测硫仪分析污泥含硫量,并用经验公式根据年污水处理量,估算焚烧污泥方法年二氧化硫排放总量。结果显示：用测硫仪测定污泥含硫量,核算二氧化硫排放量,与现有方法相比,操作简便易行,结果不受采样条件、时间、环境、布点等因素影响,重现性好、完整、精密。同时发现部分污泥含硫量超过规定用煤中含硫量,建议用焚烧方法处置污泥,净化尾气。