森林土壤有机氮的X光吸收近边结构光谱技术测定

本研究通过采用氮的K边X光吸收近边结构(XANES)技术来了解森林土壤有机氮,以此深入研究土壤中有机氮种类与其转化的定量关系。土壤样品采自台湾中部的云杉、铁杉林与草地。结果表明,氮的 XANES 可以揭示样品中不同的氮的种类。在土壤腐植质、可溶性氮及本体土壤中胺态及吡咯氮占了主要的比率。然而不同处理及植被下的土壤样品氮的种类分布是不同的。云杉与铁杉土壤可溶性有机氮在402.3 eV 能量处有显著的差异。在A层土壤中,吡啶类氮含量要显著高于O层土壤,说明氮在不同土层中的转化率存在极大的差异,这种变化对于氮在森林土壤中的循环将起重要作用。图3表1参8。     

Forage potential of eight woody species: intake and growth rates of local young goats in the highland region of Rwanda

Eight woody fodder species adapted to the highlands of Rwanda were evaluated in terms of dry matter intake in one experiment. Animals were offered a daily diet comprising 4.0 of fresh matter of Setaria splendida grass supplemented with or without one of the eight fodder species tested. In all cases, total daily feed intake was increased by the addition of woody fodder. Daily intake of the woody fodder was high for Acacia koaia, Mimosa scabrella and Acacia koa at 43.7, 42.6 and 41.9 g/kg BW^0.75, respectively. The dry matter intake of the other five species (Alnus acuminata, Chamaecytisus palmensis, Hagenia abyssinica, Acacia mearnsii and Acacia melanoxylon) ranged from 18.9 to 30.1 g/kg BW^0.75 per day. In another experiment, a basic daily diet of 4.0 kg of fodder (in fresh weight) was given to each animal. This ratio comprised S. splendida supplemented with M. scabrella and incorporated at 0 (control), 45% and 66% (fresh weight basis) of the total daily diet. Improved weight gain was obtained when setaria was supplemented with M. scabrella with daily weight gain of 31, 47 and 51 g/animal for 0, 45 and 66% M. scabrella, respectively.     

The pH change in rhizosphere ofPinus koraiensis seedlings as affected by different nitrogen sources and its effect on phosphorus availability

Root mat method described by Kuchenbuch and Jungk was used to study the rhizosphere processes. The experiment was carried out on two years oldPinus koraiensis seedlings. Soil samples collected from the upper 20-cm soil layer in Changbai Mountain were treated with three different forms of nitrogen fertilizers: NO₃ ⁻−N, NH₄ ⁺−N and NH₄NO₃. The results showed that the soil pH and available P near the roots were all lower than in the bulk soil in control treatment. NH₄ ⁺−N application greatly decreased the soil pH near the roots compared to the control treatment and promoted the absorption of phosphorus, which led to a more remarkable depletion region of available P. On the contrary, the rhizosphere soil pH was higher than in the bulk soil in treatments with NO₃ ⁻−N and retarded the P absorption, which led to a nearly equal available P contents to the bulk soil. In treatment with NH₄NO₃, the rhizosphere soil pH was only a little lower than that in the control treatment and its effects on P absorption is mediate between the treatments with NH₄ ⁺−N and NO₃ ⁻−N. Foundation item: This paper was supported by National Natural Science Foundation of China (Grant No. 30170167). Biography: Chen Yong-liang (1969-), male, Ph. Doctor, lecture of Northeast Forestry University, Harbin 150040, Post-doctor in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P.R. China. E-mail: ylchin@sohu.com Responsible editor: Seng Funan     

杉木根际与非根际土壤酶活性比较

杉木根际与非根际土壤酶活性比较陈ｆ竣（中国林业科学研究院林业研究所北京１０００９１）李传涵（华中农业大学土化系武汉４３００７０）关键词杉木,根际土壤,土壤酶,杉木中毒由于林木生长的影响,使得林木根际土壤ｐＨ值、养分含量、微生物数目、生化活性等性质发生...     

Soil carbon distribution and quality in a montane rangeland-forest mosaic in northern Utah

Relatively little is known about soil organic carbon (SOC) dynamics in montane ecosystems of the semi-arid western U.S. or the stability of current SOC pools under future climate change scenarios. We measured the distribution and quality of SOC in a mosaic of rangeland-forest vegetation types that occurs under similar climatic conditions on non-calcareous soils at Utah State University's T.W. Daniel Experimental Forest in northern Utah: the forest types were aspen [Populus tremuloides] and conifer (mixture of fir [Abies lasiocarpa] and spruce [Picea engelmannii]); the rangeland types were sagebrush steppe [Artemisia tridentata], grass-forb meadow, and a meadow-conifer ecotone. Total SOC was calculated from OC concentrations, estimates of bulk density by texture and rock-free soil volume in five pedons. The SOC quality was expressed in terms of leaching potential and decomposability. Amount and aromaticity of water-soluble organic carbon (DOC) was determined by water extraction and specific ultra violet absorbance at 254 nm (SUVA) of leached DOC. Decomposability of SOC and DOC was derived from laboratory incubation of soil samples and water extracts, respectively.

Although there was little difference in total SOC between soils sampled under different vegetation types, vertical distribution, and quality of SOC appeared to be influenced by vegetation. Forest soils had a distinct O horizon and higher SOC concentration in near-surface mineral horizons that declined sharply with depth. Rangeland soils lacked O horizons and SOC concentration declined more gradually. Quality of SOC under rangelands was more uniform with depth and SOC was less soluble and less decomposable (i.e., more stable) than under forests. However, DOC in grass-forb meadow soils was less aromatic and more bioavailable, likely promoting C retention through cycling. The SOC in forest soils was notably more leachable and decomposable, especially near the soil surface, with stability increasing with soil depth. Across the entire dataset, there was a weak inverse relationship between the decomposability and the aromaticity of DOC. Our data indicate that despite similar SOC pools, vegetation type may affect SOC retention capacity under future climate projections by influencing potential SOC losses via leaching and decomposition.     

基于Hyperion光谱信息的鲁西北盐碱地特性探析

利用Hyperion影像及盐碱地分布端元提取了鲁西北典型盐碱地光谱数据并对其特性进行了探析,以证实光谱信息对于该区盐碱地研究的可用性。利用生成的原始及包络线去除的光谱曲线,分别从土壤电导率、土壤盐分含量及一系列诊断性指标入手,借助诊断性吸收波段对本区盐碱地特性进行了分析。结果表明：该区盐碱地兼具其他地点盐碱地光谱吸收共性及自身特性,证实了基于遥感光谱信息的盐碱地特性分析是可行的,可用于区域盐碱地遥感监测。     

污染土壤的微生物修复原理与技术进展

微生物修复是土壤环境生物修复技术的重要组成部分,是最具发展和应用前景的生物学环保新技术.本文以土壤中重金属及典型有机污染物为对象,从土壤微生物与污染物质的相互作用入手,较为系统地综合评述国内外污染土壤的微生物修复原理与技术,并结合当前土壤污染的新特点,提出了需进一步认识和解决微生物修复过程中出现的新现象和新问题,以不断丰富和拓展土壤环境微生物修复范畴与内涵.     

砷污染土壤的蜈蚣草修复研究进展

本文评述了As污染土壤的蜈蚣草植物修复及其对As的解毒机制的研究进展,内容着重包括蜈蚣草对As的富集特征,As在蜈蚣草中的赋存形态、迁移及其转化,土壤以及土壤中P、Ca和K等元素对蜈蚣草吸收、转运As的影响等方面。     

土壤环境中多环芳烃的微生物降解及联合生物修复

研究土壤环境中持久性有机污染物的生物降解及其生物修复技术是当今国际环境修复科学技术前沿领域的重要课题。本文重点论述了土壤环境中持久性有机污染物多环芳烃的微生物降解机理及其在生物修复中的应用等,并结合当前研究进展,展望了基于多种修复措施相结合的多环芳烃污染土壤联合生物修复工程技术的开发与应用前景。     

不同分层土壤对锌的吸附解吸特性

为探究重金属锌在不同分层土壤中的吸附解吸特性,了解锌在分层土壤中的迁移规律,试验通过批量平衡试验,分析了锌在4个分层土壤(耕作层、犁底层、心土层、母质层)中的吸附解吸行为。结果表明:各分层土壤对锌的吸附动力学过程包括快速吸附、慢速吸附、吸附平衡3个阶段,准二级动力学方程对吸附过程的拟合效果优于准一级动力学方程,Langmuir方程能更好的拟合4种分层黑土对锌的等温吸附过程,4种土壤分层对锌的吸附能力由大到小的顺序为耕作层、犁底层、心土层、母质层,是因为随着土壤深度的增加,土壤有机质质量分数逐渐减小,4种分层土壤对锌的吸附能力逐渐降低。吸附热力学试验表明,随着温度的升高,各分层土壤对锌的吸附量均逐渐增大,ΔG<0(ΔG为吉布斯自由能的变化),ΔH>0(ΔH是标准焓变),ΔS>0(ΔS是标准熵变)说明了4个分层土壤对锌的吸附过程为自发、吸热、无序的过程。Zn的解吸量与吸附量呈正比,最大解吸量随着剖面深度的增加而减小,且均存在滞后效应。N、P质量浓度的增加,可以提高土壤固定Zn的能力,减小Zn对土壤农作物、地下水的重金属危害。