中老缅泰交界地区土地利用变化信息挖掘与国别对比

基于Landsat TM/ETM数据,从土地利用空间分布特征、时空变化规律、土地利用程度三个方面,对中老缅泰交界地区1990-2010年土地利用变化特征进行分析。研究表明：① 橡胶园、茶园为增幅最大的土地利用类型,轮歇农地、建设用地、长期性农地也有一定幅度的增加,有林地、灌木林、草地、水域有所减少。② 有林地、灌木林之间的转移及其与长期农地、轮歇农地、橡胶园之间的转移,决定着中老缅泰交界地区土地利用变化特征。中老缅泰交界地区土地利用变化本质上受到市场经济、国家政策、人口迁移、基础设施建设等因素的影响。③ 橡胶园和茶园的时空变化基本表现为面积净值增加,空间位置交换变化非常小。长期农地面积变化不大,但存在较大幅度的空间位置转变;水域、轮歇农地变化以空间位置交换为主。草地、灌木林、有林地、建设用地交换变化和净变化比例相当。④ 1990-2010年,中老缅泰交界地区土地利用程度有所增加,其中,泰国境内土地利用程度最高,老挝和缅甸境内的土地利用程度最低。2000年后中老缅泰交界地区土地利用程度增幅明显加大。其中,中国和缅甸境内土地利用程度后期增幅减小,泰国境内土地利用程度后期增幅变大,老挝境内土地利用程度实现了由前期减少到后期增加的转变。     

黄土塬区土地利用变化对硝态氮累积和淋溶的影响

为了分析黄土塬区土地利用变化对土壤中NO₃--N迁移规律的影响,在陕西长武黄土塬区沿东西方向设置6个样地,每个样地内均选择耕地、由耕地转变来的果龄10 a和20 a左右的苹果园(下称耕地、10 a果园和20 a果园)3种土地利用方式采集土壤样品,分析土地利用变化对NO₃--N迁移的影响,并初步评估其对地下水污染的潜在风险. 结果表明:不同土地利用方式下土壤中NO₃--N均出现累积现象,达到累积峰时的土层深度表现为果园＞耕地,NO₃--N最大累积量表现为20 a果园＞10 a果园＞耕地. 耕地、10 a果园和20 a果园土壤w(NO₃--N)平均稳定深度分别为300、400和500 cm,平均稳定值分别为2.4、2.5和2.6 mg/kg. 地下水中ρ(NO₃-)为15.3 mg/L,而3种土地利用方式下土壤中ρ(可移动态NO₃-)分别为14.2、26.2和26.3 mg/L,可见,与耕地相比,果园土壤中NO₃--N淋溶至地下水的风险更大. 但由于土地利用变化导致的土壤水分运动和地下水补给存在差异,各土地利用方式对地下水中NO₃--N的贡献率尚需进一步量化.      

浑河底泥反硝化厌氧甲烷氧化菌群落结构时空特征

为了解在反硝化厌氧甲烷氧化反应过程中起主要作用的微生物——Candidatus Methylomirabilis oxyfera(M. oxyfera)在河流底泥环境中的时空变化特征,利用克隆文库及实时荧光定量PCR技术考察了浑河流域部分底泥中M. oxyfera-like的16S rRNA和pmoA功能基因的多样性及丰度. 结果表明:从浑河上游至下游丰水期各采样点底泥中M. oxyfera-like的16S rRNA的多样性无明显地域性差异,其OTU(operational taxonomic unit,独立操作单元)数变幅不大;pmoA功能基因的多样性则存在较为明显的地域性差异,上游采样点A(章党大桥)底泥中OTU数为5,下游采样点E(三岔河大桥)底泥中仅为1. 采样点A底泥中M. oxyfera-like的16S rRNA和pmoA功能基因的多样性均存在一定的季节性差异,平水期16S rRNA和pmoA功能基因的Shannon-Wiener多样性指数分别为1.48和2.19,在各期中最高;而枯水期时二者均最低,分别为0.83和1.26. 丰度分析结果显示,所有采样点底泥中M. oxyfera-like的16S rRNA丰度均表现为平水期(2.42×106~1.74×107 copies/g)(以干质量计)最高、枯水期(2.87×104~4.19×106 copies/g)居中、丰水期(1.29×103~2.04×104 copies/g)最低,说明浑河底泥中M. oxyfera-like的丰度亦存在一定的季节性差异.      

Assessing the effects of land use changes on soil sensitivity to erosion in a highland ecosystem of semi-arid Turkey

There has been increasing concern in highlands of semiarid Turkey that conversion of these systems results in excessive soil erosion, ecosystem degradation, and loss of sustainable resources. An increasing rate of land use/cover changes especially in semiarid mountainous areas has resulted in important effects on physical and ecological processes, causing many regions to undergo accelerated environmental degradation in terms of soil erosion, mass movement and reservoir sedimentation. This paper, therefore, explores the impact of land use changes on land degradation in a linkage to the soil erodibility, RUSLE-K, in Cankiri–Indagi Mountain Pass, Turkey. The characterization of soil erodibility in this ecosystem is important from the standpoint of conserving fragile ecosystems and planning management practices. Five adjacent land uses (cropland, grassland, woodland, plantation, and recreational land) were selected for this research. Analysis of variance showed that soil properties and RUSLE-K statistically changed with land use changes and soils of the recreational land and cropland were more sensitive to water erosion than those of the woodland, grassland, and plantation. This was mainly due to the significant decreases in soil organic matter (SOM) and hydraulic conductivity (HC) in those lands. Additionally, soil samples randomly collected from the depths of 0–10 cm (D ₁) and 10–20 cm (D ₂) with irregular intervals in an area of 1,200 by 4,200 m sufficiently characterized not only the spatial distribution of soil organic matter (SOM), hydraulic conductivity (HC), clay (C), silt (Si), sand (S) and silt plus very fine sand (Si + VFS) but also the spatial distribution of RUSLE-K as an algebraically estimate of these parameters together with field assessment of soil structure to assess the dynamic relationships between soil properties and land use types. In this study, in order to perform the spatial analyses, the mean sampling intervals were 43, 50, 64, 78, 85 m for woodland, plantation, grassland, recreation, and cropland with the sample numbers of 56, 79, 72, 13, and 69, respectively, resulting in an average interval of 64 m for whole study area. Although nugget effect and nugget effect–sill ratio gave an idea about the sampling design adequacy, the better results are undoubtedly likely by both equi-probable spatial sampling and random sampling representative of all land uses.     

浅谈如何选择温湿度箱

主要阐述了电子设备应用于不同场所,遇到的各种复杂的环境因素、;如高温、高湿、低温等,这些环境因素的存在将影响电子信息产品的可靠性,本文简要介绍了如何选用温湿度箱。     

基于经济发展阶段理论的土地利用变化研究——以广西江州区为例

土地利用在不同的经济发展阶段表现出不同特点。广西江州区属于我国西部经济欠发达地区,经济发展正处于工业化初期的起步阶段,土地利用变化特点主要表现为:以农业生产用地和生态用地竞争为主,耕地变化是土地利用变化的主要内容;建设用地低效、缓慢增长,农村居民点增长面积占较大比重;人均农村居民点面积逐渐增加。以1978-2002年的统计数据为基础,用主成分分析和回归分析相结合,对耕地面积变化的驱动力进行了研究,结果表明:人口增长、经济发展和土地管理使得耕地面积不断增长,收入和消费的提高以及农业产业结构调整导致耕地面积减少。发达地区的发展历程表明,经济高速发展必然引起农地快速非农化,江州区在土地利用中,必须注意节约用地,保护耕地,减少土地资源浪费,防止环境污染,实现区域土地的可持续利用。     

黄河中游城镇化与生态系统服务耦合关系的时空变化

城镇化是影响区域生态安全格局的重要因素,厘清城镇化与生态系统服务之间的关系,可为促进黄河流域生态保护与高质量发展提供决策参考。在分析2000—2018年黄河中游城镇化与生态系统服务时空格局的基础上,采用耦合协调度模型剖析了二者耦合关系的时空变化特征。研究发现：2000—2018年间,黄河中游地区综合城镇化水平提高72.24%,空间分布总体呈“南高北低”、以经济发达县区或城市群为中心向外递减的趋势;粮食生产、水源涵养、土壤保持和固碳服务量均呈增加趋势,且呈不同的空间分布态势;粮食生产、水源涵养、土壤保持和固碳服务与综合城镇化水平的耦合协调度总体呈上升趋势,但汾渭平原的耦合协调度普遍较低,而经济发达县区的耦合协调度普遍较高。     

Dynamic changes in microbial activity and community structure during biodegradation of petroleum compounds： A laboratory experiment

With 110-d incubation experiment in laboratory,the responses of microbial quantity,soil enzymatic activity,and bacterial community structure to different amounts of diesel fuel amendments were studied to reveal whether certain biological and biochemical characteristics could serve as reliable indicators of petroleum hydrocarbon contamination in meadow-brown soil,and use these indicators to evaluate the actual ecological impacts of 50-year petroleum-refining wastewater irrigation on soil function in Sbenfu irrigation area.Results showed that amendments of≤1000 mg/kg diesel fuel stimulated the growth of aerobic beterotrophic bacteria,and increased the activity of soil dehydrogenase,hydrogenperoxidase,polypbenol oxidase and substrate-induced respiration.Soil bacterial diversity decreased slightly during the first 15 d of incubation and recovered to the control level on day 30.The significant decrease of the colony forming units of soil actinomyces and filamentous fungi can be taken as the sensitive biological indicators of petroleum contamination when soil was amended with≥5000 mg/kg diesel fuel.The sharp decrease in urease activity was recommended as the most sensitive biochemical indicator of heavy diesel fuel contamination.The shifts in community structure to a community documented by Sphingomonadaceae withinα-subgroup of Proteobacteria could be served as a sensitive and precise indicator of diesel fuel contamination.Based on the results described in this paper,the soil function in Shenfu irrigation area was disturbed to some extent.     

河北省38°N生态样带生态系统服务功能时空变化

河北省38°N生态样带是一条由太行山区-山前平原区-低平原区-滨海平原区组成的典型生态样带。论文引进区域修正系数和环境成本系数对前人的生态系统服务功能价值评估模型进行改进,并对该生态样带土地利用变化驱动下的生态系统服务功能时空变化进行了研究。结果表明:1990-2008年,该生态样带的生态系统服务功能价值总量由334.83×10⁸元增至360.13×10⁸元,但食物生产功能价值持续减少,累计减少了4.67%。太行山区的生态系统服务功能单位面积价值为西高东低,主要由林地和草地提供;山前平原区和低平原区的生态系统服务功能单位面积价值较低且分布均匀,主要由农田提供;滨海平原区的生态系统服务功能单位面积价值东部明显高于中西部,主要由水体和湿地提供。     

花江小流域石漠化过程中的土壤有机碳氮的变化

以花江峡谷区1.2 km2小流域为研究对象,通过设置不同喀斯特石漠化强度的样地,研究不同等级石漠化样地的土壤有机碳、全氮含量在石漠化过程中的变化。结果表明,喀斯特生境中土壤具有高度异质性,人为干扰方式对土壤有机碳、全氮含量变异性的影响很大;樵采石漠化样地小生境土壤有机碳、全氮含量维持在较高水平,开垦石漠化样地小生境土壤有机碳、全氮含量较低;随着石漠化程度的加剧,樵采和开垦系列样地土壤有机碳、全氮含量呈现不断降低的趋势,这在一定程度上体现了石漠化过程的土壤退化本质。小流域内石漠化成因类型的划分对揭示石漠化过程中的土壤退化是必须的。