沙尘暴的成因与防治措施初探

针对今春我国北方地工百北京连续７次的扬尘和沙尘暴龙击,分析其成因及危害,提出了防治沙尘暴的具体措施及建议,为沙尘暴的有效治理提供一定的科学依据和参考。     

祁连山中部四种典型生态系统土壤氮矿化的研究

水热因素对土壤氮矿化的影响直接关系到陆地生态系统功能对气候变化的响应趋势。祁连山是青藏高原北沿的典型山地,对气候变化影响十分敏感和脆弱,为了定量确定祁连山土壤氮分解对水热因素变化的响应趋势,在人工气候箱内以正交试验设计方法培养土壤,分析了祁连山高寒草甸、山地森林、荒漠草原和干草原土壤氮矿化及其与温度、湿度和土层的关系。结果显示:以土壤氮矿化量极差计,海拔高度影响最大,其次是温度和湿度;以土壤氮矿化比例极差计,温度和海拔高度影响较大。海拔高度对土壤氮矿化量的影响显著(p<0.05)。除湿度外,其它因素对土壤氮矿化比例影响也达到显著程度(p<0.10)。35℃下土壤氮矿化比例显著比5℃下高,而不同湿度下土壤氮矿化及其矿化比例差异不显著(p<0.05)。海拔高度3000m和3300m处土壤氮矿化量比2800m和2200m处高,2800m处比2200m处高,3000m处土壤氮矿化比例显著比2200m和3300m处高(p<0.05)。森林和干旱草原土壤中氮矿化比例较高,荒漠草原和高寒草甸中较低。以土壤氮矿化速率计,5℃升高到15℃下和15℃升到25℃,Q10较低;以土壤氮矿化比例计,5℃升高到15℃下,Q10较高,15℃到25℃较低。研究结果说明高寒草甸和山地森林土壤氮矿化量较高,干旱草原和荒漠草原土壤氮矿化量较低;森林和干旱草原中土壤氮矿化比例较高,荒漠草原和高寒草甸中较低。     

综合治理沙漠化灾害

本文对我国沙漠化灾害有自然和人为的两方面原因，进行了具体的分析和介绍。     

Past desertification processes of Minqin Oasis in arid China

Irrigated farming has affected most natural oases in western China since the Han Dynasty employed advanced agricultural techniques in dryland areas. To date, little is documented about the process through which these oases were modified by human systems. In this study, a multi-disciplinary approach incorporating analysis of historical documents, archaeological field surveys, satellite imagery, and GIS data was used to understand desertification processes in the Minqin Basin in Gansu Province, China, over the historical period. Results suggest that initial reclamation efforts around the Minqin Oasis were launched in the Han Dynasty (220–121 BC) and culminated in the Wei and Jin Dynasty (220–420). During the following 800 years from the Southern and Northern Dynasties (420–581) to the Yuan Dynasty (1271–1368), farmland disappeared and became desert when the region was taken over by nomadic people. The second period of intense development occurred in the Ming Dynasty (1368–1644) and was followed by another more aggressive development in the Qing Dynasty (1644–1911), which resulted in the largest reclaimed area in history. Oases were constantly reclaimed and subsequently abandoned and desertified over the whole historical period. The causes were complex, but the major cause was related to dynastic transition that often resulted in changes in national policies.     

Changes in desert steppe soil culturable bacteria from northwestern China and correlation with physicochemical parameters

Seasonal variations effects on desert steppe soil culturable bacteria in northwestern China and physicochemical parameters were investigated. Soil temperature ranged from 5.37 to 23.73 °C. Moisture content varied from 3.22% to 7.62%. The pH was between 7.98 and 8.72. Soil nutrients were altered in different seasons. Total potassium (K) remained the same, but available K levels ranged from 101.29 to 227.55 mg/kg. The culturable bacterial counts in January, April, July and October were 0.13 × 10⁷, 4.09 × 10⁷, 5.33 × 10⁷ and 1.8 × 10⁷ colony forming units (cfu)/g, respectively. Bacterial populations were most abundant in surface layers and declined with increase of soil depth. Seventy-two bacterial strains were isolated and classified according to 27 genera of 5 phyla groups: Firmicutes, Actinobacteria, Alphaproteobacteria, Gammaproteobacteria and Bacteroidates. The bacterial diversities varied according to seasons. In spring, only Firmicutes and Actinobacteria were isolated. In summer, Firmicutes, Actinobacteria and Bacteroidetes were detected with Firmicutes the dominant species. In autumn and winter, Firmicutes, Actinobacteria, α-Proteobacteria and γ-Proteobacteria predominated. Our results indicated that climatic variations, vegetation coverage and soil physicochemical parameters are critical factors for maintaining culturable bacterial populations and diversity in the desert steppe. Soil moisture content and temperature exerted marked influence on bacterial quantities and diversities.     

腾格里沙漠民勤沙丘CO_2浓度与昼夜变化规律研究

为查明沙漠区CO2浓度和对大气CO2的影响以及在全球碳循环中的作用,利用红外CO2监测仪于2009年9月对腾格里沙漠民勤实验点不同类型不同深度的沙层CO2含量变化进行了昼夜连续观测.根据12个钻孔CO2浓度的昼夜观测结果可知,民勤沙漠区不同观测点CO2浓度差异较大,各观测点昼夜CO2浓度变化在310×10-6～2 630×10-6之间;夜间沙层CO2浓度低,白天CO2浓度高;CO2浓度在深度上也有明显的差异,不同深度CO2浓度由大到小的顺序是:4 m(3m)2 m1m;与温带半湿润的西安地区相比,位于极端干旱区的民勤沙漠区CO2浓度显著低;CO2浓度昼夜变化明显,从当日09:00左右到次日09:00左右均呈现由低到高再到低的变化规律;在沙层水分一定的条件下,昼夜温度变化是造成沙层CO2浓度昼夜变化的主要原因,两者呈显著正相关关系;含水量较高沙层CO2浓度明显高于含水量较低沙层,沙层含水量高低是决定沙层CO2浓度的主要因素;4 m深度以上沙层CO2浓度均高于地表空气CO2浓度,表明极端干旱的沙漠区可能是CO2的来源区,也指示环境恶劣的裸露流动沙丘微生物活动产生的沙层CO2浓度仍然超过了大气CO2浓度.     

塔克拉玛干沙漠腹地四种植物根系分形特征分析

采用全根挖掘法,运用分形理论对塔克拉玛干沙漠腹地阿克苏牛皮消、河西菊(Hexinia polydichotoma(Ostenf.)H.L.Yang)、白麻(Apocynum venetum L.)、沙拐枣(Cynanchum amplexicaule Hemsl)四种多年生野生植物根系的分支状况、分形特征与拓扑特征之间的关系进行了研究。研究发现:⑴四种植物根系分形特征较明显,分形维数大小与拓扑参数连接总数、外部连接数之间具有显著的相关关系;⑵根丰度与根系长度、平均连接长度之间具有显著的指数关系,分别可用以下方程表示:y1=2.7694e1.5496x,y2=0.036 9e2.026 7x(其中y1、y2分别为总根长、平均连接长度,R2分别为0.935 3、0.983 2)。因此,通过分形和拓扑理论对比分析了沙漠腹地4种野生植物根系的空间分形特征、资源占有能力与吸收率,有利于为沙漠腹的植物根系研究提供相关参数和一定的理论依据。     

塔里木沙漠石油公路风沙危害

为了给沙漠石油公路防沙工程设计和未业公路养护提供科学依据,综合野外观测及风洞模拟实验资料,分析了塔里木沙漠石油公路风沙危害的形成,建立了风沙危害程度的评价模式,从而得出公路沿线的风沙危害具有如下时空分布规律：（１）在时间上,风沙危害主要集中于春、夏季节（４－９月）,其中４月份最强;（２）在空间上,愈向沙漠深入,风沙危害愈烈,风沙危害程度指数的理论估算值与风沙现象观测记录相吻合。     

荒漠草原土壤线虫对氮沉降及降雨变化的响应

为了解氮沉降和降雨变化对短花针茅荒漠草原土壤线虫的影响,试验设计采用主区为增雨30％(W)和减雨30％(R)、自然降雨(CK)3种水分处理,副区为0(N0)、30(N30)、50(N50)和100(N100)kg/(hm2·a)4个氮素梯度共12个处理.结果表明:研究区共鉴定土壤线虫隶属41属,群落优势属为丽突属(Ac...     

极端干旱区咸水灌溉人工防护林土壤可溶性碳的垂直分布及其影响因素

可溶性碳(DC)是土壤中最活跃的碳组分,植被恢复与重建加速了干旱荒漠区的碳循环过程.研究咸水灌溉下沙漠人工防护林地土壤剖面DC的分布,可为干旱荒漠区人工林的管理和开发利用提供理论支撑和决策依据.本研究选取塔克拉玛干沙漠公路沿线5个不同矿化度咸水滴灌林地作为研究样地,流沙地为对照(CK),分析并讨论了0～1 m剖面土壤可溶性有机碳(SDOC)和可溶性无机碳(SDIC)的垂直分布特征及其与各因子间的相关关系.结果表明,CK与2.82 g·L^-1矿化度滴灌处理SDOC、SDIC呈"I"型分布,其分布满足线性函数关系,其他各样地SDOC和SDIC均呈"Γ"型分布,分布满足幂函数关系;所有处理表层SDOC、SDIC波动能力及贡献度均高于下层土壤,且SDOC波动及贡献度均大于SDIC, 2.82 g·L^-1之外的各林地SDOC平均含量是SDIC的2～4倍;2.82 g·L^-1样地SDOC平均含量低于CK,其他各样地SDOC是CK的3～5倍,各样地SDIC含量较CK增加了15.0%～57.9%;矿化度高于2.82 g·L^-1...