沙坡头苔藓生物结皮层土壤特性演变研究

Study on soil properties evolution of moss biological crust layer in Shapotou area

苔藓结皮是沙漠生物结皮发育成熟类型,对改善风沙区生态环境状况、促进风沙土发育等具有良好效果。采集了不同时间固沙植被下的苔藓结皮层样品,采用常规方法和电感耦合等离子体发射光谱仪(PE ICP-OES)分析测定了苔藓结皮层颗粒组成、腐殖质特征和全量化学元素含量变化。结果表明,苔藓结皮层颗粒物粒径集中分布在350~400μm范围,并且随着固沙植被时间的增加,苔藓结皮层<10μm粒径的颗粒物含量呈现增加趋势。随着固沙植被时间增加,苔藓结皮层有机质含量从8.61 g/kg增加到11.95 g/kg,腐殖酸从2.10 g/kg增加到2.20 g/kg,胡敏酸含量从0.40 g/kg增加到0.90 g/kg,并且胡敏酸的光学特性E4、E6吸光值增加,而E4/E6值在减少。苔藓结皮层全量化学元素组成(SiO2除外)含量均高于流动沙土;随着固沙植被时间增加,苔藓结皮层SiO2含量呈现出明显降低的趋势,其它全量化学元素含量均呈现增加趋势。苔藓结皮层硅铁铝率低于对照流动沙土,且随着固沙植被时间的增加,苔藓结皮层硅铁铝率均呈现降低趋势。风沙环境下苔藓结皮层的形成和长期保留,能够提高细颗粒物含量,改善腐殖质特征,提高矿物质元素含量,对促进风沙土形成演变具有积极作用。

Moss crust is the top type of desert crusts.The mossy crust layer also has a good effect on improving the ecological environment of the aeolian area and promoting the development of aeolian sandy soil.In this paper,samples of mossy crust layers under different sand fixation ages were collected.The particle size,humus characteristics and total chemical element content of the moss crusts layer were determined by conventional methods and inductively coupled plasma optical emission spectrometry(PE ICP-OES).The results showed that the particle size of the mossy crust layer was mainly distributed in the range of 350 ~ 400μm,and with increasing sand-fixing age,<10 μm particle size of the particulate matter content of mossy crust layer showed an increase trend.With increasing sand-fixing age,the organic matter content of mossy crust layer increased from 8.61 g/kg to 11.95 g/kg,total humid acid increased from 2.10 g/kg to 2.20 g/kg,the humic acid content increased from 0.40 g/kg to 0.90 g/kg,and the optical properties of the absorbance of the humic acid E4 and E6 were increased,but the E4/E6 ratio was decreased.The total chemical composition(except SiO2) of the moss crust layer was higher than that of the flowing sand,and with increasing sand-fixing age,the content of Si O2 in mossy crust layer showed a significant decrease trend,but the content of other total chemical elements showed an increasing trend.The rate of ferrosilicon in the moss crust layer was lower than that of the control flowing sand,with increasing sand-fixing age,the ferrosilicon ratio of mossy crust layer showed a decrease trend.The content of total chemical elements and the ferrosilicon ratio in atmospheric dustfall were better than those of mossy crust and control flowing sand.The formation and long-term retention of the mossy crust layer in the aeolian environment could improve the content of fine particles,improve the characteristics of soil humus,increase the content of mineral elements,and reduce the rate of ferrosilicon,which had a positive effect on promoting the formation and evolution of aeolian sandy soil.