北极新奥尔松地区土壤中生物硅含量及形态特征

摘要

硅循环与碳循环密切相关，生物硅作为硅的重要载体，在全球硅循环中占有十分重要的地位。目前，人们对陆地生态系统的硅循环做了大量研究，但对极地地区硅的研究却极为少见。利用中国第五次北极考察获得的土壤与植物样品，对北极新奥尔松地区中国黄河站站基表层土壤中生物硅的含量及土壤和植被中生物硅（主要为植硅体）的形态进行了初步研究。主要结论为：北极新奥尔松地区中国黄河站站基附近表层土壤中颗粒有机碳的含量为1．00—69．3 mg· g－1，平均值为13．7 mg· g－1；颗粒有机氮含量为0．11—9．84 mg· g－1，平均值为1．43 mg· g－1；可溶态硅含量为3．90—26．3μg· g－1，平均值为10．7μg· g－1；生物硅含量为5．60—9．97 mg· g－1，平均值为7．56 mg· g－1，且其含量与土壤颗粒态有机碳和颗粒有机氮呈正相关关系，表明三者具有相似来源。北极表层土壤生物硅比温带、热带地区生物硅含量要高。植物样品中植硅体形态以帽形、圆形、平滑棒形、齿形、刺棒形和哑铃形等形态为主，大小在10—100μm之间。土壤样品中的植硅体主要来源于植物，形态分别为平滑棒形、刺棒形、圆形、哑铃形、鞍形、尖形和帽形，另外硅藻也是北极土壤中生物硅的组成部分，其中裸露土壤中藻类（羽纹纲硅藻）占生物硅的多数（93．3％）。对比发现，有植被覆盖的土壤中，土壤有机碳、可溶出态硅、生物硅含量和植硅体形态丰富度往往比无植被覆盖或寡植被区土壤高，这表明尽管该地区植被稀少，但植物生长对该地区土壤硅循环存在显著影响，值得进一步关注。%The global silicon cycle is closely related to the carbon cycle.Biogenic silica ( BSi) is an important carrier in the silicon cycle.There have been many studies on the silicon cycle of terrestrial ecosystems, but few on the silicon cycle in poplar regions.BSi content and phytolith morphology were analyzed in soil and plant samples obtained near the Chinese Yellow River Station in Ny-Ålesund, Svalbard, during the fifth Chinese Arctic Scientific Expedition.In the topsoil of Svalbard, the content of particulate organic carbon ( POC) and particulate organic nitrogen ( PON) ranged from 1.00 to 69.3 mg· g-1 and 0.11 to 9.84 mg· g-1 , with an average of 13.7 mg· g -1 and 1.43 mg· g-1 , respectively.The concentration of soluble silica in the soil of this study area ranged from 3.90 to 26.3 μg· g-1 , with an average of 10.7 μg· g -1 , and the BSi ranged from 5.60 to 9.97 mg· g-1 , with an average of 7.56 mg· g -1 .There was a positive correlation between BSi and both PON and POC in soil, indicating that their sources were similar.The BSi content in the topsoil of the Arctic is higher than that in temperate and tropical regions.Phytoliths in the plant samples showed various forms including cap-shaped, round, smooth rods, tooth-shaped, spiny bars and dumbbell-shaped, with sizes between 10 and 100μm.Phytoliths and diatoms were found in soil samples as compositions of BSi.Phytoliths were the dominant BSi in soil with vegetation cover while pennate di-atoms were dominant in bare soils, where they accounted for about 93.3% of the BSi.Phytoliths in soil samples were mainly from plants, inferred from similarity of the morphology to that of phytoliths in plants.The contents of POC, PON, soluble silica, BSi, and the abundance of phytoliths were higher in samples from soil with vegetation covered than in samples of bare soil, suggesting that the silicon cycle in the soil of the Arctic is strongly influenced by plants.