北极新奥尔松地区土壤中生物硅含量及形态特征

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。

BIOGENIC SILICA CONTENT AND MORPHOLOGY OF SOIL AT Ny-ALESUND,THE ARCTIC

Global silicon cycle is closely related to carbon cycle. Biogenic silica (BSi) is an essential part in the global silicon cycle as an important carrier of silicon. Lots of studies on the silicon cycle of terrestrial ecosystems have been reported, but researches on silicon in poplar regions are extremely rare. Using the soil and plant samples obtained from the fifth Chinese Arctic Scientific Expedition, BSi content and phytolith morphology were analyzed in the soil near Chinese Yellow Station in the Ny-?lesund, Arctic. The main conclusions are as follows: In the topsoil of Svalbard, the content of particle organic carbon (POC) and particle organic nitrogen (PON) ranges 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 is from 3.90 to 26.3 μg?g-1, with an average of 10.7 μg?g-1 in soil. And BSi is between 5.60 and 9.97 mg?g-1, with an average of 7.56 mg?g-1 in soils of this study area. It shows a positive correlation between BSi and PON and POC, indicating that their sources were same to some extent in soil. And BSi content is higher in the topsoil of Arctic than that in temperate and tropical regions. Phytoliths in the plants are observed in forms of cap-shaped, round, smooth rod, tooth-shaped, spiny bar and dumbbell-shaped, etc, with a size between 10 and100 μm. Phytolith and diatom are both found in soil samples as compositions of BSi. Phytolith is the dormant BSi in the soil with vegetation covered. While Diatoms (Pennatae) are mostly found in the bare soils, which account for ~93.3% of the BSi. Phytolith in soil samples are mainly from plants inferred from the similarity of the morphology to phytolith in plants. The contents of POC, PON, soluble silica, BSi and the abundance of phytolith are higher in soil samples with vegetation covered than in the bare soil, suggesting that the silicon cycle in soil are significantly affected by plants in Arctic area.