Fate and availability of dust-borne phosphorus in a sub-humid temperate forest
Fate and availability of dust-borne phosphorus in a sub-humid temperate forest
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DOI：
10.1016/j.chemgeo.2021.120628
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发表时间：
2021-11
期刊：
影响因子：
3.9
通讯作者：
Zhuo‐Jun Zhang;Hairuo Mao;Zhiqi Zhao;Shilu Wang;Cong-Qiang Liu;Yongfeng Hu;Mengqian Zhu
中科院分区：
文献类型：
--
作者：
Zhuo‐Jun Zhang;Hairuo Mao;Zhiqi Zhao;Shilu Wang;Cong-Qiang Liu;Yongfeng Hu;Mengqian Zhu
风沙沉积是陆地生态系统重要的磷输入源，但缺乏关于沙尘输入如何供给速效磷并影响亚湿润生态系统土壤磷地球化学和动态的证据。在半湿润温带森林生态系统的弱酸性土壤剖面（2.5 m厚）中，我们利用磷素k边缘x射线吸收近边缘光谱测定了土壤磷素的形态，并利用改进的Hedley顺序化学提取法测定了磷的有效性。根据Sr同位素分析，土壤剖面接受大量粉尘输入，占深度土壤质量的34.8% - 53.5%。酸性表层土壤（5 < pH < 5.5）含有钙结合磷（Ca-P），占土壤总磷的4%-18%。由于Ca-P化合物不稳定，在pH < 5.5时转化为其他形式，因此必须持续输入富含Ca-P的粉尘物质以维持表层土壤中相当多的Ca-P。在所有深度，土壤Ca-P与土壤活性Pi（树脂和nahco3提取）成比例正相关，表明粉尘携带的Ca-P化合物的溶解补充了活性Pi。另一方面，富铁粉尘的风化作用导致丰富的氧化铁的形成，从而有利于封闭P（44-85%）和铁（和铝）结合P（57-83%）的形成，这可能会固定粉尘携带的Ca-P溶解释放的P，并长期降低土壤P的有效性。有趣的是，腐岩层具有出乎意料的高风化程度，Ca-P几乎耗尽，可能是由于灰尘输入增加了土壤水分和微生物活动，从而导致风化。我们的研究表明，在酸性土壤中，粉尘携带的钙磷化合物的持续沉积和随后的溶解维持了土壤磷的有效性。该研究还强调，在亚湿润森林生态系统中，风沙输入不仅通过作为生物有效磷源，而且通过改变土壤化学和风化，影响土壤磷的有效性和动态。
Aeolian dust deposition is an important phosphorus (P) input to terrestrial ecosystems, but it lacks evidence of how dust inputs supply available P and affect P geochemistry and dynamics in soils of sub-humid ecosystems. We determined soil P speciation using P K-edge X-ray absorption near edge spectroscopy and P availability using modified Hedley sequential chemical extractions in a weakly acidic soil profile (2.5 m thick) in a sub-humid temperate forest ecosystem. The soil profile receives substantial dust inputs that account for 34.8% - 53.5% of the soil mass at depths based on a Sr isotope analysis. The acidic topsoils (5 < pH < 5.5) contain Ca-bound P (Ca-P) that accounts for 4%–18% of total soil P. Since Ca-P compounds are unstable and transform to other forms at pH < 5.5, continuous inputs of dust materials rich in Ca-P must occur to sustain the considerable Ca-P in the topsoils. Across all depths, soil Ca-P positively correlates with soil labile Pi(both resin and NaHCO3extracted) in proportion, suggesting that dissolution of dust-borne Ca-P compounds replenishes the labile Pipool. On the other hand, weathering of the Fe-rich dusts leads to formation of abundant iron oxides that in turn favors formation of occluded P (44–85%) and Fe (and Al)-bound P (57–83%), which may fix released P from the dust-borne Ca-P dissolution and reduce soil P availability in a long term. Interestingly, the saprolite layer has an unexpectedly high weathering degree with nearly depleted Ca-P, likely caused by dust inputs that increase soil moisture and microbial activities and accordingly weathering. Our study identifies that continuous deposition and subsequent dissolution of dust-borne Ca-P compounds in acidic soils sustain soil P availability. The study also highlights that aeolian dust inputs affect soil P availability and dynamics in a sub-humid forest ecosystem not only by acting as a bioavailable P source but also altering soil chemistry and weathering.