Sequential iron extraction in acidic and non-acidic tundra, Toolik, Alaska (2021)

The goal of this study was to measure the various species of iron in soils with differing soil pH and soil moisture conditions. Soils were collected over the summer of 2021 along two tundra hillslopes (one acidic and one non-acidic) near Toolik Lake. Each study hillslope had three sites with soil moisture conditions delineated as Dry, Mesic, and Wet, with three replicate 5 x 5 meter (m) plots at each site. Soil samples were collected from each replicate plot at three sampling events over the summer of 2021. Soils were extracted using a 2-inch stainless steel corer and were frozen upon return from the field. The sampled soils were separated by horizon and then underwent a sequential iron extraction to measure iron associated with soil organic matter, poorly crystalline forms of iron, and crystalline forms of iron.本研究旨在测定不同土壤pH值与土壤含水量条件下，土壤中各类铁形态的含量。2021年夏季，研究人员于图利克湖（Toolik Lake）附近的两处苔原山坡（分别为酸性山坡与非酸性山坡）采集土壤样本。每条研究山坡设置三个采样站点，各站点的土壤含水量分别划分为干旱、中湿与湿润三类，每个站点设置三个重复的5×5米样地。2021年夏季共开展三次采样工作，从每个重复样地中采集土壤样本。土壤样本采用2英寸不锈钢取土钻（stainless steel corer）采集，野外采样结束后立即冷冻保存。采集得到的土壤样品按土层（horizon）分离后，通过连续铁提取法（sequential iron extraction）测定与土壤有机质（soil organic matter）结合的铁、低结晶态铁以及结晶态铁的含量。