Soil pH from soil Ambient and CO2

This dataset comprises soil pH measurements collected from controlled greenhouse experiments designed to evaluate the effects of single and combined heavy metal (HM) treatments on paddy soil under ambient (RK) and elevated CO₂ (RKCO₂) conditions. Three heavy metals—Cadmium (Cd), Zinc (Zn), and Iron (Fe)—were applied individually and in binary combinations across multiple concentration levels. Soil pH was monitored at three rice growth stages: 65, 95, and 130 days after planting. Heavy Metal Treatment Structure Heavy metals were applied at five concentrations each: Cd (ppm): 5, 10, 15, 20, 25 Zn (ppm): 150, 200, 250, 300, 350 Fe (ppm): 200, 250, 300, 350, 400 Combined treatments followed matched pairs representing increasing HM stress: Cd+Zn: (5–150), (10–200), (15–250), (20–300), (25–350) ppm Cd+Fe: (5–200), (10–250), (15–300), (20–350), (25–400) ppm Zn+Fe: (150–200), (200–250), (250–300), (300–350), (350–400) ppm All treatments included a 0 ppm control for both greenhouse environments. Soil Sampling and Preparation Soil samples were air-dried, gently ground, and sieved through a 250 μm mesh to remove debris, following standard soil preparation procedures (Jones et al., 2021). The processed samples were subsequently used to assess soil pH and heavy-metal-related physicochemical properties. Soil pH Determination Soil pH was measured using a 1:2.5 soil-to-deionized-water ratio, modified from established protocols (Duddridge & Wainwright, 1981; Smith et al., 2020). For each sample, 10 g of soil was mixed with 50 mL of deionized water, shaken for 30 minutes, and the pH was recorded using a glass-electrode pH meter (WTW INOLAB Level 1). Dataset Structure The dataset contains: pH values for single-metal treatments (Cd, Zn, Fe) pH values for combined-metal treatments (Cd+Zn, Cd+Fe, Zn+Fe) Measurements across two atmospheric conditions: RK (ambient CO₂) RKCO₂ (elevated CO₂) Measurements at three time points: 65 days 95 days 130 days Statistical significance assessed at p < 0.05 Purpose of the Dataset This dataset provides high-resolution soil pH responses to heavy metal stress under current and future CO₂ scenarios, enabling evaluation of: soil acidification dynamics, HM–CO₂ interaction effects, temporal shifts in soil chemistry during rice growth, early indicators of soil degradation under combined environmental stressors本数据集收录自受控温室实验的土壤pH测量数据，旨在评估单一及复合重金属（Heavy Metal, HM）处理对大气本底（RK）与高CO₂浓度（RKCO₂）环境下水稻田土壤的影响。实验选用镉（Cadmium, Cd）、锌（Zinc, Zn）与铁（Iron, Fe）三种重金属，分别设置单一施加与二元复合施加两种处理方式，并设置多个浓度梯度。在水稻种植后的第65、95、130天三个生长阶段，对土壤pH值进行监测。 ### 重金属处理方案 每种重金属均设置5个浓度梯度： - 镉（Cd，ppm）：5、10、15、20、25 - 锌（Zn，ppm）：150、200、250、300、350 - 铁（Fe，ppm）：200、250、300、350、400 复合处理采用匹配浓度对以代表递增的重金属胁迫水平： - Cd+Zn：(5–150)、(10–200)、(15–250)、(20–300)、(25–350) ppm - Cd+Fe：(5–200)、(10–250)、(15–300)、(20–350)、(25–400) ppm - Zn+Fe：(150–200)、(200–250)、(250–300)、(300–350)、(350–400) ppm 两种温室环境均设置0 ppm的空白对照组。 ### 土壤采样与前处理 参照标准土壤前处理流程（Jones等，2021），土壤样品经风干、轻磨后过250 μm筛以去除杂质，经上述处理后的样品将用于测定土壤pH值及与重金属相关的理化性质。 ### 土壤pH测定 参照已有规程（Duddridge & Wainwright，1981；Smith等，2020）并稍作修改，采用1:2.5的土水比开展pH测定。具体操作如下：称取10 g土壤与50 mL去离子水混合，振荡30分钟后，使用玻璃电极pH计（WTW INOLAB Level 1）记录pH值。 ### 数据集结构 本数据集包含以下内容： 1. 单一重金属处理（Cd、Zn、Fe）下的土壤pH值 2. 复合重金属处理（Cd+Zn、Cd+Fe、Zn+Fe）下的土壤pH值 测试涵盖两种大气环境条件： - RK：大气本底CO₂浓度 - RKCO₂：高CO₂浓度环境 共三个采样时间点： - 种植后65天 - 种植后95天 - 种植后130天 本数据集的统计显著性检验阈值设置为p < 0.05。 ### 数据集用途 本数据集提供了当前及未来CO₂情景下，土壤pH对重金属胁迫的高分辨率响应数据，可用于评估以下内容： 1. 土壤酸化动态 2. 重金属-CO₂交互效应 3. 水稻生长周期内土壤化学性质的时序变化 4. 复合环境胁迫下土壤退化的早期指示因子