Department of Plant & Soil Sciences, University of Delaware, Newark, DE, 19716, USA.
Department of Earth & Environmental Sciences, Rutgers University, Newark, NJ, USA.
Environ Pollut. 2023 Apr 15;323:121302. doi: 10.1016/j.envpol.2023.121302. Epub 2023 Feb 16.
Sea level rise (SLR) is estimated to impact 25% of the world's population along coastal areas leading to an increase in saltwater intrusion. Consequently, changes in the soil biogeochemistry of currently non-saline and/or well-drained soils due to saltwater intrusion are of major concern. Saltwater intrusion is expected to affect farmland across large broiler producer regions, where large amounts of manure containing organic arsenicals were applied over the past decades. To determine how SLR may impact the speciation and mobility of adsorbed inorganic and organic As, we used in situ real-time attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) to determine the adsorption and desorption mechanisms of As(V) and 4-aminophenylarsonic (p-ASA, a poultry feed additive) on ferrihydrite (Fh) in the presence of sulfate at varying pH. The adsorption of As(V) and p-ASA increased at lower pH, with As(V) showing IR features consistent with the formation of inner-sphere of As-Fh surface complexes, while p-ASA also formed others structures as H-bonded As-surface complexes, likely mediated by outer-sphere complexes, based on our FTIR and batch experiments data. No observable As(V) or p-ASA desorption from the Fh surface was promoted by sulfate, however sulfate adsorption on the Fh surface was remarkably larger for p-ASA than for As(V). Complimentary, we carried out batch studies of As(V) and p-ASA desorption by Fh, using artificial seawater (ASW) at varying concentrations. The 1% ASW desorbed ∼10% of initially sorbed p-ASA, while at 100% ASW desorbed ∼40%. However, <1% of As(V) was desorbed by 1% ASW solution and only ∼7.9% were desorbed at 100% ASW. The spectroscopic data support the more extensive desorption of p-ASA compared to As(V) observed in batch experiments, suggesting that organoarsenicals may be easily desorbed and, after conversion to inorganic forms, pose a risk to water supplies.
海平面上升（SLR）预计将影响沿海地区 25%的世界人口，导致海水入侵增加。因此，由于海水入侵，目前非盐渍和/或排水良好的土壤的土壤生物地球化学变化引起了极大的关注。预计海水入侵将影响大型肉鸡生产地区的农田，在过去几十年中，大量含有有机砷的粪便被施用于这些农田。为了确定 SLR 如何影响吸附态无机和有机砷的形态和迁移性，我们使用原位实时衰减全反射-傅里叶变换红外光谱（ATR-FTIR）来确定在不同 pH 值下，硫酸盐存在时，砷（V）和 4-氨基苯胂酸（p-ASA，一种家禽饲料添加剂）在针铁矿（Fh）上的吸附和解吸机制。在较低的 pH 值下，砷（V）和 p-ASA 的吸附增加，砷（V）的红外特征表明形成了内球砷-Fh 表面络合物，而 p-ASA 也形成了其他结构，如氢键砷-表面络合物，可能是由外球络合物介导的，这是基于我们的 FTIR 和批量实验数据。然而，硫酸盐并没有促进 Fh 表面上砷（V）或 p-ASA 的可观察到的解吸，但是硫酸盐在 Fh 表面上的吸附对于 p-ASA 比对砷（V）大得多。作为补充，我们使用不同浓度的人工海水（ASW）进行了 Fh 上砷（V）和 p-ASA 解吸的批量研究。在 1%的 ASW 中解吸了约 10%最初吸附的 p-ASA，而在 100%的 ASW 中解吸了约 40%。然而，只有约 7.9%在 100%的 ASW 中解吸。光谱数据支持在批量实验中观察到的 p-ASA 比砷（V）更广泛的解吸，这表明有机胂可能很容易解吸，并且在转化为无机形式后，对供水构成威胁。
