Environmental Science Graduate Program , The Ohio State University , Columbus , Ohio 43210 , United States.
Department of Chemistry and Biochemistry , Old Dominion University , Norfolk , Virginia 23529 , United States.
Environ Sci Technol. 2019 Jun 4;53(11):6273-6281. doi: 10.1021/acs.est.9b00202. Epub 2019 May 22.
Acid mine drainage (AMD) formed from pyrite (iron disulfide) weathering contributes to ecosystem degradation in impacted waters. Solar irradiation has been shown to be an important factor in the biogeochemical cycling of iron in AMD-impacted waters, but its impact on dissolved organic matter (DOM) is unknown. With a typical AMD-impacted water (pH 2.7-3) collected from the Perry State Forest watershed in Ohio, we observed highly efficient (>80%) photochemical mineralization of DOM within hours in a solar simulator resembling twice summer sunlight at 40°N. We confirmed that the mineralization was initially induced by OH formed from FeOH photodissociation and was inhibited 2-fold by dissolved oxygen removal, suggesting the importance of both the photochemical reaction and oxygen involvement. Size exclusion chromatography and Fourier transform ion cyclotron resonance mass spectrometry elucidated that any remaining organic matter was comprised of smaller and highly aliphatic compounds. The quantitative and qualitative changes in DOM are likely to constitute an important component in regional carbon cycling and nutrient release and to influence downstream aquatic ecosystems in AMD-affected watersheds.
由黄铁矿（二硫化铁）风化形成的酸性矿山排水（AMD）导致受影响水域的生态系统退化。太阳辐射已被证明是 AMD 影响水域中铁的生物地球化学循环的重要因素，但它对溶解有机物质（DOM）的影响尚不清楚。我们使用来自俄亥俄州佩里州立森林流域的典型 AMD 影响水（pH 值为 2.7-3），在太阳能模拟器中观察到 DOM 在数小时内发生高效（>80%）光化学矿化，该模拟器类似于北纬 40°的两倍夏季阳光。我们证实，矿化最初是由 FeOH 光解形成的 OH 诱导的，并且通过去除溶解氧抑制了 2 倍，这表明光化学反应和氧气参与都很重要。尺寸排阻色谱和傅里叶变换离子回旋共振质谱阐明，任何剩余的有机物都由更小和高度脂肪族化合物组成。DOM 的定量和定性变化可能构成区域碳循环和养分释放的重要组成部分，并影响 AMD 影响流域的下游水生生态系统。
