Fine‐grained hypermonosulfidic sediments are widespread on the coastal plains of the northern Baltic Sea that when drained, cause the formation and dispersion of acid and toxic‐metal species. In this study, a 30‐month laboratory oxidation experiment with such a sediment was performed in incubation cells. To minimize or prevent acidification, limestone was applied in two grain sizes: agricultural limestone with particles that were all <3.15 mm and half of them <0.80 mm, and fine‐grained limestone with a median grain size of 2.5 μm. The amount of limestone applied corresponded to the theoretical acidity contained in the sulfides, as well as four times that amount. Another treatment included addition of peat to the low limestone dose to test its effects on immobilizing sufhur and metals. The pH of the drainage water and solid phase decreased to pH <4.0 in the control, and to pH <5.0 in the coarse‐grained low‐limestone treatment, but remained near‐neutral in the other treatments. Hence, the fine‐grained limestone effectively hindered acidity formation in contrast with the coarse‐grained limestone when applied in amounts corresponding to the potential acidity held in the sulfides. The limestone treatments further overall decreased the rate of pyrite oxidation, slowed down the movement of the oxidation front, strongly minimized the formation of dissolved and solid‐phase labile Al, and caused formation of gypsum as well as more labile secondary Fe(III) phases than corresponding Fe phases formed in the control. The limestone and peat treatments also caused shifts in the 16S rRNA gene‐based microbial communities, where the control developed acidophilic iron and sulfur oxidizing communities that promoted acidity and metal release. Instead, the limestone‐treated unacidified incubations developed acid tolerance to neutrophilic communities of iron and sulfur oxidizers that promoted sulfate formation without acidity release. The results showed that limestone treatments have several biogeochemical effects, and that using a fine‐grained limestone as amendment was favourable in terms of minimizing acidity formation and metal release.

中文翻译：

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石灰岩和泥炭处理培养的高单硫化沉积物的地球化学和微生物反应


细粒高一硫化沉积物广泛分布在波罗的海北部的沿海平原上，当排干时，会导致酸和有毒金属物种的形成和扩散。在这项研究中，在孵育细胞中对这种沉积物进行了为期 30 个月的实验室氧化实验。为了最大限度地减少或防止酸化，石灰石有两种粒度：颗粒均为 <3.15 mm，其中一半为 <0.80 mm 的农业石灰石，以及中位粒度为 2.5 μm 的细粒石灰石。施用的石灰石量对应于硫化物中所含的理论酸度，是该量的四倍。另一种处理方法包括在低剂量的石灰石中添加泥炭，以测试其对固定 sufhur 和金属的效果。在对照中，排水和固相的 pH 值降至 pH <4.0，在粗粒低石灰石处理中降至 pH <5.0，但在其他处理中保持接近中性。因此，与粗粒石灰石相比，当施用量与硫化物中的潜在酸度相对应时，细粒石灰石有效地阻碍了酸度的形成。石灰石处理进一步总体上降低了黄铁矿氧化的速率，减缓了氧化前沿的运动，大大减少了溶解和固相不稳定 Al 的形成，并导致石膏的形成以及比对照中形成的相应 Fe 相更不稳定的次级 Fe（III） 相。石灰石和泥炭处理还引起了基于 16S rRNA 基因的微生物群落的变化，其中对照产生了嗜酸性铁和硫氧化群落，促进了酸度和金属释放。 相反，石灰石处理的未酸化孵育对铁和硫氧化剂的嗜中性群落产生了耐酸性，从而促进了硫酸盐的形成而不释放酸度。结果表明，石灰石处理具有多种生物地球化学效应，使用细粒石灰石作为改良剂在最大限度地减少酸度形成和金属释放方面是有利的。