Abstract：
Dissolved black carbon (DBC) plays a crucial role in the migration and bioavailability of iron in water. However, the properties of DBC releasing under diverse pyrolysis conditions and dissolving processes have not been systematically studied. Here, the compositions of DBC released from biochar through redox processes dominated by bacteria and light were thoroughly studied. It was found that the DBC released from straw biochar possess more oxygen-containing functional groups and aromatic substances. The content of phenolic and carboxylic groups in DBC was increased under influence of microorganisms and light, respectively. The concentration of phenolic hydroxyl groups increased from 10.0∼57.5 mmol/gC to 6.6 ∼65.2 mmol/gC, and the concentration of carboxyl groups increased from 49.7∼97.5 mmol/gC to 62.1 ∼113.3 mmol/gC. Then the impacts of DBC on pyrite dissolution and microalgae growth were also investigated. The complexing Fe3+ was proved to play a predominant role in the dissolution of ferrous mineral in DBC solution. Due to complexing between iron ion and DBC, the amount of dissolved Fe in aquatic water may rise as a result of elevated number of aromatic components with oxygen containing groups and low molecular weight generated under light conditions. Fe-DBC complexations in solution significantly promoted microalga growth, which might be attributed to the stimulating effect of dissolved Fe on the chlorophyll synthesis. The results of study will deepen our understanding of the behavior and ultimate destiny of DBC released into an iron-rich environment under redox conditions.
摘要：
溶解黑碳(DBC)在水中铁的迁移和生物有效性中起着至关重要的作用。然而,在不同的热解条件和溶解过程下的DBC释放特性尚未得到系统研究。这里,深入研究了生物炭通过细菌和光主导的氧化还原过程释放的DBC的组成。发现秸秆生物炭释放的DBC具有较多的含氧官能团和芳香物质。在微生物和光照的影响下，DBC中酚类和羧基的含量增加，分别。酚羟基的浓度从10.0~57.5mmol/gC增加到6.6~65.2mmol/gC，羧基浓度从49.7~97.5mmol/gC增加到62.1~113.3mmol/gC。然后研究了DBC对黄铁矿溶解和微藻生长的影响。证明了络合的Fe3在DBC溶液中亚铁矿物的溶解中起着主要作用。由于铁离子与DBC的络合,由于在光照条件下产生的具有含氧基团和低分子量的芳族组分的数量增加，水中溶解的Fe的量可能会增加。溶液中的Fe-DBC络合显著促进微藻生长，这可能归因于溶解的Fe对叶绿素合成的刺激作用。研究结果将加深我们对在氧化还原条件下释放到富铁环境中的DBC的行为和最终命运的理解。
