Photoreduction of Hg (II) is of great importance but remains not fully understood especially in the presence of SO42-. In this study, laboratory experiments were conducted to investigate the reduction of Hg (Cl)2with various SO42-concentrations under artificial solar radiation. The whole process was tracked by changing Hg (0) concentrations in argon; the rate constants were calculated by trial method and were compared with other experiment. The results show the reaction rate decreased with increasing SO42-concentrations (0-20 mg L-1) and the cause of inhibitory effect is assumed with two explanations. The concentration of Hg (0) in argon increased firstly and decreased later in each treatment, since the main reactions in rising and dropping period are different. The comparison indicates that reduction rate is influenced by combined factors such as the form of mercury, the quantity of DOM and TSSs, depth of water and quality of light source.

13Interspecific mycelial interactions between white rot fungi are always accompanied by increased 14 production of laccase. In this study, the potential of white rot fungi Dichomitus squalens for 15 enhancing laccase production during interaction with two other white rot fungi Trametes 16 versicolor or Pleurotus ostreatus was identified. To probe the mechanism of laccase induction and 17 the role of laccase played during the combative interaction, we analyzed the laccase induction 18 response to stressful conditions during fungal interaction related to the differential gene expression 19 profile. We further confirmed the expression patterns of 16 selected genes by qRT-PCR analysis. 20We noted that many differential expression genes (DEGs) encoding proteins were involved in 21 xenobiotics detoxification and ROS generation or reduction, including aldo/keto reductase, 22 glutathione S-transferases, cytochrome P450 enzymes, alcohol oxidases and dehydrogenase, 23 manganese peroxidase and laccase. Furthermore, many DEG-encoding proteins were involved in 24 antagonistic mechanisms of nutrient acquisition and antifungal properties, including glycoside 25 hydrolase, glucanase, chitinase and terpenoid synthases. DEGs analysis effectively revealed that 26 laccase induction was likely caused by protective responses to oxidative stress and nutrient 27 competition during fungal interspecific interaction. 28 29 All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.