A hierarchical control framework governing the molecular composition and reactivity of dissolved organic matter in subtropical rivers - Guanglong Zhang; Zhenli Guo; Jinfang Du; Yue Ke; Hanyi Li; Mingbao Feng; Jingchun Liu; Haoliang Lu; Xilin Xiao; Hualong Hong; Chongling Yan; Nianzhi Jiao (Science China Earth Sciences, 2026)