NOM plays an overwhelmingly important role in the transport of most organic and inorganic pollutants, notably POPs and heavy metals thus strongly affecting their environmental fate, bioavailability and toxicity. We have characterized NOM in a wide range of environmental conditions typical for China and major river systems in China (e.g., the Yangtse River) and other countries (e.g., Amazon River, Seine River). These activities will help establish effects of NOM site-specificity on its behavior in water treatment, and model interactions between NOM, contaminants and particulates in engineered and major river systems.