Bryan Downing


I am a research hydrologist at the USGS California Water Science Center, with a principal interest in studying aquatic organic matter (dissolved and particulate) and nutrients to better understand their impact on ecosystem functioning. My research involves the use of optical measurements (attenuation, absorbance, fluorescence and backscatter) to better understand complex biogeochemical cycling of organic matter and nutrients in rivers, estuaries and the coastal ocean. Measuring water quality using optical sensor technology represents a significant new direction in water quality research, where cycling of nutrients and organic matter can be measured in-situ, on time scales ranging from seconds to years. One of my study goals is to help provide enhanced optical instrumentation and methodologies, to improve real-time measurements of nitrate, phosphate, fluorescent dissolved organic matter (FDOM), algal pigments (chlorophyll-a and phycocyanin - a common blue-green algae proxy) and detection of harmful algal blooms (HABs). Currently, my colleagues and I have developed a boat based, high speed mapping system that measures transects of nutrients, WQ, stable water isotopes (δ2H, δ18O) with GPS location at sampling frequencies of 1Hz in real time.