Metals play a critical role in soils and sediments. Essential metals like manganese, iron, zinc, and copper are vital for various physiological processes, including enzyme function, photosynthesis, and nutrient uptake. These metals also influence soil/sediment structure and microbial activity, which can affect plant health and growth. Adequate metal availability in the rhizosphere ensures optimal plant development and supports a balanced soil ecosystem, while deficiencies or imbalances can lead to poor plant performance and reduced agricultural productivity. Understanding the redox dynamics of metals in these systems is key to improving soil fertility, metal availability in freshwaters and plant phytoremediation, among others.
Watershed Dynamics
Aquatic ecosystems are influenced by dynamic hydrology and nutrient cycling. In the U.S., diverse land use and land cover (LULC) create a complex interplay in stream biogeochemistry, especially with intermittent streams linking uplands to downstream areas. Metals like Fe and Mn play a crucial role, affecting nutrient solubility and transport. These metals can accumulate in disconnected pools during low-flow conditions and contribute to nutrient export during high-discharge events. Understanding how trace metals partition between sediments, colloids, solution, and biomass is essential for improving biogeochemical models and assessing the impact of land use changes.
At SSRL, we are investigating the partitioning and speciation of Fe, Mn, Cu (redox-sensitive), and Zn (redox-stable) in sediments, particulates, and periphyton collected from headwater streams under different flow regimes and land cover (forested vs urban) along a mid-order stream corridor, as part of the ORNL science focus area (WaDE). This project is in collaboration with ORNL and postdoc Manny Vejar is the lead on this project.
Aquatic ecosystems are influenced by dynamic hydrology and nutrient cycling. In the U.S., diverse land use and land cover (LULC) create a complex interplay in stream biogeochemistry, especially with intermittent streams linking uplands to downstream areas. Metals like Fe and Mn play a crucial role, affecting nutrient solubility and transport. These metals can accumulate in disconnected pools during low-flow conditions and contribute to nutrient export during high-discharge events. Understanding how trace metals partition between sediments, colloids, solution, and biomass is essential for improving biogeochemical models and assessing the impact of land use changes.
At SSRL, we are investigating the partitioning and speciation of Fe, Mn, Cu (redox-sensitive), and Zn (redox-stable) in sediments, particulates, and periphyton collected from headwater streams under different flow regimes and land cover (forested vs urban) along a mid-order stream corridor, as part of the ORNL science focus area (WaDE). This project is in collaboration with ORNL and postdoc Manny Vejar is the lead on this project.
Phototroph-Heterotroph Interactions
Interactions between phototrophs and heterotrophs significantly influence productivity, resource balance, and the functionality of the surrounding microbiome. For example, bioenergy grasses and their associated microbes illustrate this dynamic interplay. Iron, a critical nutrient for plant growth, is vital for chlorophyll production and various enzymatic processes like photosynthesis and respiration. Certain beneficial endophytes, which reside within plant tissues, can enhance iron uptake by mobilizing it from the soil and increasing its availability. These endophytes interact with plant roots and modify soil conditions to improve iron assimilation, ultimately boosting plant health, growth, and productivity.
This research is in collaboration with the LLNL micro-biospheres SFA. At SSRL, Manny Vejar is the lead on Fe XRF and XAS of switchgrass roots inoculated with various endophyte strains. In addition, this research is an example of multimodal imaging, where fluorescence microscopy is combined with XRF to identify microbial and plant material, and their associated Fe chemistry.
Interactions between phototrophs and heterotrophs significantly influence productivity, resource balance, and the functionality of the surrounding microbiome. For example, bioenergy grasses and their associated microbes illustrate this dynamic interplay. Iron, a critical nutrient for plant growth, is vital for chlorophyll production and various enzymatic processes like photosynthesis and respiration. Certain beneficial endophytes, which reside within plant tissues, can enhance iron uptake by mobilizing it from the soil and increasing its availability. These endophytes interact with plant roots and modify soil conditions to improve iron assimilation, ultimately boosting plant health, growth, and productivity.
This research is in collaboration with the LLNL micro-biospheres SFA. At SSRL, Manny Vejar is the lead on Fe XRF and XAS of switchgrass roots inoculated with various endophyte strains. In addition, this research is an example of multimodal imaging, where fluorescence microscopy is combined with XRF to identify microbial and plant material, and their associated Fe chemistry.
Phytoremediation
Plants can uptake, accumulate, and detoxify nanoparticles from the soil and water through their roots. This process involves nanoparticles being translocated into plant tissues, where they are either transformed into less harmful forms or stored safely. Phytoremediation of nanoparticles offers a sustainable and cost-effective method for removing these contaminants from the environment, leveraging the natural abilities of plants to enhance soil and water quality.
In collaboration with researchers at the University of Puerto Rico, we are investigating phytoremediation of Mn and Zn nanoparticles by basil
Plants can uptake, accumulate, and detoxify nanoparticles from the soil and water through their roots. This process involves nanoparticles being translocated into plant tissues, where they are either transformed into less harmful forms or stored safely. Phytoremediation of nanoparticles offers a sustainable and cost-effective method for removing these contaminants from the environment, leveraging the natural abilities of plants to enhance soil and water quality.
In collaboration with researchers at the University of Puerto Rico, we are investigating phytoremediation of Mn and Zn nanoparticles by basil