Native fluorescence imaging direct push probe

A fluorescence imaging method comprising the following steps:

• penetrating a subsurface soil environment to a plurality of depths at a given location with a cone penetration testing (CPT) direct push probe;
• illuminating through a window in the probe the subsurface soil adjacent to the probe at the given depth with white light;
• recording, in-situ and in real time, a first image of the white-light-illuminated subsurface soil at the given depth;
• illuminating through the window the subsurface soil adjacent to the probe at the given depth with only ultra violet (UV) light such that fluorescence is excited in microbes and minerals that may be present in the subsurface soil at the given depth;
• recording, in-situ and in real time, a second image of the UV-light-illuminated subsurface soil at the given depth after the UV excitation light has been filtered from the second image such that only the fluorescence response is recorded, wherein the first and second images are recorded with a charge-coupled device (CCD) camera;
• superimposing the second image over the first image to create a composite image of the subsurface soil, wherein a separate composite image is created at each depth;
• and
• determining biogeochemical processes that are occurring in the subsurface soil at each of the plurality of depths based on the composite image taken at each depth.