IN-SITU SOIL NITRATE ION CONCENTRATION SENSOR

• US 20090166520A1
• Filed: 11/10/2008
• Published: 07/02/2009
• Est. Priority Date: 11/09/2007
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Hopmans, Jan W., Shaw, Benjamin D., Kamai, Tamir, Tuli, Atac
• Granted Patent: US 7,927,883 B2
• Time in Patent Office: Days
• US Class Current: 250/253
• CPC Class Codes: G01N 33/245 for agricultural purposes
• CPC Class Codes: G01V 9/00 Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00
• CPC Class Codes: Y10T 436/173076 Nitrite or nitrate
• CPC Class Codes: Y10T 436/25375 Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]

Abstract

A method and apparatus for near real-time in-situ soil solution measurements is presented. An outer sleeve is placed in soil where ionic concentrations of organic or inorganic species are to be measured. A porous section connects with the outer sleeve (the porous section initially loaded with distilled water) equilibrates with the solution present in soil pores to form a solution to be measured. The initial distilled water is displaced within the porous section by a removable plunger. After substantial equilibration of the solution to be measured within the apparatus, the plunger is removed and a removable probe replaced. The probe may be an Ion Selective Electrode, or a transflection dip probe. The probe then may be used under computer control for measurement of solution properties. The Ion Selective Electrode may measure nitrate (NO₃⁻) concentrations. The transflection dip probe may be read with spectrometer with an input deuterium light source.

Claims

1. An in-situ probe, comprising:

a tube with a distal end; and

means for measuring one or more chemical species that enters into a distal end of the tube.

2. The in-situ probe of claim 1, wherein the distal end of the tube contacts soil at a porous section of the distal end of the tube.

3. The in-situ probe of claim 2, wherein the porous section comprises a solution.

4. The in-situ probe of claim 3, wherein the means for measuring comprises:

measuring a concentration of an ion in the solution that flows into the distal end of the tube through the porous section.

5. The in-situ probe of claim 4, wherein the means for measuring comprises:

an Ion Selective Electrode.

6. The in-situ probe of claim 5, wherein the Ion Selective Electrode comprises:

a nitrate Ion Selective Electrode.

7. The in-situ probe of claim 4, wherein the means for measuring comprises:

an optical probe.

8. The in-situ probe of claim 7, wherein the optical probe comprises:

a transflection dip probe.

9. A method of in-situ measurement of solution ion measurement in soil, comprising:

placing a measurement system, comprising an outer tube sleeve, into a soil that is to be measured, wherein the distal section of the outer tube sleeve comprises a porous section;

initially contacting a quantity of distilled water with the porous section;

allowing the quantity of distilled water to equilibrate with a soil solution to be measured, through the porous section, so as to equilibrate into a solution to be measured;

contacting the solution to be measured with a probe; and

measuring the solution to be measured with the probe.

10. The method of in-situ measurement of solution ion measurement in soil of claim 9, comprising:

inserting a plunger into the outer tube sleeve, thereby contacting the distilled water with the porous section; and

after the solution equilibrates,

replacing the plunger with the probe.

11. The method of in-situ measurement of solution ion measurement in soil of claim 10, wherein the probe comprises one of a group of probes consisting of:

an Ion Selective Electrode probe, and

a transflection dip probe.

12. The method of in-situ measurement of solution ion measurement in soil of claim 11, wherein the Ion Selective Electrode probe is a nitrate Ion Selective Electrode probe.

13. The method of in-situ measurement of solution ion measurement in soil of claim 11, wherein the transflection dip probe is capable of measuring absorbance in the range of 235-240 nm.

14. The method of in-situ measurement of solution ion measurement in soil of claim 13, wherein the transflection dip probe measures absorbance at one or more of the wavelengths selected from the group of wavelengths consisting of:

235, 238, and 240 nm.

15. An in-situ ion measurement system, comprising:

an outer sleeve tube;

a porous section attached to the outer sleeve tube, wherein the porous section allows diffusion and bulk fluid flow therethrough;

a removable probe placed within the outer sleeve tube, wherein a sensitive portion of the probe contacts a measurement solution that has passed through, or equilibrated through, the porous section.

16. The in-situ ion measurement system of claim 15, wherein the probe is an Ion Selective Probe.

17. The in-situ ion measurement system of claim 16, wherein the probe is a nitrate Ion Selective Probe.

18. The in-situ ion measurement system of claim 15, wherein the probe is a transflection dip probe.

19. The in-situ ion measurement system of claim 18, wherein the transflection dip probe allows absorption of an input light source as the input light passes through the measurement solution into an output signal.

20. The in-situ ion measurement system of claim 19, comprising:

a deuterium light source that provides an input light source;

an optical spectrometer that measures an output signal from the passage of the input light source through the solution.

21. The in-situ ion measurement system of claim 20, comprising:

a computer that controls a collection of in-situ measurements through the spectrometer.

22. The in-situ ion measurement system of claim 21, wherein the in-situ spectrometer measurements are ion concentration measurements.

23. The in-situ ion measurement system of claim 21, wherein the in-situ spectrometer measurements are nitrate ion concentration measurements.

24. The in-situ ion measurement system of claim 21, wherein the in-situ spectrometer measurements are measured on one or more components of BTEXS concentration measurements.

25. The in-situ ion measurement system of claim 24, wherein BTEXS comprises one or more of a contaminant selected from a group of contaminants consisting of:

benzene, toluene, ethyl benzene, xylene, and styrene.

26. The in-situ ion measurement system of claim 21, wherein the in-situ spectrometer measurements are measured on one or more of a contaminant selected from a group of contaminants consisting of:

a polychlorinated biphenyl, tetrachloroethylene, sulfur dioxide, arsenic, selenium, petroleum, petroleum distillates, petroleum byproducts, hydrocarbon, pentachlorophenol, creosote, a pesticide, a polycyclic aromatic hydrocarbon (PAH), a volatile organic carbon (VOC), a dioxin, a dibenzofuran, copper, lead, zinc, hexavalent chromium(VI), cadmium, and mercury.