In-situ soil nitrate ion concentration sensor

• US 8,444,937 B2
• Filed: 03/28/2011
• Issued: 05/21/2013
• 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: Tuli, Atac, Hopmans, Jan W., Kamai, Tamir, Shaw, Benjamin D.
• Primary Examiner(s): Soderquist, Arlen
• Application Number:
  US13/073,551
• Publication Number:
  US 20110242530A1
• Time in Patent Office: 785 Days
• Field of Search: 422 8201- 8209, 422534-535, 436/25, 436/28, 436/110, 436149-151, 436/164, 436171-172, 436177-178, 738/632.3, 738/647.4, 175/21, 175/59
• US Class Current: 422/535
• CPC Class Codes: G01N 2033/245 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 ion measurement system, comprising:

a tube, said tube having a distal end;

wherein the distal end of said tube comprises a porous section; and

wherein the porous section comprises pores sized to allow diffusion and bulk fluid flow of a soil solution therethrough to form a measurement solution;

a probe body having a central bore, said probe body coaxial with said tube; and

a probe placed within the central bore of the probe body, wherein a sensitive portion of the probe measures at least one characteristic of the measurement solution.

2. The in-situ ion measurement system as recited in claim 1, wherein the probe is an Ion Selective Probe.

3. The in-situ ion measurement system as recited in claim 1, wherein the probe is a nitrate Ion Selective Probe.

4. The in-situ ion measurement system as recited in claim 1, wherein the probe is an optical probe.

5. The in-situ ion measurement system as recited in claim 4, wherein the probe is a transflection dip probe.

6. The in-situ ion measurement system as recited in claim 5, 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.

7. The in-situ ion measurement system as recited in claim 4, further 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 measurement solution.

8. The in-situ ion measurement system as recited in claim 7, further comprising:

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

9. The in-situ ion measurement system as recited in claim 8, further comprising:

a program executable on the computer, capable of performing steps comprising;

collecting the in-situ measurements through the spectrometer,

wherein the in-situ measurements are ion concentration measurements.

10. The in-situ ion measurement system as recited in claim 8, further comprising:

a program executable on the computer, capable of performing steps comprising;

collecting the in-situ measurements through the spectrometer,

wherein the in-situ measurements are nitrate ion concentration measurements.

11. The in-situ ion measurement system as recited in claim 8, further comprising:

a program executable on the computer, capable of performing steps comprising;

collecting the in-situ measurements through the spectrometer,

wherein the in-situ measurements are measured on one or more components of BTEXS concentration measurements.

12. The in-situ ion measurement system as recited in claim 11, wherein BTEXS comprises one or more of a contaminant selected from a group of contaminants consisting of:

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

13. The in-situ ion measurement system as recited in claim 7, further comprising:

a program executable on the computer, capable of performing steps comprising;

collecting the in-situ measurements through the spectrometer,

wherein the in-situ 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.

14. The in-situ ion measurement system of claim 1, wherein the porous section comprises a tubular section concentric with the tube.

15. The in-situ ion measurement system of claim 1, wherein the porous section has the same inner and outer diameter as a reservoir cup that terminates in a conical section.

16. An in-situ measurement system, comprising:

a tube, said tube having a distal end;

wherein the distal end of said tube comprises a porous section; and

wherein the porous section comprises pores sized to allow diffusion and bulk fluid flow therethrough;

a probe body having a central bore;

wherein said probe body is coaxial with said tube;

a solution in material surrounding the probe body that diffuses and flows through the porous section to produce a measurement solution;

a probe placed within the central bore of the probe body, wherein a sensor portion of the probe measures at least one characteristic of the measurement solution; and

a computer that controls a collection of in-situ measurements from the sensor portion of the probe.

17. The in-situ measurement system as recited in claim 16, wherein the probe comprises an Ion Selective Electrode probe.

18. The in-situ measurement system as recited in claim 16, wherein the probe comprises a transflection dip probe.

19. The in-situ measurement system as recited in claim 18, wherein the transflection dip probe is capable of measuring absorbance in the range of 200 nm through 1100 nm.

20. The in-situ measurement system as recited in claim 18, wherein the transflection dip probe is capable of measuring absorbance in the range of 235 nm through 240 nm.

21. The in-situ measurement system as recited in claim 18, wherein the transflection dip probe is capable of measuring solution absorbance at one or more of the wavelengths selected from the group of wavelengths consisting of:

235 nm, 238 nm, and 240 nm.

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

a tube, said tube having a distal end;

wherein the distal end of said tube comprises a porous section; and

wherein the porous section comprises pores sized to allow diffusion and bulk fluid flow therethrough;

an in-situ probe body having a central bore;

wherein said probe body is coaxial with said tube;

a soil solution in soil surrounding the probe body wherein the soil solution diffuses and flows through the porous section to form a measurement solution; and

a probe placed within the central bore of the probe body, wherein a sensitive portion of the probe measures at least one characteristic of the measurement solution.

23. The in-situ ion measurement system of claim 22, further comprising:

a deuterium light source, wherein the deuterium light source provides illumination to the sensitive portion of the probe.

24. The in-situ measurement system of claim 22, further comprising:

a spectrometer, wherein the spectrometer provides measurement solution absorption spectra to a computer.

25. The in-situ measurement system of claim 22, further comprising:

a displacement attachment situated on the probe;

wherein the probe is an optical probe, said optical probe having a bottom; and

wherein the displacement attachment protrudes from the bottom of the optical probe;

whereby the optical probe senses the measurement solution.

26. The in-situ measurement system of claim 22, further comprising:

a plano-convex lens that transmits a deuterium light source from an illumination source fiber to a mirror through the measurement solution; and

a returning signal fiber disposed to collect the light reflected through the measurement solution from the mirror and focused by the plano-convex lens.

27. The in-situ measurement system of claim 22, wherein the probe is removable.