Document Sample
Combustion and Ignition of
 Energetic Nancomposites
              Harrison Hsu
 Under supervision of Dr. E. L. Dreizin and A.
 Ermoline, New Jersey Institute of Technology
•Mixtures blended on the scale of nanometers
•They are exceptionally homogeneous

                   A regular        A nanocomposite
More about Nanocomposites
 •Produced by blending fine powders
 •Powders manufactured in ball mill
 •Nanocomposite powders can be pressed
 into easier-to-handle pellets

                                         Ball milling
                                         pictures from
  Reactive Nanocomposites
•Nanocomposites have effectively infinite
reaction surface area
•They react faster and more intensely than
macro-size composites
•Can be: space propellant,
explosive, incendiary
        The Laser Chamber

•A hermetically sealed chamber
•Equipped with CO2 and red lasers
•Data collection instruments: light and sound
•Used to heat and ignite pellets
                     First Project: Zirconium

     A diagram of the                                             • The phase chemistry of Zr
     compositions used                                              with N and O is not well-

                      G           D
                     20    A          80
                                                                  • Research could lead to
                40                         60
                                                E                   discovery of new materials,
                                                    40              particularly explosives and
     80                                                      20

Zr         20         40          60            80       H        ZrN
            Current Results
          •Local heating is currently
             •Multiple heatings a
             promising possibility
          •Compositions A, B, C, and
            E have been used so far
formation for uniform
        Results (cont.)
       SEM reveals morphologies:

Spherical Inclusions

      Burn temperatures about 2000K
                                                            Run 4,July 7th 2004

                                5000                                                                                         12

Temperature in degrees Kelvin


                                                                                                                                  Pyrometer Intensity (V)





                                  0                                                                                          0
                                       0   1   2   3    4             5           6   7   8               9             10
                                                                   Tim e (s)                  Temperature (K)
                                                                                              Channel B
                                                                                              25 per. Mov. Avg. (Temperature (K))
     Second Project: Thermite
 •A reactive metal exchanges
 oxygen with an inert oxide for
 large energy release.

•Aluminum-      Example Reaction:
Iron            Al+Fe2O3 => Al2O3+Fe
       Thermite Preparation
Arrested Reactive Milling
•Milling cut short boosts reaction power and
•Used to compare with conventional milling
•Pulsed Detonation
•ARM releases more energy faster than the blend
•Frequent saturation of camera

    Intensity (V)




                          0   0.5   1   1.5      2        2.5   3   3.5   4
                                              Tim e (s)
       Future Research

Added Variables:              Applications of
•Temporary levitation for     Technology:
ignitions                     •Munitions
•Teflon nanocomposite (CF2) n •Propellant
+ Al)
•New Pellet Binders
•New formulations of Zr-O-N
   Analysis of Aerosol Particle
   Concentration Using MFRSR

• Goddard Institute For Space Studies
• The City College Of New York,
  Department of Electrical Engineering
• Xavier Estevez
        What are aerosols?
• Air consists of molecules of N2, O2, CO2,
  and various other gases
• Aerosols are fine solid or liquid particles
  suspended in a gas
• Some examples of atmospheric aerosols
  are smoke, sulfates, volcanic ash,
  pollen, mold spores
               Remote Sensing
• Is the observation of some attribute of a subject by
  means that do not involve direct contact with that
• In other words, “look don’t touch”
• A familiar remote sensing system is that of your eyes
  and brain
• Examples of remote sensing: weather radar, satellite
  imagery, climbing a mountain and looking at things,
  LIDAR, seismometers, telescopes, radio telescopes, x-
  rays, MRI. The applications are almost endless.
    Remote Sensing of Aerosols
• In order to determine the
  concentration of aerosols in
  the atmosphere, we use             Long wavelength light
  optical remote sensing.
• Aerosol particles reflect light.
  We can detect these particles
  by measuring the loss of
  intensity of light as it passes
  through an aerosol-bearing
  medium                             Short wavelength light
• Different wavelengths of
  light can detect different
  particle sizes.
• Simply put, short wavelength
  light detects smaller
  particles, and long
  wavelength light detects
  larger particles
                   What is the MFRSR?
Multi-Filter Rotating Shadowband Radiometer
 – Multi-Filter
    • Senses several different wavelengths of light
 – Rotating Shadowband
    • Has a motorized arm that
      periodically covers the
 – Radiometer
    • Measures intensity of
      solar radiation 
             How Is It Used?                   Laptop
                    Control Unit /
                   Data Acquisition   RS-232

•Data Acquisition System (DAS) controls the
 MFR, stores data in internal memory
•Laptop is connected to the DAS to download
 the data
•Data files are analyzed using various software
      What Does It Tell Us?
The moving shadowband allows one
 instrument to collect direct and diffuse
 intensity readings
Data analysis tells us how much light is
 reflected by the atmosphere
Variations in this amount are related to
 concentration of aerosol particles
                          Beer’s Law
            The deeper the glass, the darker the brew,
            The less the amount of light that gets through

                                                 Ig = intensity of sunlight as
            Ig = I0                              measured at the instrument
                                                 I0 = intensity of sunlight outside
                                                 of the atmosphere
 Loge Ig = Loge I0 – tm                          e = Napier’s constant
                                                 m = airmass factor
                                                 t = optical depth

•The intensity of the light that reaches the earth’s surface is decreased
by two factors– the length of its path through the atmosphere, and the
optical properties of the atmosphere
•The relationship can be modeled as a linear equation.
•The slope of this line is equal to the total optical depth (how effectively
the atmosphere blocks light)
   Langley Regression Analysis
• As the sun moves across the sky, sunlight must pass through
  varying amounts of air
• The light’s path is shortest at noon, and longest at sunrise
  and sunset
• Beer’s law tells us that there is a direct relationship between
  path length and light intensity– light that passes through a
  path twice as long is affected twice as much.
• We assume that the optical depth of the atmosphere remains
  constant over a half-day period, and can therefore determine
  optical depth by plotting light intensity against path length
  (the secant of the solar zenith angle).
                                         The optical depth for the time
Data Filtering                           period in this graph is equal to
                                         the slope of the red line.
                                         The red line was not drawn
                                         mathematically, it “just looks
                                         This technique is not
                                         statistically valid, we have to
                                         use a linear regression
                                         equation to draw the trend line
Secant of solar zenith angle vs. Solar   That regression applied to this
radiation intensity (W/m2/nm)            data set would yield a line with
415 nm, afternoon of 22-June-2004        a less severe slope and a lower
                                         y-intercept, due to the
                                         disproportionate effect of
                                         outlying points.
            Linear Regression
• Linear regression is a technique used to plot a
  straight line from a 2-dimensional collection of
  plotted data points
• This allows one to model real-world data
• The line produced will pass as closely as possible
  to as many of the data points as possible
• The equation which returns the slope of the best-
  fit line is as follows:
• The final product of my research is a list of optical
  depths for approximately 70 days, and the Java
  application that I used to calculate these values.
• I do not see any discernible patterns in these
  optical depths. They do not appear to conform to
  any linear or periodic functions as far as I can tell.
• One potential source of error is the fact that due
  to cloudy or overcast conditions, some days did
  not yield any acceptable data-points, or yielded
  too few data-points to obtain any statistically valid
• Another error source is the fact that even the best
  data-cleaning algorithm cannot determine with
  absolute certainty which readings are invalid.
• “Atmospheric Aerosols: What are they, and why are they so
• “Linear Regression”
• “Excel Tutorial On Linear Regression”
• “Langley Method”
Supercritical Fluid
 Assisted Particle

          Antoinette Kretsch
   New Jersey Institute of Technology
Supercritical Fluid Extraction
                                  Supercritical CO2

Solvent enters

                                     Collection trap

                                         Left over particles

        Exiting CO2 and solvent
             Analytical Techniques
•   Beckman Coulter N4 Plus: Submicron Particle Size Analyzer
    –   determines particle size by measuring the rate of change in laser light
        intensity scattered by particles as they diffuse through a fluid

•   Leo 1530 VP: SEM Microscope
    –   Produces 3-D image magnified x100,000 by spraying specimen with
        fine metal coating and sending beam of electrons over the surface to
        be projected onto fluorescent screen

•   SigmaScan: Systat software program
    –   Collects data such as diameter and area of nanoparticles using pictures
        taken by the SEM

•   FTIR: Fourier Transform Infrared Spectroscopy
    –   Used to identify chemical bonds in various substances by interpreting
        the infrared absorption spectra
• A smaller nozzle will yield smaller, less agglomerated

• A pressure closer to supercritical pressure (78 bar for CO2)
  will yield smaller particles, so 82 bar had smaller particles
  than 100 bar

• The higher ratio of acetone to DCM will yield smaller
  particles with a narrow size distribution although the
  particles will have a distorted shape
   Suggestions for Further Study
• Can a stronger pump be used for force the solution through
  tinier micronozzles (ex: 10 μm and 5 μm)?

• Is there a better way to increase yield of particles (particles
  stick to sides of, top of, and apparatus inside the collecting
  chamber and are hard to remove) and decrease amount lost
  to air?

• What would the results be if another supercritical fluid was
  used instead of CO2?

• Can the durability of the micronozzles be increased so they
  last more than one or two trials?
Skeletal Response to Weightlessness
    in the Female Murine Tibia

  Amy Brazin, NASA Apprentice
  Maria Squire, Ph.D. Candidate
       Stefan Judex, Ph.D.
        August 20, 2004
        Effects of Disuse are Site-
• Metaphyseal BV/TV is       Example:
  30% lower in disuse mice

                                BV/TV (% difference from control)
                                      Metaphysis                    Epiphysis
• Metaphyseal Ct.Ar is lower     0

  by 15%as a result of a      -10

  decrease in Ps.Ar and        -20

  increase in Ec.Ar            -30

• Yet, diaphyseal Ct.Ar was    -40

  only minimally affected      -50

  (3%)due to an               -60
  insignificant increase in
  both Ps.Ar and Ec.Ar
  If I had more time, I would….
• Analysis male F1 mice for similar effects in
  the tibia
• Examine the osteoclast, osteoblast, and
  osteoid growth and population density in
  specific sites
• Research other causes of bone loss such as
  hormonal secretions
Image Segmentation of Bone Density

          Rebecca Kamins
            Quick Overview
• Trying to find a deconvlution algorithm that
  will give us the real image.
  – g(x,y)= f(x,y)*h(x,y)+n(x,y)
• We took a PSF (represents blur in a micro
  CT scanner) and altered it 3 ways.
• Deconvolved the images using each PSF
  and analyzed the results
• Symmetrically rotated
  Gaussian PSF yielded
  the best results
• Circular PSF good
  too- not the best
• Create 3D volume estimates of the mouse
• Use pattern recognition to determine genetic
  trends in mice with bone loss
• Write a code to be implemented in a micro
  CT scanner
•   Dr. John Daponte
•   Megan Damon
•   Michael Clark
•   Thomas Sadowski
•   Charles Tirrell
•   SCSU
 Enhancing Air Gap Membrane
                           Melissa Deutsch
In conjunction with the Goddard Institute for Space Studies at the New
                    Jersey Institute of Technology
         Dr. Chao Zhu – professor of mechanical engineering
                Tong Lee, Qun Yu – PhD candidates
                            Summer 2004
               Research Findings
• Distillation system used to       • Found that the magnetic stirrer
  extract chemically pure             did little to increase both the
  water from dirty water              rate of water production and
  through a hydrophobic               the volume of water produced
  membrane                          • Larger temperature difference
• Theoretically, pure water has       did produce a greater rate of
  a resistance of infinity, since     production
  it cannot conduct electricity     • Hot side cavity is too large to
• This system produced water          effectively increase the rate of
  of 300kΩ resistance from an         water production
  initial source feed of salt       • Folded membrane would make
  water at 90kΩ                       the system more feasible for
• Huge jump in resistance of          use on a lunar base
  water shows that the system       • Vacuum pump necessary to
  is largely effective in its end     increase rate of flow
                       Future Work
• Test the AGMD apparatus
  against various concentrations
  of dissolved particles (ie –
  NaCl, dyes)
• Test the AGMD apparatus
  against various temperature
• Install an ultrasonic inducer to
  potentially enhance the
  effectiveness of the membrane
  distillation system
• Build a new AGMD apparatus
  with a folded membrane
  module to increase flow rate       AGMD apparatus
• Introduce a vacuum into the
  air gap
  York College Radio Telescope

York College Radio Telescope
 York College Observatory
        Ian O’Leary
       Tim Paglione
• We will be receiving Radio waves from various
• Radio waves we are focusing on is the 21 cm
  hydrogen wave emissions.
• Radio waves allow us to understand more about
  what we are focusing on.
• Hydrogen gives creates a 21 cm wave when it
  moves from its excited state to its ground state.
             Project Goals
• Construction of a Radio Telescope.
• Connections between telescope and
  computer (server).
• Observe radio wave emissions from
  hydrogen emitting sources.
    ex: Sun (stars), Moon, and Galaxies
• Record and plot all data found.
        Personal Air Vehicle

                         By Robert
Contributions from:      Brown and
Dr. Siva Thangam
This is an artist's
concept of a dual-
mode road to air
vehicle, a 'flying
A Flying Car—What would it
• A “roadable” aircraft that gives people the
  option to drive or to fly

• Basically, a question of time
• “Point to point mobility” can be dramatically
  increased with a dual-mode vehicle
              The Process
• Research: Websites, Magazines, News
  Articles, other published works
• Comparison/rating of existing designs using
  evaluation metrics
• Preliminary conceptual design
• Testing of design using principles of fluid
• Building a prototype?
 Sample Metrics (Specifications)
• Ease/Speed of
• Fits on roads/parking
• Propulsion: fuel
  efficiency, type of engine
• Size: passenger capacity,
  cargo, fuel
• Takeoff/Landing: runway
  length, noise
• Weight distribution
            Important Guidelines
•   Fuel Sources Involved
•   Emissions
•   Noise issues
•   Cost Analysis

• Surveys for user
• Ground systems to support
                              Nikhil’s design
             Radio Emission of
             Jupiter and the Sun

                 NASA SHARP
       Goddard Institute for Space Studies
              Medgar Evers College
By: Junior Soto, Melissa Feliciano, Tiffany Walker
            Mentor: Dr. Leon Johnson
The general task that we perform was receiving
 electromagnetic waves from the Sun. After receiving
 the electromagnetic waves we had to find out how
 this affected that Planet Earth. The result that we
 received was that we heard two solar bursts. We had
 to keep in mind that there was a lot of interference at
 our site which is located at Medgar Evers college.
 During the time that we were receiving
 electromagnetic waves we also were hearing a lot of
                 Future Work
As we continue to gather more information on Radio
 Jove and also gathering electromagnetic waves from
 the Sun we came to the conclusion that there should
 be further work on this experiment. Such
 experiments includes listening for more solar bursts
 near in the future and also identifying how this
 emission from the Sun can affect the communication
 on Earth. By doing all of this we could come and
 find a way in which our communication can be
 stronger and not be disturbed, nor interrupted by any
 solar emission.
   Precision Robot Navigation
      Configuring a PS2 optical mouse to
       interface with a BASIC Stamp 2
                        Summer 2004
Our Robot

            Researchers: Calley Levine and Ali Moussawi
            Mentor: Professor Vikram Kapila
            Teaching Assistant: Mr. Mishah Salman
                     Our Project
• The precision navigation robot was created in order to
  provide a cheap and practical method for determining the
  position of a robot.
• This was done using a PS/2 optical mouse and
  the BASIC Stamp 2 (BS2) microcontroller
• Difficulty: Interfacing communication between the mouse
  and the BS2
• Many attempts were made to write a program which would
  successfully enable the communication… simply said, we failed
   – Factors: timing, power, and data transfer
• Instead, the PAK-Via pic was used and its displacement
  readings were then applied in order to restrict the
  movement of the robot to an area inscribed by specified
  parameters (i.e. a room)
             What We Learned…
• Circuitry (basics; use of transistors; integration of
  sensors, processors, actuators, etc.)
• Computer programming using PBASIC
• Responsibilities of employment… the work wasn’t too bad
• Managing time and keeping to deadlines is
  extremely important
  (AIM, Minesweeper, and Microsoft Paint are destructive forces!!!)
Advanced Composition Explorer

  Measuring the Solar Wind and Solar Flares

                           Oscar Puente
                           Mentor: Dr. Paul Marchese
                Research Findings
• The solar wind contains more low energy particles
  than it does those of higher energies
   – These particles can escape the sun’s gravity more easily
      • They require less energy to be excited and shot away from the sun
• Electrons are more abundant in the solar wind than
  protons, and they travel more quickly
   – Electrons weigh less than protons and therefore require less
     energy to enter the solar wind
• Elements of higher weights (He, O, Fe) are only
  present in the solar wind during times of great solar
   – They weigh more than H+ ions and electrons
               Future Work
• Compare solar wind data from ACE to
  magnestosphere/ionoshphre data from the
  – Find out how the solar wind affects the earth’s
    magnetic fields
  – Find predictable patterns in changes caused by
    the solar wind
(electron paramagnetic resonance)

           Jonathan Spagnola
    Dr. Flowers, Hunter college/MEC
                        EPR Theory

• Electrons have two spin energy
• When no magnetic-field, the
  energy of the spin states are
• In presence of magnetic field,
  the energy of spin states diverge
• EPR is only used on
  paramagnetic species
               EPR spectroscopy

 The instrument used in the
  lab is Bruker EMX model
 The frequency of the
  microwaves that the
  spectrometer produce is
 EPR spectrum of LiMn2O4
                 EPR Practicality

• The spectrometer can also be used to test the efficiency of different
  combinations of atoms, such as Li-ion batteries.
• The batteries for the mars rover were developed by those in the lab I
  currently work in.
• So, why Lithium….Lithium ion batteries are one of the most common
  rechargeable sources of energy.
     High Pressure NMR:
Study of Proton Movement in a

                BY: Rahsaan Bascombe
 Mentor: Professor Steve Greenbaum, Eugene Mananga
        What I Learned

   1) Some Science behind NMR
2)How to run an experiment varying
           different Parameters
 3) How to Use Mat lab to graph my
4))Not all work done in Lab is Nobel
               Prize worthy.
         Further Work
1) Running another polymer under
         the same conditions
2) Finding the diffusion under each
 3) Comparing it to the coefficients
       found in the BB2 sample
  4)Determining which would be
      better to use in a Fuel Cell
The Great Dark Vortex on Jupiter

        Harry Charalambous

          Dr. James Frost
• The Great Dark Spot of Jupiter is a mysterious anomaly
  that occurs in the north pole of Jupiter at a latitude of 60
  degrees and a longitude of 180 degrees. It is located in the
  same vicinity as the Aurora, which suggests the dark spot
  is related to the Aurora. With a size three times the size of
  Earth, roughly the size of the Great Red Spot, and a
  lifespan of only approximately ten weeks, the Great Dark
  Spot is a mystery. The Great Dark Vortex was first
  discovered by accident by the Hubble Space Telescope in
  1997. Scientists at NASA did not know what to make of
  the spot until it was once again seen during the CASSINI
  fly-by of Jupiter in 2000.
• Our study of the Great Dark Vortex on Jupiter is meant to
  discover how and why the vortex forms and what factors
  contribute to its formation. The Great Dark Vortex, also
  known as the Great Dark Spot is currently under
  investigation for its peculiar formation and deterioration.
  The three dates I am studying are on September 1997 with
  the dark spot clearly visible, November 1997 with signs of
  the deterioration of the Great Dark Spot and its trail, and
  on August 1999 with no sign of the Great Dark Spot. This
  information is gathered using the Hubble Space Telescope.
• The Great Dark Spot can be seen clearly as it was supposed to
  be during September 1997 under filters of 218nm, 255nm,
  336nm, and 890nm. These are not new results, but they are
  worth discovering for myself.
• Ratios under an assortment of filters further reveal the Dark
  Spot and its trail during September 1997, and its deterioration
  during November 1997 in the north pole of Jupiter under a
  CML of roughly 180 degrees.
• The deterioration of the Great Dark Spot is revealed in some of
  the ratio plots from November 1997. The possible remnants of
  the Great Dark Spot may be involved in the reformation of the
  Great Dark Spot as shown with the CASSINI flyby of Jupiter.
             Conclusion (cont’d)
• Thus, in the future, we may be able to use the remnants of
  the dark spot to tell us the composition of the spot. It also
  suggests that the Great Dark Spot again and possibly
• A ratio of 336/218 during September 1997 seems to reveal
  another dark spot in the south pole of Jupiter. This spot is
  of similar nature to the Great Dark Spot because it is
  located in the Aurora and last for approximately the same
  amount of time. Therefore, the Great Dark Spot can be
  inferred to be directly related to the Aurora.
• A comparison of point values at the Great Dark Spot for
  different frequencies suggests that the Great Dark Spot’s
  composition has a spectrum near a frequency of 410nm.
                   Gil Zamfirescu, in conjunction with
                   Dr. Leonard Druyan,
                   Dr. Matthew Fulakeza, and
                   Abdelrahim Mansour

High-resolution Weather Analysis and Prediction: West Africa
              1) The resolution of the Regional Model.
                   do we think we can do better?

                     Satellite Imagery (TRMM)

                      How do we collect data?
                      NCEP/NCAR Reanalysis

                      The Regional Model

2) The algorithm used by the Regional Model to simulate precipitation.
Detail of storm patterns.
Variability of data.
            The All-Optical Threshold Device


                        Stephen Brandes, NASA Apprentice
                          Dr. Roger Dorsinville, Mentor
                     Muhammad Ali Ummy, Graduate Student

The City College of New York
   All-Optical Threshold Device
• A device that can discriminate between two
  intensity levels is a Threshold Device
                          • Loop mirror contains SOA,
                          attenuator, and 50:50 coupler
                          • Phase change occurs in clockwise
                          beam during transmission in 50:50
                          • Destructive or constructive
                          interference at the ports
                          • To set a threshold value,
                          attenuator is set to constant value
                          while SOA is varied
Experimental Setup
Graphical Results
    Experimentation and Results
• SOA set to three different gain levels
• VOA varied periodically to change input intensity
• Threshold values of all-optical threshold device
  were inversely proportional to the value of the
• In future, threshold device can be used for optical
   • Faster
   • More efficient
 Nanoscale Cr4+ Doped Olivine
  Crystallites Used In Optical
    Amplifiers and Lasers
By: Denise Asafu-Adjei (Bronx H.S. of Science)
 Caesar Pereira (Archbishop Stepinac H.S.)
Supervising Scientist: Prof. Petricevic (CCNY)
     Senior Scientist: Dr. Bykov (CCNY)
 Analysis of Cr doped Powders
• 0.1% and 0.5% samples seem to be the optimal
  concentrations for laser emissions.
• When heated to 1050C in general, the light
  emissions increased and encompassed a longer
  range of wavelengths.
• In conclusion, we can see that because the light
  emissions for 1050C surpassed 1000nm, Cr4+ ions
  are present now in our powders.
  Importance of this Research
• To synthesize an effective amplifying
  medium for the purpose of creating a
  “tunable laser” that will be able to emit
  light at multiple wavelengths
• This is of significance for NASA research
  because these lasers would be more
  versatile, spatially efficient, convenient,
  and cost-effective
       Applications of Lasers
•   Optical communication
•   Remote sensing
•   Medical imaging
•   Surgery and LASIK
•   Tissue welding
• Studying the light emissions from the
  crystals synthesized from the powders
• Attaining the optimal Cr concentration in
  the crystals, which will provide the
  maximum light emissions
• In this final part of our project x-ray
  spectroscopy will be utilized for further
  analysis of our crystals that will be grown
  Classification of NYC Aerosols by
     X-Ray and Optical Methods

By: John Sangobowale (Mount St. Michael Academy)
    and William Dennis ( John F. Kennedy H.S.)
     Mentors: Marc Cesaire (Graduate student) and
               Dr. Elizabeth Rudolph
               EAS Department CCNY
The Principal objective of our work is:
• Elemental Characterization of Aerosols
   collected by two methods for comparison:
    –   EBAM: beta mass attenuation
    –   Millipore apparatus: Vacuum Filtration
•   Ultimately: to understand how weather
    patterns affect the chemical composition
    and darkness of aerosol particles
              What are Aerosols?
• Aerosols are small solid or liquid
  particles suspended in the atmosphere. Their sizes
  vary from a few nanometers (0.000000001 meters)
  to almost 100 micrometers (0.0001 m, the thickness
  of a hair.
      •   Volcanic dust
      •   Combustion products
      •   Soot
      •   Smoke
          Optical Microscopy
• Why do we use optical microscopy?
  – New approach at characterizing aerosol samples
  – Build upon other experimental work and
    correlate with XRF techniques and (later down
    the road…weather data)
• Nikon Fluorescence Microscope with
  CCD Camera
• Titanium and Iron are present in aerosols in
  variable and sometimes high concentrations
• At first pass, optical darkness of filters
  correlates with weather characteristics
  suggesting that high humidity and rain events
  correlate with higher concentrations of metals
Thanks To…..