Characterization of Road Dust in Western North

Dakota

ByDanijela Ljepoja

M.S. StudentEnvironmental and

ConservationScience Program

Acknowledgments

This work is the result of a collaborative project between the Dept. of Geosciences, the Dept. of Agricultural and Biosystems

Engineering (ABEN), and the Dickinson Research Extension Center (DREC).

Funding provided by DREC, Kris Ringwall, Director

Thanks to: Shafiqur RahmanMd. BorhanDhan GautamArjun ThapaKris RingwallBernhardt Saini-Eidukat Environmental and Conservation Sciences Graduate Program

INTRODUCTION

The oil boom in western North Dakota that began several years ago has led to a rapid heavy traffic volume increase in that area.

Oil well sites in Western North Dakota (www.dmr.nd.gov, 2013)

A typical shale oil well

requires 2,300 truck trips in its lifetime

driven mostly over unpaved

road (High Country News,

2014)

In this work I will aim to answer some of the questions related to the dust in western North Dakota.

The focus is on the air quality in the Manning area, Dunn County, using MiniVol™ TAS samplers (Air metrics, Springfield, OR, USA), SEM and ImageJ Analysis Software.

Samples were collected at three locations near the Dickinson Research Extension Center Ranch Headquarters (DREC)

The main sources of airborne particles were traffic emission, road dust re-suspension, and biological sources.

These types of dust particles are shown to contribute to aggravated health problems (WHO, 1999).

This study would help track the changes and document baseline values of particle volumes.

INTRODUCTION

What is dust?

Particulate Matter (PM)

Study Area

Sampling Method

Analytical Method

Results and Discussion

Outline:

Conclusion

What is dust?

Any solid particle in the air < 500 µm in diameter Dust can be found everywhere in the air, as well is as in

space.

Domestic Dust

Which is found in our

homes, offices and any other interior

Atmospheric Dust In the atmosphere of

Earth• natural or

• anthropogenic

Cosmic dustouter space

dust

Atmospheric Dust

“Small, dry, solid particles projected into the air by natural forces, such as wind, volcanic eruption, and by mechanical or man-made processes such as crushing, grinding, drilling, demolition, shoveling, conveying, screening, bagging, and sweeping. Dust particles are usually in the size range from about 1 to 100 µm in diameter, and they settle slowly under the influence of gravity.” (IUPAC, 1990)

Anthropogenic sources are more widespread and more important for public health.

Key in air quality monitoring is the measurement of levels of atmospheric particulate matter.

PM or particulate matter pollution is the term for liquid, solid or a complex mixture of liquid and solid particles suspended in the air.

Depending on particle size and their predicted penetration into the lung, EPA groups particles into two categories (EPA,2013).

Inhalable coarse particles (PM10)–are Inhalable particle size between 2.5-10 µm found near dusty roads, and industries

Fine particles (PM2.5) – inhalable particle size less than 2.5µm;

Particulate Matter (PM)

Larger particles than 10 micrometers are not regulated by EPA.

Inhalable particulate fraction or particulate matter with aerodynamic diameter less than 100 micrometers may enter the body through the nose and can be trapped in the nose,

throat, and upper respiratory tract

Thoracic particulate fraction or particulate matter with aerodynamic diameter less than 30 micrometers may penetrate

the head airways and enter the airways of the lung.

Respirable particulate fraction or particulate matter less than 10 micrometers in diameter, is that fraction which is small enough

to penetrate deep into the lungs (WHO, 1999).

Definition

Particulate matter could be classified by site of deposition in the respiratory tract, inhalable, respirable and thoracic particles.

Think about a single hair from your head. The average human hair is about 70 micrometers in diameter – making it 30 times larger

than the largest fine

The smaller, lighter particles have a tendency to travel further and stay longer in the air compared with bigger, heavier particles, and may be inhaled through the mouth and through the nose easier. Therefore, they have a stronger impact on human health.

Particulate matter and health problems

If left uncontrolled, dust can be public health hazard. When inhaled, fine dust particles travel deep into the lungs, increasing breathing problems, damaging lung tissue, and aggravating existing health problems.

Other problems:

Visibility

Road safety

Crop productivity in the area

Where does PM come from?

Particulate matter can come from different sources. Any activity which involves burning of materials or any dust generating activity are sources of PM.Some sources are natural, such as volcanoes, dust storm, pollen and some sources are anthropogenic, such as factories, cars, farming, mining …Particles can be divided into two groups depending on the source

Primary particles ( emitted directly from sources) –

construction sites, fields, unpaved roads, or forest fires

Secondary particles (secondary sources) let off

gases that can form particles

• Smoke, dirt, farms, roads

• Mold, spores, and pollen

Crushing and grinding rocks and soil, and then

blown by wind

Study Area

Samples were collected at the Dickinson Research Extension Center (DREC) Ranch Headquarters, located 2 miles S and 3 miles W of

Manning, ND.

Sampling Locations

Sampling was carried out in three locations on and near the Manning Ranch . All samplers were placed at 1.5 m above the ground.

Sampling location 1

Samplers were installed on the north and south sides of 15th St. SW. On the first day of sampling, June 24, 2014, TSP was collected at locations L1-N1 and L1-S1, both 38 ft. from the road center and at two sample locations along a service road in the DREC agricultural test fields. These locations, L1-S2 and L1-S3, were 100 ft. and 150 ft., respectively, south of the road center. The second day, June 25, 2014, at Location 1 TSP sampling was carried out only at location L1-N1 and L1-S1.

During the second sampling campaign, July 8, 2014, samplers were set up adjacent to one another at locations L1-N1 and L1-S1 to collect PM10 and PM2.5 simultaneously.

Sampling Location 2

Two samplers were installed on June 25, 2014 at a location adjacent to what would become the access road to the drill pad. Samplers

were installed on the North (location L2-N) and South (location L2-S) sides, 78 ft. from the middle of the projected road location. On June

25, 2014, TSP was collected at both L2-N and L2-S.

On July 9 and August 14, 2014, PM10 and PM2.5 were collected at adjacent sites at both L2-N

and L2-S.  

a.

b.

Sampling Location 3

Four samplers were installed, two each on the N and S sides, of the drill pad to collect PM10 and PM2.5. This location was sampled on August 13, 2014.

Sampling Method

MiniVol™ TAS Samplers (Air metrics, Springfield, OR, USA) were used for sampling air quality.

The MiniVol™ TAS Sampler is a portable, lightweight and battery operated air sampler for particulate

matter.

Prior to taking instruments to the field, a lab check

was performed, to insure proper operation.

In the field we adjusted the sampler for each sampling location.

The sampler can be configured to collect in one of three modes: total suspended particulate matter (TSP), PM10 and PM2.5.

a. Exterior Sampler, b. Interior Sampler, c. Impactor/Filter Holder Assembly, d. Schematic diagram of how particles are collected MiniVol TAS Operation Manual

a.

b.

c.

Filters

Pump

Flow meter

CPU

Air

d.

Whatman High purity Quartz (SiO2) fiber circle filters were used for sampling.

Filters were conditioned in a temperature and relative humidity controlled environment for a minimum of 24 hours prior to weighing.

Filters were weighed on a Sartorius Microbalance. The microbalance was calibrated priorto each weighing session; and weighing was performing by the same analyst.

Filters were installed in a protected area (in the car) using gloves.

The cassette separator was used for insertion and removal of quartz filters from the cassette

Filters

The cassette separator/quartz filter

Hobo Temperature/Relative Humidity Data Logger

The Hobo Temperature/Relative

Humidity Data Logger is used for monitoring

temperature, relative humidity and pressure at

the sampling site.

HOBO data

logger

Analytical Methods

Scanning Electron Microscopya. Sample preparation

b. Calculating mineral/phase formulas

ImageJ Software (NIH,2014)

Calculation of TSP, PM2.5 and PM10 Concentration

Scanning Electron Microscopy

Scanning electron microscopy (SEM) coupled with Energy-Dispersive X-ray analysis (EDS) was used for characterization of

atmospheric particulate matter. SEM analysis was carried out on a JEOL JSM-6490LV high-performance variable pressure SEM

at the NDSU Electron Microscopy Laboratory.

a. Sample preparation

Filter paper that had been exposed to dust was cut out with a razor blade in small section (5x5mm). The cut sections were attached to cylindrical aluminum mounts with double-stick carbon adhesive tape.

Sample preparation

b. Calculating mineral/phase formulas from SEM-EDS results

Example of using SEM/EDS data for wt.% and % atom to calculate an approximate empirical formula

O Si

53.26 46.74 wt. %

16.0 28.09 grams/mol

3.33 1.66 mols

(normalize)

2.006 1.000 mols

The particle is most likely quartz, SiO2

ImageJ software

Used to measure size of particles and to define particle morphology

1. Original Image (SEM)

2.“Free Hand Tool” the particle surface was selected

3.“Edit-Fill tool” used to fill in particle

4. Threshold

1. 2. 3. 4.

Calculation of particulate matter concentration

Net filter weight, the volume of air that passed through the filter during the sampling period at actual ambient conditions (Vact) must

be calculated first. 

Vact = (60min/hrX Qact thr) / 1000l/m3

Where :

Vact = Volume at ambient condition (m3)

Qact = Actual Flow Rate (liters/min)

t = sampling period, in hours (hr)

To calculate net mass, the initial weight was subtracted from the post sampling weight (the weight of the

particulate matter). To calculate the concentration of particulate matter, net mass of the filter was divided by

the volume at ambient condition.

PMact = Mpm / Vact

 

Where:

PMact = actual PM concentration, in micrograms per cubic meter (µm/m3)

Mpm = Mass of particulate matter collected on the filter (µm)

Results and Discussion Concentration of particles

Preliminary results indicated that measured concentration is lower then the air quality standard (for 24 hour period) except at location 1

Classification of particle groups

Quartz group (33%) particles are characterized by chemistry (high O and Si), and morphology (tabular). At location 1 they show high abundance.

Aluminosilicates (15%) Ca-Mg-Aluminosilicates (irregular shape) and Mg-Fe-Aluminosilicates (nearly spherical shape).

Feldspar group (13%)- Na-feldspar, Ca-feldspar, and K-feldspar (irregular shape).

Wollastonite (10%) Ca -silicate with irregular morphology. These particles are often dominated by suspended dust and crystal material from paved and unpaved roads.

Carbonate minerals (14%) including Dolomite (Ca-Mg-carbonate) and Calcite (Ca-carbonate) showing irregular shape with rough surface.

C rich particles - Biological - This group of particles contributes about 24% of the total particles analyzed at location 2

Particle size distribution

The results indicate that particle size distribution between 2.5µm<particle size<10µm (PM10) were most common in all three locations.

Quantity of particles were different in all three locations due to road condition, traffic frequency and road construction.

Conclusions

The element composition, identity, morphology and distribution of particles were investigated using SEM/EDS and ImageJ Software.

The results indicate that silicates contributed the highest percentage of total analyzed particles at both locations.

C rich particles - Biological particles - contributed about 24% of the total particles analyzed at location 2.

The results indicate that particle size distribution between 2.5µm<particle size<10µm were most common in all three locations.

Preliminary results indicated that measured concentration is below the air quality standard (for 24 hour period) except at location 1.

Quantity of particles were different in all three locations due to road condition, traffic frequency and road construction.

Thank you all for your hard work

T H A N K Y O U!

QUESTIONS ?