UNCG Geography

Environmental Magnetism

Environmental Magnetism: the use of natural and induced magnetic properties of earth materials to solve environmental problems

 

 

All materials react to being placed in a magnetic field. Reactions are measurable and diagnostic of material type and particle size. Some materials react by augmenting the applied magnetic field, and others by diminishing it. The response magnitude can change with the frequency of the applied field. Some types of materials retain a portion of their magnetism after being placed in a magnetic field.

 

 

There are several types of magnetic measurement useful for solving environmental problems. The most common are:

 

Magnetic Susceptibility, the magnetizability of a substance, measured by its reaction to placement in a weak magnetic field.

 

Frequency dependent susceptibility, the percent or absolute difference in magnetic susceptibility between measurements made in low and high-frequency fields.

 

Saturation Isothermal Remanent Magnetization (SIRM), the strength of magnetic field held by a substance after being placed in a high magnetic field, then removed from it. SIRM may be combined with susceptibility measurements to provide more specific information on the magnetic nature of a substance than either measure alone can provide.

 

 

Current environmental magnetism equipment available within the UNC-Greensboro Geography Department includes:

 

Bartington MS2 and MS3 magnetic susceptibility meters

 

Bartington MS2B dual frequency sensor

 

Bartington MS2D search loop sensor with probe handle (for spatially distributed field survey in archaeology, geomorphology and soil mapping)

 

Bartington MS2E high resolution core logging sensor

 

Bartington MS2F surface point probe

 

Bartington MS2G single frequency small sample sensor

 

Bartington MS2H downhole sensor

 

ASC Scientific IM-10 impulse magnetizer

 

MOLSPIN Minispin portable fluxgate spinner magnetometer

 

 

From upper left going clockwise, the MS2 meter with MS2B sensor, MS3 meter, MS2D search loop, MS2G small sample sensor, and the MS2E core logging sensor.

 

 

 

 

The ASC IM10 Impulse Magnetizer, and the MOLSPIN Minispin fluxgate spinner magnetometer

 

 

 

 

Applications of environmental magnetism include:

 

Studies of fluvial and lacustrine sediment, sediment source tracing and erosion,

 

 

 

 

 

Soil mapping and erosion assessment

 

 

 

 

 

 

Magnetic remote sensing of archaeological sites, and the analysis of artifacts.

Magnetism has been used in archaeological surveying for many years at many locations around the world. Iron-bearing construction materials and other artifacts, and changes in soil caused by intense burning (such as with hearths) and earth moving activities can be sensed with magnetic instruments.

 

 

 

 

Airborne particulate pollution

Research has demonstrated the ability to delineate airborne particulate plumes downwind of emissions sites by magnetic analysis of ground surface samples. (UNCG geoscientists are not currently involved in magnetics based research on air pollution, but are open to inquiries regarding such applications)