Sampling soil for organochlorine contaminants
You can sample soil to determine the level of organochlorine contamination in areas of your property.
To sample soil in grazing paddocks:
- collect sub-samples at a depth of 10-15mm, at 10-20 separate sites chosen at random across the whole paddock
- thoroughly mix the sub-samples together
- submit a combined (composite) 500g sample of soil to the laboratory.
Contaminated hot spots
You will need to take specific samples from any contaminated hot spots (e.g. dip site or the pump-out area). You should collect surface soil samples of 200-300g (about a trowel full) from each site.
For pens immediately adjacent to a contaminated area, you should:
- take 5 soil samples from places evenly spaced around the pen
- combine the samples into 1 container for each pen to give an average chemical contaminant level for that pen.
For holding paddocks, you should:
- take samples from contour lines drawn 2m, 4m and 8m from the contamination area
- collect from 5 sites equally spaced along each contour line
- combine the samples into one container
- submit 1 sample for each of the 3 contour lines.
Submitting the soil samples to the laboratory
Before you submit your soil samples to the laboratory, place them in a clean sealed glass jar or polythene bag. Mark the jar or bag with:
- date of collection
- property name
- a unique identifier for each location.
Keep an accurate map showing the location of each sample that has been submitted to the laboratory.
It is important the samples you have collected are not contaminated with plant foliage or root material and that each soil type is sampled separately. If you suspect a high level of OC, mark the sample with the words 'hot spot' to avoid contaminating the laboratory.
You should also contact the laboratory to confirm the cost of testing before sending your samples.
Soil sampling methods are screening tests only and will give you an indication of the concentration of OC contaminants at a site. The results are not absolute statements of the presence or absence of OC contamination, but they are indicators that you can use for risk assessment and to support the decisions you make about OC risk management and grazing of food-producing animals on a property.
The National Association of Testing Authorities (NATA) can provide you with a list of laboratories that are approved for OC testing in Queensland. You can telephone NATA on (07) 3870 3844 or contact them by fax on (07) 3848 3660.