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particulate matter

Definition

The weight of dry material retained after passing a water sample through a fine filter is the total particulate matter (suspended solids). Recommended filtration method: vacuum filtration (l2-5 mg Hg) through l µm (e.g. Whatman GF-C) and 0.22 µm (e.g. Millipore) filters (0.45 l µm filters are commonly used by aquatic biologists). In sea water, wash residue with 0.9% ammonium formate. Filters must be pre-weighed, because individual filter sheets vary drastically in weight, sometimes exceeding the dry weight of the retained particles. Additionally, filters lose weight during filtering; thus, several controls must be run to determine a correction factor. Particulate matter may also be estimated by substracting dissolved solids from total solids.

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