13.02.2013 Views

Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Table AX7-2.2.1. NAWQA Land Use Categories and<br />

Natural/Ambient Classification<br />

NAWQA Land Use Categories Classification<br />

Agricultural Ambient<br />

Commercial/Industrial Ambient<br />

Cropland Ambient<br />

Forest Ambient/Natural<br />

Mining Ambient<br />

Mixed Ambient<br />

NA Ambient<br />

Orchard/Vineyard Ambient<br />

Other/Mixed Ambient<br />

Pasture Ambient<br />

Rangeland Ambient/Natural<br />

Reference Ambient/Natural<br />

Residential Ambient<br />

Urban Ambient<br />

Agency, 2004b). Finally, in addition to the natural/ambient classification, tissue samples were<br />

further divided into “whole organism” and “liver” groups.<br />

All data were compiled in spreadsheets wherein non-detect values were converted to one-<br />

half the detection limit and the total number <strong>of</strong> samples, percentage <strong>of</strong> non-detect values (percent<br />

censorship), minimum, maximum, median, mean, standard deviation, and cumulative density<br />

functions were calculated <strong>for</strong> each endpoint <strong>for</strong> both the natural and ambient groups.<br />

As discussed below, some datasets were highly censored; however, deletion <strong>of</strong> non-detect data<br />

has been shown to increase the relative error in the mean to a greater extent than inclusion <strong>of</strong><br />

non-detects as ½ <strong>of</strong> the detection limit (Newman et al., 1989); there<strong>for</strong>e means and other<br />

statistics were calculated using the latter method <strong>for</strong> this analysis. Finally, since all data were<br />

geo-referenced, a geographic in<strong>for</strong>mation system (GIS; ArcGIS) was used to generate maps,<br />

conduct spatial queries and analyses, and calculate statistics.<br />

AX7-125

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!