2.3 Shoreline Land Use 
Research has indicated that there tend to be relationships between land use or 
land cover types and indicators of estuarine condition. Both Comeleo et al. (1996) and 
Rodriguez et al. (2007) found significant associations between levels of urban land use 
and sediment contaminants in east coast estuaries. Generally such analyses require 
considerable effort in generating GIS coverages with associated land uses around the 
sampling points. The 2002 EMAP intertidal study included a pilot indicator of adjacent 
land use which was determined by the field crews at the time of the sample site visit. 
Crews provided a qualitative assessment of the dominant land use aspect for the 
shoreline most immediately adjacent to the sampling station by selecting a category 
from a list of land use types. Land use type was supplemented by additional 
descriptions in the form of comments and digital photos. Categories included 
agriculture, armored, commercial, highway, industrial, undeveloped, residential, urban, 
sanctuary, natural area, recreational, and fisheries uses. Several categories were 
combined in the final analysis with commercial being combined with industrial, and 
natural area plus sanctuary being combined with undeveloped. Fisheries use was only 
designated in Oregon and was relabeled oyster aquaculture to reflect the specific use 
noted. 
2.4 Quality Assurance 
2.4.1 Quality Assurance/ Quality Control of Chemical Analyses 
The quality assurance/quality control (QA/QC) program for the National Coastal 
Assessment - West program is defined by the “Environmental Monitoring and 
Assessment Program (EMAP): National Coastal Assessment Quality Assurance Project 
Plan 2001-2004" (U.S. EPA, 2001). A performance-based approach is used, which 
depending upon the compound includes 1) continuous laboratory evaluation through the 
use of Certified Reference Materials (CRMs), Laboratory Control Materials (LCMs), or 
Standard Reference Material (SRM); 2) laboratory spiked sample matrices, 3) 
laboratory reagent blanks, 4) calibration standards, 5) analytical surrogates, and 6) 
laboratory and field replicates. 
One measure of accuracy is “relative accuracy” which is based on comparing the 
laboratory’s value to the true or “accepted” values in CRMs or LCMs. The requirements 
for PAHs, PCBs, and pesticides are that the “Lab’s value should be within ±30% of true 
value on average for all analytes; not to exceed ±35% of true value for more than 30% 
of individual analytes” (U.S. EPA 2001). For metals and other inorganic compounds, 
the laboratory's value for each analyte should be within ±20% of the true value of the 
CRM, LCM, or SRM. Another measure of accuracy is the percent recovery from matrix 
spikes. High percent recoveries indicate that the analytical method and instruments can 
adequately quantify the analyte but do not evaluate the ability to actually extract the 
compound from tissue or sediment. Measures of precision are the “relative percent 
differences” (RPD) or coefficient of variation (CV) of duplicate samples, with the 
objective that the RPD or CV should be <30%. 
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