any number of water-quality (class "qw") or numeric vectors. The length
of the water-quality data must all agree, but numeric values are replicated to the 
length of the water-quality data. See Details.

&#8230;

the name of the analyte, if not supplied, generated from &#8230;.

analyte

the parameter code of the analyte or any othe unique identifier the user chooses.

pcode

logical, if <code>TRUE</code>, then force values to be strictly non-negative on 
subtraction, otherwise negative values are permitted.

Adds or subtracts water-quality data while trying to maintain the 
integrity of the data.

internal

Enable users to evaluate long-term trends using a Generalized
Additive Modeling (GAM) approach. The model development includes selecting a
GAM structure to describe nonlinear seasonally-varying changes over time,
incorporation of hydrologic variability via either a river flow or salinity,
the use of an intervention to deal with method or laboratory changes
suspected to impact data values, and representation of left- and
interval-censored data. The approach has been applied to water quality data
in the Chesapeake Bay, a major estuary on the east coast of the United
States to provide insights to a range of management- and research-focused
questions.

add: Add Water-Quality Data

Description

Usage

Arguments

Value

Details