geochm: NGS database samples for Indiana State
In GSIF: Global Soil Information Facilities

Description Usage Format Note Author(s) References Examples

A subset of the National Geochemical Survey (NGS) samples covering the Indiana and Illinois State. Contains a total of 2681 point samples.

1	data(geochm)

Data frame; contains the following columns:

REC_NO: factor; unique record identifier
DATASET: factor; abbreviated dataset group e.g. "AK+MI"
TYPEDESC: factor; abbreviated description of sample type: stream, pond, spring, soil etc
COLL_DATE: integer; sampling date
LONGITUDE: numeric; longitude in decimal degrees (NAD27 datum)
LATITIUDE: numeric; latitude in decimal degrees (NAD27 datum)
DATUM: factor; geodetic datum if different from NAD83
RELIEF: factor; relief in drainage basin from which sample was collected
FORMATION: factor; code or name of geologic formation in which sample area was located
ROCK_TYPE: factor; rock type in area of sample collection e.g. "carbonate"
SOIL_HORIZ: factor; soil horizon from which the sample was collected
COLOR: factor; observed color of powdered sample during splitting
MEDIUM: factor; sample medium — rock, sediment, standard, or unknown
SOURCE: factor; geological source of the sample medium that was collected e.g. "Beach"
AS_ICP40: numeric; As (ppm) by Inductively Coupled Plasma Spectrometry (ICP) after acid dissolution
CD_ICP40: numeric; Cd (ppm)
CR_ICP40: numeric; Cr (ppm)
CU_ICP40: numeric; Cu (ppm)
NI_ICP40: numeric; Ni (ppm)
ZN_ICP40: numeric; Zn (ppm)
AS_AA: numeric; As (ppm) by Hydride Atomic Absorption
HG_AA: numeric; Hg (ppm) by Hydride Atomic Absorption
PB_ICP40: numeric; Pb (ppm)
C_TOT: numeric; total carbon (weight percentage) by combustion
C_ORG: numeric; organic carbon (weight percentage) as a difference between C_TOT and C_CO3
C_CO3: numeric; carbonate carbon (weight percentage) by Coulometric Titration
S_TOT: numeric; total sulfur (weight percentage) by combustion

Negative values of the heavy metal concetrations indicate a determination that is below the limit of detection for the analytic method used. The magnitude of the negative number indicates the detection limit. For example, -10 ppm means the result should be regarded as < 10 ppm.

National Geochemical Survey database is maintaned by the USGS National Geochemical Survey Team (contact: Peter Schweitzer). This subset has been prepared for the purpose of testing various geostatistical mapping algoriths by Tomislav Hengl (tom.hengl@isric.org).

The National Geochemical Survey Team, (2008) The National Geochemical Survey: database and documentation. U.S. Geological Survey Open-File Report 2004-1001, U.S. Geological Survey, Reston VA.
National Geochemical Survey database (http://mrdata.usgs.gov/geochem/)

library(sp)

# Load the NGS data:
data(geochm)
coordinates(geochm) <- ~LONGITUDE+LATITUDE
proj4string(geochm) <- CRS("+proj=longlat +ellps=clrk66 +datum=NAD27 +no_defs")
## Not run: 
require(plotKML)
data(SAGA_pal)
# replace the missing values with half the detection limit:
geochm$PB_ICP40 <- ifelse(geochm$PB_ICP40 < 0, 2, geochm$PB_ICP40) 
shape = "http://maps.google.com/mapfiles/kml/pal2/icon18.png"
kml(geochm, shape = shape, colour = log1p(PB_ICP40), labels = "", 
    colour_scale = SAGA_pal[[1]], kmz = TRUE)

## End(Not run)