Variable
cobalt
gadolinium
zinc
neodymium
tin
sodium
selenium
elemental_carbon
beryllium
organic_carbon
barium
terbium
tungsten
rubidium
hafnium
antimony
europium
lead
calcium
lutetium
cerium
nitrate
yttrium
samarium
thorium
strontium
ytterbium
silicon
tantalum
cesium
titanium
scandium
praseodymium
arsenic
chromium
carbonate
total_carbon
thulium
chloride
nickel
potassium
sulphate_total
bismuth
lanthanum
zirconium
erbium
magnesium
iron
dysprosium
aluminium
gallium
thallium
uranium
holmium
lithium
ammonium
cadmium
germanium
phosphorus
vanadium
manganese