Reported ammonium concentration (pre-QC)
- 90,509
- values
- 0
- flagged
- 3,670
- sampling events
- 2008–2021
- years
- 1
- dataset
- 0–3,542 m
- depth
- Jan · Feb · Mar · Apr · May · Jun · Jul · Aug · Oct · Nov
- seasons
H4N+ · ammonium · 18.039 g/mol · CHEBI:28938
Concentration of ammonium per unit volume of the water column. Ammonium may be expressed in terms of mass or quantity of substance.
Seal Analytical continuous-flow AutoAnalyzer 3 (AA3)
660 nm
Bottle sampling methods on calcofi.org ↗Is the biomass of the ocean changing?
CalCOFI holds 90,509 values of it from 3,670 sampling events in one dataset, 2008–2021, from the surface to 3,542 m.R Ammonium is nitrogen recycled by zooplankton and bacteria; phytoplankton take it up before nitrate, so production fed by it is “regenerated” rather than “new”.C
other ways to say why · 4
- Most nitrogen in the sunlit layer is recycled several times before it sinks; ammonium measures that recycling, excreted by animals and released as bacteria break organic matter down. needs a citation before it can be the pick
- GOOS asks Is the biomass of the ocean changing? source
- Wikipedia Nitrogen cycle source
- Wikipedia Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) molecular ion with the chemical formula NH4+ or [NH4]+. Ammonium · CC BY-SA 4.0 · rev. 1376536172
The measurement
Measured in i
One row per series, one cell per year, darker with more values — the same strip the front
door draws per dataset and a species page draws per taxon. Each row is one dataset's own
measurement_type; the label is written once, in the title above.
i
One row per series, one cell per year, darker with more values — the same strip the front door draws per dataset and a species page draws per taxon. Each row is one dataset's own measurement_type; the label is written once, in the title above.
-
series
r_ammonium· source columnr_nutsreported · pre-QC no flag at this grain
The structure
ChEBI: “An onium cation obtained by protonation of ammonia.” · RDKit 2026.03.6 from the ChEBI molfile, in the page’s ink · CC BY 4.0. ChEBI’s roles are never shown.
How it is measured
The Berthelot reaction: hypochlorous acid and phenol react with ammonium in alkaline solution to form indophenol blue, read in a 10 mm flow cell (a modification of Koroleff 1969, 1970). (calcofi.org Bottle sampling methods)
- NH4+ + phenol + hypochlorite (alkaline) -> indophenol blue
- absorbance read at 660 nm
Why it matters
The familiar scale i
Bars are each series' 5th–95th percentile, the line its minimum to maximum, the ring its median;
the marks are metadata/measurement_scale.csv's, each hovering to its own source.
i
Bars are each series' 5th–95th percentile, the line its minimum to maximum, the ring its median;
the marks are metadata/measurement_scale.csv's, each hovering to its own source.
The record’s own history i
Deeper than the climatology reaches: 21 values at 1000–2000 m, 31 values at 2000+ m have no
normal to depart from, because the release’s climatology stops at its
deepest built bin. Carrying it to the bottom is one argument of
build_climatology() and puts these bands on the page too.
i
Deeper than the climatology reaches: 21 values at 1000–2000 m, 31 values at 2000+ m have no
normal to depart from, because the release’s climatology stops at its
deepest built bin. Carrying it to the bottom is one argument of
build_climatology() and puts these bands on the page too.
the GOOS specification sheet for this Essential Ocean Variable lists it, and asks
GOOS asks
- Is the biomass of the ocean changing?
GOOS specification sheet ↗ · quoted, not copied
The record
Ways in i
Read from measurements.json of release
v2026.10.08, written at release by
calcofi4db::build_measurements_catalog() beside
taxa.json. The catalog's index is
/measurements/; the JSON-LD on this page is a
schema.org/DefinedTerm in the NERC P01 term set with a
PropertyValue per series.
ExplorerExplorer · a depth section vs normaldb-queryi
Read from measurements.json of release v2026.10.08, written at release by calcofi4db::build_measurements_catalog() beside taxa.json. The catalog's index is /measurements/; the JSON-LD on this page is a schema.org/DefinedTerm in the NERC P01 term set with a PropertyValue per series.
SELECT * FROM read_json('…/v2026.10.08/catalog.json')
-- objects[] WHERE table = 'obs_env'
-- AND partition_value = 'r_ammonium'library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "obs_env") |> filter(measurement_type %in% c("r_ammonium"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM obs_env WHERE measurement_type IN ('r_ammonium')").df()By depth i
Values per depth band at the release grain, one thin bar per series. The bands are the
record's own (0-10 … 2000+ m).
i
Values per depth band at the release grain, one thin bar per series. The bands are the record's own (0-10 … 2000+ m).
By month i
Values per calendar month, one row per series: CalCOFI's quarterly cruises show as peaks in
the months the ships sail.
i
Values per calendar month, one row per series: CalCOFI's quarterly cruises show as peaks in the months the ships sail.
Range & quality
details
- bounds
- The registry declares
0 … 100 µmol/Lforr_ammonium; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- Hydrographic Bottle
r_ammonium0 · median 0 · 33.58 µmol/L (5th–95th percentile 0–0.37) - flags
- Hydrographic Bottle
r_ammoniumcarries no quality code at the release grain; qual_ok keeps all 90,509. - baseline
- A monthly climatology exists for this measurement (the release's climatology table: 1993–2013, dataset × station × the cruise's month × 10 m bin), so the Explorer can draw anomalies against it rather than values.
- derivation
- reported value interpolated to standard depth (pre-QC, decodr); carries no quality code by design; not an input for further interpolation
Related measurements i
The same quantity from another platform or another kind of sample, each its own page and
never merged into this one: a dataset's own bottle samples would count that dataset twice, an underway intake
is not a cast, and a replicate is not a mean. The reason is the record's
(related[].why).
i
The same quantity from another platform or another kind of sample, each its own page and never merged into this one: a dataset's own bottle samples would count that dataset twice, an underway intake is not a cast, and a replicate is not a mean. The reason is the record's (related[].why).
- Ammonium concentration (QC'd ammonia · Hydrographic Bottle · 2008–2021 · 90,489 values · P01 AMONZZXX the source's own reported value before its QC — this page is the QC'd twin
- Bottle ammonium btl_ammonium · CTD Cast Files · 2008–2026 · 69,507 values · P01 AMONZZXX the same quantity from the CTD files' own bottle samples — plausibly the same physical bottles, so merging them would count the bottle dataset twice
Cite
Cite the release; each dataset's own citation, licence and DOI are on its page — Hydrographic Bottle. The Explorer's Share → Cite writes it for the view you make.