Ammonium concentration (QC'd
Ammonium concentration (QC'd; the source column is named NH3)
- 90,489
- values
- 0
- flagged
- 3,669
- 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 90,489 values of it from 3,669 sampling events in one dataset, 2008–2021, from the surface to 3,542 m. At 10–50 m it has risen 0.02 per decade since 2009.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
ammonia· source columnnh3u_m· flag columnnh3q
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
v2026.10.05, 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 v2026.10.05, 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('…/v2026.10.05/catalog.json')
-- objects[] WHERE table = 'obs_env'
-- AND partition_value = 'ammonia'library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "obs_env") |> filter(measurement_type %in% c("ammonia"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM obs_env WHERE measurement_type IN ('ammonia')").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/Lforammonia; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- Hydrographic Bottle
ammonia0 · median 0 · 33.58 µmol/L (5th–95th percentile 0–0.37) - flags
- Hydrographic Bottle
ammonianh3qon 27,689 of 90,489 rows:427,689; qual_ok keeps 90,489. The codes are this dataset's own vocabulary, uninterpreted. - baseline
- A monthly climatology exists for this measurement (the release's climatology table: 1993–2013, dataset × grid cell × calendar month × 10 m bin), so the Explorer can draw anomalies against it rather than values.
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).
- 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
- Reported ammonium concentration (pre-QC) r_ammonium · Hydrographic Bottle · 2008–2021 · 90,509 values · P01 AMONZZXX the source's own reported value before its QC — this page is the QC'd twin
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.