Phosphate
Phosphate concentration
µmol/Lkey phosphateNERC P01 PHOSZZXXP06 units UPOXseries phosphate
CalCOFI holds 440,909 values of it from 17,259 sampling events in one dataset, 1949–2021, from the surface to 5,351 m. At 10–50 m it has fallen 0.01 per decade since 1984.R Phosphate is one of the two fertilisers a bloom cannot do without; off Southern California it has risen in the lower pycnocline as oxygen fell, and the nitrogen-to-phosphorus ratio of the water that feeds upwelling has shifted with it.C
- 440,909
- values
- 305
- flagged
i
305 of these 440,909 values (under 0.1 %) are flagged by their provider as questionable or bad. The Explorer, the climatology and its anomalies leave them out; do the same when you read the data yourself (cc_qual_ok_sql()in calcofi4r,qual_ok_sql()in calcofi4py). - 1949–2021
- years
- 1
- dataset
- 0–5,351 m
- depth
- every month
- months
Measured in
1 dataset
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
phosphate· source columnpo4u_m· flag columnpo4q305 flagged
Explorera depth section vs normaldb-queryERDDAPThis page as JSON R · Python · Parquet
Every way in 8 ways · ERDDAP · Parquet · R · Python · JSON
Read from measurements.json of release v2026.10.21, 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-querySELECT * FROM read_json('…/v2026.10.21/catalog.json')
-- objects[] WHERE table = 'obs_env'
-- AND partition_value = 'phosphate'library(calcofi4r)
con <- cc_get_db() # the promoted release
tbl(con, "obs_env") |> filter(measurement_type %in% c("phosphate"))import calcofi4py as cc
con = cc.cc_get_db()
con.sql("SELECT * FROM obs_env WHERE measurement_type IN ('phosphate')").df()The structure O4P3− phosphate(3−)
ChEBI: “A phosphate ion that is the conjugate base of hydrogenphosphate.” · 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 Seal Analytical continuous-flow AutoAnalyzer 3 (AA3) at 820 nm
A modification of Bernhardt and Wilhelm: acidic ammonium molybdate forms phosphomolybdic acid, reduced by dihydrazine sulfate to a blue compound, heated to about 55C to develop color, and read in a 10 mm flow cell. (calcofi.org Bottle sampling methods)
Bottle sampling methods on calcofi.org ↗Why it matters 5 ways to say it · EOV Nutrients
the GOOS specification sheet for this Essential Ocean Variable lists it, and asks
GOOS asks
- How do the eutrophication and pollution impact ocean productivity and water quality?
- Is the biomass of the ocean changing?
GOOS specification sheet ↗ · quoted, not copied
other ways to say why · 4
- Where phosphate is high at the surface, deep water has arrived recently and little has yet grown on it. needs a citation before it can be the pick
- GOOS asks How do the eutrophication and pollution impact ocean productivity and water quality? source
- GOOS asks Is the biomass of the ocean changing? source
- Wikipedia A phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid, a.k.a. Phosphate · CC BY-SA 4.0 · rev. 1376284687
The record’s own history 6 depth bands against the 1993–2013 normal
Each year against the normal i
Deeper than the climatology reaches: 7,425 values at 1000–2000 m, 1,682 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: 7,425 values at 1000–2000 m, 1,682 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.
Units and range µmol/L · 0 … 10 declared · 305 flagged
µmol/L (umol/L in metadata/measurement_type.csv) · P06 units UPOX
details
- bounds
- The registry declares
0 … 10 µmol/Lforphosphate; a value outside it is dropped at the ingest (drop_out_of_bounds()). - observed
- Hydrographic Bottle
phosphate0 · median 1.57 · 5.21 µmol/L (5th–95th percentile 0.27–3.16) - flags
- Hydrographic Bottle
phosphatepo4qon 306 of 440,909 rows:41 ·8305; qual_ok keeps 440,604. 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 × station × the cruise's month × 10 m bin), so the Explorer can draw anomalies against it rather than values.
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.
By depth · by month 0–5,351 m · every month
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.
Cite the release, v2026.10.21
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.