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The share of Poland in the phosphorus pollution status of Baltic Sea in the light of HELCOM PLC research Cover

The share of Poland in the phosphorus pollution status of Baltic Sea in the light of HELCOM PLC research

Current Agronomy
Volume 54 (2025): Issue 2 (June 2025)
By: Alicja Pecio  
Open Access
|Jan 2026

Figures & Tables

Figure 1.

The catchment area and basins of the Baltic Sea covered by PLC monitoring. BOB – Bothnian Bay, BOS – Bothnian Sea, GUF – Gulf of Finland, GUR – Gulf of Riga, BAP – Baltic Proper, DS – Danish Straits, KAT – Kattegat Source: Svendsen, Gustafsson, 2024

Figure 2.

Significant reductions of total annual inputs of phosphorus achieved in 2022 (in %) since the reference period 1997–2003 (blue arrow) and recent changes (red arrow) where: recent changes are significant changes since last breakpoint of the timeseries. The arrows indicate decreasing (↓) inputs, and only significant changes are shown. Source: Svendsen et al., 2024

Figure 3.

Actual total waterborne annual input of phosphorus (TP) to the Baltic Sea and sub-basins from 1995 to 2022 (tons per year). BAS – Baltic Sea, BOB – Bothnian Bay, BOS – Bothnian Sea, BAP – Baltic Proper, GUF – Gulf of Finland, GUR – Gulf of Riga, DS – Danish Straits, KAT – Kattegat. The normalized total annual inputs of phosphorus are given as a black line. The trend line for normalized total phosphorus is given as a green line with markers. In cases when a break point divides the trend into two parts, the second part (called trend 2) is shown by a green line without marker. In cases with two breaks points the third part (called trend 3) is indicated as a purple line. (Solid trend line shows statistically significant trend and dotted line no statistically significant trend). The MAI as adopted by the 2013 HELCOM Copenhagen Ministerial Meeting (HELCOM 2013) is shown as the bold dotted blue line. Source: Svendsen et al., 2024

Figure 4.

Overall progress results towards NIC implementation by 2020 in terms of total phosphorus (TP) input. Source: NIC, 2023

Figure 5.

Structure of phosphorus loads at sources in five regions – absolute values. MUN–municipal point sources, IND – industrial point sources, AQU – aquaculture, ATS – atmospheric deposition, TRS – transgenic cargo, SWS – overflows and surface runoff from urbanized areas, SCS – sewage from unsewered areas, AG – agriculture, ATS – direct atmospheric deposition MFS – commercial forests and wastelands, NBS – natural background TRS – cross-border cargo Source: National Report, 2020

Figure 6.

The structure of river phosphorus loads in five regions – absolute values. River loads from: MUN – municipal point sources, IND – industrial point sources, AQU – aquaculture, SWL – sewage from storm overflows of combined sewers and surface, subsurface and ground runoff from undeveloped areas (excluding loads from sanitary sewage from unsewered areas and from the natural background), SCL – sanitary sewage from non – sewered areas, ATS – atmospheric deposition, AGL – agriculture, ATL – atmospheric precipitation on the surface of inland waters, MFL forests and wastelands, NBL – natural background, TRL – transboundary sub – catchments outside Poland, UKL – unknown sources Source: National Report, 2020

Figure 7.

Normalized phosphorus loads at sources from Polish part of the Baltic Sea catchment area in 2000, 2006, 2012, 2018 MUN – municipal point sources, IND – industrial point sources, AQU – aquaculture, SWS – overflows and surface runoff from urbanized areas, SCS – sewage from unsewered areas, AGS – agriculture, ATS – direct atmospheric deposition, MFS – commercial forests and wastelands, NBS – natural background, TRS – transgenic cargo, UNS – loads of unknown origin, D – direct, I – indirect Source: National Report, 2020

Figure 8.

Normalized river loads of phosphorus from Polish part of the Baltic Sea catchment area in in 2000, 2006, 2012, 2018 River loads from: MUN – municipal point sources, IND – industrial point sources, MWL – municipal sewage treatment plants, INL – industrial sewage treatment plants, INL – industrial sewage treatment plants, FIL – aquaculture (salmon farming), SWL – sewage from storm overflows of combined sewers and surface, subsurface and ground runoff from undeveloped areas (sanitary sewage from unsewered areas and from the natural background), SCL – sanitary sewage from non-sewered areas, AGL – agriculture, ATL – atmospheric precipitation on the surface of inland waters, MFL – municipal sewage treatment plants, NBL – natural background, TRL – transgenic sub-catchments outside Poland, UNL – unknown sources, D – direct, I – indirect Source: National Report, 2020

The trend-based estimate for normalized annual inputs of phosphorus (TP) in 2022_

Baltic Sea Sub-basinMAI#P input 2022Statistical uncertainty 2022P input including stat. uncert. 2022Exceedance of MAI in 2022Input 2022 including stat. uncertainty % MAIClassification of achieved reduction
t year−1
Bothnian Bay (BOB)2 6752 3501492 499 93
Bothnian Sea (BOS)2 7732 1491062 255 81
Baltic Proper (BAP)7 36012 38680713 1935 833179
Gulf of Finland (GUF3 6004 2427234 9651 365138
Gulf of Riga (GUR)2 0201 9032342 138118106
Danish Straits (DS)1 6011 148571 205 75
Kattegat (KAT)1 6871 360671 427 85
Baltic Sea (BAS)21 71624 9581 25926 2174 501121

Assessment of progress towards total phosphorus NIC by 2020 for Poland by Baltic Sea basins_

Total N (TN)Baltic Sea basin#
BOBBOSBAPGUFGURDSKAT
A: Input Ceiling (NIC BSAP2021) [t] 4198
B: Estimated input 2020 [t] 8167
C: Inputs 2020 [t] incl. uncertainty (test value) 8964
Extra reduction by 2020 (A-C) [t]
Remaining reduction to fulfill NIC by 2020 4766
Remaining in % ceiling 114
Significant changes [%] since reference period to 2020 −22

NIC assessment results of Poland for total phosphorus (TP) from Table 7 (taking into account extra reduction in neighboring basins) combined with the results of the PLC-7 (HELCOM by Sveden and Tornbjerg, 2022) source apportionment assessment for the main sources indicated for Poland_

Baltic Sea basin#TP NIC assessmentRemain tonsRemain % 2020 inputTP input 2020 [t]Main TP sources [%]
natural background loadsother diffuse waterborne sourcespoint## sources
BOB 00
BOS 00
BAP↓47665881675.06827
GUF 00
GUR 00
DS 00
KAT 00

Total phosphorus (TP) input ceilings in tons per year for total river as well as the country contribution to each of the transboundary rivers_

RiverBasin#NICCountry
DEFILTLVPLRUBYCZUA
NemunasBAP913--628---285--
BartaBAP25--520-----
VentaBAP106--2086-----
LielupeGUR302--135167-----
DaugavaGUR941--40395-99407--
OderBAP1554132---1365--57-
VistulaBAP2350----2240-63-47
PregolyaBAP147----5196---
NevaGUF1399-20---1379---

Years with the statistically identified breakpoints in trend lines of total phosphorus TP) inputs to the Baltic Sea and its sub-basins during 1995–2022_

BreakpointsChange [%] since reference periodChange [%] after last breakpoint
Bothnian Bay −18n.r.
Bothnian Sea −23n.r.
Baltic Proper −26n.r.
Gulf of Finland2012−48-
Gulf of Riga −32n.r.
Danish Straits2000−22−17
Kattegat −20n.r.
Baltic Sea −32n.r.

Remaining phosphorus reduction country in tons by 2020_

CountryBaltic Sea basin#
BOBBOSBAPGUFGURDSKAT
Denmarkn/an/a26n/an/a--
Estonian/an/a118867n/an/a
Finland-100 338n/an/an/a
Germanyn/an/a241n/an/a-n/a
Latvian/an/a111n/a255n/an/a
Lithuanian/an/a388n/a-n/an/a
Polandn/an/a4766n/an/an/an/a
Russian/an/a365101025n/an/a
Sweden31-410n/an/a--
Belarusn/an/a518n/a248n/an/a
Czech Republicn/an/a65n/an/an/an/a
Ukrainen/an/a131n/an/an/an/a

Country – Baltic Sea basin total phosphorus input ceilings in tons per year (2021)_

CountryBaltic Sea basin#
BOBBOSBAPGUFGURDSKAT
Germany (DE)--203--401
Denmark (DK)--21--979815
Estonia (EE)--922185--
Finland (FI)16831246 315---
Lithuania (LT)--703-175--
Latvia (LV)--167-1061--
Poland (PL)--4198----
(Russia (RU)--242290999--
Sweden (SE)8111133318--116753
Atmospheric deposition181394104615093105118
Belarus (BY)--349-407--
Czech Republic (CZ)--57----
Ukraine (UA)--47----
MAI2675277373603600202016011687

Total phosphorus (TP) inputs to the Baltic Sea basins compared with detailed source apportionment_ As in Table 8, but with a more detailed breakdown of sources_

Baltic Sea basin#Discharging into inland waters TP [%]Discharging directly into the sea TP [%]
AGLATLMFLNBLSCLSWLAQLINLMWLAQLINLMWL
BOB
BOS
BAP601.01.55.092.81.82.01.52300.280.45
GUF
GUR
DS
KAT

Remaining phosphorus reduction country by basin in percentages of NIC by 2020_

CountryBaltic Sea basin#
BOBBOSBAPGUFGURDSKAT
Denmarkn/an/a125n/an/a--
Estonian/an/a1173936n/an/a
Finland-8.0 107n/an/an/a
Germanyn/an/a119n/an/a-n/a
Latvian/an/a66n/a24n/an/a
Lithuanian/an/a55n/a-n/an/a
Polandn/an/a114n/an/an/an/a
Russian/an/a1513526n/an/a
Sweden3.8-129n/an/a--
Belarusn/an/a148n/a61n/an/a
Czech Republicn/an/a114n/an/an/an/a
Ukrainen/an/a279n/an/an/an/a
DOI: https://doi.org/10.2478/cag-2025-0015 | Journal eISSN: 3071-740X | Journal ISSN: 2081-2787
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Language: English
Page range: 169 - 183
Submitted on: Aug 18, 2025
|
Accepted on: Nov 28, 2025
|
Published on: Jan 31, 2026
Published by: Institute of Soil Science and Plant Cultivation
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
HELCOM,
Pollution Load Compilation (PLC),
Baltic Sea,
phosphorus pollution,
Nutrient Input Ceiling,
Poland
Related subjects:
Life sciences,
Plant science,
Ecology

© 2026 Alicja Pecio, published by Institute of Soil Science and Plant Cultivation
This work is licensed under the Creative Commons Attribution 4.0 License.

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