Nutrient loss from three small-size watersheds in the southern Baltic Sea in relation to agricultural practices and policy

E Wojciechowska; S Pietrzak; K Matej-Łukowicz; N Nawrot; P Zima; D Kalinowska; P Wielgat; H Obarska-Pempkowiak; M Gajewska; G Dembska; P Jasiński; G Pazikowska-Sapota; K Galer-Tatarowicz; L Dzierzbicka-Głowacka

doi:10.1016/j.jenvman.2019.109637

Nutrient loss from three small-size watersheds in the southern Baltic Sea in relation to agricultural practices and policy

J Environ Manage. 2019 Dec 15:252:109637. doi: 10.1016/j.jenvman.2019.109637. Epub 2019 Oct 7.

Authors

Affiliations

¹ Gdansk University of Technology, Faculty of Civil and Environmental Engineering, Narutowicza 11/12, 80-233, Gdańsk, Poland. Electronic address: esien@pg.edu.pl.
² Institute of Technology and Life Sciences in Falenty, Department of Water Quality, Hrabska Al. 3, 05-090, Raszyn, Poland.
³ Gdansk University of Technology, Faculty of Civil and Environmental Engineering, Narutowicza 11/12, 80-233, Gdańsk, Poland.
⁴ Maritime Institute in Gdansk, Department of Environmental Protection, Dlugi Targ 41/42, 80-830, Gdańsk, Poland.
⁵ Institute of Oceanology Polish Academy of Sciences, Powstańców Warszawy 55, 81-712, Sopot, Poland.

PMID: 31600684
DOI: 10.1016/j.jenvman.2019.109637

Abstract

Agriculture is the major contributor of waterborne nutrient fluxes into the Baltic Sea, one of the world's most eutrophication-sensitive areas. Poland, as a large, densely populated state ohf the Baltic Region, with dominating agricultural land use, largely contributes to riverborne loads of N and P. The aim of our study was to examine the input of nutrients from three small first-order agricultural watersheds (Bladzikowski Stream, Gizdepka river and Mrzezino canal) in the Pomerania region, into the Bay of Puck, inner part of the Gulf of Gdansk. This study attempts to give a partial answer as to the question if inputs of nutrients from the 3 analysed watersheds comply with the targets of the Baltic Sea Action Plan (BSAP) and Country Allocated Reduction Targets (CART). The impact of agricultural practices was assessed on the basis of farm questionnaires and calculations of nutrient balances for the examined farms. The nutrient concentrations in the soil and drainage ditches were examined, followed by an assessment of nutrient concentrations in the watercourses at the sampling points located close to the estuaries. The average mineral N fertiliser consumption (109 kg N/ha) in the analysed watersheds was higher than Poland's average. The average N and P surpluses for surveyed farms (96.4 kg/ha and 4.4 kg/ha, respectively) were higher than the EU mean in case of N and markedly lower in case of P. We used Principal Component Analysis which confirmed that there were correlations between nutrient surpluses and nutrient concentrations in streams and/or drainage ditches. The N-NO₃ and P_min concentrations were also correlated to precipitation. The average N concentrations in the analysed watercourses were equal to 1.53 mg/L for Gizdepka, 1.88 mg/L for Mrzezino canal and 3.52 mg/L for Bładzikowski Stream. The mean P concentrations observed in the investigated watercourses were markedly higher than 0.1 mg/L. With regard to BSAP objectives, as well as CART set for Poland, the average nutrient concentrations in rivers should be approximately at the level of 2.5 mg N/L and 0.07 mg P/L.

Keywords: Agricultural land use; Eutrophication; Fertilisation; Nutrient surplus; Nutrients.

MeSH terms

Agriculture
Baltic States
Environmental Monitoring*
Nitrogen
Nutrients*
Oceans and Seas
Phosphorus
Poland
Rivers

Substances

Phosphorus
Nitrogen