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Review: long-term trends of pesticide residues in the Danube River Basin
expand article infoNicoleta Matei‡§, Daniela Seceleanu-Odor§, Adrian Burada§, Petre-Bogdan Gheorghe§‡, Mihaela Tiganus§, Iasemin Suliman§, Orhan Ibram§‡, Cristina Despina§
‡ Dunărea de Jos University of Galati, Galati, Romania
§ Danube Delta National Institute for Research and Development, Tulcea, Romania

Corresponding author: Nicoleta Matei ( cioceanu.nicoleta@ddni.ro )

Corresponding author: Iasemin Suliman ( iasemin.suliman@ddni.ro )

Academic editor: Iulian Nichersu
© 2025 Nicoleta Matei, Daniela Seceleanu-Odor, Adrian Burada, Petre-Bogdan Gheorghe, Mihaela Tiganus, Iasemin Suliman, Orhan Ibram, Cristina Despina.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Matei N, Seceleanu-Odor D, Burada A, Gheorghe P-B, Tiganus M, Suliman I, Ibram O, Despina C (2025) Review: long-term trends of pesticide residues in the Danube River Basin. Scientific Annals of the Danube Delta Institute 30: 1-16. https://doi.org/10.3897/saddi.30.160456
Open Access

Abstract

Pesticides play an important role in boosting agricultural production by controlling pests. Pesticides can be algicides, antimicrobials, disinfectants, herbicides, insecticides, molluscicides, pheromones, rodenticides (raticides), and biopesticides. Despite regulations, pesticide pollution remains a threat to human health, food security, and the environment. Pesticides can harm the environment, affecting water quality and biodiversity, and can be toxic to non-target species. This study aimed to assess the impact of pesticide residues on the surface waters of the Danube River through concentrations determined in the period 1995–2023 in the Danube River Basin. In the present study, scientific techniques were used to collect scientific evidence, consulting academic literature databases such as Google Scholar, Science Direct, MDPI, etc. The study also looked at the quantities of pesticides used in the countries of the Danube River Basin compared to agricultural production during 2014–2022. Five compounds from the pesticide class were selected from the literature. This selection was based on the frequency of determination in surface waters from the Danube River Basin. Pesticides have a negative effect on both the aquatic ecosystem and humans, directly affecting the proper functioning of the body. Continuous monitoring of pesticide residues is essential for determining the quality of the Danube water, as well as for biodiversity.

Key words:

Danube River Basin, pesticide, pollutants, water

Introduction

Pesticides are essential due to their significant role in increasing agricultural production by controlling pests. Pesticides are chemical compounds used to prevent or control pests, including insects, fungi, rodents, or other unwanted plant species that can cause damage during crop production and storage. The broad term “pesticides” includes insecticides, herbicides, fungicides, and rodenticides used to destroy specific pests (Pathak et al. 2022).

Over time, new generations of pesticides have been constantly developed, with increasingly complex chemical structures and enhanced phytosanitary efficacy. Thus, if copper and iron sulphates were predominantly used at the beginning of the 1900s, later, in the 1940s–1950s, organomercuric compounds, organochlorine insecticides, and organophosphorus insecticides emerged. Then, up to 1980–1990, most of the current chemical compounds had been synthesised (Alloway et al. 1997).

National and international agencies such as FAO (Food and Agriculture Organisation), WHO (World Health Organisation), EPA (Environmental Protection Agency), and FDA (Food and Drug Administration of the USA) play an important role in public health and health policies. However, pesticide pollution and their harmful active substances still pose significant risks to human health and food security and contribute to environmental changes.

In addition to legislative restrictions, the use of pesticides is partly influenced by economics—the most profitable crops are the most economically viable to treat—and partly by local pedoclimatic conditions that can cause the vulnerability of a site to pest infestation. It also depends on the type of agriculture, whether conventional or organic. Annual variations may depend on weather conditions, pest outbreaks, or pesticide sales prices. The use of pesticides has negative environmental effects on water quality, terrestrial and aquatic biodiversity, and persistence and toxic effects on non-target species (Popa et al. 1986).

Environmental risk caused by pesticide use varies considerably from one compound to another, depending both on the intrinsic characteristics of the active substance (such as toxicity and persistence) and the way it is used (volume applied, period and method of application, type of crop and soil, etc.) (Lewis et al. 2016).

It is estimated that 45% of global food production is lost every year due to pests and plant diseases. This leads to the need for efficient management practices to address these problems. It is known that the widespread use of pesticides increases both the quantity and quality of crops while maintaining low costs (Kadiru et al. 2022).

Pesticide residues are defined by the Food and Agriculture Organisation of the United Nations as “any specified substance in food, agricultural commodities, or animal feed resulting from the use of a pesticide.” The same organisation points out that “the term includes any derivatives of a pesticide, such as conversion products, metabolites, reaction products, and impurities considered to be of toxicological significance” (fao.org, FAO 2025).

The largest river in Europe after the Volga, the Danube River collects the wastewater of nineteen countries and forms eight European borders (Sommerwerk et al. 2022). In order to protect the aquatic environment of the Danube River Basin, the International Commission for the Protection of the Danube River (ICPDR) was established in 1994 (Habersack et al. 2016).

Anthropogenic activities have a negative impact on the Danube River Basin in terms of pollution from agriculture, industry, sewage treatment plants, transport, fishing, and tourism. The Danube River Basin is divided into three subregions: the upper sector (from the source in Germany to Bratislava, Slovakia), the middle sector (Bratislava, Slovakia, to the Serbia–Romania border), and the lower sector (Serbia–Romania border to the discharge area into the Black Sea, including the Danube Delta) (icpdr.org).

At the European level, the presence of these contaminants in water is regulated by the EU Groundwater Directive (European Parliament 2006), EU Drinking Water Directive (European Parliament 2020), and EU Water Framework Directive (European Parliament 2020), which has been amended. These establish a maximum concentration of 100 ng/L for individual pesticides and pesticide metabolites and 500 ng/L for total pesticides in the sample (Szekacs et al. 2015).

Materials and methods

Study area

The Danube River Basin is the second largest river basin in Europe (Fig. 1), covering an area of 801,463 km2. According to the ICPDR, over 80 million people living in 19 countries share the Danube River Basin, making it the most international basin in the world. Before discharging into the Black Sea, the river splits into three main branches, creating the Danube Delta, with an area of ​​4,180 km2.

Along its entire pathway from the Black Forest to the Black Sea, the Danube River gathers water from twenty-seven large tributaries and over three hundred small rivers. Although tourism, agriculture, and industry are important from an economic perspective and depend heavily on the Danube River’s natural resources, they also bring significant amounts of discharged pollutants originating from human activities, which negatively affect the Danube waters and their biodiversity in multiple ways (Simionov et al. 2021).

Figure 1. 

The countries in the Danube River Basin (source: Ene et al. 2024).

Methods

In this paper, we used an internet web search technique to collect the scientific basis by consulting the Web of Science, ScienceDirect, and Google Scholar academic literature databases. National and international agencies that control and monitor pesticide consumption at European and global levels were also consulted during the study period, along with data on the quantities of agricultural production. This search targeted scientific articles, laws, and regulations written in English. The common search syntax for scientific articles was “pesticide residues in water.” It was not a complex syntax, to ensure that as much information on this topic as possible could be identified.

During this search activity, as listed in Table 1, a total of 1,490,000 scientific papers were identified on Google Scholar, 100,191 on ScienceDirect, and 202 scientific papers were identified on MDPI. From the total number of 1,590,393 detected scientific articles, 54 were selected after analysis. As shown in Table 2, most of the selected key articles were published in the period 2001–2024.

Table 1.
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Selected articles from databases.

Database Number of results Selected Papers
Google Scholar 1,490,000 18
ScienceDirect 100.191 16
MDPI 202 3
Other 12
Table 2.
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The publication year of the scientific articles selected for this study.

Publication year Numbers of papers
1986 1 (Popa et al)
1996 1 (Balinova)
1997 1 (Alloway et al.)
: :
2001 1 (Karlaganis et al.)
2003 1 (Schrader et al.)
2005 3 (Watt et al.; Xing et al.; Zhang et al.)
2006 1 (Muir et al.
2008 2 (Domotorova; Balinova et al.)
2010 1 (Loos et al.)
2011 2 (Bridier et al.: Carsten von der Ohe et al.)
2013 1 (Shorey)
2014 5 (O’Brien et al.; Olaitan et al.; Rocha-Gaso et al.; Weerathung et al.; Slobodnik et al.)
2015 6 (Geissen et al.; Kabir et al.; Szeckacs et al.; Slobodnik et al; Iancu et al.; Radovic et al.)
2016 4 (Habersack et al.; Laxminarayan et al.; Lewis et al.; Pavela et al.)
2017 1 (He et al.)
2018 4 (Saari et al.; Nagy-Kovacs et al.; Ginebrada et al.; Moldovan et al.)
2019 1 (Shao et al.)
2020 2 (Diamanti et al.; Zaller et al.)
2021 3 (El-Nahhal et al.; Simionov et al.; Ansari et al.)
2022 4 (Kadiru et al.; Pathak et al.; Radu et al.; Sommerwerk et al)
2023 1 (Sauer et al.)
2024 3 (Ene et al.; Orou-Seko et al.; Ahmad et al.)

Pesticides: general characterisation

Pesticide residues in water have become a major challenge in recent years. Pesticides are synthetic organic compounds with specific properties and exhibit high stability to degradation. Table 3 presents the main types of pesticides frequently utilised and their intended use.

In areas where intensive farming, specialised in only one type of product, is practiced, hazardous organic substances have been used as a standard method for pest control. Unfortunately, alongside the benefits of chemistry, losses have also emerged over time—some of them serious—with highly negative consequences for human health and, in the long term, affecting ecosystems and even leading to biodiversity loss.

Agriculture is one of the very few activities where chemicals are intentionally introduced into the environment, due to their ability to control pests.

Environmental contamination with pesticides can result from spraying, volatilisation, surface runoff, and subsurface loss through leaching or runoff. The persistence of pesticides in the environment varies considerably and depends on several factors, such as their susceptibility to microbial and enzymatic degradation, soil temperature, or water content.

Over the last decade, more efforts have been made in the agricultural sector to limit the negative effects of pesticide residues. In 2021, organic farming—a phenomenon that has been continuously growing—covered 9.9% of the EU’s utilised agricultural area. There is a constant trend of increasing the number of approved non-chemical, basic, and low-risk active substances, from fewer than 60 in 2009 to almost 120 in 2019 (COM 2020).

Assessment of pesticide levels in water samples involves several stages: the sampling stage, which is carried out in accordance with the standards in force for each type of water (groundwater, surface water); sample preparation; separation; detection; and the final stage of data analysis (Fig. 2). For surface waters, sampling is carried out by immersing the container below the water surface. In the case of wastewater, the sampling point must be located at a depth representing one-third of the total height of the residual effluent. The collected surface water samples are then subjected to a pre-filtration process using a 0.45 μm glass fibre filter to eliminate suspended particles that may interfere with the pre-concentration process on solid-phase extraction (SPE) cartridges (Olaitan et al. 2014). Solid-phase extraction is performed by concentrating the analytes relative to the initial sample and represents the first step in the qualitative and/or quantitative determination of pesticide residues.

Table 3.
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Types of pesticides used for various purposes.

Nr. Ctr. Types of pesticides Acțion Bibliography
1. Algaecides Intended for the control of algae in various water bodies. Schrader (2003)
2. Antimicrobials Intended for the control of bacteria and viruses Laxminarayan et al. (2016)
3. Disinfectants Intended for the control of microorganisms that cause various diseases. Bridier et al. (2011)
4. Herbicides Intended for the control of weeds, unwanted plants. Saari and Mauvais (2018)
5. Insecticides Intended for the control of insects. O’Brien et al. (2014)
6. Mollucicides Intended for the control of molluscs. He et al. (2017)
7. Pheromones Biochemical substances used to disrupt the mating behavior of insects. Shorey (2013)
8. Rodenticides (raticides) Intended for the control of rodents. Watt et al. (2005)
9. Biopesticides Derived from natural materials of plant, animal, microbial, or mineral origin Pavela and Benelli (2016)
Figure 2. 

Analytical steps for pesticide determination.

Results and discussion

In the last century, there was a dramatic increase in the global production of synthetic chemicals such as pesticides, hydrocarbons, soaps, detergents, and plastics. Once released into the environment, these compounds stimulate a series of biochemical reactions, most of which are alarming from a human health perspective due to their high toxicity, persistence, and bioaccumulation (Xing et al. 2005).

Many countries produce, use, import/export, and release a wide range of pesticide contaminants into the environment. These pollutants have been, and continue to be, a major concern with regard to environmental components, particularly due to their ecotoxicological effects on the environment and, implicitly, on human health (Zhang et al. 2005). For this reason, it is essential to assess the contamination level of these pollutants, which are extremely resistant to natural degradation (Kabir et al. 2015).

A significant proportion of pesticides are classified as persistent organic pollutants due to their environmental persistence, accumulation in living organisms, and the risks they pose to health and ecosystems. The main sources of water body pollution by organic pollutants include industrial discharges, municipal sewage, and agricultural activities. Common pollutants include agricultural waste, animal and vegetable waste, detergents, household and municipal waste, furans, dioxins and organohalogens, waste from food processing, petroleum products, and oils.

Pollutants in aquatic ecosystems can be classified based on their applicability or their nature (Geissen et al. 2015). It is important to prioritise potentially persistent compounds, alongside the selection of bioaccumulative and harmful substances that are in use or in production (Karlaganis et al. 2001). The half-life of contaminants is among the most commonly used criteria in evaluating persistence and is taken into account when assessing the harm they may cause to the environment and human well-being (Muir and Howard 2006). The ecological effects of hazardous organic substances are varied and overlapping and are considered indicators of pollution.

At the European Union level, the FOOTPRINT PPDB database was developed by the University of Hertfordshire (UK), Agricultural and Environmental Research Unit. This database covers both the active ingredients of pesticides (approximately 2,300 active substances) and a large number of metabolites (over 700), along with their most important physicochemical characteristics, toxicology, metabolism, environmental behaviour, and ecotoxicology.

Quantities of pesticides used in the countries of the Danube River Basin

According to data provided by the European Commission (AGRIDATA.ec.europa) (Fig. 3B), Germany recorded the highest agricultural production during the period 2014–2022, followed by Poland, Hungary, and Romania. In contrast, although Italy registered the largest quantities of pesticides sold, it had the lowest agricultural production among the countries considered (Fig. 3A).

Figure 3. 

Quantities of pesticides used in relation to agricultural production during the period 2014–2022. A. Total quantities of pesticides sold; B. Agricultural production.

The quantities of pesticides, expressed in tonnes, used in the countries of the Danube River Basin during the period 2014–2022 are presented in Table 4. According to these data, Italy, Germany, and Poland recorded the highest quantities of pesticide use during the period under review. According to information from the International Trade Administration, Germany ranked third globally in 2021—after China and the United States—in terms of agricultural product import and export (trade.gov). This suggests that Germany has a mechanised and automated agricultural sector, particularly in terms of irrigation systems, fertilisation, production, and harvesting technologies.

Five studies on pesticides in water samples were identified (Table 5), covering ten countries in the Danube River Basin (Serbia, Austria, Slovakia, Croatia, Bulgaria, Romania, Germany, Hungary, Ukraine, and Moldova). Among the chemical compounds that were identified in the Danube River Basin are: acetochlor (28–40 ng/L), atrazine (<3–392 ng/L), avicides (2–44 ng/L), bentazone (9.1–65 ng/L), carbendazim (3–755 ng/L), cybutrine (irgarol, 0.18–0.83 ng/L), chlortoluron (<1 ng/L), carbaryl (<55.8–1353 ng/L), dimethoate (<0.5–85.2 ng/L), desethylterbuthylazine (40 ng/L), DEET (1.93–81 ng/L), dimethenamid (<0.84–1189 ng/L), diuron (<10.9–1197 ng/L), galaxolide (HHCB, 1.5 ng/L), isoproturon (<1 ng/L), imidacloprid (14.6–107 ng/L), malathion (67–69 ng/L), MCPA (2-methyl-4-chlorophenoxyacetic acid, 0.15–12 ng/L), nicosulfuron (<2.24–32.5 ng/L), terbuthylazine (41.4–200 ng/L), tonalide (AHTN, 0.9 ng/L), triisobutyl phosphate (>2 ng/L), terbutryn (0.64–11 ng/L), tebuconazole (3.3–11.2 ng/L), propazine (6–8 ng/L), and simazine (70–2010 ng/L). Of the listed compounds, metolachlor was the compound most consistently detected, with the maximum concentration of 4612 ng/L recorded at sampling points in Ukraine and the Republic of Moldova. It is worth noting that in Serbia, Moldova, Ukraine, and the Republic of Moldova, the greatest number of determinations of chemical compounds were carried out. In contrast, in Austria, Slovakia, Croatia, Bulgaria, and Romania, the determinations targeted the following classes of compounds: avicides (2–44 ng/L), fungicides (45–118 ng/L), herbicides (355–422 ng/L), insecticides (24–295 ng/L), and repellents (101–243 ng/L). The concentration of atrazine (392 ng/L) determined in 2015 in Serbia was almost 40 times higher than that reported in Moldova (5.1–9.5 ng/L) during the period 2011–2012.

Pesticides have various negative effects on the environment and human health. When applied at the recommended dose, their toxicity to non-target organisms is reduced. Even so, there may still be adverse effects on the neurological, respiratory, reproductive, nervous, and hormonal systems (Zaller 2020; Ansari et al. 2021). Adjuvants used in pesticide formulations can influence the efficacy and phytotoxicity of the active ingredient. By using adjuvants, the persistence or degradation rate of the active substances may be altered (Hayo van der Werf 1996). Exposure to these toxic compounds may occur through ingestion (via food or water), inhalation, or dermal absorption. The type and severity of adverse health effects caused by pesticides are determined by the chemical category, dose, duration of exposure, and route of entry (Hernandez et al. 2013). Resistance to pesticides may develop through prolonged and intensive use. When pests develop resistance, higher doses or alternative pesticides are required, which can further amplify the environmental and human health impacts (Fig. 4) (Ahmad et al. 2024).

Taking into account the information presented in Fig. 3, the quantities of pesticides used in the countries of the Danube River Basin, in relation to agricultural production, reflect the efficiency and sustainability of agricultural practices. The data on agricultural production were provided by the International Trade Administration, which noted that for Montenegro and Switzerland, no production data were available. The ratio between pesticide use and agricultural production is directly influenced by crop types specific to each country, the number of treatments required, and the technologies used. In recent years, sustainable agricultural practices have increasingly been adopted, aiming to reduce pesticide use through annual crop rotation, biological control measures at the point of sale, and the careful and precise application of chemicals to maintain a balance between crop protection and environmental conservation.

The frequent and inappropriate use of pesticides poses a risk to both human health and the environment. To minimise these risks, it is essential for farmers to participate in training and awareness programmes on pesticide use and to adopt agricultural practices that reduce the consumption of these toxic substances, which ultimately reach watercourses (Orou-Seko et al. 2024).

Soil organic matter, colloidal particles, and clay minerals are crucial for the sorption of pesticides in the soil via the aqueous phase. High temperatures can lead to soil desiccation and erosion, causing the mobilisation of adsorbed particles and their transfer into aquatic systems.

Even though the application of these substances is a priority for obtaining a high-yield agricultural crop, it leads to contamination of food and water, since over 90% of the pesticides applied do not reach the target species (El-Nahhal et al. 2021).

Based on information collected from the specialised literature, a long-term dynamic evolution of pesticide residues determined in the Danube River Basin during the period 1995–2019 was developed. In this context, the main compounds encountered were atrazine, 2,4-D (2,4-dichlorophenoxyacetic acid), diuron, and metolachlor, which are part of the herbicide class, and dimethoate, which is a commonly used insecticide. In order to establish benchmarks regarding the concentrations of active compounds present in the Danube River Basin, ten studies were reported that targeted the presence of these compounds in surface water. Nagy-Kovács et al. (2018), Loos et al. (2010), Shao et al. (2019), Iancu et al. (2015), Ginebreda et al. (2018), Loos et al. (2010), Sauer et al. (2023), von der Ohe et al. (2011), Slobodnik et al. (2015), and Balinova et al. (2008) identified in their studies concentration values that ranged between 0.6 and 55.6 ng/L for atrazine, 0.2 and 25.6 ng/L for 2,4-D, 0.1 and 20.8 ng/L for diuron, 1 and 6 ng/L for dimethoate, and 0.5 and 163 ng/L for metolachlor (Fig. 4).

If we refer to the variations of the five compounds identified in the aquatic environment, their persistence and mobility can be influenced by their chemical properties, solubility, degradation processes, and the persistence and absorption of the compounds in the soil. Metolachlor presented a high average concentration of up to 50 ng/L (Fig. 5).

This may indicate a more frequent use in agricultural activities in the countries of the Danube River Basin, a higher solubility in water, or a slow degradation process, unlike dimethoate. Dimethoate shows low values, with an average below 10 ng/L. Thus, this chemical compound’s behaviour indicates a faster degradation, a higher absorption in the soil, or perhaps even a reduced application of this insecticide. These variations highlight the importance of continuous monitoring of pesticide residues in the surface water of the Danube to assess the impact on water quality and biodiversity.

Table 4.
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Thousands of tonnes of pesticides used in the countries of the Danube River Basin during the period 2014–2022.

Country Quantity (thousands of tons)
2014 2015 2016 2017 2018 2019 2020 2021 2022
Albania N/A N/A N/A N/A N/A N/A N/A N/A N/A
Austria 1,642 2,131 2,007 1,992 2,269 2,068 1,931 2,005 2,427
Bosnia-Herzegovina N/A N/A N/A N/A N/A N/A N/A N/A N/A
Bulgaria 186 619 1,049 1,287 1,798 1,579 1,698 1,634 1,541
Croatia 1,005 1,315 932 727 767 656 701 583 604
Czech Republic 1,782 2,109 1,785 1,854 1,755 1,651 1,545 1,511 1,419
Germany 12,916 12,818 12,141 13,266 11,682 10,218 9,505 9,693 11,521
Hungary 3,612 3,782 3,835 4,171 3,535 2,796 3,372 3,510 2,890
Italy 37,226 39,187 36,852 32,687 31,539 24,286 316,447 31,114 29,183
Moldova N/A N/A N/A N/A N/A N/A N/A N/A N/A
Montenegro N/A N/A N/A 67 61 64 72 68 60
North Macedonia N/A N/A N/A N/A N/A N/A N/A N/A N/A
Poland 7,442 7,742 7,534 6,927 7,992 6,867 9,278 10,051 7,080
Romania 4,113 4,112 4,526 4,600 4,542 4,021 3,878 3,808 3,117
Serbia N/A N/A N/A N/A N/A N/A N/A N/A N/A
Slovakia 559 620 640 685 676 653 662 635 499
Slovenia 724 759 860 795 849 752 731 669 628
Switzerland 1,037 1,034 996 979 979 954 980 1,165 1,013
Ukraine N/A N/A N/A N/A N/A N/A N/A N/A N/A

Note: N/A – not available; source: Eurostat (2025) (online data: aei_fm_salpest09); N/A – lack of data.
Table 5.
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Pesticide residues determined in the waters of the Danube River Basin.

Sampling point Year of determination/ Period Determined concentrations of the determined compounds Ref.
Serbia 2015 Carbendazim (3–88 ng/L), atrazine (4–392 ng/L), malathion (67–69 ng/L), carbendazim (8–23 ng/L), terbuthylazine (200 ng/L), atrazine (<3 ng/L), propazine (6–8 ng/L), carbofuran (<1.1 ng/L), dimethoate (<0.5 ng/L), metolachlor (150 ng/L), acetochlor (40 ng/L), desethylterbuthylazine (40 ng/L), galaxolide (HHCB, 1.5 ng/L), tonalide (AHTN, 0.9 ng/L), triisobutylphosphate (>2 ng/L), tri-n-butylphosphate (2 ng/L), chlortoluron (<1 ng/L), isoproturon (<1 ng/L), carbendazim (<2 ng/L) Radovic et al. 2015
2009–2011 Antic et al. 2014
Austria, Slovakia, Croatia, Bulgaria, Romania 2013 DEET (N,N-diethyl-m-toluamide) (1.93–81 ng/L), metolachlor (1.73–39 ng/L), terbutryn (0.64–11 ng/L), 2,4-D (2,4-dichlorophenoxyacetic acid) (0.22–22 ng/L), MCPA (2-methyl-4-chlorophenoxyacetic acid) (0.15–12 ng/L), cybutryne (irgarol) (0.18–0.83 ng/L) Loos et al. 2017
Germany, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania 2019 Avicides (2–44 ng/L), fungicides (45–118 ng/L), herbicides (355–422 ng/L), insecticides (24–295 ng/L), repellents (101–243 ng/L) Sauer et al. 2023
Moldova 2011–2012 Bentazone (9.1–65 ng/L), atrazine (5.1–9.5 ng/L), terbuthylazine (ND–41.4 ng/L), acetochlor (ND–28 ng/L), metolachlor (ND–33 ng/L), 4-phenylbenzophenone (ND–323 ng/L), 2,4-D (5.4–8.9 ng/L) Moldovan et al. 2018
Ukraine and Republic of Moldova 2019 Acetochlor (<28.6–238 ng/L), atrazine (<7.82–55.2 ng/L), carbaryl (<55.8–1353 ng/L), carbendazim (<7.1–755 ng/L), 2-aminobenzimidazole (<5.39–311 ng/L), dimethenamid (<0.84–1189 ng/L), dimethoate (<9.13–85.2 ng/L), diuron (<10.9–1197 ng/L), imidacloprid (<14.6–107 ng/L), metolachlor (<3.41–4612 ng/L), nicosulfuron (<2.24–32.5 ng/L), 2,4-D amine (5.4–8.9 ng/L), simazine (70.4–2010 ng/L), tebuconazole (3.3–11.2 ng/L). Diamanti et al. 2020

ND – not detected.
Figure 4. 

Variation of the identified compounds depending on the determined concentration.

Figure 5. 

The average concentrations of the identified compounds.

Conclusion

This study highlighted the quantities of pesticide residues identified in the Danube River Basin, based on information collected from the specialised literature using scientific techniques to gather evidence, consulting academic literature databases such as Google Scholar, Science Direct, MDPI, and others.

Pesticides are essential in the agricultural system, but their widespread use pollutes the environment and increases the risk to human health. The persistence of these compounds, their degree of toxicity, the method of application, and the concentrations used amplify the negative effects of these pollutants in the aquatic environment.

The Danube is highly vulnerable to pesticide pollution from agriculture, which affects both the quality of water used for consumption and regional biodiversity.

Italy, Germany, and Poland reported the highest amounts of pesticides used between 2014 and 2022. In the case of Germany, the amounts correlate with the intensive agricultural sector, accounting for 28% of total agricultural production.

The concentrations of the five compounds from the pesticide class identified in the surface water of the Danube indicate that water quality is influenced by the presence of these pollutants, which ultimately reach the watercourse.

Acknowledgements

This research was funded by the Ministry of Research, Innovation, and Digitisation within the framework of Danube Delta Nucleus, Contract number 35N/2023, Project No. PN 23 13 03 02.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Use of AI

No use of AI was reported.

Funding

No funding was reported.

Author contributions

Nicoleta Matei designed the study and collected the data and wrote the manuscript with the support of Daniela Seceleanu-Odor, Adrian Burada, Petre-Bogdan Gheorghe, Mihaela Țigănuș, and Iasemin Suliman. Orhan Ibram was responsible for graphic design. Cristina Despina supervised the article. All co-authors reviewed and edited the article draft.

Author ORCIDs

Nicoleta Matei https://orcid.org/0009-0009-9274-5176

Daniela Seceleanu-Odor https://orcid.org/0000-0002-4630-5315

Adrian Burada https://orcid.org/0000-0002-6149-6666

Petre-Bogdan Gheorghe https://orcid.org/0009-0005-5579-800X

Iasemin Suliman https://orcid.org/0000-0002-8615-8145

Orhan Ibram https://orcid.org/0000-0003-2608-1489

Cristina Despina https://orcid.org/0000-0002-0066-5518

Data availability

Data on pesticide quantities and agricultural production are available at: https://agridata.ec.europa.eu/extensions/DashboardCereals/CerealsProduction.html, https://ec.europa.eu/eurostat/databrowser/view/aei_fm_salpest09/default/bar?lang=en.

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