More river pollution from untreated urban waste due to the Russian-Ukrainian war: a perspective view

ABSTRACT Since 24 February 2022, the Russian-Ukrainian war has impacted Ukrainian water resources including river pollution. In this perspective paper, our proposition is that the Russian-Ukrainian war causes likely more river pollution with untreated urban waste compared to the pre-war period. In order to check this assumption, we synthesize the current knowledge with a focus on the Dnipro Basin, containing 80% of the national water resources. Our synthesis reveals three main arguments. First, water-related infrastructures that were damaged as a result of the Russian-Ukrainian war are the important causes of pollutant release to water systems. These infrastructure damages are estimated, on average, for rural (30% of irrigation systems) and urban (35–40% of treatment plants and sewage connections) areas or both (40–90% of bridges and dams). Second, water pollution sources tend to change towards direct inputs of untreated urban waste with multiple pollutants compared to the pre-war period. Third, our illustrative example for nutrients, a painkiller, an antibacterial agent, and microplastics from urban waste showed an increase of 2–34% in their loadings into the Dnipro River due to damaged sewage pipes and wastewater treatment plants in 2022. In addition, 20–62% of those pollutants are from untreated urban waste (point sources). We propose a framework for future steps including visualizing (V) and integrating (I) the impacts into tools for quantification as well as translating (T) those quantified insights into actionable strategies and assessing (A) their feasibilities for pollution reduction. Highlights The Russian-Ukrainian war damaged 30–90% of water infrastructures in the Dnipro Basin River pollution sources tend to change towards untreated urban waste compared to the pre-war period River pollution is estimated to increase by 2–34% in the Dnipro Basin due to damaged sewage and treatment Untreated urban waste is responsible for 20–62% of pollutants in rivers of the Dnipro Basin The VITA framework is proposed for actionable pollution reduction strategies

• The Russian-Ukrainian war damaged 30-90% of water infrastructures in the Dnipro Basin • River pollution sources tend to change towards untreated urban waste compared to the pre-war period • River pollution is estimated to increase by 2-34% in the Dnipro Basin due to damaged sewage and treatment • Untreated urban waste is responsible for 20-62% of pollutants in rivers of the Dnipro Basin • The VITA framework is proposed for actionable pollution reduction strategies

Introduction
Since 24 February 2022, the Russian-Ukrainian war has resulted in various consequences on the environment in Ukraine (Wilson 2022;Pereira et al. 2022;Neyter et al. 2022) with river pollution being one of those (Unicef 2022;Júnior et al. 2022).Many infrastructures have been damaged in urban and rural areas.This includes water-related infrastructures such as flood-protection dams, wastewater treatment plants, and sewage connection pipes (Shumilova et al. 2023).This happens, for example, as a result of the explosions associated with missiles and/or mines.However, our understanding of which waterrelated infrastructures are damaged and to what extent is limited.Yet, the impact of these damages on river pollution levels and their sources is not well studied.Ukraine has several transboundary river basins (Strokal and Kovpak 2020;Strokal 2021).The Dnipro Basin (Dnieper) is one of them containing 80% of the national water resources (Vasylenko and Koshkina 2020;Iaroshevych et al. 2021).It is the third largest European basin covering 49% of the Ukrainian surface area (Iaroshevych et al. 2021) and hosts 21 million people (44% of the national population), of which over two-thirds live in urban areas (Iaroshevych et al. 2021).Rivers in the Dnipro Basin are already polluted with nutrients (Strokal and Kovpak 2020;Strokal 2021;Iaroshevych et al. 2021) chemicals (e.g.triclosan), and plastics (e.g.microplastics) (Strokal et al. 2022(Strokal et al. , 2023) ) from livestock manure (NGO 2022b), and urban sewage systems (Strokal and Kovpak 2021).Considerable amounts of nutrients in the river are from diffuse agricultural sources such as the use of fertilizers (Osypov et al. 2016).Emerging pollutants such as microplastics often come from urban sewage systems, which are point-source water pollution (Strokal et al. 2022(Strokal et al. , 2023)).The Russian-Ukrainian war is expected to introduce impacts on water pollution and its diffuse and point sources, but these effects are not well studied.
In this perspective paper, our proposition is that the Russian-Ukrainian war causes likely more river pollution with untreated urban waste compared to the pre-war period.For this, we synthesize the current knowledge to increase our understanding of how damaged water-related infrastructures influence water pollution from urban and rural sources as a result of the Russian-Ukrainian war.We take the Dnipro River Basin as a case study.

Argumentation
Our literature synthesis reveals three main arguments to support our proposition.We elaborate on them below.

Argument 1:damaged water infrastructures as a result of theRussian-Ukrainian war are important causes of pollutant release to water systems
We identified five main types of water-related infrastructures in urban and rural areas that are likely damaged as a result of the Russian-Ukrainian war (Figure 1a-b).These five types include (1) bridges, (2) flood-protection dams, (3) sewage connection pipes, (4) wastewater treatment plants (WWTPs), and (5) irrigation systems.In general, the Russian-Ukrainian war has resulted, on average, in 30-90% of damaged water infrastructures in the Dnipro Basin (Figure 1b, Text S1, Tables S1-S5) (Pereira et al. 2022; Ministry of Ukraine 2022; Van der Vet et al. 2022;Rawtani et al. 2022;Strokal and Kovpak 2022;NGO 2022a).Both rural and urban areas (Vasylenko and Koshkina 2020;Iaroshevych et al. 2021) have bridges and flood-protection dams in the Dnipro Basin, which is similar to the design of water infrastructures in other countries (e.g (Preethikha 2020).Based on literature insights, we estimate that, on average, roughly 40% of flood-protection dams (located within the cascade drainage area of the Dnipro Basin, see Table S2) and 90% of bridges (located mainly in occupied areas by Russian troops, Table S1) have been damaged either slightly or severely since 24 February 2022 in the Dnipro Basin (Insider 2022; Averin and Huliaieva 2022;Ladyka and Starodubtsev 2022).This percentage on average is 35-40% for WWTPs and sewage connection pipes (sewage system networks, Figure 1b, Tables S3-S4) (Strokal and Kovpak 2022;NGO 2022a;Averin and Huliaieva 2022).These WWTPs and sewage pipes are mostly located in urban areas (Tables S3-S4).In rural areas, irrigation systems have suffered from war activities.We estimate that, on average, 30% of irrigation systems have been damaged in the basin (Neyter et al. 2022; Ministry of Ukraine 2022; Averin and Huliaieva 2022; Woertz 2022) (Table S5).Irrigation systems are, for example, irrigation canals and water storage facilities (Conde et al. 2021).The number of damaged waterrelated infrastructures varies largely within the basin.For example, in the south part of the Dnipro basin (downstream sub-basin), up to 90% of sewage pipes (Table S4) and WWTPs  S1-S5).Source: the figure synthesizes the current knowledge based on literature (references can be found in the text of Section 2, text S1, and Tables S1-S5).
(Table S3) are estimated to have been largely damaged during the period when the areas were occupied by Russian troops (Text S1 in the Supporting Information) (NGO 2022a; Insider 2022; ZODA 2022).In the Desna sub-basin (one of the four sub-basins of the Dnipro Basin, see Table S3 for the definition), our literature-based estimates indicate that up to 50% of WWTPs (Table S3) and 60% of the sewage pipes (Table S4) have been damaged in 2022 (Strokal and Kovpak 2022;Averin and Huliaieva 2022;WHO 2022).Generally, the occupied areas show larger damages compared to non-occupied areas in Ukraine (examples are given in Table S1).Furthermore, the damaged infrastructures are expected to influence river pollution and its sources (see below).However, it is not entirely clear what type of pollutants have been released into water systems due to damaged water infrastructures in the Dnipro basin (Shumilova et al. 2023).An example is the recently disrupted Kakhovka Hydropower Dam on the 6 th of June 2023.This dam supports the Kakhovka reservoir with a depth of 16 meters, a surface water area of 2,155 km 2 , and a volume of 18,2 km 3 .Water in this reservoir is used for hydropower generation, irrigation, and drinking purposes for people living in the southern area of Ukraine.Because of the damaged dam, 70% of reservoir water was released resulting in severe floods downstream (14 June 2023) (Epravda 2023) and a release of 150 tons of oil materials into the Dnipro River (9 June 2023 (Ecozagroza 2023).It is difficult to estimate all the environmental and economic damages associated with these floods and water pollution.Water scarcity and soil deterioration are expected to become more severe, especially in the southern part of Ukraine.
Argument 2: water pollution sources tend to change to direct inputs of untreated urban and rural waste (point sources) that are rich with multiple pollutants Our synthesis reveals the three main aspects.First, sources of river pollution tend to change towards direct inputs of untreated urban and rural waste (point sources) as a result of damaged water-related infrastructures during the Russian-Ukrainian war (Figure 1c-d).Before this war, both diffuse (agricultural runoff (Strokal and Kovpak 2021) and point (sewage systems (Wear et al. 2021) sources were important contributors to river pollution (Figure 1c) (Strokal et al. 2023).During the Russian-Ukrainian war, point sources start adding more pollution: e.g.untreated human waste entering rivers as a result of damaged WWTPs, sewage overflows, and damaged sewage pipes (point source, Figure 1d) (Pereira et al. 2022;Neyter et al. 2022;Van der Vet et al. 2022;Rawtani et al. 2022;Averin and Huliaieva 2022;Woertz 2022).This holds especially for urban areas in which many WWTPs and sewage pipes are located, but largely damaged (see Tables S3-S4 for examples).
Second, more multiple pollutants are expected to enter rivers as a result of damaged water-related infrastructures (Figure 1c-d) (Strokal and Kovpak 2022;Averin and Huliaieva 2022).This holds for both rural and urban areas.For rural areas, damaged irrigation systems, bridges and flood-protection dams (Tables S1-S2, S5) can result in flooded agricultural fields.Often, these fields are rich in nutrients.Floods may bring those nutrients to rivers (Ladyka and Starodubtsev 2022;Makarenko et al. 2022).On the other hand, due to military actions in the southern parts of Ukraine (known for its dry climate and developed agricultural sector) and heavy fighting, the agricultural campaign in 2022 was partly cancelled or could not happen at all (see Text S1).Hence, this could lead to a decrease in the application of fertilizers and less pollution from nutrient runoff.For urban areas, damaged WWTPs and sewage systems may lead to river pollution with untreated waste (point sources).Multiple pollutants such as nutrients, pathogens, painkillers (e.g.diclofenac), antibacterial agendas (e.g.triclosan), and plastics (e.g.macro-and microplastics) are found in sewage influents (Strokal et al. 2022).The choice for these pollutants is justified by their high concentrations in water contributing to impacts such as eutrophication (Lapyga 2019), and toxicity effects (Ho et al. 2020).For example, triclosan was detected in sewage influents in Kyiv (the capital of Ukraine) and had the highest concentrations in nearby water (Ho et al. 2020).The sewage influents are collected from households (sources of nutrients, diclofenac, microplastics, triclosan) and roads (sources of microplastics from car tire wear) and enter WWTPs via sewage pipes (Strokal et al. 2023).However, due to the damage to these infrastructures (Tables S3-S4), the pollutants are expected to enter rivers directly without treatment (point source) (Ministry of Ukraine 2022; NGO 2022a; Averin and Huliaieva 2022;ZODA 2022).
Third, the availability of clean water is expected to decrease as a result of damaged water-related infrastructures.Ukraine is a country contributing considerably to global food security and thus sustainable Development Goal 2 (food production).Thus, clean water is needed to support food production as well as domestic sectors with drinking water (Júnior et al. 2022;Woertz 2022;Shubravska and Prokopenko 2022;Jagtap et al. 2022).However, the availability of clean water is challenged under the Russian-Ukrainian war (Figure 1d) (Averin and Huliaieva 2022;WHO 2022;IOM-UN 2022).On top of this, climate change adds more impacts: e.g.droughts in the south where considerable food production takes place (Karamushka et al. 2022).All of this poses the risk to water as well as food security in Ukraine (Neyter et al. 2022;NGO 2022b;Woertz 2022; Shubravska and Prokopenko 2022) and globally.There is a need to better understand trade-offs between the damaged infrastructures and other water pollution sources (e.g.overfertilization, poor manure management) to identify opportunities for the post-war recovery solutions that can minimize damage for food production and maximize the use of clean water resources.
Argument 3: Our illustrative example showed an increase of 2-34% in the loadings of pollutants into the Dnipro River due to damaged WWTPs and sewage systems in urban areas, and 20-62% of this pollution is from untreated urban waste (point sources).
We focus on urban areas and selected water infrastructures that have been damaged during the period of February 2022-December 2022 (see Figure 1): WWTPs (Table S3) and sewage systems (Table S4).We use an existing MARINA-Multi model (Strokal et al. 2023) to illustrate the impact of damaged urban water infrastructures on sources of river pollution in the Dnipro Basin.MARINA-Multi stands for a Model to Assess River Inputs of pollutaNts to seAs.We apply the version that was developed for Ukraine (Strokal et al. 2023) with updated removal fractions (Micella et al. 0000) and added diclofenac (Zhang et al. Forthcoming).We focus on dissolved total nitrogen (N), dissolved total phosphorus (P), diclofenac (painkillers, DCL), triclosan (antibacterial agent, TCS), and microplastics (Mi).The model provides annual inputs of pollutants to rivers for the reference case (RC), which is the situation without the damaged water-related infrastructure and reflects the recent past.We added an alternative case (AC) in which we assume the impact of damaged urban water infrastructures relative to RC: the fraction of urban people connected to sewage systems is decreased by 40-90%, and removal fractions in WWTPs are decreased by 35-90% depending on sub-basins (see Text S2, Tables S3-S4 in the Supporting Information).We assume that urban human waste that is in the damaged sewage systems enters waters without treatment.Our assumptions are debatable, and should be treated with caution.Our intension is to illustrate potential impacts of damaged WWTPs and sewage pipes on river pollution and its urban sources, rather than estimate pollution levels due to the war.Our illustration is a starting point towards a better quantitative analysis of the war impact on water quality in Ukraine.
We illustrate that the total river pollution (diffuse and point sources) is estimated to increase by 2-34% depending on pollutants and sub-basins in the Dnipro Basin compared to the RC case (pre-war conditions, Figure 2a).In general, higher increases are estimated for the downstream sub-basin: 20% for TCS, 14% for DCL, and 21% for N.This is associated with the relatively larger impact of the damaged WWTPs and sewage pipes in this sub-basin compared to the other sub-basins.For the Prypiat sub-basin (upstream), the model estimates the highest increase for TCS (34%) and the lowest increase for Mi (2%).The difference between TCS and Mi is associated with different levels of wastewater treatment.For the Desna sub-basin (upstream), sewage pipes have been largely damaged (up to 60%, Text S1 and Table S4).The impact of the damaged pipes is higher TCS and DCL than for Mi, N, and P (Figure 2a).This is the net effect of reducing sewage connections, poor wastewater treatment, and increasing direct discharges of untreated human waste to rivers.We also illustrate that untreated urban waste becomes responsible for 20-62% of the considered pollutants in rivers of the Dnipro Basin under the AC case (Figure 2b).This is a point source of pollutants that was not important before the Russian-Ukrainian war (RC case in Figure 2b).In particular, 62% of TCS and around half of DCL and P in rivers are estimated to originate from untreated human waste in the rivers of the Dnipro basin (AC case in Figure 2b).For N and Mi, these percentages are around 20% and 40%, respectively.We did not account for the impacts of damaged infrastructures in rural areas.Thus, our pollution levels might be underestimated.We take damaged urban infrastructures as an illustrative example of the potential impacts of the Russian-Ukrainian war on urbanrelated river pollution.Our illustrative example should be interpreted as potential impacts on river pollution considering model limitations (more details can be found in (Strokal et al. 2023).Important limitations are related to our assumptions (Text S2, Tables S3-S4) and model inputs for population, treatment and sewage connections that were taken from the published model (Strokal et al. 2023) for 2010.We do realize the number of people, treatment, and sewage connections may have changed between 2010 and today.Our pollution levels might be underestimated because we did not consider the damaged water infrastructures in rural areas in 2023 (Shumilova et al. 2023) and other war-related pollutions (oil spills, pollution from specific military explosives).We believe that much more waste directly (point source) has entered the Dnipro River, especially in downstream areas after the disruption of the Kakhovka Hydropower Dam in June 2023 (Epravda 2023).All this waste has been transported to the Black Sea.Thus, the war-associated impacts might be larger on river pollution than we show.Nevertheless, our intension was to illustrate the potential impact on increasing or decreasing river pollution from untreated urban waste due to damaged water-related infrastructures (e.g. percentage change, see Figure 3).Thus, we believe that our illustrated perspective on the extent of the potential impacts on sources of river pollution is valuable insight as a starting point to set future research agenda.

A framework for actionable pollution reduction strategies
We propose a VITA framework, which is short for Visualizing, Integrating, Translating, and Assessing (Figure 3).This framework has four steps that are needed to identify actionable strategies to mitigate the consequences of the Russian-Ukrainian war on river pollution: • Visualizing the current knowledge on the impacts of the war on river pollution (V); • Integrating this current knowledge to (modelling) tools and/or indicators to quantify impacts (I); • Translating the quantified impacts into actionable strategies for pollution reduction together with stakeholders (T); • Assessing the technical, economic, institutional, and societal feasibilities of those strategies (A).
In this perspective paper, we illustrated examples of the V and I from the framework for river pollution.We visualized the impacts of damaged water-related infrastructures on river pollution as a result of the Russian-Ukrainian war.We also used the MARINA-Multi model to estimate some of the impacts (damaged water-related infrastructures in urban areas).The next steps are to build on this perspective study and include (V) and estimate (I) other impacts associated with the Russian-Ukrainian war.We used the MARINA-Multi model for quantifications.However, other tools can also be used such as indicators (van Vliet et al. 2021) to estimate the impacts.After that, quantitative insights can be translated to support policy debates (T) and identify actionable strategies to reduce river pollution.Participatory approaches can be used to involve stakeholders (e.g.municipalities, and local managers) (Nilsson et al. 2017).Such strategies should consider the socioeconomic situation and the Russian-Ukrainian war.To identify such strategies, the assessment of technical, economic, institutional, and societal feasibilities should be promoted (A).

Concluding remarks and future outlook
In this perspective paper, we discussed a proposition "The Russian-Ukrainian war causes likely more river pollution with untreated urban waste compared to the pre-war period".For this, we illustrated the impact of damaged water-related infrastructures on sources of river pollution as a result of the Russian-Ukrainian war taking the Dnipro River Basin as a case study.We used an existing model to show some potential impacts.It is recommended to perform a monitoring study with direct measurements of pollutant concentrations in water when it becomes feasible.Nevertheless, our synthesized literature serves as a starting point to better understand the potential impacts of the war on river pollution.We discussed the main arguments to support our proposition.First, our literature-based estimate shows that the Russian-Ukrainian war has resulted in 30-90% of damaged water infrastructures in the basin (on average) considering the period of February-December 2022.This percentage is likely higher considering damages in 2023.Second, water pollution sources tend to change towards untreated urban and rural waste (point sources) that are rich with multiple pollutants.Third, using an existing water quality model, we illustrated the potential impact of damaged WWTPs and sewage systems in urban areas on total river pollution.The model estimated that these damaged infrastructures (which happened during February-December 2022) are expected to increase river pollution by 2-34% in the Dnipro Basin depending on the pollutants and sub-basins.Untreated urban waste becomes responsible for 20-62% of pollutants in the rivers of the basin.We propose the VITA framework for actionable strategies to reduce river pollution during the post-war recovery.This framework includes visualizing (V) and integrating (I) the impacts of the Russian-Ukrainian war into tools for quantification, and then translating (T) those quantified insights into actionable strategies for river pollution reduction and assessing (A) the feasibilities of those strategies for the post-war recovery.Our study serves as an example for other basins that experience political instabilities.Future research can build on our insights and add more impacts of the Russian-Ukrainian war on water and food security nationally and globally.

Figure 1 .
Figure 1.Summarized overview of the impact of damaged water-related infrastructures on river pollution and its rural and urban sources as a result of the Russian-Ukrainian war.(a) the overall impact.(b) examples of the damaged infrastructures for the Dnipro Basin.(c) and (d) the water pollution sources (rural and urban) before (c) and during (d) the Russian-Ukrainian war.We consider solely flood-protection dams.Values in fig.1b are average estimates based on collected literature (see justifications in TablesS1-S5).Source: the figure synthesizes the current knowledge based on literature (references can be found in the text of Section 2, text S1, and TablesS1-S5).

Figure 2 .
Figure 2. The estimated impact of damaged sewage connections and wastewater treatment plants (WWTPs) in urban areas on total river pollution in four sub-basins of the Dnipro basin draining into the black Sea.(a) increases in river pollution relative to the reference case (RC, % change).(b) shares of the sources of river pollution in the reference case (RC) and alternative case (AC) (%).The RC case represents the situation of the recent past.The AC case assumes the impact of the damaged sewage and WWTPs based on values in fig.1b and justified estimates in Tables S3-S4.Source: the existing MARINA-Multi model for Ukraine (Strokal et al. 2023) with updated removal fractions (Micella et al. 0000) and added diclofenac (Zhang et al.Forthcoming).

Figure 3 .
Figure 3.A VITA framework for actionable strategies to reduce river pollution that is caused by the Russian-Ukrainian war.VITA is short for Visualizing, Integrating, Translating, and Assessing.