Monitoring of Contamination of the Warta River in Poznan by Non-Steroidal Anti-Inflammatory Drugs and Antibiotics

Abstract

The pharmaceutical active compounds: non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, hormones, as well as detergents and pesticides that help improve human life are considered a source of water contamination. The amount of pharmaceutical active compounds in the environment is constantly increasing due to their widespread use by humans. Medicines sales in Poland are very high and rank sixth among European countries; moreover, sales are growing dynamically. Analysis of water samples from Warta River made it possible to study the dependence of NSAIDs, analgesics, and antibiotics concentrations in water due to season, month, and pandemic time. Analytes from the surface water were separated and concentrated by solid phase extraction (SPE) and determined by high-performance liquid chromatography coupled with tandem mass spectrometry technique (LC-MS/MS). The concentration of pharmaceuticals in the Warta River was subject to significant (or moderate) fluctuations during the study period. Concentrations depended on weather conditions and disease periods (seasonal, epidemic).

1. Introduction

The main sources of pharmaceutical active compounds (PhACs) in the environment are wastewater treatment plants (WWTPs) effluents, uncontrolled spills during drug production and landfills. PhACs enter WWTPs as residues from industrial production at pharmaceutical companies, from improper disposal of expired or unused pharmaceuticals (municipal waste, toilets) and as PhACs metabolites (after ingesting PhACs, humans and animals produce and release metabolites) [1,2,3]. WWTPs remove contaminants using activated sludge; however, they do not remove pharmaceuticals completely from the water [4,5]. In the 1970s, clofibric acid was first detected in treated wastewater in the United States at levels of 0.8–2 µg/L. At the end of the 20th century, Germany carried out the first monitoring of rivers. The results were also confirmed in other countries of Europe (Spain, Switzerland, France, Norway, Poland) [6,7,8,9,10,11]. In the aquatic environment, we can most often detect non-steroidal anti-inflammatory drugs, drugs from the beta-blocker group, hormones, antibiotics, regulators of lipid metabolism, and antiepileptic drugs. The most common non-steroidal anti-inflammatory drugs (NSAIDs) are ibuprofen, ketoprofen, the analgesic drug paracetamol, and the antibiotic sulfamethoxazole (their structures are presented in Table S1). It is not possible to determine the exact amount of drugs that have been consumed worldwide. More than 4000 different pharmaceuticals are currently used in the European Union [1,12,13].

The concentrations of various types of PhACs in water oscillate only in the order of ng/L or even μg/L. Such contamination can cause danger to water organisms (fish feminization, increased vulnerability of fish to predation, fish activity/boldness/sociality/feeding rate) and, indirectly, humans (through the selection of antibiotic-resistant bacteria) [14,15,16,17,18].

It is important to control the concentrations of pharmaceuticals, metabolites and transformation products in surface water. Over the years, scientists have determined pharmaceuticals in water, and the results from some studies conducted in Europe are shown in

Table 1. Concentration of selected PhACs in surface waters and rivers in Europe.

Type	Name	Location	Concentration [ng/L]	References
Non-steroidal anti-inflammatory drugs	Ibuprofen	Poland (surface waters)	50–100	[15]
		Poland (Gdańsk-sea water)	170	[19]
		Poland (lake in Somonino)	55	[19]
		Poland (lake in Gdańsk)	104	[19]
		France (surface waters)	<4.5	[15]
		Italy (Po River)	17.4
		Germany (Elbe River)	70–87	[20]
	Diclofenac	Greece (Saronikos Gulf and the Elefsis Bay)	>1.4–16.3	[21]
		Estonia (river Pärnu)	11–53	[22]
		Poland (river Rokitnica)	12–2200	[22]
		Germany (Tollense river)	0–350	[22]
	Ketoprofen	Germany (surface waters)	120	[23]
		Czech Republic (Leba River)	929.8	[24]
		Spain (Ebro River)	70	[25]
		Poland (river Rokitnica)	2.4–280	[22]
		Estonia (river Pärnu)	>2.1	[22]
		Germany (Tollenseriv-er)	0–2.13	[22]
	Naproxen	Poland (Warta River)	100	[26]
		Poland (river Rokitnica)	5.7–56	[22]
		Hungary (Danube River)	5.7–62	[27]
		Slovenia (surface waters)	17–80	[28]
		Greece (Aisonas River)	72	[29]
		Greece (Saronikos Gulf and the Elefsis Bay)	>0.01–0.8	[21]
		Germany (Tollense river)	0–35	[22]
		Estonia (river Pärnu)	1.0–12	[22]
	Fenoprofen	Germany (Leba River)	2–54	[30]
		Poland (river in Straszyn)	84	[19]
		Poland (river in Somonino)	55	[19]
		Poland (lake in Somonino)	20	[19]
		Poland (lake in Gdańsk)	24	[19]
Analgesic and antipyretic	Paracetamol	Spain (Madrid’s surface waters)	188–2813	[31]
		Greece (Saronikos Gulf and the Elefsis Bay)	>40.5	[21]
Antibiotics	Sulfamethoxazole	France (Seine River)	75	[32]
		Portugal (Douro River)	53.3	[33]
		Portugal (The Tejo estuary)	1.11–2.01	[13]
		Poland (Paprocany resort, the Gostynia Stream)	75.88	[34]
		Poland (Mikołów-rural location)	34.18	[34]
		Greece (Saronikos Gulf and the Elefsis Bay)	>0.1–6.3	[21]
	Trimethoprim	France (Seine River)	20	[32]
		Portugal (Douro River)	15.7	[33]
		Portugal (The Tejo estuary)	4.57–5.18	[13]
		Estonia (river Pärnu)	<1.2	[22]
		Poland (river Rokitnica)	0–54	[22]
		Germany (Tollense river)	0–5.7	[22]

.

Contamination by PhACs has been shown to have negative effects on the whole environment—living organisms in water, and humans [7,21,22]. Acquired resistance of bacteria to antibiotics is one of the significant problems. Bacteria change their metabolic pathways or produce enzymes that reduce the effect of antibiotics and can cause about 700,000 deaths per year globally [23]. The presence of hormones in water can also increase the risk of cancer of the reproductive organs in both men and women [1,35].

Non-steroidal anti-inflammatory drugs work in a similar way to steroidal drugs while offsetting unwanted side effects [24]. These pharmaceuticals inhibit cyclooxygenase enzymes (COX-1 or COX-2) reversibly or irreversibly. NSAIDs in surface water do not cause visible side effects but the contaminants formed by drug mixtures and their transformation products could have several side effects; for example, a mixture of four drugs: caffeine, ibuprofen, carbamazepine, and diclofenac increases their toxicity up to 100% [36] and a mixture of Prozac, carbamazepine, and venlafaxine can adversely affect the fetus [14,37]. Antibiotics under the influence of temperature, pH, and radiation can increase their toxicity. Such conditions also promote the transformation of PhAC into more harmful metabolites. Even if several transformation products of lower molecular weight and lower toxicity are formed, their mixture makes them more toxic than the original pharmaceutical [38]. Pharmaceutical concentrations in the water should be subjected to monitoring. New methods for their purification should be developed [2].

The pharmaceutical industry is growing significantly from year to year, all over the world. One could say that it is one of the fastest-growing industries. That growth is also associated with the wide availability of over-the-counter drugs (OTC), which are widely used in modern times because people like to treat themselves alone at home [6]. Some of the most popular drugs are non-steroidal anti-inflammatory drugs. In Central and Eastern Europe, Poland is the country with the largest pharmaceutical industry which includes the hospital and pharmacy segments. The largest companies in Poland are Biofarm, Delpharm, Novartis, GSK, Polpharma, Roche, Farmacol, Sanofi-Group, and Jelfa [25]. In 2020, the best-selling drugs were immune-boosting drugs and non-steroidal anti-inflammatory drugs. The profit from drug sales was up to 37.7 billion PLN [26,27].

According to the IQVIA report, the use of medicine in 2021 reach 409 billion defined daily doses (DDD) for Western Europe and 400 billion for Eastern Europe. The report showed a rapid increase in medication consumption in 2021. This is a delayed effect of the COVID-19 pandemic. In 2022, drug consumption fell to the levels before pandemic [39].

From 2010 to 2021, the antimicrobial consumption of sulfonamides and trimethoprim in the total care (community and hospital) sector in Europe changed from 0.540 DDD per 1000 inhabitants per day in 2010 to 0.583 DDD per 1000 inhabitants per day. Over the years, the changes are negligible. However, from 2012 to 2013, there was a significant increase in antibiotic use (0.725 and 0.738 DDD per 1000 inhabitants per day). In contrast, in Poland from 2014 to 2021, there was a decrease in antibiotic consumption from 0.574 to 0.294 (Figure 1) [40].

The research presented in this paper was carried out on Warta River in Poznan (near 500,000 citizens supplied with drinking water mostly originated from Warta), Poland. Warta is the third longest river in Poland, the second fully within its borders, and the main, right tributary of the Oder River. Warta Dolna (68.2 km, from Santok to the mouth of the Oder) is an element of the International Waterway E70, established in 1996 in the AGN (European Agreement on Main Inland Waterways of International Importance) [28].

The aim of this work is to determine changes in the degree of contamination of the Warta River waters with the following non-steroidal anti-inflammatory drugs: ketoprofen, naproxen, ibuprofen, fenoprofen, paracetamol, and the following antibiotics: sulfamethoxazole and trimethoprim, based on the measurements made by LC-MS/MS method, taking in consideration three time periods, the first one in 2012, second one in 2013/2014, and the third one during pandemic 2019–2022.

2. Materials and Methods

2.1. Chemicals and Materials

Acetonitrile, methanol, ammonia (28%), and ammonium acetate (99.9%) were obtained from Sigma-Aldrich; hydrochloric acid (30%) and formic acid (90%) were obtained from Merck. NSAIDs: ibuprofen (≥98%), ketoprofen (≥98%), paracetamol (≥97%), naproxen (98%), and fenoprofen (≥98%) and antibiotics: sulfamethoxazole (≥99%) and trimethoprim (≥99%) were obtained from Sigma-Aldrich. SPE polypropylene columns: C18 (pore size 60 Å) were obtained from Baker and Oasis; HLB column (pore size 60 Å) were obtained from Waters.

2.2. Instrumentation

NSAIDs and antibiotics were determined by LC-MS/MS technique. Chromatographic separation of analytes was performed on a Hypersil Gold C18 RP chromatography column (100 mm × 2.1 mm).

An API 4000 QTRAP tandem mass spectrometer (Biosystem/MDS Sciex) was used for the detection of all compounds. The mobile phase used was a mixture of 5 mM ammonium acetate (A) and methanol (B) for NSAIDs and a mixture of 5 mM solution of formic acid (A) and acetonitrile (B) for antibiotics. The gradient program for NSAIDs was 30% B at 0 min, increased to 67% B in 10 min, and stepped to 100% in 2 min. Isocratic elution was used for the antibiotics (A:B ratio, 4:6). The flow rate was 0.2 mL/min. The injection volume was 5 µL. The process temperature was 35 °C and the analysis took 20 min for NSAIDs and antibiotics. Operating conditions of an APU 4000 QTRAP tandem mass spectrometer are shown in

Table 2. Operating parameters of the tandem mass spectrometer for NSAIDs and antibiotics.

Name	Operating Parameters for NSAIDs	Operating Parameters for Antibiotics
Mode of ionization	ESI	ESI
Mode of operation	Negative	Positive
Temperature [°C]	400	600
Curtain gas [psi]	20	20
Nebulizer [psi]	50	40
Auxiliary gas [psi]	50	45
Ion spray voltage [V]	−4500	5500

. MS/MS parameters for the acquisition of NSAIDs and antibiotics are shown in

Table 3. MS/MS parameters for the acquisition of NSAIDs and antibiotics.

Compound	Precursor Ion [M−H]− m/z [M+H]+ *	Declustering Potential (V)	MRM 1 Transition-Quantitation Ion (Precursor Ion m/z → Product Ion m/z)	Collision Energy (V)	MRM 2 Transitions-Confirmation Ion (Precursor Ion m/z → Product Ion m/z)	Collision Energy (V)
Naproxen	229	−45	229 → 161	−12	205 → 159	−8
Ketoprofen	253	−50	253 → 209	−12	253 → 197	−10
Ibuprofen	205	−50	205 → 161	−12	205 → 159	−8
Paracetamol	150	−20	150 → 107	−24	150 → 60	−14
Fenoprofen	241	−40	241 → 197	−12	241 → 93	−52
Trimethoprim *	291	11	291 → 230	33	291 → 123	35
Sulfamethoxazole *	254	76	254 → 156	21	254 → 108	31

Note: * is for Trimethoprim and Sulamethoxazole.

.

2.3. Method Validation

The newly developed LC-MS/MS method for the determination of four NSAIDs, one analgesic and two antibiotics in water samples was validated.

Table 4. Validation parameters.

Compound	Linearity [ng/L]	Correlation Coefficient	LOD [ng/L]	LOQ [ng/L]	Recovery [% ± RSD]	Concentration Factor
Naproxen	6.0–750	0.9994	1.96	5.88	100.5 ± 6.97	2000
Ketoprofen	2.5–750	0.9999	0.67	2.02	100.0 ± 5.00	2000
Ibuprofen	9.5–750	0.9996	3.02	9.04	100.3 ± 5.98	2000
Paracetamol	0.21–750	0.9996	0.07	0.21	81.2 ± 3.69	2000
Fenoprofen	6.5–750	0.9999	2.14	6.41	100.5 ± 7.96	2000
Trimethoprim	100–1.0 × 105	0.9994	5	100	82.4 ± 4.85	100
Sulfamethoxazole	250–1.0 × 106	0.9942	20	250	71.0 ± 4.93	100

shows the resume of optimization and validation procedure.

2.4. Sample Collection

Water samples (n) were collected in the middle stream flow region of Warta River (location: 52.352447, 16.917856) (Figure 2) in accordance with the Polish standard PN-EN ISO 5667-6:2016–12 [41]. The sampling site was located close to the infiltration ponds of the city of Poznan. Apart from the wastewater treatment plant, there are two large pharmaceutical companies nearby and one hospital. Samples were collected in 2012 (n = 10), 2013 (n = 2), 2014 (n = 4), 2019 (n = 6), 2020 (n = 5), and 2021 (n = 3). Three periods each were selected for the winter, spring, summer, and fall seasons. Each time, 2 L of water was collected. Selective water collection in the 2020/2021 period was related to restrictions due to the coronavirus pandemic. Samples were stored at 4 °C in the dark and treated immediately as described in SPE procedure section. All water samples were subjected to a filtration process. The water was filtered through a paper filter (ɸ125 mm). The first 50 mL (saturation of the filter and glass with analytes from the filtrate) were discarded. The remaining filtrate was collected and subjected to SPE extraction.

2.5. SPE Procedure

NSAIDs extraction of the samples was carried out in few steps. The C18 columns were washed and activated with 5 mL of methanol and 5 mL of H₂O. A total of 400 mL of the previously filtered test sample was added to the prepared column. The cartridge was dried for 20 min under a gentle stream of nitrogen. Then, the analyte was eluted with 5 mL of methanol.

To extract antibiotics, Oasis HLB columns were washed and activated with 5 mL of methanol and 5 mL of H₂O. A total of 100 mL of previously filtered test sample was added to the prepared columns with HCl to correct the pH to 2.5. The column was washed with 5 mL H₂O and dried for 20 min under a gentle stream of nitrogen. The analyte was eluted with 7 mL of methanol with NH _3aq to change the pH.

Two different columns were used because HLB columns are more expensive than C18 columns. The extraction process differs depending on the analyte group. For NSAIDs, extraction and elution were carried out without pH adjustment, whereas for antibiotics extraction and elution were carried out with pH adjustment.

The difference in the volume of the analyzed samples is due to sensitivity. The final determination method for antibiotics is more sensitive—lower LOQ; therefore, extraction can be performed from a smaller sample volume.

3. Results

Sampling dates and water samples temperatures are presented in

Table 5. Water parameters.

Date	Water Temperature [°C]
2012 March
2012 April
2012 May
2012 June
2012 July
2012 August	-
2012 September
2012 October
2012 November
2012 December
2013 November	8.9
2013 December	4.9
2014 January	4.8
2014 February	4.8
2014 March	14.6
2014 April	16.0
2019 May	13.1
2019 June	25.9
2019 August	24.4
2019 September	14.6
2019 October	10.9
2019 November	5.3
2020 January	2.1
2020 March	5.1
2020 July	21.5
2020 August	20.2
2020 October	11.8
2021 January	-
2021 May	15.5
2021 June	26.1

.

Concentrations of drugs in the water were recalculated so that the final value corresponded to the amount of individual pharmaceuticals in 1 L of analyzed water. The results obtained are shown in

Table 6. Concentrations of pharmaceuticals in water samples taken from the Warta River.

	Drug	Ketoprofen	Paracetamol	Naproxen	Ibuprofen	Fenoprofen	Sulfamethoxazole	Trimethoprim
Date		[ng/L]
2012 March		2.00	4.60	12.10	23.20	7.10	-	-
2012 April		1.80	13.50	65.00	28.50	6.10	-	-
2012 May		12.30	67.60	8.20	25.00	5.30	-	-
2012 June		41.40	51.60	12.60	99.30	19.10	-	-
2012 July		12.30	2.90	14.70	16.80	18.10	-	-
2012 August		0.40	18.60	9.60	13.10	9.00	-	-
2012 September		5.20	9.50	54.70	20.20	3.40	-	-
2012 October		2.50	3.30	11.10	22.10	1.10	-	-
2012 November		2.90	3.90	13.00	25.90	1.30	-	-
2012 December		20.70	107.20	13.70	34.40	9.10	-	-
Median 2012		4.05	11.50	12.80	24.10	6.60	-	-
2013 November		37.64	-	30.57	14.79	4.15	-	-
2013 December		11.83	-	21.30	180.92	13.24	-	-
2014 January		29.45	-	43.32	495.95	12.06	-	-
2014 February		47.86	-	103.78	90.79	0.22	-	-
2014 March		10.00	-	7.58	8.08	12.29	-	-
2014 April		7.14	-	14.73	15.05	1.73	-	-
Median 2013–2014		20.64	-	25.94	52.92	8.11	-	-
2019 May		-	-	-	-	-	105.90	1.24
2019 June		-	-	-	-	-	107.31	2.53
2019 August		16.46	0.01	0.01	3.51	-	-	-
2019 September		5.91	1.46	1.46	12.28	-	-	-
2019 October		7.09	3.91	3.91	5.60	-	-	-
2019 November		4.04	9.39	9.39	7.33	-	-	-
2020 January		4.35	0.37	10.83	9.48	-	-	-
2020 March		5.39	0.52	11.08	32.33	-	-	-
2020 July		19.66	3.91	9.03	251.17	3.17	1.90	670
2020 August		5.46	4.33	11.96	59.17	3.27	1.00	9.80
2020 October		8.33	3.66	10.42	13.62	3.26	9.60	6.40
2021 January		8.51	3.97	17.27	15.92	3.31	55.70	8.80
2021 May		19.51	3.68	13.90	5.33	3.06	3.40	11.10
2021 June		9.36	3.54	8.88	23.22	3.35	7.30	5.80
Median 2019–2021		7.71	3.67	9.91	12.95	3.27	8.45	6.55

.

The highest concentration of pharmaceuticals was recorded for ibuprofen in January 2014 (495.95 ng/L). High concentrations of ibuprofen in water were also recorded in July 2020 in samples taken from the Warta River (251.17 ng/L), December 2013 (180.92 ng/L), and June 2012 (99.30 ng/L). Attention should also be paid to the concentrations of paracetamol in May and June 2012, which were 67.60 ng/L and 51.60 ng/L. The concentrations of ketoprofen were greatest in February 2014 (47.86), June 2012 (41.4 ng/L), and July 2020 (19.66 ng/L). Antibiotics monitoring was conducted only for samples taken in May 2019, June 2019, July 2020, August 2020, October 2020, January 2021, May 2021, and June 2021. The highest concentration of sulfamethoxazole was in June 2019 (107.31 ng/L).

The lowest concentrations of pharmaceuticals in water were recorded in October 2012, October 2019, and October 2020, whereas the highest concentrations were recorded in June 2012, July 2020, August 2020, and June 2021.

The results obtained during the Warta water study indicate similar/lower PhACs concentrations than those shown in Table 1.

Figure 3 and Figure 4 show example chromatograms for water samples from the Warta River in Poznan.

4. Discussion

In different months, various concentrations of non-steroidal anti-inflammatory drugs and antibiotics were detected. It can be caused by specific atmospheric conditions, difficult conditions for the biodegradation process, and people’s sickness periods. Important aim of this study was to check whether the pandemic period affected water pollution or not.

To observe the changes in concentrations in time, the graphs of relationships of concentration vs. time for tested pharmaceuticals are presented (Figure 5, Figure 6 and Figure 7). The research was conducted during three time periods: the first one in 2012, second one in 2013/2014, and the third one during pandemic. Analyzing these periods allows us to compare how the concentration of pharmaceuticals have changed in selected months and years. The interpretation of data also allows us to determine whether the pandemic influenced selected NSAIDs and antibiotics occurrence in natural waters.

The highest concentrations of ketoprofen were observed in February 2014. From 2019 to 2021, the fluctuations in concentrations were smaller, ranging from 4.04 to 19.66 ng/L. The median during this period was equal to 7.71, which was higher than the median for the 2012 period of 4.05 and lower for the median of the 2013/2014 period, which was 20.64 ng/L. The high values marked in 2012 may indicate poor biodegradation effects in municipal wastewater treatment plants located above the water intake points for analysis or may indicate contamination of natural waters with wastewater from the pharmaceutical industry or from animal breeding farms using feeds enriched with pharmaceuticals as well as from the runoff of fields fertilized with manure. The relatively high and less fluctuating concentration of ketoprofen (4.04–19.66 ng/L) throughout the pandemic period indicates some increase in consumption of this pharmaceutical in 2019–2021 compared to 2012, when an incidentally high concentration of 41.4 ng/L was observed, with other average and low concentrations compared to those determined during the pandemic period. The detected concentrations of ketoprofen are smaller than those shown in Table 1. The highest concentration of this compound detected in Polish waters, presented by Helene Ek Henning et al. (2020), was 280 ng/L [22].

Paracetamol is one of the most popular pharmaceutical active compounds. The lowest concentration of paracetamol was detected in August 2019. The concentration of paracetamol in the 2019–2021 period in the Warta River has remained constant at 0.01–9.39 ng/L. In 2012, the concentration of paracetamol was higher; it was 2.90–107.20 ng/L. In December 2012, the highest concentration of paracetamol was detected—107.20 ng/L, which indicates a higher consumption of the PhACs during the cold season. In comparison with the results obtained by Valcárcel et al. (2011), the Warta River in Poznan is cleaner than the surface waters of Madrid in terms of paracetamol concentrations [31].

A similar pattern was observed for naproxen. A steady increase with slight fluctuations in naproxen concentrations in the Warta River was observed from August 2019 to spring 2021.

Analysis of ibuprofen content in the Warta River showed the highest concentration of the drug in January 2014 (495.95 ng/L). Such a high value can be caused by the illness period occurring during the winter. The second highest value was detected in July 2020, at the end of the first high wave of COVID-19 cases. As of August 2019, ibuprofen concentrations in the Warta River increased steadily from a value of 3.51 to a maximum value of 251.17 ng/L. This was followed by a decrease in the concentration of ibuprofen in the analyzed water to a constant value, but higher than immediately before the onset of the pandemic in Poland (end of 2019). Results obtained by Guzik et al. (2013), Debska et al. (2005), and Winkler (2001) for waters in Poland, France, Italy, and Germany did not exceed concentrations greater than 170 ng/L [15,19,20]. This indicates the deteriorating state of Poland’s water supply.

The case of fenoprofen concentrations is different from the previously discussed drugs. In the period 2012–2014, there were very large fluctuations in the concentration of fenoprofen in the Warta River. During the pandemic period, analyses showed an almost constant concentration of fenoprofen in the water in the range of 3.06–3.35 ng/L. Thus, it can be concluded that it was not a drug whose consumption increased during the COVID-19 pandemic.

It is also important to compare the determined concentrations according to the season. For this purpose, the following periods were selected. January 2014, 2020, and 2021 were chosen to compare drug concentrations during the winter season. For paracetamol, the highest PhACs concentrations in January were in 2021. The significantly higher concentrations of the others PhACs in January 2014 may indicate a higher flu season in 2014. Medicine consumption in 2014 was lower than in 2021, according to IQVIA data, which may indicate inadequate wastewater treatment in 2014.

The spring season is represented by March 2012, 2014, and 2020, with average temperatures in selected periods. We can see a correlation indicating higher PhACs pollution in 2012–2014. Among the measured results, only the concentration of ibuprofen in March 2020 stands out, which may indicate the effect of the first wave of the coronavirus pandemic.

In summer (August 2012, 2019, and 2020), the relationship is different from the winter and spring seasons. High concentrations of naproxen and ibuprofen in August 2020 may be due to the coronavirus pandemic. In contrast, high concentrations of ketoprofen in August 2019 may be due to its accumulation in water.

During the autumn period (October 2012, 2019, 2020), drug concentrations oscillated between 1.10 ng/L and 22.10 ng/L, indicating the constant presence of pharmaceuticals in water in connection with the autumn flu season.

Sulfamethoxazole concentrations increased from summer to spring. The lowest concentrations of this compound in summer may be related to its photodegradation process [42,43]. Fenoprofen, on the other hand, is found in the environment in similar concentrations regardless of the season.

Figure 8 shows the change in median concentrations of the analyzed NSAID drugs over the three study periods.

Summarizing the results of the concentrations of NSAIDs in those study periods, it can be concluded that the consumption of NSAIDs apparently increased during the 2013–2014 period, which was manifested by an increase in the concentration of this drug in natural waters regarding the 2012 and 2019–2021 periods.

It can be concluded that during the pandemic period (2019–2021), in the water of the Warta River the highest median concentrations of the analyzed drugs were recorded for ibuprofen (12.95 ng/L), and the lowest for fenoprofen (3.27 ng/L).

The antibiotics sulfamethoxazole and trimethoprim were also included in the 2019–2021 study (Figure 9). The concentration of sulfamethoxazole in the Warta River water reached a maximum value in June 2019. The data on sulfonamides and trimethoprim showed in Figure 1 are coherent with detected concentrations. Since 2019, the consumption of those antibiotics is increasing. Higher concentration value of sulfomethaxazole in January 2021 can be effected by pandemic wave. However, antibiotics have proven ineffective against viral infections and should not be used for treating viral infections such as COVID-19.

High concentrations of antibiotics, but also of NSAIDs during the summer months, can be caused by low water flow due to drought. The dilution factor is very low during a drought, so the water straight from the wastewater treatment plant makes up the largest portion of the water in the river [44].

Similar effects can be seen in results from winter periods. The ice cover slows down the flow of water in the river, which causes the accumulation of PhACs in the river [45].

An additional factor affecting the concentration of antibiotics and NSAIDs in water can be their sorption into the sediments. This occurs in the process of resuspension [46].

5. Conclusions

The presence of pharmaceuticals in the Warta River in Poznan at similar levels over three time periods (2012, 2013/2014, and 2019/2021) testifies to its constant and unchanging pollution with PhACs. This indicates an ineffective process for treating pharmaceuticals in wastewater treatment plants or the uncontrolled discharge from pharmaceutical companies, or even from the agricultural point and surface discharge to the Warta River. The need is demonstrated for the comprehensive natural water monitoring including all mentioned above sources of pharmaceutical contamination.

There were five waves of the SARS-CoV-2 in Poland: the first one was in the middle of 2020, the second one was at the end of 2020, and the third one was at the beginning of 2021. The concentrations of detected drugs are various during those waves. Restrictions that were in place at the time of the pandemic made it difficult to access doctors, which caused people’s fear of becoming infected and people tended to self-medicate. The results of the study indicate that the public readily took NSAIDs as a result of the pandemic, especially ibuprofen.

Non-steroidal anti-inflammatory drugs and antibiotics are consistently present in the Warta River in Poznan in concentrations of the order of ng/L. Diseases, changes in water flow, and seasons affect the pharmaceutical concentrations in water.

Wide fluctuations in drug concentrations in natural waters and the occurrence of peak values are characteristic of pharmaceuticals from the NSAID group and antibiotics, the consumption of which increases during periods of increased illness of influenza and colds. The pandemic caused a decrease in the fluctuation of concentrations of the analyzed pharmaceuticals of the NSAID group in the Warta River, which indicates a steady increase in the consumption of these drugs in 2019–2021.

The increased consumption manifests itself in increased concentrations of these substances in rivers. Wastewater goes to a wastewater treatment plant, whose task is to remove pollutants through physical (sedimentation) as well as chemical (chemical precipitation) and biological (biodegradation in activated sludge processes) processes. Pharmaceuticals, due to their chemical nature and purpose (control of microorganisms), sometimes show very high resistance to biodegradation processes. This, of course, limits the effects of wastewater treatment in municipal treatment plants. Pharmaceuticals that are not disposed of enter natural waters. Moreover, difficult weather conditions influence the biodegradation process. It is important to focus on enhancing the treatment effects and improve ineffective wastewater treatment processes. The best way to improve natural water conditions is to enhance wastewater treatment plants effectiveness and control other sources of contamination.