In Europe, more than 150,000 chemicals are used commercially. Annually, their number increases by several thousand. For example, in\u00a02015, this represented the\u00a0consumption of\u00a0350 million tons of\u00a0chemicals, of\u00a0which 63 % were classified as\u00a0hazardous to\u00a0human health and 36 % as\u00a0hazardous to\u00a0the\u00a0environment [1].
\nThese substances enter the\u00a0environment not only through wastewater from chemical production and other industries, but also from significant consumption by the\u00a0population via municipal wastewater [2]. The\u00a0active ingredients of\u00a0plant protection products reach surface waters directly through erosion during rainfall-runoff events.<\/p>\n
Many water reservoirs in\u00a0the\u00a0Czech Republic are located in\u00a0anthropogenically affected areas. Much attention has long been paid to\u00a0the\u00a0basin of\u00a0the\u00a0\u017delivka river basin with the\u00a0largest water reservoir (hereinafter WR) \u0160vihov supplying drinking water to\u00a0over one million inhabitants. The\u00a0dynamics of\u00a0pesticide leaching into surface waters in\u00a0\u0160vihov WR basin has been investigated by several authors [e.g. 3\u20135].<\/p>\n
The\u00a0water reservoirs in\u00a0the\u00a0Morava and Dyje river basins are also located in\u00a0areas with significant agricultural activity and, in\u00a0the\u00a0case of\u00a0V\u00edr I WR, also industrial activity. V\u00edr I WR is\u00a0the\u00a0largest of\u00a0them (Fig.\u00a01), coming into operation in\u00a01957. The\u00a0purpose is\u00a0to\u00a0ensure minimum flows, water supply abstraction, operational abstraction, electricity generation, flood protection, and improvement of\u00a0flows for irrigation downstream from Brno. The\u00a0total volume of\u00a0the\u00a0reservoir is\u00a056.193\u00a0million\u00a0m3<\/sup>. The\u00a0most important tributary is\u00a0the\u00a0Svratka. The\u00a0Fry\u0161\u00e1vka and the\u00a0B\u00edl\u00fd stream are important tributaries of\u00a0the\u00a0Svratka. The\u00a0total area of\u00a0the\u00a0catchment upstream from the\u00a0reservoir is\u00a0410.35 km2. The\u00a0theoretical water retention time in\u00a0V\u00edr I WR is\u00a0154 days (5.14 months) at\u00a0the\u00a0average long-term flow of\u00a0the\u00a0Svratka (3.7 m3) if\u00a0we consider the\u00a0reservoir volume of\u00a049.342 million m3 up to\u00a0the\u00a0spillway level and 138\u00a0days (4.59 months) in\u00a0in the\u00a0case of\u00a0a reservoir volume of\u00a044.056 mil m3 (useful water level). The\u00a0largest human settlement is\u00a0located in\u00a0the\u00a0upper part of\u00a0the\u00a0B\u00edl\u00fd stream basin, namely the\u00a0town of\u00a0Poli\u010dka (8,700 inhabitants). of\u00a0the\u00a0municipalities directly related to\u00a0the\u00a0water reservoir, the\u00a0village of\u00a0Dale\u010d\u00edn (660 inhabitants), and further up the\u00a0river Svratka, the\u00a0township of\u00a0Jimramov (1,200 inhabitants) have a\u00a0municipal wastewater treatment plant (WWTP). Important industrial enterprises in\u00a0the\u00a0area include Poli\u010dsk\u00e9 stroj\u00edrny, a. s., Masokombin\u00e1t Poli\u010dka, a. s., Poli\u010dka municipal WWTP, and Jimramov WWTP. The\u00a0landscape of\u00a0Svrateck\u00e1 vrchovina is\u00a0approximately 55 % forested and has a\u00a0high recreational potential. In\u00a02021, intensive logging took place in\u00a0the\u00a0immediate vicinity of\u00a0the\u00a0reservoir as\u00a0a\u00a0result of\u00a0a large-scale bark beetle outbreak.<\/p>\n Opatovice WR (Fig. 2) was put into operation in 1972. The main purpose is to ensure a source of drinking water for the population. The total volume of the reservoir is 10.634 million m3. The main tributary is the Mal\u00e1 Han\u00e1. The larger part of the catchment upstream from the reservoir is occupied by the forested landscape of Drahansk\u00e1 vrchovina, partially encroaching on the military district of B\u0159ezina in the south. The upper part of the Mal\u00e1 Han\u00e1 basin is typical of intensive agricultural activity. The catchment area is 43.87 km2. The nearest human settlement is the village of Ruprechtov (600 inhabitants) in the upper part of the Ruprechtovsk\u00fd stream. The WR volume up to the spillway level is\u00a07.84 million m3. At\u00a0the\u00a0average flow of\u00a0the\u00a0Mal\u00e1 Han\u00e1 (0.160 m3.s-1), the\u00a0theoretical retention time in\u00a0the\u00a0reservoir is\u00a0567 days, i.e. 18.9 months.<\/p>\n Ludkovice WR (Fig.\u00a03) was put into operation in\u00a01968. It is\u00a0the\u00a0smallest reservoir that was chosen for the\u00a0project. Its total volume is\u00a0only 0.69 million m3. Its main purpose is\u00a0to\u00a0ensure sufficient water for Luha\u010dovice collective water supply system and a\u00a0minimum flow in\u00a0the\u00a0stream below the\u00a0dam, which is\u00a0the\u00a0Ludkovick\u00fd stream.<\/p>\n The\u00a0catchment area is\u00a013.1 km2. The\u00a0theoretical retention time of\u00a0water in\u00a0the\u00a0reservoir is\u00a0the\u00a0shortest; if\u00a0we consider the\u00a0volume of\u00a0the\u00a0reservoir up to\u00a0the\u00a0overflow level of\u00a00.498 million m3, the\u00a0retention time is\u00a0only 62\u00a0days at\u00a0the\u00a0long-term mean daily flow of\u00a0the\u00a0Ludkovick\u00fd stream of\u00a00.096 m3.s-1. The\u00a0dynamics of\u00a0the\u00a0pollution of\u00a0selected tributaries to\u00a0the\u00a0water supply reservoirs was investigated using passive samplers. It is\u00a0a\u00a0continuous capture of\u00a0pollutants for a\u00a0specified period of\u00a0time on\u00a0a\u00a0suitable type of\u00a0sampler according to\u00a0the\u00a0type of\u00a0monitored substances. In\u00a0contrast to\u00a0spot sampling, this makes it possible to\u00a0gather accidental pollution (in the\u00a0case of\u00a0pesticides during rainfall-runoff episodes) or very low concentrations of\u00a0substances that, even at\u00a0low levels in\u00a0water, show adverse effects on\u00a0the\u00a0aquatic environment and, consequently, on\u00a0humans. The\u00a0exposure time is\u00a0chosen so that it takes place in\u00a0the\u00a0linear region of\u00a0pollution reception by the\u00a0sampler (Fig.\u00a04).<\/p>\n In surface waters, the\u00a0exposure time is\u00a0usually three weeks; due to\u00a0the\u00a0sampling of\u00a0cleaner waters an exposure of\u00a0around four weeks was chosen. Alvarez [7] also confirms that the\u00a0typical exposure time in\u00a0the\u00a0linear region of\u00a0substance uptake by a\u00a0POCIS does not exceed 28 days, although for some of\u00a0the\u00a0substances tested by him linearity of\u00a0reception was maintained even after 56\u00a0days of\u00a0exposure. Sampling took place throughout the\u00a0growing season from April to\u00a0November, i.e. in\u00a0a total of\u00a0eight sampling campaigns. The\u00a0exact dates of\u00a0installation and replacement of\u00a0passive samplers are given in\u00a0Tab. 1.<\/p>\n Suitable locations for placing the samplers were selected together with the employees of Povod\u00ed Moravy State Enterprise. It is necessary to choose such places where the submersion of the sampler is guaranteed for the entire duration of the exposure and unauthorized handling or theft is minimized.<\/p>\n The following types of passive samplers were used to capture a wide range of pollutants:<\/p>\n The\u00a0samplers were protected from mechanical damage in\u00a0a stainless steel canister or casing (Fig.\u00a05). The\u00a0samplers were anchored to\u00a0the\u00a0riparian vegetation with a\u00a0stainless steel cable. The\u00a0closing profile was the\u00a0inflow of\u00a0raw water into the\u00a0water treatment plant or, if\u00a0this was not possible, in\u00a0the\u00a0water reservoir near the\u00a0intake facility at\u00a0the\u00a0dam. At\u00a0the\u00a0main inflow and outflow from the\u00a0water reservoir, the\u00a0sampling canisters were equipped with a\u00a0HOBO Pendant MX 2202 data logger for continuous recording of\u00a0temperature and light intensity throughout the\u00a0exposure period.<\/p>\n Before use, the\u00a0samplers were stored according to\u00a0the\u00a0data given by the\u00a0manufacturer; after exposure they were transported to\u00a0the\u00a0laboratory at\u00a0a\u00a0temperature of\u00a0+2 to\u00a0+4 \u00b0C and, before processing, they were stored at\u00a0a\u00a0temperature of\u00a0-18 \u00b0C.<\/p>\n The\u00a0spectrum of\u00a0verified substances included 36 active substances of\u00a0plant protection products and 14 metabolites of\u00a0pesticides (a total of\u00a050 substances). The\u00a0criterion for the\u00a0selection of\u00a0pesticides was the\u00a0evaluation of\u00a0the\u00a0results of\u00a0surface water monitoring carried out by the\u00a0basin manager during 2017\u20132019 and significant consumption of\u00a0plant protection products recorded by the\u00a0Central Institute for Supervising and Testing in\u00a0Agriculture (\u00daKZ\u00daZ) in\u00a0the\u00a0affected districts [8].<\/p>\n After being removed from the\u00a0freezer, the\u00a0exposed samplers (shown in\u00a0Fig.\u00a06) were allowed to\u00a0reach laboratory temperature before processing. At\u00a0the\u00a0same time, they remained closed in\u00a0their original packaging to\u00a0prevent secondary contamination from the\u00a0surrounding environment. Subsequently, they were removed from the\u00a0transport package and rinsed with deionized water. In\u00a0the\u00a0next step, they were disassembled on\u00a0aluminium foil (releasing the\u00a0metal surround). The\u00a0sorbent placed between the\u00a0PES membranes was quantitatively transferred with deionized water to\u00a0SPE columns, dried under vacuum and nitrogen, and then eluted with the\u00a0necessary volume of\u00a0methanol as\u00a0recommended by Grabic [9]. The\u00a0eluate was concentrated to\u00a0a volume of\u00a01 ml and transferred to\u00a0LC-MS\/MS analysis. Pesticides were measured in\u00a0positive mode, pesticide metabolites in\u00a0negative mode. Agilent 1290 Infinity II + Sciex X500R Q-TOF and Exion LC (Shimadzu) + Sciex Triple QuadTM 7500 were used for analysis.<\/p>\n POCIS-Gly was processed according to\u00a0the\u00a0procedure published by Claude [10]. After transferring the\u00a0sorption media with deionized water on\u00a0the\u00a0frit, the\u00a0sorbent was dried under vacuum and nitrogen. Elution was carried out with 8 ml of\u00a00.1 M hydrochloric acid. The\u00a0obtained extract was concentrated to\u00a0dryness under a\u00a0stream of\u00a0nitrogen and supplemented with a\u00a0mixture of\u00a0methanol and water to\u00a0a ratio of\u00a01 : 1. The\u00a0determination of\u00a0glyphosate and its metabolite AMPA was carried out by the\u00a0LC\/MS\/MS method in\u00a0negative mode.<\/p>\n The\u00a0resulting substance concentrations are based on\u00a01 ml of\u00a0extract.<\/p>\n The\u00a0locations of\u00a0passive sampling of\u00a0the\u00a0tributaries to\u00a0V\u00edr I WR are shown in\u00a0Fig.\u00a07. They include the\u00a0left- and right-hand small tributaries to\u00a0WR, the\u00a0main tributary of\u00a0the\u00a0Svratka, and the\u00a0outflow from the\u00a0reservoir. Information on\u00a0the\u00a0type of\u00a0cultivated crops and the\u00a0area in\u00a0the\u00a0catchments of\u00a0interest was created by the\u00a0classification of\u00a0multitemporal remote sensing images (RSI). Their representation in\u00a0V\u00edr I WR basin is\u00a0documented in\u00a0Tab. 2. Non-agricultural use prevails. of\u00a0the\u00a0crops, cereals are the\u00a0most common, to\u00a0a lesser extent oilseed rape and maize. Intensive agricultural activity takes place mainly in\u00a0the\u00a0basins of\u00a0the\u00a0left-hand tributaries of\u00a0the\u00a0Svratka, the\u00a0B\u00edl\u00fd stream, the\u00a0\u010cern\u00fd stream, and their tributaries.<\/p>\n Source: Czech Hydrometeorological Institute<\/sup><\/p>\n Of the\u00a0pesticides and pesticide metabolites, 29 substances and DEET (N,N-di- The\u00a0highest concentrations of\u00a0pesticides were found in\u00a0the\u00a0tributaries to\u00a0the\u00a0reservoir in\u00a0the\u00a0second, third, and fourth sampling campaigns (May to\u00a0July 2021) (Figs. 8 and 9). The\u00a0Chlumsk\u00fd stream was the\u00a0most polluted left-side tributary, with a\u00a0high content of\u00a02,4-dichlorophenoxyacetic acid (2,4-D) in\u00a0the\u00a0second sampling campaign. This stream is\u00a0the\u00a0shortest of\u00a0the\u00a0monitored tributaries to\u00a0V\u00edr I WR (less than 1 km long) and originates from a\u00a0small pond below the\u00a0village of\u00a0Chlum. 2,4-D is\u00a0an organochlorine selective herbicide used on\u00a0dicotyledonous weeds and applied mainly to\u00a0cereals, to\u00a0a lesser extent to\u00a0maize and forage crops. Its significant occurrence in\u00a0this small watercourse may be related to\u00a0a rainfall-runoff episode that occurred in\u00a0the\u00a0area on\u00a014 May 2021, with a\u00a0total of\u00a026 mm of\u00a0rainfall (Fig.\u00a010). It was the\u00a0first significant spring rainfall. In\u00a02021, spring cereals were grown in\u00a0the\u00a0Chlumsk\u00fd stream basin.<\/p>\n The P\u00edse\u010densk\u00fd stream (length 3.05 river km), originating at the upper end of the P\u00edse\u010dn\u00e1 village, dominated the right-hand tributaries with the variety of captured pesticides. Terbuthylazine and its metabolites, metazachlor and its metabolites and alachlor metabolites were significantly represented. Terbuthylazine, which is\u00a0used to\u00a0treat maize, was predominant in\u00a0the\u00a0form of\u00a0the\u00a0metabolite Terbuthylazine-2-hydroxy (Fig.\u00a011) with a\u00a0maximum in\u00a0the\u00a0fourth sampling campaign (7\/2021). The\u00a0areas sown with maize were very small in\u00a0the\u00a0location in\u00a02021, namely in\u00a0the\u00a0uppermost part of\u00a0the\u00a0catchment. The\u00a0\u201eparent\u201c substance was thus confirmed only in\u00a0minimal amounts. It is\u00a0probably a\u00a0load from previous years or a\u00a0transformation of\u00a0the\u00a0original active substance during transport to\u00a0the\u00a0watercourse through the\u00a0soil profile from a\u00a0greater distance.<\/p>\n Metazachlor is\u00a0used for oil crops that were not grown in\u00a0the\u00a0P\u00edse\u010densk\u00fd stream basin in\u00a02021. Solely the\u00a0metabolite metazachlor ESA was confirmed by\u00a0passive sampling in\u00a0the\u00a0first sampling campaign in\u00a0April (Fig.\u00a012). This indicates its leaching from applications in\u00a0previous years; the\u00a0dynamics of\u00a0concentrations is\u00a0different and not so dependent on\u00a0rainfall-runoff episodes. The\u00a0dynamics of\u00a0alachlor was similar, the\u00a0use of\u00a0which has been prohibited since 2007 and was represented in\u00a0surface water exclusively by the\u00a0ESA metabolite with a\u00a0maximum in\u00a0the\u00a0sixth sampling campaign (9\/2021).<\/p>\n In the\u00a0Svratka above WR (Dale\u010d\u00edn) profile, the\u00a0amount of\u00a0pesticides captured was mostly lower than in\u00a0the\u00a0small left and right tributaries to\u00a0the\u00a0reservoir. Agriculture is\u00a0particularly intensive in\u00a0the\u00a0B\u00edl\u00fd stream basin in\u00a0its upper part around the\u00a0town of\u00a0Poli\u010dka, i.e. at\u00a0the\u00a0very upper border of\u00a0the\u00a0Svratka basin. Higher concentrations of\u00a0pesticides in\u00a0the\u00a0B\u00edl\u00fd stream are gradually diluted further downstream. The\u00a0exception was the\u00a0third sampling campaign with a\u00a0confirmed high content of\u00a0pethoxamid in\u00a0the\u00a0Svratka above WR (Fig.\u00a09). This\u00a0pesticide is\u00a0used to\u00a0treat maize and oil crops alone or in\u00a0combination with terbuthylazine (e.g., BALATON). Its high capture in\u00a0this sampling campaign is\u00a0probably related to\u00a0the\u00a0heaviest precipitation event on\u00a022 June 2022 (58 mm) (Fig.\u00a010) and flushes from locations between the\u00a0township of\u00a0Jimramov and the\u00a0village of\u00a0Strachujov, just a\u00a0few kilometres above the\u00a0sampling profile.<\/p>\n Intensive agricultural activity around Poli\u010dka with a\u00a0significant proportion of\u00a0cereals, maize and oilseed rape (Fig.\u00a013) was manifested in\u00a0the\u00a0B\u00edl\u00fd stream profile \u2013 above the\u00a0\u010cern\u00fd stream influx, mainly by the\u00a0capture of\u00a0terbuthylazine with the\u00a0predominance of\u00a0its metabolites with a\u00a0gradual concentration increase until July 2021 in\u00a0the\u00a0fourth sampling campaign (Fig.\u00a014) and chlorotoluron with a\u00a0maximum in\u00a0the\u00a0third sampling campaign (Fig.\u00a015).<\/p>\n The\u00a0dynamics of\u00a0concentrations of\u00a0glyphosate and its metabolite AMPA is\u00a0interesting. It is\u00a0normally used at\u00a0the\u00a0beginning of\u00a0spring, before sowing, and at\u00a0the\u00a0end of\u00a0summer, before sowing winter cereals. Since 1 January 2019, glyphosate has been prohibited from being used for desiccation of\u00a0crops that are used for food purposes [11]. Glyphosate is\u00a0relatively rapidly transformed into the\u00a0AMPA metabolite depending on\u00a0temperature, moisture, and soil microbial activity. The\u00a0kinetics of\u00a0the\u00a0transformation under different conditions defines its decrease in\u00a0the\u00a0interval of\u00a01.5 to\u00a053.5 days for DT50 and 8 to\u00a0280 days for DT90. The\u00a0AMPA metabolite is\u00a0more stable, its persistence is\u00a011 to\u00a021 times greater [12]. It always depends on\u00a0specific conditions, and even the\u00a0type of\u00a0cultivated crops [13]. At\u00a0low temperatures (+5 \u00b0C), the\u00a0transformation of\u00a0glyphosate is\u00a08.3 times slower than at\u00a0+30 \u00b0C.<\/p>\n Two different cases of\u00a0the\u00a0dynamics of\u00a0the\u00a0concentrations of\u00a0these two compounds can be seen in\u00a0Fig.\u00a016 and 17. In\u00a0the\u00a0P\u00edse\u010densk\u00fd stream basin, the\u00a0maximum concentration of\u00a0the\u00a0AMPA metabolite was demonstrated in\u00a0the\u00a0first sampling campaign in\u00a0April, and in\u00a0the\u00a0sixth campaign in\u00a0September, where mainly the\u00a0parent substance was captured. In\u00a0the\u00a0Karas\u00ednsk\u00fd stream basin, glyphosate was only applied before autumn sowing.<\/p>\n In the\u00a0Svratka, at\u00a0the\u00a0tributary to\u00a0WR, glyphosate slightly prevailed over the\u00a0AMPA metabolite, with a\u00a0maximum in\u00a0the\u00a0third sampling campaign. The\u00a0locations of\u00a0passive sampling on\u00a0tributaries to\u00a0Opatovice WR are shown in\u00a0Fig.\u00a018. The\u00a0water reservoir only has two significant tributaries: the\u00a0Mal\u00e1 Han\u00e1 and the\u00a0Ruprechtovsk\u00fd stream. The\u00a0left-hand tributary of\u00a0the\u00a0Mal\u00e1 Han\u00e1 is\u00a0the\u00a0Rakovec stream, which partly extends into the\u00a0military district of\u00a0B\u0159ezina. Small left-hand tributaries to\u00a0the\u00a0WR, with a\u00a0length of\u00a0300\u2013400 m in\u00a0the\u00a0cadastres of\u00a0Rycht\u00e1\u0159ov and Pa\u0159ezovice, were not included in\u00a0the\u00a0project due to\u00a0their minimum water bearing. Information on\u00a0the\u00a0type of\u00a0cultivated crops and the\u00a0area in\u00a0the\u00a0basins of\u00a0interest was created by classification of\u00a0multitemporal remote sensing images (RSI). Their representation in\u00a0the\u00a0Opatovice WR basin is\u00a0shown in\u00a0Fig.\u00a019 and documented in\u00a0Tab. 4. Non-agricultural use makes up 81\u00a0% of\u00a0the\u00a0catchment area. Nevertheless, the\u00a0pesticide load on\u00a0the\u00a0water reservoir is\u00a0considerable. Cereals and oilseed rape are the\u00a0most represented crops. Intensive agricultural activity takes place in\u00a0the\u00a0upper parts of\u00a0the\u00a0Ruprechtovsk\u00fd stream, the\u00a0Mal\u00e1 Han\u00e1 around the\u00a0village of\u00a0Kr\u00e1sensko, and on\u00a0the\u00a0left side of\u00a0the\u00a0reservoir around the\u00a0villages of\u00a0Rycht\u00e1\u0159ov and Pa\u0159ezovice.<\/p>\n Source: Czech Hydrometeorological Institute<\/sup><\/p>\n Of the verified pesticides and metabolites, 27 substances and DEET (N,N-diethyl–3-methylbenzamide) were confirmed in the passive samplers. Summary results indicating the maximum concentration of pesticides found, including their metabolites, from eight sampling campaigns are shown in Tab. 5. The dynamics of pesticide concentrations compared to the previous water reservoir was different. Metazachlor, metolachlor, terbuthylazine and their metabolites, glyphosate including its AMPA metabolite, and alachlor metabolites were most significantly represented (Fig.\u00a020\u201323). In\u00a0the\u00a0Rakovec basin, agricultural activity is\u00a0developed only in\u00a0the\u00a0upper part around the\u00a0village of\u00a0Studnice; passive sampling confirmed that the\u00a0presence of\u00a0pesticides in\u00a0this watercourse is\u00a0very low. The\u00a0main pesticide load of\u00a0the\u00a0reservoir comes from the\u00a0Mal\u00e1 Han\u00e1 and the\u00a0Ruprechtovsk\u00fd stream.<\/p>\n In the\u00a0April first sampling campaign, glyphosate and especially the\u00a0metabolite AMPA prevailed in\u00a0both of\u00a0the\u00a0above-mentioned tributaries; the\u00a0load of\u00a0other pesticides was minimal. In\u00a0the\u00a0second sampling campaign, increased and almost equivalent concentrations of\u00a0metolachlor, metazachlor, and terbuthylazine, including their metabolites, were confirmed in\u00a0the\u00a0main tributary to\u00a0the\u00a0reservoir.<\/p>\n S-metolachlor applied to\u00a0maize was represented almost exclusively in\u00a0the\u00a0form of\u00a0its metabolite ESA on\u00a0its way from the\u00a0upper parts of\u00a0the\u00a0Mal\u00e1 Han\u00e1 basin to\u00a0the\u00a0reservoir. It repeatedly occurred in\u00a0significant concentrations in\u00a0other sampling campaigns. The\u00a0half-life of\u00a0S-metolachlor in\u00a0soil ranges from 23.6 to\u00a040.1 days, depending on\u00a0soil temperature and moisture [14]. The\u00a0rate of\u00a0its representation in\u00a0surface water was high, although the\u00a0area planted with maize was small in\u00a0the\u00a0Han\u00e1 basin in\u00a02021.<\/p>\n Metazachlor, also exclusively represented by the\u00a0ESA metabolite, showed the\u00a0same concentration dynamics with a\u00a0gradual increase up to\u00a0the\u00a0eighth sampling campaign in\u00a0the\u00a0Mal\u00e1 Han\u00e1. It is\u00a0used to\u00a0treat oil crops, which were an important cultivated crop in\u00a0this basin in\u00a02021. According to\u00a0[15], the\u00a0half-life of\u00a0the\u00a0parent compound in\u00a0the\u00a0aquatic environment is\u00a019.3 days, with only microbial processes participating in\u00a0its degradation. Metazachlor is\u00a0stable against hydrolysis and photolysis. Terbuthylazine, which is\u00a0used to\u00a0treat maize, was detected in\u00a0the\u00a0Mal\u00e1 Han\u00e1 only in\u00a0the\u00a0second sampling campaign and to\u00a0a\u00a0lesser extent in\u00a0the\u00a0seventh sampling campaign, both times as\u00a0terbuthylazine-2 hydroxy.<\/p>\n Terbuthylazine-2 hydroxy was only detected in\u00a0the\u00a0Ruprechtovsk\u00fd stream in\u00a0the\u00a0fourth and fifth sampling campaigns (July to\u00a0August). In\u00a02021, maize was not cultivated in\u00a0its catchment; this late increase in\u00a0its concentration in\u00a0the\u00a0watercourse was most probably caused by erosion due to\u00a0use in\u00a0previous years by intense flushes during precipitation episodes during summer occurring in\u00a0late June (Fig.\u00a024). The\u00a0rainfall-runoff event beginning on\u00a022 June 2021 was so enormous that the\u00a0passive samplers of\u00a0the\u00a0third sampling campaign were torn off and lost, even though they were fixed to\u00a0a tree trunk with steel cable.<\/p>\n For technical reasons, it was not possible to\u00a0place passive samplers in\u00a0the\u00a0stream of\u00a0raw water at\u00a0the\u00a0treatment plant in\u00a0the\u00a0village of\u00a0Lhotka. Therefore, they were placed in\u00a0a water reservoir near the\u00a0outlet tower with the\u00a0samplers submerging to\u00a0a depth of\u00a03\u20134 m below the\u00a0surface. The\u00a0concentration of\u00a0pesticides in\u00a0this location has gradually increased since the\u00a0sixth sampling campaign (from 9\/2021). Fig.\u00a025 and 26 show the\u00a0dynamics of\u00a0concentrations of\u00a0the\u00a0two most significantly represented metabolites, metazachlor and metolachlor. Concentrations increased significantly in\u00a0autumn sampling campaigns.<\/p>\n On the\u00a0other hand, increased concentrations of\u00a0glyphosate and the\u00a0metabolite AMPA at\u00a0the\u00a0tributary to\u00a0Opatovice WR were not manifested in\u00a0the\u00a0reservoir near the\u00a0dam during the\u00a0entire sampling season. However, it should be borne in\u00a0mind that the\u00a0theoretical retention time of\u00a0water in\u00a0the\u00a0reservoir is\u00a0over 1.5 years.<\/p>\n Ludkovice WR has only one tributary \u2013 the Ludkovick\u00fd stream. The second sampling profile was the reservoir in close proximity to the outlet tower at the dam (Fig. 27). Information on the type of cultivated crops and the area in the catchments of interest was created by the classification of multitemporal remote sensing images (RSI). Their representation in the WR basin is shown in Fig. 28 and documented in Tab. 6. Non-agricultural use makes up 91.7 % of the catchment area. of\u00a0the\u00a0crops, winter cereals were the\u00a0most represented in\u00a02021.<\/p>\n Of the\u00a0verified pesticides and their metabolites, 24 substances and DEET In the\u00a0reservoir near the\u00a0dam, increased concentrations of\u00a0pesticides were detected only in\u00a0the\u00a0sixth sampling campaign in\u00a0September (Fig.\u00a031). Metolachlor metabolites ESA and OA were most abundantly represented, without the\u00a0presence of\u00a0the\u00a0parent substance. Metolachlor is\u00a0used to\u00a0treat maize. However, it was not cultivated in\u00a0the\u00a0catchment area that year. Simultaneously, significant concentrations of\u00a0acetochlor metabolites, the\u00a0use of\u00a0which has been banned for ten years, were identified in\u00a0this campaign. Metabolites of\u00a0original substances from applications in\u00a0previous years were captured by the\u00a0passive sampler, probably due to\u00a0the\u00a0autumn circulation in\u00a0the\u00a0reservoir between the\u00a0epilimnion and the\u00a0hypolimnion.<\/p>\n The\u00a0third important herbicide identified in\u00a0the\u00a0reservoir by the\u00a0sixth sampling campaign was metazachlor, or again only its metabolites ESA and OA. This herbicide is\u00a0used to\u00a0treat oil crops. Given that neither metazachlor nor its metabolites were confirmed by passive sampling in\u00a02021 at\u00a0the\u00a0tributary in\u00a0the\u00a0Ludkovick\u00fd stream, it is\u00a0also a\u00a0matter of\u00a0capturing pollution from previous years originating from deeper layers of\u00a0the\u00a0water column during their circulation in\u00a0the\u00a0reservoir.<\/p>\n The\u00a0amount of\u00a0pesticides captured by a\u00a0POCIS can be converted to\u00a0an average concentration during the\u00a0exposure time (CTWA) if\u00a0the\u00a0sampling rate Rs is\u00a0known for the\u00a0substance and the\u00a0type of\u00a0passive sampler. In\u00a0the\u00a0case of\u00a0POCIS for polar organic substances, the\u00a0following equation applies to\u00a0the\u00a0conversion [16]:<\/p>\n where:\u00a0\u00a0\u00a0\u00a0\u00a0 Nt\u00a0 \u00a0 \u00a0 \u00a0 \u00a0is the amount of substance captured by the sampler in ng<\/p>\n Rs\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sampling rate in\u00a0l.day-1<\/p>\n t\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sampler exposure time in\u00a0days<\/p>\n![\"\"](\"https:\/\/www.vtei.cz\/wp-content\/uploads\/2023\/02\/Micanik-obr-1.jpg\")
<\/a>\nFig.\u00a01. V\u00edr\u00a0I\u00a0water supply reservoir<\/h6>\n
<\/a>\nFig.\u00a02. Opatovice water supply reservoir<\/h6>\n
<\/a>\nFig.\u00a03. Ludkovice water supply reservoir<\/h6>\n
\nImmediately above the\u00a0reservoir is\u00a0a\u00a0part of\u00a0the\u00a0village of\u00a0Ludkovice, called Pradlisko. The\u00a0village of\u00a0Provodov (780 inhabitants) is\u00a0located in\u00a0the\u00a0upper part of\u00a0the\u00a0Ludkovick\u00fd stream basin. Treated wastewater from the\u00a0village is\u00a0transferred outside the\u00a0Ludkovick\u00fd stream catchment area. Its length above Ludkovice WR is\u00a0about 7 km. 60 % of\u00a0the\u00a0catchment area is\u00a0forested, the\u00a0remaining area is\u00a0dominated by meadows; fields make up about 10 % of\u00a0the\u00a0catchment area.<\/p>\nMETHODOLOGICAL APPROACH<\/h2>\n
<\/a>\nFig.\u00a04. General curve of\u00a0the\u00a0pollution capture by passive sampler depending
\non the\u00a0sampling time [6]<\/h6>\nTab.\u00a01. The\u00a0installation and removal terms of\u00a0the\u00a0passive samplers in\u00a0sampling campaign 2021<\/h5>\n
<\/a>\n\n
\n10 Rue Richard Dufour, 76 770 Le Houlme, France.<\/li>\n<\/ul>\n<\/a>\nFig.\u00a05. Passive sampler POCIS in\u00a0big canister (left) and in\u00a0the\u00a0casing (right)<\/h6>\n
<\/a>\nFig.\u00a06. Exposed passive samplers POCIS<\/h6>\n
RESULTS<\/h2>\n
V\u00edr I water supply reservoir basin<\/h3>\n
<\/a>\nFig.\u00a07. Spots of\u00a0passive sampling on\u00a0the\u00a0tributaries into V\u00edr\u00a0I\u00a0water supply reservoir in\u00a02021<\/h6>\n
Tab.\u00a02. Cultivated crops in\u00a0the\u00a0river basin above V\u00edr\u00a0I\u00a0water supply in\u00a02021 from the\u00a0SSE<\/h5>\n
<\/a>\n
\nethyl-3-methylbenzamide), which is\u00a0part of\u00a0mosquito and tick repellents, were confirmed in\u00a0the\u00a0passive samplers. The\u00a0most prominently represented were 2,4-dichlorophenoxyacetic acid (2,4-D), atrazine, metazachlor, terbuthylazine and their metabolites, and glyphosate including its metabolite AMPA (aminomethylphosphonic acid). Summary results indicating the\u00a0maximum concentration of\u00a0pesticides found, including their metabolites, from eight sampling campaigns are shown in\u00a0Tab. 3.<\/p>\nTab.\u00a03. Maximal concentrations of\u00a0pesticides and metabolites established by passive sampling on\u00a0the\u00a0tributaries into V\u00edr\u00a0I\u00a0water supply reservoir in\u00a02021 (in ng\/POCIS)<\/h5>\n
<\/a>\n<\/a>\nFig.\u00a08. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0V\u00edr\u00a0I\u00a0water supply reservoir \u2013 2nd sampling campaign (May 2021)<\/h6>\n
<\/a>\nFig.\u00a09. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0V\u00edr\u00a0I\u00a0water supply reservoir \u2013 3rd sampling campaign (June 2021)<\/h6>\n
<\/a>\nFig.\u00a010. Rainfall-runoff relationships in\u00a0the\u00a0basin of\u00a0V\u00edr\u00a0I\u00a0water supply reservoir in\u00a02021<\/h6>\n
<\/a>\nFig.\u00a011. Terbuthylazine and metabolites concentration dynamics in\u00a0the\u00a0outfall
\nof P\u00edse\u010densk\u00fd stream in\u00a02021<\/h6>\n<\/a>\nFig.\u00a012. Metazachlor and metabolites concentration dynamics in\u00a0the\u00a0outfall
\nof P\u00edse\u010densk\u00fd stream in\u00a02021<\/h6>\n<\/a>\nFig.\u00a013. Cultivated crops in\u00a0the\u00a0river basin above V\u00edr\u00a0I\u00a0water supply in\u00a02021 from the\u00a0multitemporal shots of\u00a0satellite survey of\u00a0the\u00a0Earth<\/h6>\n
<\/a>\nFig.\u00a014. Terbuthylazine and metabolites concentration dynamics in\u00a0B\u00edl\u00fd stream above the\u00a0outfall of\u00a0\u010cern\u00fd stream in\u00a02021<\/h6>\n
<\/a>\nFig.\u00a015. Chlorotoluron concentration dynamics in\u00a0B\u00edl\u00fd stream above the\u00a0outfall
\nof \u010cern\u00fd stream in\u00a02021<\/h6>\n<\/a>\nFig.\u00a016. Glyphosate and AMPA concentration dynamics in\u00a0the\u00a0outfall of\u00a0P\u00edse\u010densk\u00fd stream in\u00a02021<\/h6>\n
<\/a>\nFig.\u00a017. Glyphosate and AMPA concentration dynamics in\u00a0the\u00a0outfall of\u00a0Karas\u00ednsk\u00fd stream in\u00a02021<\/h6>\n
\nIt is\u00a0interesting that glyphosate was not completely transformed in\u00a0V\u00edr I WR and was also confirmed in\u00a0outflow from the\u00a0water reservoir.<\/p>\nOpatovice water reservoir catchment area<\/h3>\n
<\/a>\nFig.\u00a018. Spots of\u00a0passive sampling on\u00a0the\u00a0tributaries into Opatovice water supply reservoir in\u00a02021<\/h6>\n
<\/a>\nFig.\u00a019. Cultivated crops in\u00a0the\u00a0river basin above Opatovice water supply in\u00a02021 from the\u00a0multitemporal shots of\u00a0satellite survey of\u00a0the\u00a0Earth<\/h6>\n
Tab.\u00a04. Cultivated crops in\u00a0the\u00a0river basin above Opatovice water supply in\u00a02021 from the\u00a0SSE<\/h5>\n
<\/a>\nTab. 5. Maximal concentrations of pesticides and metabolites established by passive sampling on the tributaries into Opatovice and Ludkovice water supply reservoirs in 2021 (in ng\/POCIS)<\/h5>\n
<\/a>\n<\/a>\nFig.\u00a020. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0Opatovice water supply reservoir \u2013 2nd sampling campaign (May 2021)<\/h6>\n
<\/a>\nFig.\u00a021. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0Opatovice water supply reservoir \u2013 4th sampling campaign (July 2021)<\/h6>\n
<\/a>\nFig.\u00a022. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0Opatovice water supply reservoir \u2013 5th sampling campaign (August 2021)<\/h6>\n
<\/a>Fig.\u00a023. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0Opatovice water supply reservoir \u2013 8th sampling campaign (November 2021)<\/h6>\n<\/a>\nFig.\u00a024. Rainfall-runoff relationships in\u00a0the\u00a0basin of\u00a0Opatovice water supply reservoir in\u00a02021<\/h6>\n
<\/a>Fig.\u00a025. Metazachlor and metabolites concentration dynamics at\u00a0the\u00a0dam
\nof Opatovice water supply reservoir in\u00a02021<\/h6>\n<\/a>Fig.\u00a026. Metolachlor and metabolites concentration dynamics at\u00a0the\u00a0dam of\u00a0Opatovice water supply reservoir in\u00a02021<\/h6>\nLudkovice water reservoir catchment area<\/h3>\n
<\/a>Fig.\u00a027. Spots of\u00a0passive sampling on\u00a0the\u00a0tributaries into Ludkovice water supply reservoir in\u00a02021<\/h6>\n<\/a>Fig.\u00a028. Cultivated crops in\u00a0the\u00a0river basin above Ludkovice water supply in\u00a02021 from the\u00a0multitemporal shots of\u00a0satellite survey of\u00a0the\u00a0Earth<\/h6>\nTab.\u00a06. Cultivated crops in\u00a0the\u00a0river basin above Ludkovice water supply in\u00a02021 from the\u00a0SSE<\/h5>\n
<\/a>Source: Czech Hydrometeorological Institute<\/sup><\/p>\n
\n(N,N-diethyl-3-methylbenzamide) were confirmed in\u00a0the\u00a0passive samplers. The\u00a0vast majority of\u00a0them (with the\u00a0exception of\u00a0glyphosate) were detected only in\u00a0low concentrations, both at\u00a0the\u00a0inflow and at\u00a0the\u00a0outflow of\u00a0the\u00a0reservoir, even though this basin also experienced several significant rainfall-runoff events in\u00a0the\u00a0summer. Summary results indicating the\u00a0maximum concentration of\u00a0pesticides detected, including their metabolites, from eight sampling campaigns are shown in\u00a0Tab. 5. The\u00a0supply of\u00a0pesticides to\u00a0the\u00a0reservoir by the\u00a0Ludkovick\u00fd stream remained unchanged from the\u00a0second to\u00a0fourth sampling campaigns (Fig.\u00a029). Glyphosate or its metabolite AMPA dominated in\u00a0the\u00a0initial sampling campaigns. Glyphosate as\u00a0the\u00a0parent compound was confirmed in\u00a0the\u00a0Ludkovick\u00fd stream before the\u00a0sowing of\u00a0winter cereals in\u00a0the\u00a0sixth sampling campaign and, surprisingly, also in\u00a0the\u00a0eighth sampling campaign in\u00a0November (Fig.\u00a030).<\/p>\n<\/a>Fig.\u00a029. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0Ludkovice water supply reservoir \u2013 2nd sampling campaign (May 2021)<\/h6>\n<\/a>Fig.\u00a030. Glyphosate and AMPA concentration dynamics in\u00a0the\u00a0outfall of\u00a0Ludkovick\u00fd stream above Ludkovice water supply reservoir in\u00a02021<\/h6>\n<\/a>Fig.\u00a031. Concentration of\u00a0pesticide residues in\u00a0the\u00a0basin of\u00a0Ludkovice water supply reservoir \u2013 6th sampling campaign (September 2021)<\/h6>\nConversion to\u00a0average concentration in\u00a0a watercourse<\/h3>\n
<\/a>\n