INTRODUCTION<\/h2>\n
Persistent substances arise as a\u00a0result of\u00a0various industrial and other anthropogenic activities. Some of\u00a0them have been produced deliberately (pesticides, brominated flame retardants, polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFAS)), while others arise as unintended by-products (polycyclic aromatic hydrocarbons (PAHs), dioxin\u00a0compounds). These substances may also be released from various consumer products, which serve as their source (flame retardants used in\u00a0furniture, household appliances or textiles, nanomaterials, chemicals used to create non-stick surfaces, plasticisers, phthalates, etc.). From their point of\u00a0origin, contaminants can be transported through the\u00a0atmosphere and subsequently distributed globally into other environmental components. Important pathways for their entry into the\u00a0environment is through wastewater, contaminated soils, and waste landfills [1]. The\u00a0high chemical stability and lipophilic nature of\u00a0these substances lead to their sorption onto solid particles, accumulation in\u00a0organisms, and subsequent transfer through food chains. Due to their ability to be transported over long distances from the\u00a0source of\u00a0pollution, some persistent organic pollutants (POPs) tend to contaminate even remote ecosystems and negatively affect the\u00a0health of\u00a0organisms on a\u00a0global scale. For example, in\u00a0polar bears, they can disrupt hormonal processes [2].<\/p>\n
In\u00a0aquatic ecosystems, contaminants are distributed among different matrices. Depending on their physicochemical properties, some substances have a\u00a0higher affinity for organic carbon and therefore primarily accumulate in\u00a0sediments or suspended solids, while others tend to accumulate in\u00a0the\u00a0fatty tissues of\u00a0organisms or bind to proteins \u2013 e.g., PFAS [3]. In\u00a0water, most POPs are found only in\u00a0minimal concentrations due to their very low solubility. For this reason, to assess the\u00a0pollution status of\u00a0an aquatic ecosystem by certain\u00a0contaminants (such as mercury, phthalates, DDT, or PCBs), it is more appropriate to monitor solid matrices. Passive samplers also play a\u00a0significant role here, as they concentrate dissolved substances directly from the\u00a0water column, allowing their effective detection even at very low concentrations [4, 5].<\/p>\n
In\u00a0addition to well-characterised environmental contaminants (DDT, PCBs, PAHs), a\u00a0number of\u00a0relatively new, so-called emerging pollutants are also entering the\u00a0environment, whose toxic effects have not yet been fully explored. This group includes a\u00a0wide range of\u00a0chemical substances, such as pharmaceuticals, personal care products, pesticides, and their metabolites. Many of\u00a0these substances are characterised by high mobility in\u00a0the\u00a0environment due to their solubility in\u00a0water, which can result in\u00a0their presence even in\u00a0drinking water [6]. It is also important to consider degradation products or synergistic interactions between different pollutants, which can induce toxic effects even at concentrations individually considered safe [7].<\/p>\n
As part of\u00a0the\u00a0regular annual monitoring of\u00a0solid matrices, the\u00a0Czech Hydrometeorological Institute (CHMI) tracks the\u00a0content of\u00a0more than 90 substances that have the\u00a0potential to accumulate in\u00a0both biotic and abiotic components of\u00a0aquatic ecosystems. The\u00a0main\u00a0aim of\u00a0this article is a\u00a0comprehensive assessment of\u00a0water pollution by hazardous substances from various perspectives, focusing on differences between individual matrices, including long-term trends and the\u00a0influence of\u00a0specific profiles.<\/p>\n
METHODOLOGY<\/h2>\n
A\u00a0total of\u00a043 profiles of\u00a0the\u00a0main\u00a0rivers in\u00a0the\u00a0Czech Republic were selected for the\u00a0assessment, where all monitored matrices are sampled in\u00a0the\u00a0long term (Fig.\u00a01<\/span><\/em>). In\u00a0the\u00a0case of\u00a0biotic matrices, these profiles are divided into two sets, which alternate every three years. The\u00a0list of\u00a0monitored matrices, the\u00a0number of\u00a0samples per year, and the\u00a0corresponding units are provided in\u00a0Tab.\u00a01<\/span><\/em>.<\/span><\/p>\n For benthic organism analyses, the\u00a0main\u00a0samples are leeches (Erpobdella<\/span> spp.<\/em>), caddisflies (Hydropsyche<\/span> spp.<\/em>), and amphipods (Gammarus<\/span> spp.<\/em>) For adult fish, the\u00a0species is the\u00a0common chub (Squalius cephalus<\/span><\/em>). Semipermeable Membrane Device (SPMD) passive samplers, used for monitoring non-polar organic micropollutants, are filled with triolein\u00a0fat and exposed to water for three weeks. Sedimentable solids are sampled for four to eight weeks, depending on the\u00a0specific location, using sediment trap boxes, and the\u00a0suspended solids are actively collected with a\u00a0mobile centrifuge.<\/span><\/p>\n The\u00a0substances selected for analysis of\u00a0aquatic ecosystems contamination include: benzo(a)pyrene (B(a)P) and fluoranthene (FLU) as representatives of\u00a0polycyclic aromatic hydrocarbons (PAHs), di(2-ethylhexyl) phthalate (DEHP), polybrominated diphenyl ethers (PBDEs), PCBs, DDT and its metabolites, perfluorooctane sulfonate (PFOS), and mercury (Hg). Of\u00a0the\u00a0selected contaminants, only PAHs are analysed in\u00a0the\u00a0biofilm. In\u00a0the\u00a0case of\u00a0abiotic matrices, concentrations are not normalised to organic carbon content. Chemical analyses are conducted in\u00a0external laboratories depending on the\u00a0matrix and the\u00a0group of\u00a0substances monitored. For the\u00a0determination of\u00a0metals and PFAS in\u00a0adult fish, muscle tissue samples were used, while other organic substances were analysed in\u00a0muscle tissue with skin.<\/span><\/p>\n Boxplots were used to interpret the data, incorporating results from 2006\u20132023 depending on the\u00a0type of\u00a0matrix and the\u00a0substance monitored. Selected substances have a\u00a0limit concentration, known as the\u00a0environmental quality standard\u00a0(EQS) for biota, established by Government Regulation\u00a0No.\u00a0401\/2015 Coll., against which the\u00a0measured concentrations are compared.<\/span><\/p>\n The\u00a0distribution of\u00a0substances differs between the\u00a0various biotic and abiotic matrices (Fig.\u00a02<\/span><\/em>). Specific differences in\u00a0the\u00a0distribution of\u00a0contaminants across matrices reflect their differing physicochemical properties and interactions with the\u00a0environment. Analytical method parameters, such as the\u00a0limit of\u00a0quantification (LOQ), may also play an important role.<\/span><\/p>\n PAHs were found above the\u00a0LOQ in\u00a0100\u00a0% of\u00a0biofilm, suspended solids, and sedimentable solids samples. Currently, PAH analyses are not conducted in\u00a0adult fish, as these substances can undergo significant metabolism within\u00a0the\u00a0fish organism [8]. This also partly affects the\u00a0occurrence of\u00a0PAHs in\u00a0juvenile fish, where, for example, B(a)P was detected in\u00a0less than half of\u00a0the\u00a0samples. PBDEs were found in\u00a0more than 75\u00a0% of\u00a0biota samples, in\u00a0contrast to abiotic matrices and water, where they were rarely detected above the\u00a0LOQ. PFOS was present in\u00a0nearly 100\u00a0% of\u00a0biota samples, with slightly lower occurrence in\u00a0abiotic matrices, except for sediments, where \u2013 similarly to water \u2013 it was detected in\u00a0only 25\u00a0% of\u00a0samples. Mercury was detected in\u00a0nearly 100\u00a0% of\u00a0solid matrices, while in\u00a0water it was recorded in\u00a0only 10\u00a0% of\u00a0cases.<\/span><\/p>\n Benzo(a)pyrene (B(a)P) and fluoranthene were assessed as representatives of\u00a0PAHs, with concentrations in\u00a0biota ranging two to three orders of\u00a0magnitude lower than in\u00a0abiotic matrices (Fig.\u00a03<\/em>). An exception is biofilm, which, unlike most animals, lacks a\u00a0metabolic transformation mechanism for PAHs, so their concentrations are comparable to those in\u00a0abiotic matrices. However, biofilm may also contain\u00a0a\u00a0certain\u00a0amount of\u00a0inseparable abiotic fraction, which can influence the\u00a0resulting concentrations. In\u00a0juvenile fish, PAH concentrations are orders of\u00a0magnitude lower than in\u00a0benthos, which can be attributed not only to differences in\u00a0metabolic capacity but also to the\u00a0fact that benthic organisms are exposed to significantly higher PAH levels from sediments than fish. Although both benthic organisms and juvenile fish metabolise PAHs through similar mechanisms involving cytochrome P450 enzyme systems, this capacity is considerably limited in\u00a0some benthic species [9]. However, the\u00a0lower measured concentrations of\u00a0parent PAHs in\u00a0organisms may be due to their rapid transformation into potentially more toxic metabolites, whose concentrations can be higher compared to the\u00a0original substances [9]. In\u00a0abiotic matrices, the\u00a0concentrations of\u00a0B(a)P and FLU were comparable in\u00a0magnitude, with FLU detected at higher concentrations in\u00a0all matrices. This difference can be explained by the\u00a0greater amount of\u00a0FLU released during combustion processes and its higher environmental stability [10].<\/p>\n Another substance evaluated was DEHP, which accumulates most in benthic organisms among the biota (Fig. 4<\/em>). It is also the substance found in the highest amount in benthos of all the contaminants monitored. In abiotic matrices, DEHP concentrations are highest in suspended solids and lowest in sediments, directly proportional to the total organic carbon content. According to Huang et al. [11], a positive correlation was demonstrated between certain water parameters, such as chemical oxygen demand and ammonium\u00a0nitrogen concentration, and DEHP concentration in\u00a0sediments; however, no effect of\u00a0water temperature was observed. In\u00a0contrast to our results, the\u00a0mentioned study measured higher DEHP concentrations in\u00a0fish than in\u00a0benthic organisms, although the\u00a0fish were predatory species (the\u00a0chub is omnivorous).<\/span><\/p>\n Mercury concentrations (Fig.\u00a05<\/span><\/em>) show a\u00a0different distribution across matrices compared to DEHP. In\u00a0fish, mercury occurs at significantly higher concentrations over the\u00a0long term than in\u00a0other biotic matrices. In\u00a0adult fish, the\u00a0majority (up to 95\u00a0%) of\u00a0total mercury may be present in\u00a0the\u00a0form of\u00a0neurotoxic methylmercury (MeHg), which primarily binds strongly to muscle tissue, where it accumulates in\u00a0the\u00a0long term. In\u00a0contrast, inorganic mercury Hg(II) tends to accumulate in\u00a0the\u00a0digestive system and liver, from where it is more easily eliminated [12]. An important property of\u00a0MeHg is biomagnification, where its concentration increases with the\u00a0trophic level of\u00a0the\u00a0organism; therefore, MeHg accumulates at demonstrably lower concentrations in\u00a0benthic organisms, which occupy a\u00a0lower level in\u00a0the\u00a0food chain, compared to predatory fish species. Unlike in\u00a0biota, most mercury in\u00a0abiotic matrices is present in\u00a0inorganic form (MeHg represents at most a\u00a0few percent of\u00a0total mercury [13]), which may explain\u00a0the\u00a0negative correlation with organic carbon content confirmed by our results.<\/span><\/p>\n From a\u00a0long-term perspective, concentrations of\u00a0DDT, PCB, and PFOS occur in\u00a0all matrices within\u00a0a\u00a0similar order of\u00a0magnitude (Fig.\u00a06<\/em>). Slight differences were measured for PCB, which are found at the\u00a0highest concentrations in\u00a0sedimentable solids, and for DDT, where the\u00a0highest accumulation was recorded in\u00a0SPMD passive samplers. In\u00a0SPMDs, concentrations are expressed only relative to fat content, which confirms the\u00a0high affinity of\u00a0DDT for lipids. The\u00a0highest concentrations of\u00a0PFOS in\u00a0biotic matrices are regularly found in\u00a0juvenile fish. This may be because, unlike the\u00a0substances mentioned above, PFOS has an amphiphilic character and, besides fatty tissue and muscle, it is also present in\u00a0high concentrations in\u00a0blood, where it binds primarily to plasma proteins [3].<\/p>\n In\u00a0the\u00a0long term, specific trends in\u00a0the\u00a0concentrations of\u00a0hazardous substances are evident in\u00a0the\u00a0monitored profiles. The\u00a0load on individual profiles is influenced not only by current industry but also by legacy environmental burdens, which include river sediments, where excavation can lead to remobilisation of\u00a0contaminants. Tab.\u00a02<\/span><\/em> summarises the\u00a0profiles most heavily burdened over the\u00a0long term by selected substances. PAHs were regularly found at elevated concentrations in\u00a0profiles from the\u00a0Moravian-Silesian Region, particularly in\u00a0the\u00a0area of\u00a0the\u00a0Ostrava-Karvin\u00e1 coal basin. DDT and PCB exhibited the\u00a0highest concentrations in\u00a0the\u00a0downstream profiles of\u00a0the\u00a0Elbe, specifically in\u00a0the\u00a0D\u011b\u010d\u00edn area, which may indicate cumulative transport of\u00a0these POPs from the\u00a0upper parts of\u00a0the\u00a0basin. In\u00a0the\u00a0\u00dast\u00ed Region, in\u00a0the\u00a0profiles of\u00a0the\u00a0B\u00edlina and Oh\u0159e rivers, PFOS was found in\u00a0the\u00a0highest concentrations. Compared to other locations, the\u00a0highest concentrations of\u00a0DDT were measured in\u00a0the\u00a0B\u00edlina \u2013 \u00dast\u00ed nad Labem profile in\u00a0samples of\u00a0not only biota but also other matrices (Fig.\u00a07<\/span><\/em>).<\/span><\/p>\n For a\u00a0more detailed assessment, bioaccumulation of\u00a0PFOS in\u00a0juvenile fish was analysed, where concentrations regularly exceeded the\u00a0EQS limit of\u00a09.1\u00a0\u03bcg\u00a0\u2219\u00a0kg-1<\/sup> (Fig.\u00a08<\/span><\/em>). Among the\u00a0biotic matrices evaluated, the\u00a0highest frequency of\u00a0this value exceedance was recorded in\u00a0juvenile fish samples, with more than 50\u00a0% of\u00a0analysed samples exceeding the\u00a0EQS. In\u00a0contrast, exceedance of\u00a0the\u00a0EQS was recorded in\u00a0only 20\u00a0% of\u00a0benthic organism and adult fish samples during the\u00a0monitored period.<\/span><\/p>\n An overview of\u00a0mercury loads in\u00a0fish at individual profiles, along with a\u00a0comparison to the\u00a0EQS value for all biotic matrices, is summarised in\u00a0Fig.\u00a09<\/span><\/em>. The\u00a0EQS for mercury, set at 20 \u03bcg \u2219 kg-1<\/span>, was exceeded in\u00a0100\u00a0% of\u00a0adult fish samples. However, within\u00a0the\u00a0framework of\u00a0the\u00a0European assessment of\u00a0surface waters in\u00a0the\u00a0Czech Republic (similarly to many other countries), due to non-standardised evaluation procedures, most profiles show good chemical status in\u00a0terms of\u00a0mercury contamination, although this status was calculated from mercury concentrations in\u00a0water, not in\u00a0fish. In\u00a0contrast, in\u00a0Sweden, which uses mercury concentrations obtained from biota to assess chemical status, all measured profiles indicate poor status, even though mercury concentrations in\u00a0fish there may be lower than ours [14, 15].<\/span><\/p>\n The long-term development of concentrations was also assessed over the monitored period. Trends do not differ among individual representatives of biotic and abiotic matrices; however, a difference between these two groups was observed for certain substances. In some profiles, a decreasing trend was identified for biotic matrices only in the case of DDT and PBDE. Mercury concentrations in all matrices, as well as B(a)P in abiotic matrices, have remained broadly stable over the years. In contrast, B(a)P in biota and PFOS in abiotic matrices show a more fluctuating development of concentrations without any\u00a0<\/span>clear systematic pattern. For example, no decreasing trend has been observed in\u00a0PFOS concentrations in\u00a0juvenile fish, despite its inclusion in\u00a0the\u00a0Stockholm Convention in\u00a02009, which significantly restricted its production [16] (Fig.\u00a010<\/span><\/em>). The\u00a0historically highest concentration of\u00a0PFOS (409 \u03bcg\u00a0\u2219\u00a0kg-1<\/span><\/sup>) was recorded in\u00a0juvenile fish at the\u00a0B\u00edlina \u2013 \u00dast\u00ed nad Labem profile in\u00a02016.<\/span><\/p>\n For a\u00a0comprehensive assessment of\u00a0aquatic ecosystem contamination, systematic monitoring of\u00a0all matrices is necessary due to the\u00a0uneven distribution of\u00a0contaminants among them. Among the\u00a0biotic matrices, the\u00a0highest concentrations of\u00a0mercury were measured in\u00a0adult fish, with accumulation directly proportional to the\u00a0trophic level within\u00a0the\u00a0food chain. In\u00a0contrast, PAHs and DEHP were detected at the\u00a0highest concentrations in\u00a0benthic organisms, which are unable to metabolise these substances effectively. PFOS predominated in\u00a0juvenile fish, where it accumulates significantly not only in\u00a0fat and muscle tissue, but also in\u00a0blood. In\u00a0abiotic matrices, elevated concentrations of\u00a0substances were detected in\u00a0suspended solids (DEHP, PFOS) and in\u00a0sedimentable solids (DDT, PCBs). In\u00a0sediments, the\u00a0concentrations of\u00a0these POPs are lower, which may be related to the\u00a0lower organic carbon content in\u00a0this matrix.<\/span><\/p>\n The\u00a0continuous development of\u00a0analytical methods enables monitoring of\u00a0an ever-wider range of\u00a0xenobiotic substances which, combined with promising technologies for the\u00a0elimination of\u00a0toxic substances, green manufacturing processes, and ongoing updates to environmental legislation, can lead to the\u00a0gradual minimisation of\u00a0anthropogenic pollution. However, evaluating current results remains challenging because limits ensuring a\u00a0good status of\u00a0aquatic ecosystems are set for biota for only a\u00a0limited number of\u00a0substances, and not at all for abiotic solid matrices (despite the\u00a0large number of\u00a0measured indicators).<\/span><\/p>\n This article was created with the\u00a0support of\u00a0the\u00a0project of\u00a0the\u00a0National Agency for Agricultural Research (NAZV) No. QL24010384 \u201cMedium-term trend in\u00a0the\u00a0behaviour of\u00a0micropollutants originating from wastewater or sludge from wastewater treatment plants in\u00a0the\u00a0soil environment\u201d and as part of\u00a0the\u00a0Long-term Concept for the\u00a0Development of\u00a0a\u00a0Research Organisation (DKRVO) of\u00a0the\u00a0Czech Hydrometeorological Institute (CHMI) for the\u00a0period 2023\u20132027, funded by the\u00a0Ministry of\u00a0the\u00a0Environment of\u00a0the\u00a0Czech Republic (MoE CR).<\/span><\/span><\/em><\/p>\n The\u00a0Czech version of\u00a0this article was peer-reviewed, the\u00a0English version was\u00a0translated from the\u00a0Czech original by Environmental Translation Ltd.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":" Monitoring of substances such as halogenated and other hazardous organic pollutants or heavy metals provides valuable information about environmental pollution. These persistent substances accumulate in both biotic and abiotic compartments, as well as in food chains, and many of them act as human carcinogens and endocrine disruptors. The Czech Hydrometeorological Institute\u2019s annual monitoring results show long-term contamination of surface water ecosystem in the Czech Republic by these substances. <\/p>\n","protected":false},"author":8,"featured_media":35497,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[87,93],"tags":[3848,3847,3850,3849],"coauthors":[3815,3816,324,3817,3105,3104],"class_list":["post-35793","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hydrochemistry-radioecology-microbiology","category-two-articles","tag-accumulation","tag-mercury","tag-rivers-of-the-czech-republic","tag-solid-matrices"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/35793","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/comments?post=35793"}],"version-history":[{"count":7,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/35793\/revisions"}],"predecessor-version":[{"id":35825,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/35793\/revisions\/35825"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/35497"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=35793"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=35793"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=35793"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=35793"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/www.vtei.cz\/wp-content\/uploads\/2025\/06\/Roztocilova-obr-1.jpg\")
<\/a>\nFig. 1. Map of\u00a0monitored profiles<\/h6>\n
Tab.\u00a01. Evaluated matrices<\/h5>\n
<\/a>\nRESULTS AND DISCUSSION<\/h2>\n
Occurrence of\u00a0selected contaminants in\u00a0monitored\u00a0matrices<\/h3>\n
<\/a>\nFig. 2. Occurrence of\u00a0selected substances above LOQ [%] in\u00a0individual matrices for the\u00a0period 2006\u20132023 (according to specific matrix and substance)<\/h6>\n
Distribution of\u00a0substances in\u00a0solid matrices of\u00a0surface\u00a0waters<\/h3>\n
<\/a>\nFig. 3. Long-term concentration of\u00a0selected PAHs: a) Biotic matrices without biofilm; b) Abiotic matrices, biofilm. Individual boxes include data from all monitored profiles for selected years (benthos: 2012\u20132023, others: 2006\u20132023). Medians (\u2013), means (\u00d7), quartiles (box boundaries), and \u201emaximum\/minimum\u201c (line endpoints) are indicated, excluding outliers<\/h6>\n
<\/a>\nFig. 4. Long-term concentration of\u00a0DEHP: a) Biotic matrices; b) Abiotic matrices. Individual boxes include data from all monitored profiles for selected years (adult fish: 2012\u20132023, others: 2010\u20132023). Medians (\u2013), means (\u00d7), quartiles (box boundaries), and \u201emaximum\/minimum\u201c (line endpoints) are indicated, excluding outliers<\/h6>\n
<\/a>\nFig. 5. Long-term concentration of\u00a0mercury: a) Biotic matrices; b) Abiotic matrices. Individual boxes include data from all monitored profiles for selected years (2006\u20132023). Medians\u00a0(\u2013), means (\u00d7), quartiles (box boundaries), and \u201emaximum\/minimum\u201c (line endpoints) are indicated, excluding outliers<\/h6>\n
<\/a>\nFig. 6. Long-term concentration of\u00a0selected POPs. Individual boxes include data from all monitored profiles for selected years (PCB, DDT: 2006\u20132023, PFOS biota: 2010\u20132023). Medians\u00a0(\u2013), means (\u00d7), quartiles (box boundaries), and \u201emaximum\/minimum\u201c (line endpoints) are indicated, excluding outliers<\/h6>\n
Contamination of\u00a0individual profiles<\/h3>\n
Tab.\u00a02. Profiles exhibiting maximal contamination by target substances in\u00a0environmental matrices<\/h5>\n
<\/a>\n<\/a>\nFig. 7. DDT Concentrations in\u00a0benthic organisms across monitored profiles for the\u00a0period 2006\u20132023; profiles with the\u00a0highest measured concentrations are marked in\u00a0red<\/h6>\n
<\/a>\nFig. 8. PFOS concentrations in\u00a0juvenile fish across monitored profiles for the\u00a0period 2010\u20132023; profiles marked in\u00a0red indicate locations where the\u00a0Environmental Quality Standard (EQS) limit (red line) was exceeded in\u00a0almost all samples (the\u00a0table presents the\u00a0percentage of\u00a0profiles exceeding the\u00a0EQS during the\u00a0monitored period in\u00a0biotic matrices)<\/h6>\n
<\/a>\nFig. 9. Hg concentrations in\u00a0adult fish across monitored profiles for the\u00a0period 2006\u20132023; profiles marked in\u00a0red indicate locations where the\u00a0Environmental Quality Standard (EQS) limit\u00a0(red line) was exceeded in\u00a0almost all samples (the\u00a0table presents the\u00a0percentage of\u00a0profiles exceeding the\u00a0EQS during the\u00a0monitored period in\u00a0biotic matrices)<\/h6>\n
Long-term trend<\/h3>\n
<\/a>\nFig. 10. Long-term trend of\u00a0PFOS in\u00a0juvenile fish with indicated maximum concentration<\/h6>\n
CONCLUSIONS<\/h2>\n
Acknowledgements<\/h3>\n