INTRODUCTION<\/h2>\n
This\u00a0article presents the\u00a0results of\u00a0long-term monitoring of\u00a0radiological indicators in\u00a0surface waters in\u00a0the\u00a0Plou\u010dnice river basin. Uranium mining took place in\u00a0the\u00a0past in\u00a0this\u00a0basin\u00a0in\u00a0the\u00a0area around Str\u00e1\u017e pod Ralskem. The\u00a0determined values of\u00a0radiological indicators are predetermined by\u00a0the\u00a0geological structure of\u00a0the\u00a0area, with the\u00a0occurrence of\u00a0uranium mineralization\u00a0and the\u00a0method of\u00a0extraction\u00a0of\u00a0raw materials containing uranium.<\/span><\/p>\n The\u00a0aim of\u00a0the\u00a0article is\u00a0to\u00a0present the\u00a0development of\u00a0the\u00a0activity of\u00a0radiological indicators in\u00a0surface waters for\u00a0the\u00a0entire monitored period 1967\u20131989 and after 1990, using archival data stored in\u00a0the\u00a0collection\u00a0database of\u00a0the\u00a0Water Quality Monitoring in\u00a0the\u00a0Czech Republic information\u00a0system (Is\u00a0ARROW), which is\u00a0provided and evaluated by\u00a0CHMI [1].<\/span><\/p>\n Uranium mineralization in the sediments of the Czech Cretaceous Basin was investigated in the first half of the 1960s. Deposit accumulations of uranium are associated with sediments of the lower (freshwater) and upper (marine) Cenomanian. The Hamr and B\u0159evni\u0161t\u011b deposits were deep mined while the Str\u00e1\u017e deposit was mined by the underground leaching method by wells from the surface. The Str\u00e1\u017e mining area was gradually expanded to 24.1 km2<\/span> [12]. Descriptive data on the uranium deposit are given in a number of reports of the mining organization (DIAMO, State Enterprise) and other publications [8, 10, 11, 13, 16, 27]. A government resolution from 1990 changed the concept of energy raw material mining and, on the basis of subsequent government decisions and resolutions [23\u201326], uranium mining slowed down. Chemical extraction at the Str\u00e1\u017e deposit was stopped as of 1st April 1996; in the following period, uranium was extracted from remediation of chemical extraction.<\/span><\/p>\n Radiological indicators in\u00a0surface water samples in\u00a0the\u00a0Plou\u010dnice basin\u00a0have been analysed in\u00a0a\u00a0laboratory since 1967, coinciding with the\u00a0start of\u00a0uranium mining in\u00a0the\u00a0vicinity of\u00a0Str\u00e1\u017e pod Ralskem, which is\u00a0located in\u00a0the\u00a0same basin.<\/span><\/p>\n In\u00a0Plou\u010dnice sub-basin, surface water sampling is\u00a0documented on\u00a0the\u00a0profiles of\u00a0Plou\u010dnice, Je\u0161t\u011bdsk\u00fd stream, Plou\u017enick\u00fd stream, Ml\u00fdnsk\u00fd n\u00e1hon, Robe\u010dsk\u00fd stream, Dobranovsk\u00fd stream, and Svit\u00e1vka. Mine water samples were taken during active uranium mining at the\u00a0Str\u00e1\u017e pod Ralskem deposit.<\/span><\/p>\n Uranium contents are determined as\u00a0metal concentrations in\u00a0dissolved substances (DS), in\u00a0non-dissolved substances (NS), and in\u00a0all substances according to\u00a0\u010cSN 75 7614 standard [6].<\/span><\/p>\n Monitoring of radioactive load is carried out on the basis of determination of radioactive indicators, i.e., total volume beta activity in dissolved (DS) and non-dissolved substances (NS). In DS, the correction of total volume beta<\/span>activity to\u00a0the\u00a040<\/span>K isotope content is\u00a0made. Monitoring of\u00a0radiological indicators is\u00a0also extended and supplemented by\u00a0determination\u00a0of\u00a0the\u00a0total volume alpha activity (DS, NS) and the\u00a0activity of\u00a0226<\/span>Ra isotope (DS, NS) [4, 5, 7].<\/span><\/p>\n Classification of profiles into quality classes is carried out according to \u010cSN 75 7221 standard [2] from October 1998; this standard was updated in 2017 [3]. The characteristic value for inclusion in quality classes, or quality according to the updated standard, is a value with a probability of not exceeding 90 %. The frequency of sampling for the entire period of more than 55 years varied in the interval from once a week to once a month, exceptionally once every two months. For statistical processing, a characteristic value defined in the mentioned standard was used, which represents a representative value for individual years. For the calculation, the values of those indicators that were analysed on representative profiles throughout the evaluated period in a continuous series were used.<\/span><\/p>\n Due to the nature of the statistical distribution of the values of radioactive indicators, when describing annual activity value, the mean value of activity measurement results is calculated, and when displayed in graphs, the value of the lower (25%) and upper (75%) quartiles is also shown.<\/span><\/p>\n Using the non-parametric Mann-Kendall test [12, 14], the values of the correlation coefficient \u03c4 and the probability measure were calculated to determine the trend of detected values of radiological indicators on the selected profiles.<\/span><\/p>\n An overview of\u00a0monitored profiles in\u00a0Plou\u010dnice river basin\u00a0(Fig. 1<\/span>) and the\u00a0time range of\u00a0their monitoring is\u00a0shown in\u00a0Tab. 1.<\/span> For\u00a0a\u00a0number of\u00a0profiles, samples were not analysed in\u00a0some periods (1 to\u00a0maximum 5 years).<\/span><\/p>\n The\u00a0highest uranium content of\u00a0up to\u00a015 mg\/l were found in\u00a0mine water in\u00a0the\u00a01980s, when the\u00a0highest total volume beta activity was\u00a0up to\u00a0684.5 Bq\/l (Fig.\u00a02<\/span>). The\u00a0highest volume beta activity on\u00a0the\u00a0monitored profiles was\u00a0documented in\u00a0the\u00a01980s at Plou\u010dnice on\u00a0the\u00a0Mimo\u0148 profile (81.64 Bq\/l), in\u00a0Str\u00e1\u017e pod Ralskem (19.1 Bq\/l), and at Ml\u00fdnsk\u00fd n\u00e1hon\u00a0on\u00a0the\u00a0Hamr profile (47.25 Bq \/l). A\u00a0clear reduction\u00a0in\u00a0total volume beta activity, or\u00a0of\u00a0this\u00a0indicator, corrected for\u00a0the\u00a0activity of\u00a0the\u00a040<\/span>K isotope, has\u00a0been recorded since the\u00a01990s. For\u00a0example, on\u00a0the\u00a0already mentioned Mimo\u0148 on\u00a0the\u00a0Plou\u010dnice profile, in\u00a0the\u00a01980s, the\u00a0mean values of\u00a0the\u00a0total volume beta activity were in\u00a0the\u00a0range of\u00a01.04\u20131.88 Bq\/l, or\u00a0in\u00a0the\u00a0range of\u00a00.9\u20131.7 Bq\/l after correction\u00a0to\u00a040<\/span>K. After mining stopped in\u00a0the\u00a01990s, the\u00a0mean value for\u00a0the\u00a0mentioned indicators decreased to\u00a00.22\u20130.4 Bq\/l and to\u00a00.05\u20130.29 Bq\/l in\u00a0the\u00a0case of\u00a0correction\u00a0to\u00a040<\/span>K. At the\u00a0beginning of\u00a0the\u00a021st century, the\u00a0values of\u00a0total volume beta activity decreased; according to\u00a0the\u00a0classification\u00a0of\u00a0\u010cSN 75 7221 standard, the\u00a0quality of\u00a0surface water already meets the\u00a0inclusion\u00a0in\u00a0class I (unpolluted waters) to\u00a0class II (mildly polluted waters) in\u00a0a\u00a0number of\u00a0consecutive years. In\u00a0recent years, the\u00a0characteristic value of\u00a0beta activity for\u00a0inclusion\u00a0in\u00a0the\u00a0quality class, as\u00a0well as\u00a0the\u00a0mean value of\u00a0the\u00a0monitored indicator, have not decreased significantly.<\/span><\/p>\n According to\u00a0\u010cSN 75 7221 standard, the\u00a0characteristic value of\u00a0uranium classifies the\u00a0quality of\u00a0surface water on\u00a0the\u00a0Mimo\u0148 profile on\u00a0the\u00a0Plou\u010dnice river during the\u00a01980s into\u00a0class V \u2013 very heavily polluted water. In\u00a0the\u00a0course of\u00a0the\u00a01990s, after the\u00a0change in\u00a0the\u00a0use of\u00a0uranium deposits, an improvement of\u00a0one qualitative class to\u00a0class IV \u2013 heavily polluted water \u2013 was\u00a0recorded on\u00a0this\u00a0profile as\u00a0well. Uranium concentrations decreased by\u00a0one order of\u00a0magnitude and did not exceed 10 \u00b5g\/l on\u00a0this\u00a0profile in\u00a0the\u00a0last 20 years (Fig. 3<\/span>). Only in\u00a0Str\u00e1\u017e pod Ralskem on\u00a0Ml\u00fdnsk\u00fd n\u00e1hon, uranium concentration\u00a0of\u00a054.5 \u00b5g\/l was\u00a0detected even after 2000.<\/span><\/p>\n Reduction in radiological indicator activity is demonstrable on profiles located lower in the direction of the Plou\u010dnice river flow. On the higher Mimo\u0148 profile on the Plou\u010dnice River, in the 1980s, the mean value of the total volume beta activity after correction to 40<\/span>K is\u00a0in\u00a0the\u00a0range of\u00a00.6\u20131.66 Bq\/l; based on\u00a0the\u00a0characteristic value it belongs to\u00a0class V \u2013 very heavily polluted water (Fig. 4<\/span>). On\u00a0the\u00a0lower profile in\u00a0B\u0159eziny, the\u00a0surface water is\u00a0classified as\u00a0class IV \u2013 heavily polluted water, the\u00a0mean value is\u00a00.182\u20130.405 Bq\/l (Fig. 5<\/span>). On\u00a0the\u00a0H\u0159ensko border profile below the\u00a0outlet of\u00a0the\u00a0Plou\u010dnice to\u00a0the\u00a0Labe\/Elbe, the\u00a0mean value is\u00a00.053\u20130.092 Bq\/l, and in\u00a0the\u00a01980s, the\u00a0water was\u00a0classified on\u00a0the\u00a0basis\u00a0of\u00a0the\u00a0characteristic value into\u00a0class III \u2013 polluted water; in\u00a0the\u00a0last 10 years the\u00a0characteristic value is\u00a0suitable for\u00a0classification\u00a0into\u00a0class I \u2013 unpolluted water (Fig. 6<\/span>).<\/span><\/p>\n The\u00a0value of\u00a0total volume alpha activity was\u00a0not determined before 1990. Alpha activity has\u00a0been decreasing since the\u00a0mid-1990s; in\u00a0the\u00a0last 10 years, for\u00a0example, increasing values of\u00a0volume alpha activity have been recorded on\u00a0the\u00a0Plou\u010dnice \u2013 Mimo\u0148 profile (Fig. 7<\/span>).<\/span><\/p>\n Activity of\u00a0226<\/span>Ra isotope on\u00a0the\u00a0monitored profiles during the\u00a0period of\u00a0intensive mining reached high values; on\u00a0the\u00a0Plou\u010dnice \u2013 Mimo\u0148 profile up to\u00a09,104 mBq\/l, according to\u00a0the\u00a0classification, the\u00a0surface water quality corresponded to\u00a0class V \u2013 very heavily polluted water. After the\u00a0end of\u00a0intensive mining, activities decreased significantly in\u00a0the\u00a01990s. After a\u00a0short period of\u00a0interruption\u00a0of\u00a0monitoring and after its resumption\u00a0about 10 years ago, the\u00a0activity of\u00a0the\u00a0226<\/span>Ra isotope increased, and in\u00a0the\u00a0last few years, based on\u00a0the\u00a0detection\u00a0of\u00a0the\u00a0activity of\u00a0this\u00a0isotope, the\u00a0water quality is\u00a0classified as\u00a0class II \u2013 slightly polluted water (Fig. 8, 9<\/span>). <\/span><\/p>\n I = increasing, D\u00a0= decreasing<\/sup><\/p>\n For the selected profiles, a trend analysis was performed for the monitored indicators. The results of the Mann-Kendall test and the values of the Kendall correlation coefficient \u03c4 for the evaluated profiles and selected indicators are shown in Tab. 2.<\/p>\n Based on\u00a0previous evaluation\u00a0of\u00a0analytical data, the\u00a0year 1990 was\u00a0chosen as\u00a0the\u00a0turning point; due to\u00a0societal changes, there was\u00a0also a\u00a0change in\u00a0the\u00a0use of\u00a0energy resources. For\u00a0the\u00a0total beta volume activity and total beta volume activity corrected to\u00a040K, an increasing trend was\u00a0confirmed before 1990 on\u00a0each of\u00a0the\u00a0three evaluated profiles. After 1990, a\u00a0downward trend was\u00a0confirmed for\u00a0the\u00a0above-mentioned indicators; however, the\u00a0trend can be confirmed by\u00a0statistical calculation\u00a0with high probability only for\u00a0two profiles. For\u00a0the\u00a0226Ra isotope, neither a\u00a0decreasing nor\u00a0an increasing trend was\u00a0confirmed in\u00a0any of\u00a0the\u00a0defined periods.<\/p>\n Based on\u00a0monitoring of\u00a0radioactive indicators for\u00a0the\u00a0period 1967\u20132021, the\u00a0following can be evaluated from the\u00a0results of\u00a0laboratory determinations of\u00a0surface water samples on\u00a0profiles in\u00a0the\u00a0Plou\u010dnice river basin:<\/p>\n The Czech version of this article was peer-reviewed, the English version was translated from\u00a0the Czech original by Environmental Translation Ltd.<\/p>\n","protected":false},"excerpt":{"rendered":" The\u00a0Czech Hydrometeorological Institute (CHMI) is\u00a0engaged in\u00a0systematic monitoring and evaluation\u00a0of\u00a0radiological indicators in\u00a0surface waters. The\u00a0article describes changes in\u00a0the\u00a0values of\u00a0radiological indicators in\u00a0surface waters in\u00a0the\u00a0time series from 1967 to\u00a0the\u00a0present. The\u00a0evolution\u00a0of\u00a0total volume alpha and beta activity, uranium concentration, and radium activity (226Ra) is\u00a0described on\u00a0characteristic profiles in\u00a0the\u00a0area of\u00a0uranium-containing raw materials mining, in\u00a0the\u00a0vicinity of\u00a0Str\u00e1\u017e pod Ralskem, where the\u00a0mining of\u00a0radioactive raw materials has\u00a0already been suppressed. The\u00a0Plou\u010dnice river flows through this\u00a0mining area and flows into\u00a0the\u00a0Elbe river in\u00a0D\u011b\u010d\u00edn near the\u00a0H\u0159ensko border crossing, where activities of\u00a0radiological indicators are also monitored and documented. Following the\u00a0cessation\u00a0of\u00a0uranium mining at the\u00a0Str\u00e1\u017e pod Ralskem deposit, uranium concentrations dropped by\u00a0two orders of\u00a0magnitude, and surface waters on\u00a0the\u00a0Plou\u010dnice \u2013 Mimo\u0148 profile have been classified as\u00a0Class I \u2013 unpolluted water for\u00a0the\u00a0last five years. The\u00a0values of\u00a0Kendall\u2019s correlation\u00a0coefficient \u03c4 for\u00a0the\u00a0profiles evaluated on\u00a0the\u00a0selected profiles during the\u00a0mining period are characterized by\u00a0an increasing trend (+0.7) for\u00a0the\u00a0indicator\u00a0of\u00a0total volume beta activity; after the\u00a0end of\u00a0mining, a\u00a0decreasing trend is\u00a0indicated (-0.5).<\/p>\n","protected":false},"author":8,"featured_media":18797,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[86,87,92],"tags":[3144,3141,3139,3095,3140,3143,3142],"coauthors":[3104,3105],"class_list":["post-21101","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hydraulics-hydrology-and-hydrogeology","category-hydrochemistry-radioecology-microbiology","category-main","tag-mann-kendall-test","tag-ploucnice-river-basin","tag-radioactive-indicators","tag-straz-pod-ralskem","tag-surface-waters","tag-the-trends-of-the-time-series","tag-uranium-deposit"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/21101","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=21101"}],"version-history":[{"count":8,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/21101\/revisions"}],"predecessor-version":[{"id":32052,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/21101\/revisions\/32052"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/18797"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=21101"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=21101"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=21101"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=21101"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Deposit characteristics<\/h3>\n
![\"\"](\"https:\/\/www.vtei.cz\/wp-content\/uploads\/2023\/04\/Stierand-obr-1-1.jpg\")
<\/a>Fig. 1. Map of the area of interest with marked profiles in Plou\u010dnice basin (those assessed in\u00a0detail are highlighted)<\/h6>\nMETHODOLOGY<\/h2>\n
RESULTS AND DISCUSSION<\/h2>\n
Tab. 1. Time range of\u00a0monitored profiles
<\/a><\/span><\/span><\/h5>\n<\/a><\/span>Fig. 2. Total volumetric beta activity in\u00a0mine water (Hamr 3 deposit)<\/h6>\n<\/a><\/span>Fig. 3. Uranium content, Plou\u010dnice \u2013 Mimo\u0148 profile<\/h6>\n<\/a>Fig. 4. Total volume activity of\u00a0beta cor. 40<\/span>K, Plou\u010dnice \u2013 Mimo\u0148 profile<\/h6>\n<\/a>Fig. 5. Total volume activity of\u00a0beta cor. 40<\/span>K, Plou\u010dnice \u2013 B\u0159eziny profile<\/h6>\n<\/a>Fig. 6. Total volume activity of\u00a0beta cor. 40<\/span>K, Labe \u2013 H\u0159ensko profile<\/h6>\n<\/a><\/span>Fig. 7. Total alpha volume activity, Plou\u010dnice \u2013 Mimo\u0148 profile<\/h6>\n<\/a><\/span>Fig. 8. Activity of\u00a0226<\/span>Ra, Plou\u010dnice \u2013 Ose\u010dn\u00e1 profile<\/h6>\n<\/a>Fig. 9. Activity of\u00a0226<\/span>Ra, Plou\u010dnice \u2013 B\u0159eziny profile<\/h6>\nTab. 2. Mann-Kendall test results
<\/a><\/span><\/span><\/h5>\nCONCLUSION AND EVALUATION<\/h2>\n
\n