Accumulation of Natural and Anthropogenic Radionuclides in Body Profiles of Bryidae, a Subgroup of Mosses
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Environmental Science and Pollution Research (2019) 26:27872–27887 https://doi.org/10.1007/s11356-019-05993-3 RESEARCH ARTICLE Accumulation of natural and anthropogenic radionuclides in body profiles of Bryidae, a subgroup of mosses Qiangqiang Zhong1 & Jinzhou Du1 & Viena Puigcorbé2 & Jinlong Wang1 & Qiugui Wang3 & Binbin Deng1 & Fule Zhang1 Received: 15 March 2019 /Accepted: 16 July 2019 /Published online: 25 July 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Mosses can be used as biomonitors to monitor radionuclide deposition and heavy metal pollution in cities, forests, and grasslands. 210 210 210 210 The aims of this work were to determine the activity concentrations of natural ( Po, Pb or Pbex (excess Pb is defined as the activity of 210Pb minus the activity of 226Ra), 7Be, 40K, 226Ra, 238U, and 232Th) and anthropogenic radionuclides (137Cs) in moss body profiles and in situ underlying soils of moss samples and to assess/determine the distribution features and accumulation of these radionuclides. Activity concentrations of radionuclides in the samples were measured using a low-background gamma spectrometer and a low-background alpha spectrometer. Consistent with their source, the studied radionuclides in the moss samples and underlying 210 210 210 7 soils were divided according to the principal component analysis (PCA) results into an airborne group ( Po, Pb ( Pbex), Be, 137 40 238 226 232 210 210 and Cs) and a terrestrial group ( K, U, Ra, and Th). The activity concentrations of Po and Pbex in moss body profiles 210 210 were mainly concentrated in the stems–rhizoid parts, in which we measured some of the highest Po and Pbex levels compared to the results in the literature. 7Be mainly accumulated in the leaves–stem parts. Different positive correlations were observed between 210Po and 210Pb and between 7Be and 210Pb, which indicated that the uptake mechanisms of 210Po, 210Pb, and 7Be by moss plants were different, to some extent. 137Cs was detected only in some moss samples, and the fraction of 137Cs in the underlying soils was much lower than that in the moss, suggesting that mosses were protecting the underlying soils from further pollution. Except for 40K, the terrestrial radionuclide (238U, 226Ra, and 232Th) content in mosses was predominantly at low levels, which indicated not only the inability of mosses to use those elements for metabolic purposes but also the rather poor capability of mosses to directly mobilize, absorb, and transport elements (U, Ra, or Th) not dissolved in water. Highlights 1. 210Po, 210Pb, 7Be, 137Cs, 40K, 226Ra, 238U, and 232Th activity concentrations in vertical moss profiles were measured. 2. PCA distinguished these radionuclides into airborne and terrestrial sources. 3. Extremely high levels of 210Po and 210Pb and the deficiency of 210Po relative to 210Pb were observed in moss bodies. 4. 7Be almost exclusively accumulated in the leaves–stem tissues of all moss samples. 5. Mosses taken from Svalbard showed very high 137Cs levels, indicating that mosses may accumulate 137Cs and protect soils from further pollu- tion. 6. Low accumulation of terrestrial radionuclides (238U, 226Ra, and 232Th) was found in mosses, suggesting the inefficient uptake mechanisms of moss plants and their inability to use these elements. Responsible editor: Georg Steinhauser * Jinlong Wang 2 School of Science, Centre for Marine Ecosystems Research, Edith [email protected] Cowan University, Joondalup, WA 6027, Australia 3 State Key Laboratory of Nuclear Resources and Environment, East 1 State Key Laboratory of Estuarine and Coastal Research, East China China University of Technology, Nanchang 330013, Jiangxi Normal University, Shanghai 200241, People’sRepublicofChina Province, People’s Republic of China Environ Sci Pollut Res (2019) 26:27872–27887 27873 Keywords Accumulation . Biomonitoring . Moss body profiles . 137Cs . 7Be . 210Po–210Pb disequilibrium . Terrestrial radionuclides Introduction 7Be (half-life 53.3 days) is a cosmogenic radionuclide pro- duced in the stratosphere and upper troposphere by the inter- Mosses are nonvascular plants that grow on various substrata actions of high-energy particles of cosmic rays with the nuclei and in various habitats, forming an important component of of the most abundant elements in the air (Du et al. 2015;Lal the terrestrial ecosystem of various climate zones. Mosses are et al. 1958). The amount of 7Be in the atmosphere depends on a highly diverse group, with more than 10,000 species record- the cosmic ray flux, proton flux from the sun during solar ed in the global dataset (Geffert et al. 2013). In contrast to activities, stratosphere–troposphere exchange, and meteoro- vascular plants, mosses have no root systems, and they lack logical conditions. After it is formed, 7Be attaches to aerosols a water-repellent cuticle on their body surface. In addition, because of its high affinity for particles. Thus, both radon mosses obtain most nutrients for growth directly from the air daughters (210Po, 210Pb) and 7Be follow all atmospheric pro- via precipitation or by dry deposition. Hence, their capacity cesses for the transport, scavenging, and deposition of aero- for accumulation of airborne elements is greater than that of sols (Chen et al. 2016). other terrestrial plants growing in the same environments Man-made radionuclides in terrestrial and marine environ- (Aleksiayenak et al. 2013; Ross and Wesley 2011). ments come from many different sources, including direct dis- Furthermore, their morphologies are not affected by seasons, charges from nuclear installations (fuel reprocessing facilities or leading to the retention and accumulation of pollutants nuclear power plants), thermonuclear bomb testing, geological throughout the year (Wattanavatee et al. 2017). Thus, these repository of high-level nuclear wastes, leakages from disposed properties make moss an ideal medium for monitoring heavy radioactive waste containers, and nuclear accidents (Hu et al. metal pollution and radionuclides in various environments, 2010; Kershaw and Baxter 1995; Steinhauser et al. 2014). such as in mining areas (Demková et al. 2017; Pettersson However, the artificial radionuclide 137Cs that has been released et al. 1988;Tsikritzis2005), coal-fired power plants into the atmosphere mostly originated from more than 400 at- ğ (Delfanti et al. 1999;Sertetal.2011;U ur et al. 2003), or mospheric nuclear weapon tests and nuclear accidents (e.g., the areas affected by nuclear accidents (Chernobyl: Celik et al. Chernobyl nuclear accident and Fukushima accident) (Krmar 2009; Dragović et al. 2010; Mitrović et al. 2016; et al. 2013). Globally, there were no significant 137Cs emissions Fukushima: Oguri and Deguchi 2018). after the Chernobyl accident; although the Fukushima accident Many studies that monitored radioactive substances taken up released 137Cs into the atmosphere, the effects were minor in by mosses have focused on one or several types of radionu- 137 clides (Boryłoetal.2017;Długosz-Lisiecka and Wróbel 2014; regions far from Japan (Betsou et al. 2018). Hence, Cs was Oguri and Deguchi 2018). To better understand the transfer and removed from the atmosphere through physical decay as well as uptake of radionuclides by wild moss species and to add to the wet and dry deposition, and subsequently, it reached aquatic and body of knowledge on the monitoring of the radionuclides re- terrestrial environments in sediments, soils, and biota leased into the environment as a whole, investigations on both (Aleksiayenak et al. 2013; Burger and Lichtscheidl 2018; natural (238U, 232Th, 226Ra, radon daughters, 40K, and 7Be) and Dragović et al. 2010). anthropogenic radionuclides (137Cs) are needed. In contrast to the airborne radionuclides, the terrestrial ra- 226Ra (half-life 1620 years) is a member of the 238U(half- dionuclides, 40K, 232Th, 238U, and 226Ra, originate from crust- life 4.47 × 109 years) decay chain. After the alpha decay of al materials in soil particles. These radionuclides can also be 226Ra in soil, the product 222Rn (half-life 3.8 days), as a nat- transported and removed from the atmosphere by the dry or ural radioactive gas, escapes from the ground and diffuses into wet deposition of dust particles, especially during dust storms. the air. 222Rn decay products include the long-lived 210Pb 40K (half-life 1.25 × 109 years) is an isotope of potassium. (half-life 22.4 years) and 210Po (half-life 138.4 days), which Although 40K is not abundant in nature, the element K is can be present as unattached radon particles and/or as attached important for the metabolism of all living cells. 238U, 232Th radon particles (Li et al. 2019) in the atmosphere. In addition, (half-life 1.40 × 1010 years), and 226Ra are ubiquitous through- 210Pb and 210Po can also be released from anthropogenic out the earth’s surface. The global average activities of 40K, sources, and their levels have increased in the environment 232Th, and 238U in soil are estimated to be 400, 35, and − as a result of human activities such as the operation of power 30 Bq kg 1, respectively (UNSCEAR 2000). plants that burn fossil fuels, agriculture, fertilizer industries, Krmar et al. (2007)measured7Be, 214Bi, and 210Pb activities and exhaust fumes from vehicles (Belivermiş et al. 2016; in moss samples collected in Serbia and suggested that terrestrial Boryłoetal.2013; Martínez-Aguirre et al. 1996;Sertetal. mosses are a possible medium for the detection of the atmo- 2011;Uğur et al. 2009). spheric deposition of 7Be