Thallium Concentrations, Sources and Ecological Risk in the Surface
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Marine Pollution Bulletin 138 (2019) 206–212 Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Baseline Thallium concentrations, sources and ecological risk in the surface T sediments of the Yangtze Estuary and its adjacent east China marginal sea: A baseline study ⁎ Wen Zhuanga,b, , Yongxia Liua, Lebin Tanga, Wen Yuea, Jinhu Liua, Yuxuan Rena, Xiping Wanga, ⁎⁎ Shanshan Xua, Shaohua Taia, Jing Zhanga, Yu Zhenga, Feng Guoa, Qian Wanga, Jinming Songb, , Liqin Duanb, Qing Chenc a College of City and Architecture Engineering, Zaozhuang University, Zaozhuang, Shandong 277160, China b Key Laboratory of Marine Ecology and Environmental Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China c College of Life Sciences, Zaozhuang University, Zaozhuang, Shandong 277160, China ARTICLE INFO ABSTRACT Keywords: The distribution characteristics, sources and ecological risk of thallium (Tl) in the surface sediments of Yangtze Thallium Estuary and its adjacent sea were studied. Tl concentrations ranged from 0.369 to 1.197 μg g−1 with an average Variation characteristics of 0.674 μg g−1, which was slightly higher than the corresponding background values. Tl concentrations were Sources relatively high in sediments of the south bank of Chongming Island and the Hangzhou Bay mouth, and gradually Ecological risk decreased from inner shelf to outer seas. The variation trend of Tl concentrations was controlled by sediment Surface sediment characteristics, hydrodynamic conditions and sources together. The sediment flux of Tl in the study area was The Yangtze Estuary and its adjacent seas 428.6 t/yr. The Yangtze River, the Yellow River and atmospheric inputs of Tl accounted for 52.7%, 10.5%, and 0.15% of the total sediment flux, respectively. The result of potential ecological index indicated that Tl insurface sediments of the study area had no threat to the ecological environment. As a natural component of the earth's crust, thallium (Tl) exists in Viraraghavan, 2005; Zhang et al., 2014; Campanella et al., 2016). almost all kinds of environmental media. Tl has higher toxicity to The average concentrations of Tl in the continental crust and the human bodies than other heavy metals such as mercury, cadmium, marine crust are 0.013 ppm and 0.49 ppm, respectively (Delvalls et al., lead, copper or zinc. The chemical properties of Tl are very similar to 1999). Tl concentrations in uncontaminated sediments are generally heavy metals such as lead, gold and silver, and alkali metals such as K, between 0.01 and 5.7 ppm, while the concentrations of Tl can reach Rb and Cs (Peter and Viraraghavan, 2005). Moreover, since the ionic tens of ppm or more in industrial contaminated sediments (Wang et al., radius of Tl (I) (1.49 Å) is similar to that of the hard cation, K (I) 2010). Previous studies suggest that Tl concentrations are higher in the (1.33 Å), the nondiscriminatory uptake of Tl (I) over K (I) has been Pacific Ocean sediments compared to other oceans of the world(Belzile suggested as a mechanism for its toxicity to biota (Duan et al., 2012). and Chen, 2017). Ferrous manganese ore containing hydrogen and Because of the very low concentrations of Tl in natural environment, oceanic clay usually contains relatively high Tl content. Tl also can be pollution and poisoning caused by Tl in natural environment are rare. crystallized in interlayers of illitic or vermiculitic clays; therefore, the Since Tl is usually associated with various metallic sulfide ores and coal distribution of Tl in sediments is often controlled by clay (Duan et al., mines, the wastes from smelting and mining activities are the main 2012). FeeMn oxides also play important roles in the distribution of Tl. sources of Tl pollution (Liu et al., 2017). Tl enrichment has been ob- A large percentage (45–70%) of Tl extracted in the reducible fraction served in the southwest of Guizhou province (China) due to weathering made of iron and manganese oxyhydroxides was reported on estuarine of Tl-Hg-As sulfides (Xiao et al., 2004). In recent years, many un- sediments (Anagboso et al., 2013). Previous studies show that MnO2 expected, occupational or deliberate Tl poisoning incidents have been has strong affinity for Tl, and this closely integrated mechanism isthat caused by mining, metal smelting, industrial production and geo- Tl (I) is oxidized to Tl (III) and thus tightly adsorbed on or precipitated thermal development and utilization (Enviro Tools, 2002; Petera and on the surface of manganese oxide to form Tl2O3 (Dahal and Lawrance, ⁎ Correspondence to: W. Zhuang, College of City and Architecture Engineering, Zaozhuang University, Zaozhuang, Shandong 277160, China. ⁎⁎ Corresponding author. E-mail addresses: [email protected] (W. Zhuang), [email protected] (J. Song). https://doi.org/10.1016/j.marpolbul.2018.11.049 Received 12 October 2018; Received in revised form 12 November 2018; Accepted 20 November 2018 Available online 24 November 2018 0025-326X/ © 2018 Elsevier Ltd. All rights reserved. W. Zhuang et al. Marine Pollution Bulletin 138 (2019) 206–212 1996). A spectacular Tl enrichment in ferromanganese nodules of the digestion tank and digested using HNO3, HF, and HClO4. The details of Pacific and Indian Oceans was also recorded (Dutta et al., 1998). Sur- analytical method were presented in our previous study (Zhuang et al., face sediments of Bohai Bay and Laizhou Bay in China showed Tl 2016a). Tl concentration was determined using ICP-MS (PerkinElmer, strongly associated to iron, aluminum and/or manganese oxide (Duan NexION 350D). Al, Fe, and Mn concentrations were determined using et al., 2010; Zhuang and Gao, 2015). ICP-OES (PerkinElmer, Optima 8000DV). Fe and Mn concentrations Estuaries often have unique geographical locations, monsoons and were showed as FeOOH and MnO2. circulation conditions, therefore, they are characterized by complex The concentrations and distribution of Tl in the surface sediments of ecosystems, changeable conditions, and diverse functions. Hazardous Yangtze Estuary were shown in Table 1 and Fig. 2. The Tl concentra- metal elements enter the estuary through various pathways such as tions ranged from 0.369 to 1.197 μg g−1 with an average of atmospheric sedimentation and surface runoff, and are absorbed into 0.674 μg g−1, most of which were slightly higher than the background particulate matters, and enter the sediment with the sedimentation of values of Tl in sediments of the Yangtze Estuary (0.53 μg g−1; He, 2018) these particulate matters. In addition, hazardous metal elements in and in Chinese Soil (0.580 μg g−1; Qi et al., 1992), and much higher sediments could enter water body and organisms through flocculation, than the background value of shallow sea sediments in China precipitation and desorption due to the complex hydrodynamic condi- (0.30 μg g−1; Zhao and Yan, 1992). tions in estuaries, and further affect human health through biological The average Tl concentration in surface sediments of the Yangtze enrichment and food chain enlargement (Zhuang and Gao, 2015). Estuary was close to that of the Bohai Bay, but the highest Tl con- Therefore, estuarine sediments are “sinks” and “sources” of metals and centration in the Yangtze Estuary was higher than that in the Bohai Bay. play important roles in the migration and transformation of metals Tl concentrations in surface sediments of the Yangtze Estuary were (Song, 2010). obviously higher than those of the Laizhou Bay. Both the Bohai Bay and The Yangtze River is the third largest river in the world, and its the Laizhou Bay belong to the Bohai Sea, but the Bohai Bay Rim is estuary is located in the Yangtze River Delta with highly developed dominated by industry and the Laizhou Bay Rim is dominated by industry and agriculture. With the rapid growth of population and de- aquaculture. The Yangtze River Delta is also dominated by industrial velopment of economy in the Yangtze River basin, the discharge of activities, which might be an important factor resulting in the high Tl industrial wastewater and domestic sewage in the coastal cities has content in sediments. increased dramatically, and the water quality has been deteriorating The Tl concentrations exhibited a large fluctuation among the sites (Song, 2010; Song et al., 2018). The Yangtze River carries huge (CV% = 27.510). The high Tl concentrations mainly occurred in two amounts of heavy metals into the sea every year. Up to now, there are regions. One region (referred to as H region) was in the south of many studies on traditional heavy metals such as As, Cd, Cr, Cu, Hg, Ni, Chongming Island, including site H1, H2 and H3; the other region Pb and Zn in sediments of Yangtze Estuary (Duan et al., 2013; Cao et al., (referred to as F-G region) was located in the northeast of Zhoushan 2015; Yao et al., 2016; Sun et al., 2018). Despite the rising global at- Islands and Hangzhou Bay mouth, including site F3, F4, G1and G2. The tention on Tl, geochemical characteristics and pollution status of Tl in low Tl concentrations mainly occurred in the region around site C5 to the Yangtze Estuary and its adjacent seas are poorly known. Conse- C7 and D6 to D8, referred to as C-D region. quently, the main objectives of this study are: (1) investigate the con- H region was adjacent to Shanghai City, so this region was sig- tents and dispersal characteristics of Tl in surface sediments of the nificantly affected by industrial activities and shipping. In addition, H Yangtze Estuary; (2) discuss the factors controlling Tl concentration region was close to one of the main sewage outlets in Shanghai, and the variation; (3) identify the origins of Tl in the surface sediments of discharge of sewage might have increased the content of Tl in sedi- Yangtze Estuary; and (4) finally evaluate the potential ecological risk of ments.