Bioaccumulation of trace elements in the hard clam, Meretrix lyrata, reared downstream of a developing megacity, the Saigon-Dongnai River Estuary, Vietnam Viet Tuan, Phuoc-Dan Nguyen, Emilie Strady To cite this version: Viet Tuan, Phuoc-Dan Nguyen, Emilie Strady. Bioaccumulation of trace elements in the hard clam, Meretrix lyrata, reared downstream of a developing megacity, the Saigon-Dongnai River Estuary, Vietnam. Environmental Monitoring and Assessment, Springer Verlag (Germany), 2020, 192 (9), pp.566. 10.1007/s10661-020-08502-z. hal-02925838 HAL Id: hal-02925838 https://hal.archives-ouvertes.fr/hal-02925838 Submitted on 1 Sep 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Bioaccumulation of trace elements in the hard clam, Meretrix lyrata, reared downstream of a developing megacity, the Saigon-Dongnai River Estuary, Vietnam Viet Tuan Tran &Phuoc-Dan Nguyen &Emilie Strady Abstract A large number of white hard clam farms are from the environment into the whole tissues of the hard in the estuary shoreline of Saigon-Dongnai Rivers, clam as well as its different organs. The samples were which flow through Ho Chi Minh City, a megacity, collected monthly in dry, transition, and wet seasons of and numerous industrial zones in the basin catchment the southern part of Vietnam from March to September area. In this study, eleven trace elements (Mn, Fe, Co, 2016. The results showed that seasonal and spatial var- Ni, Cu, Zn, As, Se, Cd, Hg, and Pb) in the hard clam iations of the studied metal concentrations in the hard Meretrix lyrata and its habitats including surface water, clam M. lyrata might be influenced by the sea current as suspended particulate matter, and sediment were evalu- well as the surface runoff in the rainy season. The ated to understand the bioaccumulation of trace metals relationship between condition index and the element concentrations in M. lyrata might be affected by the living environment conditions and farming methods. In addition, the hazard index values of all trace elements in the hard clam M. lyrata harvested in the sampling time show that the hard clams farmed in the study area V. T. Tran were safe for local consumers. Vietnam Institute for Tropical Technology and Environmental Protection (VITTEP), 57A Truong Quoc Dung St., Phu Nhuan District, Ho Chi Minh City, Vietnam Keywords White hardclam . Trace metal. Condition index . Biomonitoring . Human health risk V. T. Tran : P.<D. Nguyen ( * ) : E. Strady Centre Asiatique de Recherche sur l’Eau (CARE), Ho Chi Minh City University of Technology (HCMUT), District 10, Ho Chi Minh City, Vietnam Introduction e-mail: [email protected] P.<D. Nguyen Trace metals in aquatic environment originate from Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, either natural processes or human activities. Natural F-38000 Grenoble, France sources are mostly from erosion, chemical rock E. Strady weathering, volcanic activity, or soil leaching, whereas Vietnam National University Ho Chi Minh City (VNU-HCM), the anthropogenic sources are mainly from urban sur- Thu Duc District, Ho Chi Minh City, Vietnam face runoff and agricultural, industrial, and domestic activities. Trace metals are ubiquitous in aquatic envi- E. Strady Aix-Marseille University, Mediterranean Institute of ronment, but their speciation is changing according to Oceanography (MIO), Université de Toulon, CNRS/IRD, the physicochemical conditions of the environment, es- Marseille, France pecially at the estuarine interface. One of the most serious problems associated with metals in the aquatic et al. 2010; Phuong and Khoa 2013). However, these environment is their bioaccumulation in organisms, studies only evaluated a few of typical metals in short which can be toxic for the aquatic organisms themselves survey time or the sampled hard clams collected at the and can present a health risk for the humans who are local markets. Hop et al. (2017) sampled hard clams consuming them (Sakellari et al. 2013; Tao et al. 2012). farmed at Tan Thanh beach in the rainy season in 2015 The Bivalvia class has the capacity to accumulate and found a significant correlation between metal con- trace metals in proportion to the environmental contam- centrations in the clams and the sediment fractions and ination levels (Baudrimont et al. 2005; Sakellari et al. safe limit for human consumption. Until now, the metal 2013). The level of accumulation in biota (both the concentrations in specific organs of the M. lyrata hard whole organism and its specific organs) is calculated clam as well as the correlation between metals in the using the accumulation factors, which are defined as the hard clam farmed in the natural habitat and its physio- ratio of the concentration of pollutants accumulated in logical state have not been deeply studied in Vietnam. biota to the concentration of pollutants in the abiotic Therefore, this study aimed (i) to determine trace ele- medium. For each environment media, a specific factor ments (Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Hg, and Pb) is used such as the bioaccumulation factor for the water, in M. lyrata and its living environment along the shore- the biota-sediment accumulation factor for sediment line of the SG-DN River Estuary in the southern part of (BSAF), and the biota-suspended particulate matter ac- Vietnam from March to September 2016 that lasted cumulation factor (BSPMAF) for suspended particles from the late half of the dry season to the early mid- (Antunes et al. 2007; Belabed et al. 2013; Rzymski et al. rainy season; (ii) to assess the spatial and seasonal 2014). The metal accumulation differed according to the variation of trace element concentrations in the hard organs and tissues of bivalves: some organs might be clam M. lyrata and its habitats; and (iii) to estimate the more sensitive and so might be a specific indicator for health risks for the local consumers of the M. lyrata an environmental pollution rather than the whole body clam using the hazard quotient. burdens (Tarique et al. 2012; Vodopivez et al. 2015). Ho Chi Minh City (HCMC), the biggest economical city in Vietnam, has a high rate of urbanization and Materials and methods industrialization that has resulted in serious water issues such as heavy metals and nutrient contaminations, in the Study area Saigon-Dongnai (SG-DN) Rivers (Tuyet et al. 2019; Strady et al. 2016; Vo 2007). Thanh-Nho et al. (2018) The sampling sites are located in the southern part of show that the metal concentrations in the estuary of the Vietnam, at the mouth of the SG-DN River system, SG-DN Rivers could be changed due to the effects of which is the third biggest river basin in Vietnam (Fig. surface runoff and soil leaching level in different sea- 1). They are under the area of tropical monsoon climate, sons. At the mouth of the SG-DN Rivers, on the left where the rainy and dry seasons last from May to bank (Can Gio District) and on the right bank (Tien November and from December to April next year, Giang Province) are localized important commercial respectively. In the year 2016, the transition period, aqua-products of Asiatic hard clam Meretrix lyrata which was determined based on the variation of mea- (G.B. Sowerby II, 1851). The area of clam farms at sured monthly rainfalls, lasted from May to July—those Can Gio was 800 ha, while it was 2000 ha at Tan Thanh were months of the late dry season and the early rainy (van Duijn et al. 2012). Normally, the hard clam farming season (Supplement 1) (IMHEN 2018). Under the trop- period suitable for market provision is in the range from ical monsoon climate, the strong northeast monsoon 12 to 18 months. Some previous studies focused on the occurs from March to April and the southwest monsoon effects of nutrients, temperature, salinity, rainwater starts in May, becoming the strongest in August quality, and tidal region on the M. lyrata hard clam (IMHEN 2018; SRHC 2018). Similarly, the sea cur- growth (Son and Tung 2011) or genetic studies (Wu et rents flow in the same direction with the monsoons (i.e., al. 2014). A few studies focused on the accumulation from the southwest to the northeast in the rainy season and excretion of Cd, As, and Pb (Pham 2007) and and vice versa in the dry seasons) (Fang et al. 2012). In monitoring of the metal concentrations in hard clam addition, the studied area is affected by semi-irregular species along the coastal of Vietnam (Le 2016; Tu diurnal tide. m The three following sites were selected in the study: CI ¼ tissue 100 ð1Þ (i) Can Thanh and (ii) Dong Hoa in Can Gio area, mshell located on the northeast part of the mouth of the SG- where mtissue is the wet weight of the soft body (g) DN Rivers, and (iii) Tan Thanh located between the and mshell is the weight of the shell (g). southwest part of the SG-DN estuary and the mouth of Each sample of whole body or dissected part was a the Tien River, the northern branch of the Mekong composite of fiveindividual clams, of which the total weight Delta. The Meretrix lyrata hard clams are reared in the was big enough to analyze the metals. Then, the composite intertidal silty sand flat beaches and are harvested during sample was dried using a freeze dryer (Alpha 1-2 LDplus ebb tide (Tong and Nguyen 2011).