163 transport and bioaccumulation

Environ Sci Pollut Res (2015) 22:14431–14441 DOI 10.1007/s11356-014-3946-9 12TH IHPA FORUM AND SELECTED STUDIES ON POPS Transport and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans at the Bien Hoa Agent Orange hotspot in Vietnam Nguyen Van Thuong & Nguyen Xuan Hung & Nguyen Thi Mo & Nguyen Manh Thang & Pham Quang Huy & Hoang Van Binh & Vu Duc Nam & Nguyen Van Thuy & Le Ke Son & Nguyen Hung Minh Received: 13 August 2014 / Accepted: December 2014 / Published online: 17 December 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract The Bien Hoa airbase (south of Vietnam) is known as one of the Agent Orange hotspots which have been seriously contaminated by Agent Orange/dioxin during the Vietnam War Hundreds of samples including soil, sediment and fish were collected at the Bien Hoa Agent Orange hotspot for assessment of the environmental contamination caused by dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) The toxicity equivalency quotient (TEQ) concentration of PCDD/Fs in soil and sediment varied from 7.6 to 962,000 and 17 to 4860 pg/g dry wt, respectively, implying very high contamination of PCDD/Fs in several areas PCDD/F levels in fish ranged between 1.8 and 288 pg/g TEQ wet wt and was generally higher than advisory guidelines for food consumption 2,3,7,8-Tetrachlorinated dibenzop-dioxins (2,3,7,8-TCDD) contributed 66–99 % of TEQ for most of the samples, suggesting 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) from Agent Orange as the major source of the Responsible editor: Roland Kallenborn This article belongs to the series “Dioxin and POP Contaminated Sites” (Weber et al 2008) edited by Roland Weber, Mats Tysklind and Caroline Gaus N Van Thuong : N X Hung : N T Mo : N M Thang : P Q Huy : H Van Binh : V D Nam : L K Son : N H Minh (*) Dioxin Laboratory Project, Vietnam Environment Administration (VEA), Nr 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam e-mail: lab.dioxin@gmail.com N Van Thuy Center for Environmental Monitoring (CEM), Vietnam Environment Administration (VEA), Nr 556 Nguyen Van Cu, Long Bien, Hanoi, Vietnam L K Son Office of the National Steering Committee 33, Ministry of Natural Resources and Environment (MONRE), Nr 83 Nguyen Chi Thanh Street, Dong Da, Hanoi, Vietnam contamination The vertical transport of PCDD/Fs was observed in soil column with high TEQ levels above 1000 pg/g dry wt (Vietnamese limit for necessary remediation activitiesTCVN 8183:2009 (2009)) even at a depth of 1.8 m The vertical transport of PCDD/Fs has probably mainly taken place during the “Ranch Hand” defoliant spray activities due to the leaks and spills of phenoxy herbicides and solvents The congener patterns suggest that transports of PCDD/Fs by weathering processes have led to their redistribution in the low-land areas Also, an estimate for the total volume of contaminated soil requiring remediation to meet Vietnamese regulatory limits is provided Keywords Dioxin Contaminated site 2,3,7,8-TCDD Agent Orange 2,4,5-T Fish Introduction Bien Hoa is a city of the Dong Nai province and located about 35 km east of Ho Chi Minh City The area of Bien Hoa city is about 155 km2 with a population of approximately million people in 2012 During the Vietnam War, Bien Hoa airbase was one of the most important military facilities of the United States (US) army in Vietnam From 1961 to 1972, under the Operation Ranch Hand carried out by the US Army, about 74 million litres of defoliants were sprayed to destroy forest canopies and crops belonging to the North Liberty Army (Alvin L Young 2009) The defoliants contained the chlorinated phenoxy herbicides 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)- and 2,4-dichlorophenoxyacetic acid (2,4-D) as active ingredients in different concentrations in the formulations labelled as Agent Orange, Agent Purple and Agent White with Agent Orange nearly contributing half of total defoliant 14432 volume (Stellman et al 2003) More importantly, most of the defoliants contained the extremely toxic by-products dibenzop-dioxins and polychlorinated dibenzofurans (PCDD/Fs), especially the most toxic isomer 2,3,7,8-Tetrachlorinated dibenzo-p-dioxins (2,3,7,8-TCDD) The total amount of PCDD/F sprayed during Vietnam war was between 366 and 1223 kg toxicity equivalency quotient (TEQ) (Stellman et al 2003) which can be compared to today’s global dioxin inventory of approximately 140 kg/year considering average per capita release of 21 μg TEQ/person per year (Fiedler et al 2012) However, similarly large amount of dioxins in hundred TEQ kilogramme scales is related with deposits of single former pesticide productions producing 2,4,5-T (Götz et al 2013; Vijgen et al 2011; Weber and Varbelow 2013), and the historic use of pesticides in Japan (approx 450 kg TEQ) or wood preservatives in Sweden (250 kg TEQ) demonstrating the historic overall relevance of pesticide use for global dioxin contamination (Weber et al 2008) PCDD/Fs are known as one of the most toxic man-made chemicals belonging to the group of persistent organic pollutants (POPs) listed in the Stockholm Convention The exposures of humans and animals to PCDD/Fs at low levels have been linked with negative health effects such as the development of cancer, reproductive problems, immune alterations, disruption of hormones, etc (Colborn et al 1993; Schecter et al 1998; US EPA 2000) It is estimated that during the Ranch Hand operation, between 2.1 and 4.8 millions of Vietnamese people were possibly exposed to dioxins by means of the Agent Orange (AO) spraying (Stellman et al 2003) In fact, environmental effects and health consequences from the AO spraying are observed in Vietnam until today Great efforts from the Vietnamese Government and international communities have been made to overcome the consequences of AO/dioxin in the environment and human health (Minh et al 2009) It was estimated that approximately 33 million litres of the defoliants (45 % of total defoliant used) were transported to Bien Hoa airbase for the Ranch Hand missions Among those, AO was accounted for about 60 % (approximately 20.4 million litres or 98,000 drums, each of 208 l) The improper handlings of the chemicals and accidental spills were the main reasons leading to the extremely high contamination of dioxins found in the airbase For example, from December 1969 to March 1970, four major accidental spills occurred at Bien Hoa airbase Two spills were associated with the 28,000-l tanks of AO and two others with the 28,000-l tanks of Agent White (AW) The spills and leakages have caused extremely high levels of AO-related dioxin (AO/dioxin) pollution at certain areas in the airbase making the airbase well known as one of the AO/dioxin hotspots in Vietnam (Dwernychuk 2005) Because of the increasing concerns on adverse impacts of AO/dioxin contamination to the local environment and human health, the Government of Vietnam had implemented Environ Sci Pollut Res (2015) 22:14431–14441 a 3-year project starting from 2006, in order to contain the highest dioxin-contaminated areas commonly known as the Z1 site (area of ha) by a secure landfill However, the airbase has been used for various military purposes, making the site assessment for environmental investigation much limited In 2007, a seminar between the US Department of Defense and the Vietnam Ministry of Defense in Hanoi for sharing information on the historical usage of the herbicides has unveiled an operation coded as Pacer Ivy which revoked and returned unused Agent Orange to the USA (Alvin L Young 2009) This has raised more concern about potential AO/dioxincontaminated sites which have not been noticed before by environmental investigators Furthermore, the existing AO/ dioxin contamination could be widely dispersed to larger areas because the contaminated soil was washed out by floods and rains (Minh et al 2009) The objective of this study is to implement a comprehensive assessment of the area including possibly affected fish to understand the present distribution and transport of the AO/dioxin contamination in Bien Hoa airbase and its vicinities The results will help to identify the extension and scale of the contamination and thus provide useful information for subsequent environmental remediation steps Materials and methods Sampling locations Topographical surveys In order to record basic features for the designing of the sampling campaign, the topographical survey for the Western contaminated area (Pacer Ivy area) and ponds and lake downstream of the most heavily contaminated area (namely Z1) of Bien Hoa airbase were carried out (Fig 1) The topography of the Western contaminated area is completely rough and divided by internal roads, ponds and lakes The slope of the Western contaminated area is downward to the west part with the elevation in the east part, and the lowest land is the bed of ponds system Rainwater from Pacer Ivy contaminated site may contain dioxins/toxicants that flows into ponds and lower land in the West, then into Dong Nai River through the sewer system (Fig 1) Hence, Pacer Ivy location and two ponds and low-land areas near Pacer Ivy site have been identified for the assessment of the spread of the contaminated soil (Fig 1) Previous sampling survey primarily focused on the assessment and mitigation of dioxin impacts in the Z1 area, the southwest area of the airbase and the southwest corner of the runway and Pacer Ivy area (Hatfield Consultants 2011) Southwest area covers an area of 2000 m2; this site has a flat terrain with a slight slope to the south Therefore, rainwater may carry the contaminated soil from the southwest area to Environ Sci Pollut Res (2015) 22:14431–14441 14433 Fig Map showing Bien Hoa airbase and relevant sampling sites (2011–2013) lakes and ponds nearby (Fig 1) The Z1 contaminated area located on the south of the airbase includes the a former storage area and washing area used for the Ranch Hand Operation Over the years, the natural influences and human activities have caused surrounding land of Z1 to considerably change its topographic feature Human activities included the digging of drainage channel, concrete capping and planting and cutting of trees caused the mobilization of contaminated soil from Z1 area to lower land in the south of the site In addition, the erosion by rain and floods can result in the accumulation of dioxin-contaminated soil which is washed out from the site The slope of the Z1 area and the surrounding land is downward from highly contaminated site towards the lake and low land of the South Basing on the field surveys, we identified suspect contaminated ponds and lakes impacted by drain water from the Z1 area including Z1 Lake, G2 Lake and Bien Hung Lake (Fig 1) Sampling of soil, sediment and biological samples In this study, 106 samples (surface and sub-surface soil down to a depth of 2.4 m) were collected in the Pacer Ivy contaminated area and vicinities based on topographic surveys The map for the sampling locations of this area is showed in Fig The whole area was divided into many lots (50×50 m), and each surface soil samples consisted of five sub-samples composites The sampling procedure followed strictly those used in previous studies implemented by Hatfield Consultants (Dwernychuk et al 2002) Core soil sampling procedure was developed by us in order to take soil samples down to 2.4 m in depth Surface sediment samples were collected by Ekman dredge from surface to depth of 10 cm underwater sediment bed Besides, sediment core were collected by a core sampler and divided into several segments of cm which were then considered sub-samples Tilapias (Oreochromis niloticus) were collected in ponds and lakes, and also, muscles were taken for analysis of PCDD/Fs A duck sample (muscle tissue) was also collected in the pond near Pacer Ivy site (Table 1) The samples were transferred into pre-cleaned glass jars and transported to the laboratory All soils or sediments and biological samples were kept at and −20 °C in a laboratory until chemical analysis, respectively Analysis of PCDD/F All samples were analyzed for 17 2,3,7,8-substitute PCDD/Fs and TEF values given by WHO; 2005 was used to calculate TEQ concentration Soil and sediment samples were expressed on a dry weight basis, while biological samples were on a fresh weight basis The analytical procedure followed the US EPA Method 1613 (US EPA (1994)) for the determination of PCDD/Fs by isotopic dilution with gas chromatography and high-resolution mass spectrometer HRGC/HRMS (Micromass Auto Spec Ultima system [Waters, UK] with Agilent 7890A gas chromatograph [Agilent, USA]) The method was according to US EPA Method 1613 with minor modifications considering available recent advanced techniques All modifications were adequately validated prior to regular usage The soil samples were dried at room temperature, crushed and sieved to less than mm Briefly, g of sample was then spiked with 13C-PCDD/Fs surrogates and extracted by pressurized liquid extraction in 60 with DCM:hexane (10:90, v/v) at 120 °C and 1700 psi Cleanup steps were performed by 14434 Environ Sci Pollut Res (2015) 22:14431–14441 the Fluid Management Systems (FMS, USA) following the recommended procedure by the manufacturer (FMS, 2008) and were validated in our laboratory Basically, pre-packed silica column (Silica #PCBS-ABN-STD, FMS), alumina column (Alumina #PCBA-BAS-011, FMS) and carbon column (Carbon #PCBC-CCE-034) were used for cleanup and fractionation of PCDD/Fs Finally, 13C-labelled injection standards were added to the concentrated aliquot of the sample and further evaporated under gentle nitrogen stream of 20 μL prior to quantification Separation and quantification was conducted using a DB5MS capillary column (60 m×250 μm i.d.×0.25 μm film thickness, J & W Scientific Inc., Folsom, CA) The oven temperature program was as follows: 140 to 220 °C at °C/min, kept at 220 °C for 16 min, increased from 220 to 235 °C at °C /min, kept at 235 °C for min, increased from 235 to 330 °C at °C/min and kept at 330 °C for The injector and interface temperatures were set at 290 and 250 °C, respectively The mass spectrometer was operated with a resolution greater than 10,000 and positive electron impact (EI) conditions Data were obtained in the selected ion record mode (Hue et al 2014) All of the sediment and biological samples were analyzed at the Eurofins Laboratory in Hamburg, Germany and the Laboratory of Organic Analytical in Wadsworth Center, USA The standard method for analysis of PCDD/F in the Eurofins Laboratory and Laboratory of Organic Analytical in Wadsworth Center was followed by EN:1948 and US EPA 1613, respectively These analytical methods have previously been reported (Link et al 2005; Kumar et al 2001) Table Quality control To ensure free cross contamination during field sampling, all utensils used were thoroughly washed and rinsed three times by acetone, followed by hexane before sampling Solvent rinses were also collected and analyzed as control samples for clean degree of samplers and utensils Besides, quality control (QC) data was carried out in order to meet requirements of the analytical method QC data included laboratory blank, laboratory duplicate and surrogate analysis for each batch of 20 samples Moreover, 30 soil samples conducted in 2011 were cross-check analyzed by an international laboratory The average recovery value of 13C-PCDD/F surrogate standards for soil or sediment and biological samples was ranged from 50 to 150 % For soil or sediment samples, the method detection limits were 0.5 and 3.33 ng/kg for tetraCDD/Fs and penta- to octa-CDD/F congeners, respectively The detection limits of the method for tissues samples were 0.1, 0.5 and 1.0 ng/kg for tetra-CDD/Fs, penta- to hepta-CDD/ Fs and octa-CDD/Fs congeners, respectively Results and discussion PCDD/F contamination status The PCDD/F contamination in vicinities of the Z1 site Although the most contaminated site namely Z1 was contained in the secure landfill (Hatfield Consultants 2011), General information of the sampling locations in Bien Hoa airbase Sampling location/ sample kind Z1 Lake Sediment Fish G2 Lake Sediment Fish Bien Hung Lake Sediment Fish Lake 4A (sediment) Lake 4B (sediment) Pacer Ivy area Surface soil Deep soil Sediment Fish Duck Location area (ha) Number of sample Year of sampling 1.6 2012 2012 1.0 2012 2012 3.8 2012 2012 0.8 1.0 4 2012 2012 59 46 10 2011–2013 2011–2013 2011–2013 2012 2012 Environ Sci Pollut Res (2015) 22:14431–14441 its existence in over 30 years has caused the transport and distribution of the dioxin contamination in the wider vicinity due to the runoff of the contaminated soil in weathering processes such as flood, rain, wind, etc In this study, sediment samples were collected in two low land areas (named as Lake Z1 and Lake G2) which could serve as reservoirs for the contaminated soil from the Z1 site (Fig 1) Mean and range of PCDD/F and TEQ levels in sediment samples from these two lakes are shown in Table The mean PCDD/F concentration on mass basis is 2720 pg/g dry wt (560–5330 pg/g dry wt) in Lake Z1 and 5680 pg/g dry wt (2600–9900 pg/g dry wt) in Lake G2 The mean TEQ concentration is 503 pg TEQ/g dry wt (147–1030 pg TEQ/g dry wt) and 317 pg TEQ/g dry wt (219–472 pg TEQ/g dry wt) in Lake Z1 and Lake G2, respectively These sediment contamination levels were higher compared to the allowance level of PCDD/Fs in bottom sediment set by the Vietnamese authorities (150 pg TEQ/g dry wt; TCVN 8183:2009 (2009)) These results revealed the highly elevated contamination of PCDD/Fs in the bottom sediment of lakes close to the Z1 site which is the major original AO/ dioxin contamination source The elevated PCDD/F contamination in the low land areas can be understood considering that runoffs from the Z1 site are being received by these lakes for more than 30 years until the present time The 2,3,7,8TCDD contribution to TEQ in all sediment samples from these two lakes was very high (95 and 92 % in Lake Z1 and G2, respectively) This congener pattern shows that the source of the PCDD/F contamination in the lakes is derived from the AO/dioxin contamination resulting from 2,4-D and 2,4,5-T syntheses (Young AL et al 2009) In the present study, sediment samples were also collected from three other lakes which distribute further to the north of the Z1 site (Lake Bien Hung, Lake 4A and Lake 4B; Fig 1) Currently, there is no direct input of the runoff from Z1 site to these lakes, and thus, it is interesting to compare the PCDD/F accumulation in these lakes with those in Lake Z1 and G2 On average, the mass concentrations of PCDD/Fs in the sediment of Lake Bien Hung, Lake 4A and Lake 4B were 8590, 1270 and 8930 pg/g dry wt, respectively with TEQ concentrations of 70, 53 and 42 pg TEQ/g The results revealed that all the sediment samples has lower PCDD/F TEQ contamination in comparison to the Vietnamese sediment standard (150 pg TEQ/g, REF) The TEQ levels in these three lakes were about 4.5- to 12-folds lower compared to those in Lake Z1 and G2, suggesting significantly less influence of the contamination from Z1 site to the three lakes However, it should be noted that the contribution of TCDD to the TEQ for these three lakes still vary in a relatively high range (73–91 %) Kishida et al (2010) reported that the contributions of 2,3,7,8-TCDD in TEQ for sediment collected at Can Gio, Hue and Ha Noi were below 30 % (Table 2) Also, the TEQ levels including PCDD/Fs and dioxin-like polychlorinated biphenyls (dlPCBs) were mostly in range of 2.0–10 pg/g dry wt which 14435 could be considered as general TEQ background levels in lake sediment in Vietnam (Kishida et al 2010) The lakes and ponds near Bien Hoa airbase have higher TEQ levels compared to the general range in Vietnam The TEQ concentrations in Lake Bien Hung, Lake 4A and Lake 4B were significantly lower than those in Lake Z1 and Lake G2 (Table 2) However, in the congener profiles which were normalized to percentages (Fig 4), the proportion of octachlordibenzodioxin (OCDD) was higher in the earlier group (Fig 4d, f) than the later group (Fig 4a–c) This phenomenon perhaps implies that there were inputs of PCDD/Fs which are dominated by OCDD to Lake Bien Hung, Lake 4A and Lake 4B These lakes might have received PCDD/Fs mainly from other sources such as pentachlorophenol (PCP) use as pesticides (Sakurai et al 1998; Zheng et al 2012) or textile, wood or leather preservative use (Karademir et al 2013; Weber et al 2008), and atmospheric deposition also dominated by OCDD and OCDF (Zhang et al 2009) which also largely originate from PCP (Baker and Hites 2000) Nevertheless, also in these lakes, the main TEQ contribution stems from 2,3,7,8-TCDD, and therefore, dioxin toxicity stems largely from the AO/dioxin with high TEQ contribution (73–91 %, Table 2) PCDD/F contamination in the Pacer Ivy site Analytical results from 59 surface soil samples showed very high TEQ concentrations of PCDD/Fs at the Pacer Ivy site The TEQ levels range from 7.6 to 962,000 pg TEQ/g with the mean concentration of 18,260 pg TEQ/g dry wt Furthermore, the 2,3,7,8-TCDD TEQ contribution for these samples were extremely high with 98 % on average (Table 2) The most elevated concentrations were found at the southwest corner of the site which is close to a taxiway of airplanes The mean and the highest TEQ concentrations in this site are hundred folds higher compared to those found in the A Luoi former airbase in the North Central Coast region of Vietnam (Dwernychuk et al 2002) and somewhat comparable to the concentrations in Da Nang AO/dioxin hotspots (Hatfield Consultants 2009) From 1970 to 1972, the Pacer Ivy operation was launched to revoke the unused defoliant barrels for transport back to the USA (Alvin L Young 2009) The AO/dioxin residues from barrels were recovered or emptied to soil, and therefore, these sites could be contaminated seriously by AO/dioxins leaking from these activities The extremely high concentration of 2,3,7,8-TCDD and its high contribution to TEQ (Table 2) support this hypothesis In the present study, it is estimated that the elevated contamination of AO/dioxin covered an area of 75,000–115,000 m2 In the current study, 10 soil column samples were collected in the Pacer Ivy site, and totally 48 samples at various depths were determined for PCDD/F residue levels The soil columns were segmented in 30-cm samples, and each soil segment was 51 9.9 51,640 30–60 cm (n=8) 60–90 cm (n=7) 45,370 90–120 cm (n=7) 26,350 120–150 cm (n=6) 3312 150–180 cm (n=5) 1639 180–210 cm (n=3) 55 128,600 1450 180 35 Sediment (n=10) Fish (n=2) Duck (n=1) Pacer Ivy deep soil 0–30 cm (n=10) Ponds in the vicinity Lake 4A (sed., n=4) 48 Lake 4B (sed., n=4) 35 Pacer Ivy area Surf soil (n=59) 17,900 Sediment (n=9) Fish (n=6) 15.6 292 Sediment (n=3) Fish (n=2) Bien Hung Lake 480 12 Sediment (n=4) Fish (n=2) G2 Lake Z1 lakes and ponds TeCDD 94 85 10 2.8 2.1 248 800 24 1.1 0.52 126 1.7 0.71 4.2 2.9 0.13 11 13 0.03 593 165 45 21 14 842 4711 92 2.0 1.0 725 3.3 2.33 17