Dynamic passive sampling of hydrophobic organic compounds in surface seawater along the South Atlantic Ocean east-to-west transect and across the Black Sea

https://doi.org/10.1016/j.marpolbul.2021.112375Get rights and content

Highlights

  • The first time application of DPS in marine surface water from cruising ships.

  • DPS allows to measure HOCs down to pg L−1 in only 3 days of passive sampler exposure.

  • HBCD was quantified for the first time in surface water in open ocean waters.

  • PBDE and NBFR were quantified for the first time in the Black Sea surface water.

Abstract

Mapping of hydrophobic organic compounds (HOCs) in surface seawater on an east-to-west transect of the South Atlantic Ocean (SAO) and across the Black Sea (BS) in 2016 was performed by a dynamic passive sampling device containing silicone-based passive samplers. In SAO as well as in BS the measurements confirmed freely dissolved concentrations of polychlorinated biphenyls, DDT and its metabolites, chlorobenzenes, cyclodiene pesticides, and brominated flame retardants in the range of units to low hundreds of pg per litre. The findings indicate that the spatial distribution of HOCs and emerging pollutants in the SAO and the BS is influenced by riverine inputs, ocean currents and atmospheric deposition from continental plumes. Observed concentration gradients indicate that eastern SAO receives DDT from sources in South Africa, whereas the emissions of endosulfan originate in South America. Elevated HOC concentrations in the northwestern BS are related to their discharge by rivers from the European continent.

Introduction

Contamination of seawater by bio-accumulative hydrophobic organic compounds (HOCs) is a concern around the globe, posing a threat to organisms, the marine ecosystem and human health. HOCs, such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenylethers (PBDEs), novel brominated flame retardants (NBFRs) or hexabromocyclododecanes (HBCDs), together with polycyclic aromatic hydrocarbons (PAHs), are toxic, and many of them undergo long-range transport around the globe (Stemmler and Lammel, 2009, Stemmler and Lammel, 2013; Xie et al., 2011; Möller et al., 2011; Lohmann et al., 2012b; Bigot et al., 2016; Luek et al., 2017; Carrizo et al., 2017). Due to HOCs lipophilic properties, persistence and bioaccumulation potential (Lavandier et al., 2013; Gu et al., 2017), the concentrations found in high trophic level animals or humans can reach toxic levels (AMAP, 2015). Chronic exposure to HOCs can lead to adverse health effects such as disruption of physiological systems, cancer or fetal development interference (El-Shahawi et al., 2010). Despite that part of HOCs, known as persistent organic pollutants (POPs), were banned or their global use was restricted (UNEP, 2019), they are still ubiquitous, and their concentrations only slowly decrease in the terrestrial and marine environment in response to abatement measures.

Seawater is one of the environmental compartments containing HOCs and representing their essential transport medium. The HOCs are mainly emitted to seawater from rivers, dominantly bound to suspended particles (Koelmans et al., 2010; Fernandez et al., 2014; Meng et al., 2017), and from the atmosphere via dry and wet deposition (Lammel et al., 2015), or released directly from ships (Endres et al., 2018). The distribution in seawater is governed by a complex system of ocean fronts and currents. Ocean fronts are narrow areas with enhanced horizontal gradients, which separate areas with possibly different vertical stratification of trace concentrations. Between these areas, along-frontal currents are then responsible for a convective mass transfer of the contaminants, either freely dissolved or bound to particles (Dachs et al., 2002; Belkin and Cornillon, 2007; Belkin et al., 2009; Lohmann and Belkin, 2014). Suspended particles can later-on settle to the seabed (Lohmann and Belkin, 2014). HOCs in seawater can also bioaccumulate in aquatic organisms and marine food webs (Arnot and Gobas, 2006). Semivolatile HOCs may be returned to the atmosphere in relaxation to chemical equilibrium (Jantunen and Bidleman, 1998; Stemmler and Lammel, 2009). Since the HOCs are distributed to seawater from other environmental compartments, undergo long-range marine transport, bioaccumulate and very little is known about their distribution in global waters, their monitoring is necessary to comprehend the underlying processes. Obtained data can be used for looking at large-scale spatial and temporal trends, but also to assess the distribution of HOCs between the atmosphere, seawater and other marine compartments (biota including plankton, sediment, sea-ice, human-made microplastics). Also, they can be used to study phenomena related to compound distribution across compartments (e.g. bioaccumulation), related contaminant mass fluxes, and for marine ecosystem risk assessment.

Sampling of HOCs in seawater is challenging since their concentrations are very low, typically in sub-ng-per-litre levels. The methods based on sampling and analysis of grab samples are generally not suitable due to insufficient sensitivity and a high potential for analyte losses or sample contamination during sampling, storage, transport, and processing. However, in situ large volume extraction methods (e.g. Infiltrex type solid-phase extraction; SPE) proved to be suitable for sampling HOCs in seawater. Several sampling cruises applied these methods for monitoring HOCs in sections of open oceans and marginal seas: Arctic Ocean (Möller et al., 2011; Carrizo et al., 2017), Atlantic Ocean (Nizzetto et al., 2008; Xie et al., 2011; Lohmann et al., 2012b; Luek et al., 2017), Indian Ocean (Huang et al., 2014), Pacific Ocean (Zhang and Lohmann, 2010; Cai et al., 2016), Southern Ocean (Xie et al., 2011; Bigot et al., 2016; Cai et al., 2016), Black Sea (Maldonado and Bayona, 2002). Most of these cruises did not address only measuring HOC concentrations in seawater but also their air-sea mass exchange fluxes. Nevertheless, all aforementioned sampling cruises used a combination of a glass fibre filter with polyurethane foam, or XAD-2, or PAD-2 resin for HOCs extraction from seawater. This approach is suitable for the measurement of total concentration in seawater samples. The total aqueous concentration is dependent on the abundance of suspended particulate matter and colloids present, and does not provide an unbiased measure of compounds' freely dissolved concentration. The freely dissolved concentration is an important parameter because it is proportional to chemical activity, needed in multi-phase distribution modelling, as well as for estimating organism exposure in marine ecosystem risk assessment (Reichenberg and Mayer, 2006; Gilbert et al., 2016). To our knowledge, only passive sampling techniques are suitable for measurements of freely dissolved concentrations of HOCs in water.

The passive sampling (PS) technique is based on diffusion-driven sorption of the freely dissolved compounds from the sampled medium to the receiving phase until the equilibrium is reached or the sampling is stopped (time integrative sampling) (Vrana et al., 2005). Reaching the equilibrium for HOCs with log KOW > 6 during a deployment is time-consuming (Vrana et al., 2019), and the PS of HOCs in water typically works in the time integrative sampling regime. The uptake of the quantifiable amount of compounds from seawater into the sampling material may take several weeks (Allan et al., 2009). Such long periods correspond to typically low effective sampling rates, in the order of litres of water extracted per day. The low sampling rate is limiting PS onboard moving research vessels since the time period available for sampling is limited. Higher sampling rates can be achieved by increasing samplers' surface area or water turbulence, as the water boundary layer (WBL) mostly limits HOCs uptake to polymer-based PS (Booij et al., 2007).

Different approaches using PS technique were tested to sample surface water in an open ocean: static deployment performed by Ma et al. (2018) with deployment over one year with sufficient uptake. However, existing infrastructure has to be available, and the sampling is done only at one spot; sampling from a research vessel by towing the sampler (Lohmann et al., 2012b), where a larger geographic area was captured. However, only low sampling rates were obtained. Sampling from moving vessels requires a PS with high sampling rates in order to sample sufficient amounts of compounds for later quantification within the short time period of several days available for sampling, while the ship covers a certain stretch along the ocean transect. Vrana et al. (2018) demonstrated the applicability of a novel “dynamic” passive sampling device (DPS) in a freshwater environment developed to maximise contaminants' sampling rates by forcing water at high flow rate along the passive sampler surface. For a sampler with a surface area of 400 cm2, they obtained an average efficient WBL-controlled sampling rate ~70 L d−1 for a model compound with a molar mass of 300 g mol-1. In this way, almost 500 L of water can be extracted within one week of integrative sampling. Even the achievable limit of quantification (LOQ) favours DPS use since units of fg L−1 up to units of pg L−1 can be obtained with LOQs comparable to or lower than those expected in seawater. Therefore, the DPS device has the potential to address the monitoring of HOCs' spatial distributions in surface seawater.

In this study, we used dynamic passive sampling from ships cruising along transects in two case studies: the South Atlantic Ocean, and the Black Sea to (i) demonstrate the applicability and performance of mobile DPS for efficient sampling of HOCs in surface seawater, (ii) indicate HOC levels and their spatial gradients along the sampled transects.

Section snippets

Sampler preparation

Passive samplers were prepared from AlteSil (Altec, UK) translucent silicone elastomer (silicone rubber, SR) sheets (7 × 28 cm or 5.5 × 9.0 cm; 0.5 mm sheet thickness). Before exposure, SR sheets were Soxhlet extracted with ethyl acetate for 100 h to remove impurities and silicone oligomers. Then, sheets were homogeneously dosed with 14 performance reference compounds (PRCs: D10-biphenyl and 13 PCB congeners absent in technical mixtures; detailed in Tables S4 and S5) according to the procedure

Passive sampler performance

In this study, passive sampling was used for in situ concentration of HOCs from seawater into SR polymer. A DPS device was applied onboard expedition ships in order to maximise the sampled volume of water within the short time available for sampling from a moving ship. The DPS was applied based on previous evidence that it can increase Rs by >5-fold in comparison with samplers deployed in cages (Vrana et al., 2018). The passive sampling performance, characterised for each sampled compound by Rs

Conclusions

In this study, we reported freely dissolved concentrations of HOCs in the South Atlantic Ocean (east-to-west transect) and across the Black Sea. The concentrations found in the SAO were at very low levels or <LOQ (hundredths to units of pg L−1). Specifically, PCBs and OCPs were found mostly <LOQ or in similar levels as reported earlier for the southern hemisphere. A spatial trend was found for endosulfans with an increasing concentration on the east-to-west transect. The opposite trend was

CRediT authorship contribution statement

Jaromír Sobotka: Investigation, Formal analysis, Data curation, Visualization, Writing – original draft. Gerhard Lammel: Conceptualization, Funding acquisition, Project administration, Resources, Investigation, Writing – review & editing. Jaroslav Slobodník: Conceptualization, Funding acquisition, Methodology, Visualization, Writing – review & editing. Anne Schink: Investigation. Roman Prokeš: Investigation, Methodology. Branislav Vrana: Conceptualization, Methodology, Writing – review &

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Research activities were carried out in the RECETOX Research Infrastructure which is supported by the Czech Ministry of Education, Youth and Sports (LM2018121) and the European Structural and Investment Funds, Operational Programme Research, Development, Education (CZ.02.1.01/0.0/0.0/16_013/0001761). The Black Sea investigations were supported by the EU/UNDP Project: Improving Environmental Monitoring in the Black Sea – Phase II (EMBLAS-II) – ENPI/2013/313 – 169. We thank the crews of RV

References (67)

  • Jenna L. Luek et al.

    Persistent organic pollutants in the Atlantic and southern oceans and oceanic atmosphere

    Sci. Total Environ.

    (2017)
  • C. Maldonado et al.

    Organochlorine compounds in the north-western Black Sea water: distribution and water column process

    Estuar. Coast. Shelf Sci.

    (2002)
  • Jing Meng et al.

    Traditional and new POPs in environments along the Bohai and Yellow Seas: an overview of China and South Korea

    Chemosphere

    (2017)
  • Axel Möller et al.

    Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants in air and seawater of the European Arctic

    Environ. Pollut.

    (2011)
  • César N. Pegoraro et al.

    Assessing levels of POPs in air over the South Atlantic Ocean off the coast of South America

    Sci. Total Environ.

    (2016)
  • Emil V. Stanev

    On the mechanisms of the Black Sea circulation

    Earth-Sci. Rev.

    (1990)
  • T.M. Tavares et al.

    Ratio of DDT/DDE in the All Saints Bay, Brazil and its use in environmental management

    Chemosphere

    (1999)
  • Norma Tombesi et al.

    Persistent organic pollutants (POPs) in the atmosphere of agricultural and urban areas in the province of Buenos Aires in Argentina using PUF disk passive air samplers

    Atmos. Pollut. Res.

    (2014)
  • Branislav Vrana et al.

    Passive sampling techniques for monitoring pollutants in water

    TrAC Trends Anal. Chem.

    (2005)
  • Branislav Vrana et al.

    Mobile dynamic passive sampling of trace organic compounds: evaluation of sampler performance in the Danube River

    Sci. Total Environ.

    (2018)
  • Branislav Vrana et al.

    Chasing equilibrium passive sampling of hydrophobic organic compounds in water

    Sci. Total Environ.

    (2019)
  • Ian J. Allan et al.

    Field performance of seven passive sampling devices for monitoring of hydrophobic substances

    Environ. Sci. Technol.

    (2009)
  • AMAP

    AMAP Assessment 2015: Human Health in the Arctic

    (2015)
  • Jon A. Arnot et al.

    A review of bioconcentration factor (BCF) and bioaccumulation factor (BAF) assessments for organic chemicals in aquatic organisms

    Environ. Rev.

    (2006)
  • Igor M. Belkin et al.

    Comparative marine ecosystem of the sea (ICES) structure and function: descriptors and characteristics fronts in the world ocean's large marine ecosystems

  • Terry Bidleman et al.

    The long-range transport of organic compounds

  • Marie Bigot et al.

    Air–seawater exchange of organochlorine pesticides in the Southern Ocean between Australia and Antarctica

    Environ. Sci. Technol.

    (2016)
  • Kees Booij et al.

    An improved method for estimating in situ sampling rates of nonpolar passive samplers

    Environ. Sci. Technol.

    (2010)
  • Kees Booij et al.

    Laboratory performance study for passive sampling of nonpolar chemicals in water

    Environ. Toxicol. Chem.

    (2017)
  • Minggang Cai et al.

    Fate of polycyclic aromatic hydrocarbons in seawater from the Western Pacific to the Southern Ocean (17.5°N to 69.2°S) and their inventories on the Antarctic Shelf

    Environ. Sci. Technol.

    (2016)
  • Daniel Carrizo et al.

    Spatial distributions of DDTs in the water masses of the Arctic Ocean

    Environ. Sci. Technol.

    (2017)
  • Adrian Covaci et al.

    Brominated flame retardants

  • Jordi Dachs et al.

    Oceanic biogeochemical controls on global dynamics of persistent organic pollutants

    Environ. Sci. Technol.

    (2002)
  • Cited by (0)

    View full text