Trophodynamics of current use pesticides and ecological relationships in the Bathurst region vegetation-caribou-wolf food chain of the Canadian Arctic

National-scale monitoring of historic used organochlorine pesticides (OCPs) and current used pesticides (CUPs) in Chinese surface soil: Old topic and new story

Along with the restriction and prohibition of historic used organochlorine pesticides (OCPs), current used pesticides (CUPs) were widely used as alternatives. In order to investigate the pollution characteristics of pesticides, the levels and spatial distributions of OCPs and CUPs in 154 surface soil across China were comprehensively compared. Totally, 107 target pesticides were screened, and 20 OCPs and 34 CUPs were detected. The numbers of co-occurred pesticides in single soil sample were from 17 to 36 indicating the diversity and complexity of pesticides pollution. The concentrations of OCPs in urban soils were higher than rural soils, while rural > urban for CUPs. Furthermore, obviously different spatial distribution patterns were found for OCPs and CUPs. For OCPs, the secondary distribution pattern was dominant. For CUPs, the primary distribution pattern was obviously observed due to their current extensive usage. In addition, higher concentrations of both CUPs and OCPs were accumulated in the Northeast China Plain due to long-range atmospheric transport and deposition. Along with the old topic of OCPs, the study pointed out the preliminary understanding of CUPs pollution characteristic in surface soil of China, which provided a new story with the deep understanding of their environmental fate in both China and the world.

Emerging persistent chemicals in human biomonitoring for populations in the Arctic: A Canadian perspective

The future of human biomonitoring in the Arctic will be influenced by the presence of emerging persistent chemicals. Many modelling studies have attempted to predict which contaminants will be of concern next in the Arctic based on chemical and physical properties as well as known risk factors from existing Arctic contaminants of concern. An amalgamated list of emerging persistent chemicals identified through predictive modelling cross referenced with Arctic wildlife monitoring results provides a basis upon which to prioritize future human biomonitoring in the Arctic. Persistent chemicals identified by this analysis are those in common across models (i.e., HCCPD, PCTP, 1,3,5-triBB, 1,2,4,5-tetrachlorobenzene, hexaBDE, pentabromochlorocyclohexane) and those both identified by models and found in Artic biota (e.g., PFNA, PFUnDA, PFDA, PFTrDA, HCBD, HBCDD, PCA, PFDoDA, BTBPE, PCNB, Endosulfan, etc.). Tracking the appearance of new chemicals in environmental monitoring will allow human biomonitoring to keep pace with emerging issues.

Legacy and Emerging Persistent Organic Pollutants (POPs) in Terrestrial Compartments in the High Arctic: Sorption and Secondary Sources

Legacy persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and emerging perfluoroalkyl substances (PFASs) were measured in vegetation and soil samples collected at remote lakes in the Canadian High Arctic. Field studies were carried out in 2015 and 2016 to assess concentrations of POPs, study the relevant sorbing phases, and determine whether Arctic soils were sinks or sources of legacy POPs to the atmosphere and to neighboring lakes. The patterns of legacy POPs in vegetation and soils were dominated by low molecular weight PCB congeners along with OCPs, confirming the importance of long-range atmospheric transport. Lipid and non-lipid organic matter was a key determinant of legacy POPs in Arctic vegetation. Soil organic matter was the main descriptor of hydrophobic PCBs and OCPs in soils, while soil inorganic carbon content, was an important driver of the sorption of PFASs in soils. While contaminant concentrations were low in soil and vegetation, higher PCBs and PFOS organic and inorganic carbon-normalized concentrations were found at Resolute Lake indicating the presence of local sources of contamination. Comparison of fugacities of PCBs in soil and air from Resolute Lake indicated soils as net sources of PCBs to the atmosphere.

Bioaccumulation of Polybrominated Diphenyl Ethers and Alternative Halogenated Flame Retardants in a Vegetation-Caribou-Wolf Food Chain of the Canadian Arctic

The trophodynamics of halogenated flame retardants (HFRs) including polybrominated diphenyl ethers (PBDEs) and alternative HFRs were investigated in the terrestrial, vegetation-caribou-wolf food chain in the Bathurst Region of northern Canada. The greatest concentrations in vegetation (geometric mean of lichens, moss, grasses, willow, and mushrooms) were of the order 2,4,6-tribromophenyl allyl ether (TBP-AE) (10 ng g^-1 lw) > BDE47 (5.5 ng g^-1 lw) > BDE99 (3.9 ng g^-1 lw) > BDE100 (0.82 ng g^-1 lw) > 1,2,3,4,5-pentabromobenzene (PBBz) (0.72 ng g^-1 lw). Bioconcentration among types of vegetation was consistent, though it was typically greatest in rootless vegetation (lichens, moss). Biomagnification was limited in mammals; only BDE197, BDE206-208 and ∑PBDE biomagnified to caribou from vegetation [biomagnification factors (BMFs) = 2.0-5.1]. Wolves biomagnified BDE28/33, BDE153, BDE154, BDE206, BDE207, and ∑PBDE significantly from caribou (BMFs = 2.9-17) but neither mammal biomagnified any alternative HFRs. Only concentrations of BDE28/33, BDE198, nonaBDEs, and ∑PBDE increased with trophic level, though the magnitude of biomagnification was low relative to legacy, recalcitrant organochlorine contaminants [trophic magnification factors (TMFs) = 1.3-1.8]. Despite bioaccumulation in vegetation and mammals, the contaminants investigated here exhibited limited biomagnification potential and remained at low parts per billion concentrations in wolves.

Endosulfan, Short-Chain Chlorinated Paraffins (SCCPs) and Octachlorostyrene in Wildlife from Greenland: Levels, Trends and Methodological Challenges

Besides globally banned "legacy" persistent organic pollutants, other compounds might be present in Arctic wildlife, for which regulation was introduced recently (the insecticide endosulfan), is considered (short-chain chlorinated paraffins, SCCPs) or does not exist (octachlorostyrene, OCS, a byproduct of manufacturing and combustion processes involving chlorine). The purpose of this study was to analyze the time trend of endosulfan (1986-2012) in ringed seals and to address the levels of SCCPs and OCS in wildlife species from Greenland (black guillemot, glaucous gull, ringed seal, polar bear), while taking a critical standpoint to analytical methods typically applied. The metabolite endosulfan sulfate was the only endosulfan compound consistently above detection limits, with a median concentration of 0.23 ng/g lipid weight (lw) and a significant annual decrease of -5.6%. The low-resolution mass spectrometry (LRMS) method appeared accurate and sufficiently precise; however, the gel permeation chromatography had to balance lipid removal and analyte loss. SCCPs and OCS were present in all samples. OCS median concentrations were between 2.8 (ringed seal blubber) and 29 (glaucous gull liver) ng/g lw, determined by a straightforward dual column electron capture detection method. SCCPs were analyzed by LRMS, following removal of potential interferences, and had median concentrations of several 100 ng/g wet weight. While the method showed good precision and recovery rates as well as acceptable accuracy in control samples, the Greenland samples had high concentrations in an Arctic context, possibly indicating limited selectivity of the LRMS method.

Plant-bacteria partnerships for the remediation of persistent organic pollutants

High toxicity, bioaccumulation factor and widespread dispersal of persistent organic pollutants (POPs) cause environmental and human health hazards. The combined use of plants and bacteria is a promising approach for the remediation of soil and water contaminated with POPs. Plants provide residency and nutrients to their associated rhizosphere and endophytic bacteria. In return, the bacteria support plant growth by the degradation and detoxification of POPs. Moreover, they improve plant growth and health due to their innate plant growth-promoting mechanisms. This review provides a critical view of factors that affect absorption and translocation of POPs in plants and the limitations that plant have to deal with during the remediation of POPs. Moreover, the synergistic effects of plant-bacteria interactions in the phytoremediation of organic pollutants with special reference to POPs are discussed.

Critical assessment of pendimethalin in terms of persistence, bioaccumulation, toxicity, and potential for long-range transport

Pendimethalin (PND, CAS registry number 40487-42-1) is a dinitroaniline herbicide that selectively controls broad-leaf and grassy weeds in a variety of crops and in noncrop areas. It has been on the market for about 30 yr and is currently under review for properties related to persistence (P), bioaccumulation (B), and toxicity (T) in the European Union (EU). A critical review of these properties as well as potential for long-range transport (LRT) was conducted. Pendimethalin has a geometric mean (GM) half-life of 76-98 d in agriculturally relevant soils under aerobic conditions in the lab. The anaerobic half-life was 12 d. The GM for field half-lives was 72 d. The GM half-life for sediment-water tests in the lab was 20 d and that in field aquatic cosms ranged from 45 to 90 d. From these data PND is not persistent as defined in the Annex II of EC regulation 1107/2009. The GM bioconcentration factor for PND was 1878, less than the criterion value. This was consistent with lack of biomagnification or accumulation in aquatic and terrestrial food chains. The GM no-observed-effect concentration (NOEC) value for fish was 43 µg/L, and 11 µg/L for algae. These do not trigger the criterion value for toxicity. In air, the DT50 of PND was estimated to be 0.35 d, which is well below the criterion of 2 d for LRT under the United Nations Economic Commission for Europe (UNECE) Aarhus protocol. Modeling confirmed lack of LRT. Because of its volatility, PND may be transported over short distances in air and was found in samples in local and semiremote regions; however, these concentrations are not of toxicological concern. Unlike other current-use pesticides, PND has not been found in samples from remote regions since 2000 and there is no apparent evidence that this herbicide accumulates in food chains in the Arctic.

Current-use pesticides in seawater and their bioaccumulation in polar bear-ringed seal food chains of the Canadian Arctic

The distribution of current-use pesticides (CUPs) in seawater and their trophodynamics were investigated in 3 Canadian Arctic marine food chains. The greatest ranges of dissolved-phase concentrations in seawater for each CUP were endosulfan sulfate (less than method detection limit (MDL) to 19 pg L(-1) ) > dacthal (0.76-15 pg L(-1) ) > chlorpyrifos (less than MDL to 8.1 pg L(-1) ) > pentachloronitrobenzene (less than MDL to 2.6 pg L(-1) ) > α-endosulfan (0.20-2.3 pg L(-1) ). Bioaccumulation factors (BAFs, water-respiring organisms) were greatest in plankton, including chlorothalonil (log BAF = 7.4 ± 7.1 L kg(-1) , mean ± standard error), chlorpyrifos (log BAF = 6.9 ± 6.7 L kg(-1) ), and α-endosulfan (log BAF = 6.5 ± 6.0 L kg(-1) ). The largest biomagnification factors (BMFs) were found for dacthal in the capelin:plankton trophic relationship (BMF = 13 ± 5.0) at Cumberland Sound (Nunvavut), and for β-endosulfan (BMF = 16 ± 4.9) and α-endosulfan (BMF = 9.3 ± 2.8) in the polar bear-ringed seal relationship at Barrow and Rae Strait (NU), respectively. Concentrations of endosulfan sulfate exhibited trophic magnification (increasing concentrations with increasing trophic level) in the poikilothermic portion of the food web (trophic magnification factor = 1.4), but all of the CUPs underwent trophic dilution in the marine mammal food web, despite some trophic level-specific biomagnification. Together, these observations are most likely indicative of metabolism of these CUPs in mammals. Environ Toxicol Chem 2016;35:1695-1707. © 2016 SETAC.