Elemental mercury (Hg0) has different behavior in the environment compared to other pollutants due to its unique properties. It can remain in the atmosphere for long periods of time and so can travel long distances. Through air-surface (e.g., vegetation or ocean) exchange (dry deposition), Hg0 can enter terrestrial and aquatic systems where it can be converted into other Hg species. Despite being ubiquitous and playing a key role in Hg biogeochemical cycling, Hg0 behavior in the environment is not well understood. The objective of this review is to provide a better understanding of how the unique physicochemical properties of Hg0 affects its cycling and chemical transformations in different environmental compartments. The first part focuses on the fundamental chemistry of Hg0, addressing why Hg0 is liquid at room temperature and the formation of amalgam, Hg halide, and Hg chalcogenides. The following sections discuss the long-range transport of Hg0 as well as its redistribution in the atmosphere, aquatic and terrestrial systems, in particular, on the sorption/desorption processes that occur in each environmental compartment as well as the involvement of Hg0 in chemical transformation processes driven by photochemical, abiotic, and biotic reactions.

Due to restrictions on polybrominated diphenyl ethers (PBDEs), market demand for alternative flame retardants is projected to increase, worldwide. Information regarding the environmental behavior of these compounds is limited. The present study involved field measurements of several alternative halogenated flame retardants (HFRs), along with PBDEs and legacy persistent organic pollutants (POPs) in surface water, bottom sediments and suspended particulate matter (SPM) within a highly urbanized watershed in Singapore. Several alternative HFRs were detected in water and sediments. Dechlornane Plus stereoisomers (syn- and anti-DP) were detected in all samples, exhibiting relatively high concentrations in water, sediments and SPM. The maximum syn-DP concentrations in water, sediments and SPM were 24.30 ng/L, 2.48 ng/g dry wt. and 7774 ng/g dry wt., respectively. 1,2-Bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromotoluene (PBT), hexabromobenzene (HxBBz) and tetrabromoethylcyclohexane (TBECH) were routinely detected. PBDE concentrations were relatively low and often non-detectable. Polychlorinated biphenyl (PCB) concentrations ranged from 0.017 to 8.37 ng/L in water, 9.86–27.92 ng/g dry wt. in SPM, and 6.48–212.3 ng/g dry wt. in sediments. Congener and isomer patterns suggested no recent inputs of PBDEs or dichlorodiphenyltrichloroethane (DDT). Rainfall was found to be an important factor influencing temporal and spatial patterns of DPs, BTBPE, PBDEs and some organochlorines in surface water. Land use index was found to be important for several organochlorines, but not HFRs. The observed sediment-water partitioning behavior of the studied HFRs and legacy POPs was highly dependent on chemical hydrophobicity. The data demonstrate that the studied HFRs have a relatively high affinity for SPM and bottom sediments. For example, the log KOC,OBS for TBECH, syn-DP and anti-DP and BTBPE in bottom sediments ranged between 8.1 and 9.6. The findings will aid future studies regarding fate, transport and bioaccumulation of these current-use contaminants of concern.

Cooling tower emissions have become an increasingly common hazard to the environment (air polluting, ice formation and salts deposition) and to the health (Legionella disease) in the last decades. Several environmental policies have emerged in recent years limiting cooling tower emissions but they have not prevented an increasing intensity of outbreaks.Since the level of emissions depends mainly on cooling tower component design and the operating conditions, this paper deals with an experimental investigation of the amount of emissions, drift and PM10, emitted by a cooling tower with different configurations (drift eliminators and distribution systems) and working under several operating conditions. This objective is met by the measurement of cooling tower source emission parameters by means of the sensitive paper technique. Secondary objectives were to contextualize the observed emission rates according to international regulations.Our measurements showed that the drift rates included in the relevant international standards are significantly higher than the obtained results (an average of 100 times higher) and hence, the environmental problems may occur. Therefore, a revision of the standards is recommended with the aim of reducing the environmental and human health impact. By changing the operating conditions and the distribution system, emissions can be reduced by 52.03% and 82% on average. In the case of drift eliminators, the difference ranges from 18.18% to 98.43% on average. As the emissions level is clearly influenced by operating conditions and components, regulation tests should be referred to default conditions. Finally, guidelines to perform emission tests and a selection criterion of components and conditions for the tested cooling tower are proposed.

Researches on associations between phthalates exposure and child attention deficit hyperactivity disorder (ADHD) are inconsistent. This study aimed to evaluate the associations of urinary phthalates with ADHD, co-occurring oppositional defiant disorder (ODD), related symptoms and behavior problems among Chinese children. We enrolled 225 ADHD cases and 225 healthy controls aged 6–13 years old in Liuzhou, China. Each child provided repeated urine samples at 4 visits. Eight phthalate metabolites were measured by high-performance liquid chromatography and tandem mass spectrometry. Child ADHD symptoms and related behaviors were assessed using Swanson, Nolan, and Pelham Version IV scale and child behavior checklist. Higher urinary concentrations of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl)-hexyl phthalate (MEHP) were dose-dependently associated with ADHD [odds ratios (ORs) ranged from 2.35 to 3.04 for the highest vs. the lowest tertile] and co-occurring ODD (ORs ranged from 3.27 to 4.44 for the highest vs. the lowest tertile) in the multivariable logistic regression models (all p for trend ≤ 0.01), which were consistent with positive trends of increased scores of inattention domain, hyperactive domain and ODD symptoms (all p for trend ≤ 0.01). Besides, the monomethyl phthalate (MMP) concentration was associated with higher scores of inattention domain and ODD symptoms (both p < 0.05). Additionally, the MEHHP, MEOHP and MEHP concentrations were related to child attention problems, aggressive behaviors and externalizing behaviors (all p < 0.05). We also observed positive associations of the MEHP concentration with depressed behaviors and internalizing behaviors (all p < 0.05). Our results indicate that child exposure to phthalates may contribute to ADHD, ODD and externalizing and internalizing behavior problems.

This study evaluates the in-situ use of field portable X-ray Fluorescence (pXRF) for metal-contaminated site assessments, and assesses the advantages of increased sampling to reduce risk, and increase confidence of decision making at a lower cost. Five metal-contaminated sites were assessed using both in-situ pXRF and ex-situ inductively coupled plasma mass spectrometry (ICP–MS) analyses at various sampling resolutions. Twenty second in-situ pXRF measurements of Mn, Zn and Pb were corrected using a subset of parallel ICP–MS measurements taken at each site. Field and analytical duplicates revealed sampling as the major contributor (>95% variation) to measurement uncertainties. This study shows that increased sampling led to several benefits including more representative site characterisation, higher soil-metal mapping resolution, reduced uncertainty around the site mean, and reduced sampling uncertainty. Real time pXRF data enabled efficient, on-site decision making for further judgemental sampling, without the need to return to the site. Additionally, in-situ pXRF was more cost effective than the current approach of ex-situ sampling and ICP–MS analysis, even with higher sampling at each site. Lastly, a probabilistic site assessment approach was applied to demonstrate the advantages of integrating estimated measurement uncertainties into site reporting.

The exposures of pharmaceutical antibiotics in water solution caused potential risks for ecological environment and human health. In the present study, porous covalent triazine frameworks (CTFs) were synthesized and the adsorption behavior of sulfamethoxazole (SMX) and tylosin (TL) was investigated. The CTFs were characterized by X-ray diffraction, transform infrared and N2 adsorption/desorption. Sulfamethoxazole displayed much stronger adsorption than tylosin on microporous CTF-1 adsorbent due to the pore-filling effect. While the adsorption of bulky tylosin on microporous CTF-1 was suppressed because of the size exclusion effect. Additionally, the porous CTFDCBP showed stronger adsorption affinity and faster adsorption kinetics than other porous adsorbents, which was attributed to wide pore size distribution and open pore structure. Findings in this study highlight the potential of using porous CTFs as a potential adsorbent to eliminate antibiotics from water, especially for selective adsorption of bulky molecular pollutant.

Human presence in the Antarctic is increasing due to research activities and the rise in tourism. These activities contribute a number of potentially hazardous substances. The aim of this study is to conduct the first characterisation of the pharmaceuticals and recreational drugs present in the northern Antarctic Peninsula region, and to assess the potential environmental risk they pose to the environment. The study consisted of a single sampling of ten water samples from different sources, including streams, ponds, glacier drains, and a wastewater discharge into the sea. Twenty-five selected pharmaceuticals and 21 recreational drugs were analysed. The highest concentrations were found for the analgesics acetaminophen (48.74 μg L−1), diclofenac (15.09 μg L−1) and ibuprofen (10.05 μg L−1), and for the stimulant caffeine (71.33 μg L−1). All these substances were detected in waters that were discharged directly into the ocean without any prior purification processes. The hazard quotient (HQ) values for ibuprofen, diclofenac and acetaminophen were far in excess of 10 at several sampling points. The concentrations of each substance measured and used as measured environmental concentration values for the HQ calculations are based on a one-time sampling. The Toxic Unit values indicate that analgesics and anti-inflammatories are the therapeutic group responsible for the highest toxic burden.This study is the first to analyse a wide range of substances and to determine the presence of pharmaceuticals and psychotropic drugs in the Antarctic Peninsula region. We believe it can serve as a starting point to focus attention on the need for continued environmental monitoring of these substances in the water cycle, especially in protected regions such as the Antarctic. This will determine whether pharmaceuticals and recreational drugs are hazardous to the environment and, if so, can be used as the basis for risk-assessment studies to prioritise the exposure to risk.

Diverse antibiotic-resistance genes (ARGs) are frequently reported to have high prevalence in veterinary manure samples due to extensive use of antibiotics in farm animals. However, the characteristics of the distribution and transmission of ARGs among bacteria, especially among different species of multiple antibiotic-resistant bacteria (MARB), have not been well explored. By applying high-throughput sequencing methods, our study uncovered a vast MARB reservoir in livestock manure. The genera Escherichia, Myroides, Acinetobacter, Proteus, Ignatzschineria, Alcaligenes, Providencia and Enterococcus were the predominant cultivable MARB, with compositions of 40.6%–85.7%. From chicken manure isolates, 33 MARB were selected for investigation of the molecular characteristics of antibiotic resistance. A total of 61 ARGs and 18 mobile genetic elements (MGEs) were investigated. We found that 47 ARGs were widely distributed among the 33 MARB isolates. Each isolate carried 27–36 genes responsible for resistance to eight classes of antibiotics frequently used in clinic or veterinary settings. ARGs to the six classes of antibiotics other than streptogramins and vancomycin were present in all 33 MARB isolates with a prevalence of 80%–100%. A total of 12 MGEs were widely distributed among the 33 MARB, with intI1, IS26, ISaba1, and ISEcp1 simultaneously present in 100% of isolates. In addition, 9 gene cassettes within integrons and ISCR1 were detected among MARB isolates encoding resistance to different antibiotic classes. This is the first report revealing the general co-presence of multiple ARGs, various MGEs and ARG cassettes in different species of individual MARB isolates in chicken manure. The results highlight a much higher risk of ARGs spreading through livestock manure to humans than we expected.

Mercury (Hg) is a globally-distributed pollutant, toxic to humans and animals. Emissions are particularly high in Asia, and the source of exposure for humans there may also be different from other regions, including rice as well as fish consumption, particularly in contaminated areas. Yet the threats Asian wildlife face in rice-based ecosystems are as yet unclear. We sought to understand how Hg flows through rice-based food webs in historic mining and non-mining regions of Guizhou, China. We measured total Hg (THg) and methylmercury (MeHg) in soil, rice, 38 animal species (27 for MeHg) spanning multiple trophic levels, and examined the relationship between stable isotopes and Hg concentrations. Our results confirm biomagnification of THg/MeHg, with a high trophic magnification slope. Invertivorous songbirds had concentrations of THg in their feathers that were 15x and 3x the concentration reported to significantly impair reproduction, at mining and non-mining sites, respectively. High concentrations in specialist rice consumers and in granivorous birds, the later as high as in piscivorous birds, suggest rice is a primary source of exposure. Spiders had the highest THg concentrations among invertebrates and may represent a vector through which Hg is passed to vertebrates, especially songbirds. Our findings suggest there could be significant population level health effects and consequent biodiversity loss in sensitive ecosystems, like agricultural wetlands, across Asia, and invertivorous songbirds would be good subjects for further studies investigating this possibility.