Ice is an important physical and chemical sink for various pollutants in cold regions. The photodegradation of emerging fluoroquinolone (FQ) antibiotic contaminants with dissolved organic matter (DOM) in ice remains poorly understood. Here, the photodegradation of ciprofloxacin (CIP) and fulvic acid (FA) in different proportions as representative FQ and DOM in ice were investigated. Results suggested that the photodegradation rate constant of CIP in ice was 1.9 times higher than that in water. When CFA/CCIP ≤ 60, promotion was caused by FA sensitization. FA increased the formation rate of cleavage in the piperazine ring and defluorination products. When 60 < CFA/CCIP < 650, the effect of FA on CIP changed from promoting to inhibiting. When 650 ≤ CFA/CCIP ≤ 2600, inhibition was caused by both quenching effects of 143.9%–51.3% and light screening effects of 0%–48.7%. FA inhibited cleavage in the piperazine ring for CIP by the scavenging reaction intermediate of aniline radical cation in ice. When CFA/CCIP > 2600, the light screening effect was greater than the quenching effect. This work provides new insights into how DOM affects the FQ photodegradation with different concentration proportions, which is beneficial for understanding the environmental behaviors of fluorinated pharmaceuticals in cold regions.

Pharmaceuticals are increasingly being detected in aquatic ecosystems worldwide. Particularly concerning are pharmaceutical pollutants that can adversely impact exposed wildlife, even at extremely low concentrations. One such contaminant is the widely prescribed antidepressant fluoxetine, which can disrupt neurotransmission and behavioural pathways in wildlife. Despite this, relatively limited research has addressed the behavioural impacts of fluoxetine at ecologically realistic exposure concentrations. Here, we show that 28-day fluoxetine exposure at two ecologically relevant dosages—one representing low surface water concentrations and another representing high effluent flow concentrations—alters antipredator behaviour in Eastern mosquitofish (Gambusia holbrooki). We found that fluoxetine exposure at the lower dosage resulted in increased activity levels irrespective of the presence or absence of a predatory dragonfly nymph (Hemianax papuensis). Additionally, irrespective of exposure concentration, fluoxetine-exposed fish entered the predator ‘strike zone’ more rapidly. In a separate experiment, fluoxetine exposure reduced mosquitofish freezing behaviour—a common antipredator strategy—following a simulated predator strike, although, in females, this reduction in behaviour was seen only at the lower dosage. Together, our findings suggest that fluoxetine can cause both non-monotonic and sex-dependent shifts in behaviour. Further, they demonstrate that exposure to fluoxetine at environmentally realistic concentrations can alter antipredator behaviour, with important repercussions for organismal fitness.

The adult zebrafish (Danio rerio) were exposed to treated-effluent concentration of bisphenol A (BPA) or 17β-estradiol (E2) for 6 months to evaluate their effects on behavioral characteristics: motor behavior, aggression, group preference, novel tank test and light/dark preference. E2 exposure evidently dampened fish locomotor activity, while BPA exposure had no marked effect. Interestingly, BPA-exposed fish reduced their aggressive behavior compared with control or E2. Both BPA and E2 exposure induced a significant decrease in group preference, as well as a weaker adaptability to new environment, exhibiting lower latency to reach the top, more entries to the top, longer time spent in the top, fewer frequent freezing, and fewer erratic movements. Furthermore, the circadian rhythmicity of light/dark preference was altered by either BPA or E2 exposure. Our results suggest that chronic exposure of treated-effluent concentration BPA or E2 induced various behavioral anomalies in adult fish and enhanced ecological risk to wildlife.

It has been postulated that road deicing salts are sufficiently diluted by spring rains to ameliorate any physiological impacts to amphibians breeding in wetlands near roads. We tested this conjecture by exposing clutches of the spotted salamander (Ambystoma maculatum) to three chloride concentrations (1 mg/L, 145 mg/L, 945 mg/L) for nine days, then transferred clutches to control water for nine days, and measured change in mass at three-day intervals. We measured mass change because water uptake by clutches reduces risks to embryos associated with freezing, predation, and disease. Clutches in controls sequestered water asymptotically. Those in the moderate concentrations lost 18% mass initially and regained 14% after transfer to control water. Clutches in high concentration lost 33% mass and then lost an additional 8% after transfer. Our results suggest that spring rains do not ameliorate the effects of deicing salts in wetlands with extremely high chloride concentrations.

Orthophosphate fixation of metal contaminated soils in environments that undergo freeze–thaw cycles is understudied. Freeze–thaw cycling potentially influences the reaction rate, mineral chemical stability and physical breakdown of particles during fixation. This study determines what products form when phosphate (triple superphosphate [Ca(H₂PO₄)₂] or sodium phosphate [Na₃PO₄]) reacts with lead (PbSO₄ or PbCl₂) in simple chemical systems in vitro, and assesses potential changes in formation during freeze–thaw cycles. Systems were subjected to multiple freeze–thaw cycles from +10 °C to −20 °C and then analysed by X-ray diffractometry. Pyromorphite formed in all systems and was stable over multiple freeze–thaw cycles. Low temperature lead orthophosphate reaction efficiency varied according to both phosphate and lead source; the most time-efficient pyromorphite formation was observed when PbSO₄ and Na₃PO₄ were present together. These findings have implications for the manner in which metal contaminated materials in freezing ground can be treated with phosphate.

The Athabasca Oil Sands Region (AOSR) in Alberta, Canada, is an important source of atmospheric pollutants, such as aerosols, that have repercussions on both the climate and human health. We show that the mean freezing temperature of snow-borne particles from AOSR was elevated (−7.1 ± 1.8 °C), higher than mineral dust which freezes at ∼ −15 °C and is recognized as one of the most relevant ice nuclei globally. Ice nucleation of nanosized snow samples indicated an elevated freezing ability (−11.6 ± 2.0 °C), which was statistically much higher than snow-borne particles from downtown Montreal. AOSR snow had a higher concentration (∼2 orders of magnitude) of >100 nm particles than Montreal. Triple quadrupole ICP-(QQQ)-MS/MS analysis of AOSR and Montreal snow demonstrated that most concentrations of metals, including those identified as emerging nanoparticulate contaminants, were much more elevated in AOSR in contrast to Montreal: 34.1, 34.1, 16.6, 5.8, 0.3, 0.1, and 9.4 mg/m³ for Cr, Ni, Cu, As, Se, Cd, and Pb respectively, in AOSR and 1.3, 0.3, 2.0, <0.03, 0.1, 0.03, and 1.2 mg/m³ in Montreal snow. High-resolution Scanning Transmission Electron Microscopy/Energy-dispersive X-ray Spectroscopy (STEM-EDS) imaging provided evidence for various anthropogenic nano-materials, including carbon nanotubes resembling structures, in AOSR snow up to 7–25 km away from major oil sands upgrading facilities. In summary, particles characterized as coming from oil sands are more efficient at ice nucleation. We discuss the potential impacts of AOSR emissions on atmospheric and microphysical processes (ice nucleation and precipitation) both locally and regionally.

Freeze–thaw cycling may influence the chemistry, mineral stability and reaction rate during metal orthophosphate fixation. This study assessed the formation and stability of Cu-, Pb-, and Zn-phosphates in chemically simple laboratory systems during 240 freeze–thaw cycles (120 days) from +10 to −20 °C, using X-ray diffractometry. In single heavy metal systems, chloro- and hydroxy-pyromorphite (Pb5(PO4)3(Cl,OH)), sodalite (Na6Zn6(PO4)6·8H2O), chiral zincophosphate (Na12(Zn12P12O48)·12H2O), and copper phosphate hydrate (Cu3(PO4)2·3H2O) were the primary phosphate minerals that formed, and were typically stable during the experiment. Zinc and Cu-phosphate formation was reduced in multi heavy metal systems, and was substantially lower in abundance than chloropyromorphite. Successful Cu-, Pb- and Zn-phosphate formation can be expected in cold and freezing environments like the polar regions. However, field implementation of orthophosphate fixation needs to consider competing ion effects, concentration of the phosphate source, and the amount of free-water.

Organochlorine (OC) contaminants are transported to the Polar Regions, where they have the potential to bioaccumulate, presenting a threat to the health of wildlife and indigenous communities. They deposit onto snowpack during winter, and accumulate until spring, when they experience prolonged solar irradiation until snowmelt occurs. Photochemical degradation rates for aldrin and dieldrin, in frozen aqueous solution made from MilliQ water, 500 μM hydrogen peroxide solution or locally-collected melted snow were measured in a field campaign near Barrow, AK, during spring–summer 2008. Significant photoprocessing of both pesticides occurs; the reactions depend on temperature, depth within the snowpack and whether the predominant phase is ice or liquid water. The effect of species present in natural snowpack is comparable to 500 μM hydrogen peroxide, pointing to the potential significance of snowpack-mediated reactions. Aldrin samples frozen at near 0 °C were more reactive than comparable liquid samples, implying that the microenvironments experienced on frozen ice surfaces are an important consideration.

An open-bottom and a closed-bottom mesocosm were developed to investigate the release of mercury from sediments to the water column in a frozen freshwater lake. The mesoscosms were deployed in a hole in the ice and particulate mercury (HgP) and total dissolved mercury (TDHg) were measured in sediments and in water column vertical profiles. In addition, dissolved gaseous mercury (DGM) in water and mercury water/airflux were quantified. Concentrations of TDHg, DGM, and mercury flux were all higher in the open-bottom mesocosm than in the closed-bottom mesocosm. In this paper we focus on the molecular diffusion of mercury from the sediment in comparison with the TDHg accumulation in the water column. We conclude that the molecular diffusion and sediment resuspension play a minor role in mercury release from sediments suggesting that solute release during ebullition is an important transport process for mercury in the lake. In a frozen lake Hg is released from contaminated sediments mainly due to gas ebullition and molecular diffusion plays a minor role.

A microextraction method for the determination of triclosan and methyltriclosan in marine environmental samples was developed. The disperser was first serves as a preliminary extractant for analytes, then as a frozen solvent to remove impurities at −20 °C, and finally as a disperser agent in the microextraction procedure. With the extractants solidified and float on the surface of the aqueous phase at low temperature, a separation was achieved to avoided use of specialized laboratory instruments. The method was optimized using Plackett-Burman design and central composite design as follows: 146 μL octanoic acid as extractant, 793 μL acetoneas disperser, 3.0 min centrifugation and 1.1 min vortex time. The limits of detection were 0.022–0.060 μg L−1 or μg kg−1 and recoveries were 83.3–103.5% for TCS and MTCS in seawater, sediments and seafood. The method has excellent prospects for sample pre-treatment and trace-level analysis of triclosan and methyltriclosan in marine environmental samples.