Evidence of low levels of trace organic contaminants in terminal lakes

Trace organic contaminants in lake waters: Occurrence and environmental risk assessment at the national scale in Canada

Numerous contaminants are produced and used daily, a significant fraction ultimately finding their way into natural waters. However, data on their distribution in lakes is lacking. To address this gap, the presence of 54 trace organic contaminants (TrOCs), representative of various human activities, was investigated in the surface water of 290 lakes across Canada. These lakes ranged from remote to highly impacted by human activities. In 88% of the sampled lakes, contaminants were detected, with up to 28 detections in a single lake. The compounds most frequently encountered were atrazine, cotinine, and deethylatrazine, each of which was present in more than a third of the lakes. The range of detected concentrations was from 0.23 ng/L to about 2200 ng/L for individual compounds, while the maximum cumulative concentration exceeded 8100 ng/L in a single lake. A risk assessment based on effect concentrations for three aquatic species (Pimephales promelas, Daphnia magna, and Tetrahymena pyriformis) was conducted, revealing that 6% of lakes exhibited a high potential risk for at least one species. In 59% of lakes, some contaminants with potential sub-lethal effects were detected, with the detection of up to 17 TrOCs with potential impacts. The results of this work provide the first reference point for monitoring the evolution of contamination in Canadian lakes by TrOCs. They demonstrate that a high proportion of the sampled lakes bear an environmentally relevant anthropogenic chemical footprint.

Recent Development of Metal-Organic Frameworks for Water Purification

Water contamination is an increasing concern to mankind because of the increasing amount of pollutants in aquatic ecosystems. To purify the polluted water, various techniques have been used to remove hazardous components. Unfortunately, traditional cleanup techniques with a low uptake capacity are unable to achieve water purification. Metal-organic frameworks (MOFs) have recently shown potential in effective water pollutant isolation in terms of selectivity and adsorption capacity over traditional porous materials. The high surface area and versatile functionality of MOFs allow for the development of new adsorbents. The development of MOFs in a range of water treatments in the recent five years will be highlighted in this review, along with assessments of the adsorption performance relevant to the particular task. Moreover, the outlook on future opportunities for water purification using MOFs is also provided.

Per- and polyfluoroalkyl substances and organofluorine in lakes and waterways of the northwestern Great Basin and Sierra Nevada

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals that occur ubiquitously in the environment and have been linked to numerous adverse health effects in humans and aquatic organisms. Although numerous environmental monitoring studies have been conducted, only one has evaluated PFAS in surface waters of the northwestern Great Basin, which features unique topography that results in dozens of endorheic basins and terminal lakes with no natural outlet, where PFAS may accumulate. To close this knowledge gap, we evaluated the occurrence of PFAS in grab samples from 15 lakes (headwater and terminal lakes) and 10 rivers in the Great Basin located in Nevada and California of the United States. PFAS and organofluorine were quantified by liquid chromatography tandem mass spectroscopy (LC-MS/MS) and combustion ion chromatography, respectively. The highest concentrations of PFAS occurred in samples taken near sites with known or suspected prior aqueous film forming foam (AFFF) application (~20 to 4754 ng/L). Samples near wastewater treatment plants and in urban areas also tended to have PFAS concentrations greater than those measured in remote, less anthropogenically influenced areas (~2 to 15 ng/L, <3 ng/L respectively). In limited snapshot sampling events PFAS appeared to accumulate in terminal lakes to some extent; in-lake concentrations were two to five times greater than those of their inflows. Fluorotelomer sulfonates were present downstream of a known AFFF application area likely to have had fluorotelomer-based foams applied to it, and the concentrations decayed in a predictable manner, suggesting they may be used as an indicator of PFAS transport away from an AFFF source. In all but two samples, organofluorine concentrations were greater than the sum of targeted PFAS (on a F basis) (median of 0.6 % of organofluorine identified via LC-MS/MS), although there was considerable variability in organofluorine measured in replicate samples.

Adaptive Evolution Laws of Biofilm under Emerging Pollutant-Induced Stress: Community Assembly-Driven Structure Response

The widely used biofilm process in advanced wastewater treatment is currently challenged by numerous exotic emerging pollutants (EPs), and the underlying principle of the challenge is the adaptive evolution laws of biofilm under EP stress. However, there is still a knowledge gap in exploration of the biofilm adaptive evolution theory. Herein, we comprehensively analyzed the morphological variation, community succession, and assembly mechanism of biofilms to report the mechanism underlying their adaptive evolution under sulfamethoxazole and carbamazepine stress for the first time. The ecological role of the dominant species was driven as a pioneer and assembly hub by EP stress, and the deterministic processes indicated the functional basis of the transformation. In addition, the characteristic responses of dispersal limitation and homogenizing dispersal adequately revealed the assembly pathways in adaptive evolution and the resulting structural variation. Therefore, the "interfacial exposure-structural variation-mass transfer feedback" mechanism was inferred to underly the adaptive evolution process of biofilms. Overall, this study highlighted the internal drivers of the adaptive evolution of the biofilm at the phylogenetic level and deepened our understanding of the mechanism of biofilm development under EP stress in advanced wastewater purification.

Simultaneous removal of heterocyclic drugs and total nitrogen from biochemical tailwater by peracetic acid/cobalt-loaded ceramsite-based denitrification biofilter

It is difficult to achieve simultaneous and efficient removal of heterocyclic drugs (HCDs) and total nitrogen (TN) in conventional denitrification biofilter (DNBF). Inspired by the effective degradation of refractory organic matter by cobalt-based advanced oxidation process and the need for in-situ upgrading of DNBF, peracetic acid (PAA)/cobalt-loaded ceramsite-based DNBF system was constructed for the first time to treat biochemical tailwater containing HCDs. Results showed that PAA/Co-DNBF had relatively high removal rates for the four HCDs with the order of CBZ > TMP > SDZ > SMX, and the optimal DNBF was H2 with 150 μg L^-1of PAA. Overall, TN and HCDs removal increased by 178%-455% and 2.50%-40.99% respectively. When the influent concentration of NO₃^--N, COD and each HCDs of 20 mg/L, 60 mg/L and 20 μg/L, below 15 mg/L of effluent TN and the highest average removal rate of SMX (67.77%) could be achieved, under HRT of 4 h in H2. More even distribution of microbial species and low acute toxicity of effluent were also achieved. More even distribution of microbial species and low acute toxicity of effluent were also achieved. In addition, high extracellular polymeric substance (EPS) content and Gordonia after the addition of PAA contributed to the degradation of HCDs. This study supplied a potentially effective strategy for the treatment of biochemical tailwater containing HCDs and provided new insight into the advance of denitrification technology.