Organic UV filters are used worldwide in various personal care products as well as textiles, paints, plastic, food, and adhesives. They are main ingredients in sunscreen lotions that are used heavily by beachgoers in the summer season. There is thus an increasing concern regarding the fate of organic UV filters in the environment and their impact on living organisms. Many of the UV filters in use are hydrophobic and are expected to accumulate in the sediment phase in aquatic systems, but this has yet to be validated in situ. We targeted the UV filters benzophenone 3 (BP3), butyl methoxydibenzoylmethane (BMDBM), diethylhexyl butamido triazone (DBT), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), and methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT) in a freshwater lake and in a coastal bay in order to understand their distribution during summer 2016. Further, we examined their environmental partitioning by collecting samples from the surface water, the sediment phase, and water surface microlayer (SML). We show for the first time the presence of DBT, BEMT, and MBBT in environmental matrices (water, SML, and sediment). Notably, these UV filters were detected at low amounts in surface waters with maximum concentrations of 9.9 ng/L for DBT, 18.4 ng/L for BEMT, and below detection limits for MBBT and somewhat higher concentrations in the SML, with maximum concentrations of 43.3 ng/L for DBT, 5625.4 ng/L for BEMT, and 45.6 ng/L for MBBT. These filters were detected at even greater concentrations in the sediments, with maximum concentrations of 652.6 ng/g for DBT, 115.0 ng/g for BEMT, and 75.2 ng/g for MBBT (dry weight sediment). We also performed controlled laboratory experiments to determine their partitioning behavior, and we verified the actual solubility of many of the filters. This will help in determining the environmental fate and finally lead to a better risk assessment of these compounds. Together, these results corroborate the hypothesis that hydrophobic UV filters accumulate in the sediment phase and highlight the importance of discerning whether these UV filters impact the benthic community and their potential for bioaccumulation.

Aquatic organisms might be exposed episodically or continuously to chemicals for long-term periods throughout their life span. Pesticides are one example of widely used chemicals and thus represent a potential hazard to aquatic organisms. In addition, these chemicals may be present simultaneously in the environment or as pulses, being difficult to predict accurately how their joint effects will take place. Therefore, the aim of the present study was to investigate how Daphnia magna (clone k6) exposed throughout generations to a model pesticide (the fungicide carbendazim) would react upon an exposure to another chemical compound (triclosan) and to a mixture of both chemicals (carbendazim and triclosan). Responses of daphnids continuously exposed to carbendazim and kept in clean medium will be compared using immobilization tests and the comet assay (DNA integrity). The results showed that triclosan presented similar toxicity to daphnids exposed for 12 generations (F12) to carbendazim (similar 48-h-LC₅₀ values for immobilization data), when compared with daphnids kept in clean medium. However, at subcellular level, daphnids previously exposed to carbendazim for 12 generations (F12) showed different responses than those from clean medium, presenting a higher toxicity; a general higher percentage of DNA damage was observed, after exposure to a range of concentrations of triclosan and to the binary combination of triclosan + carbendazim. The patterns of toxicity observed for the binary mixture triclosan + carbendazim were generally similar for daphnids in clean medium and daphnids exposed to carbendazim, with a dose level deviation with antagonism observed at low doses of the chemical mixture for the immobilization data and a dose ratio deviation with synergism mainly caused by triclosan for DNA damage. With this study, we contributed to the knowledge on long-term induced effects of carbendazim exposure, while looking at the organismal sensitivity to another chemical (triclosan) and to a mixture of carbendazim and triclosan using lethality as an endpoint at the individual level and DNA damage as a subcellular endpoint.

A novel furnace throat structure was designed to reduce dust particle concentration in the flue gas emitted from the copper smelting industry. A two-stage turbulence model of the furnace throat based on the RNG k-ε model combined with the stochastic trajectory model was developed to analyze the gas flow and particle trajectories in this furnace throat structure. The resulting turbulent flow fields and particle trajectories under different operating conditions were shown and discussed. It indicates that the furnace throat plays an important role in separating the dust particles from the flue gas by applying centrifugal force and subsequent resistance force. Moreover, the effects of the radius of the inner flue, the number of the spiral plate, and the number of the spiral plate turns on the particle collection efficiency were analyzed to optimize the throat structure. The simulation results show that the furnace throat with inner flue radius of 0.05 m, two spiral plates, and two spiral plate turns has the highest particle collection efficiency. Furthermore, a series of experimental tests were conducted to validate the accuracy of the simulation results, and the measured experimental data show a good correlation with the numerical results.

One hundred and fifty years of mineral extraction throughout the mountainous Ruby Creek watershed, Washington has left a legacy of historical hard rock mines and placer claims and their wastes. We conducted a watershed-scale chemical analysis of these gold-bearing tributaries, accounting for seasonal variability in streamflow, to identify spatial and temporal changes in stream chemistry and attribute them to natural processes or mining activities. We used hierarchical cluster analysis (HCA) to group chemically similar water samples based on concentrations of 23 metals, pH, and conductivity and compared the chemistry of HCA-generated clusters of water samples using pairwise comparisons to find chemical patterns. Total concentrations of As, Ba, Ca, Mg, Na, Sb, and Se, dissolved concentrations of Fe, and conductivity increased as streamflow progressed from snowmelt-influenced to baseflow. High total concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, V, and Zn during spring snowmelt and after rains were attributable to acid mine drainage at historical hard rock mines and prospect sites. Smaller-scale placer mining, by way of suction dredging and motorized gold panning, was associated with high concentrations of Al, Ba, Cd, Co, Fe, Mg, Mn, Mo, and Zn downstream. Stream biota may be adversely affected by exposure to Pb, which exceeded USEPA’s Aquatic Life Criteria, and exposure to particulate metals suspended in the water column.

Every year, the leather tanning industry produces substantial quantities of residues such as chrome-tanned leather shavings (CTLS), which contain considerable amounts of Cr(III) salts. The residues have no particular value and under natural conditions can transform into toxic Cr(VI) wastes. The objective of the present work is to evaluate the transformation of these residues into carbon adsorbents at low temperatures (< 600 °C), using ZnCl₂ as an activating agent. The pyrolysis temperature and residence times were studied. The materials were characterized and qualified by Acid Black 210 (AB) adsorption. The results indicated that low amounts of chromium oxides (less than 2% of Cr), in the form of 50–200 nm particles, remained after the synthesis procedure. The deposited chromium oxides were present in (II), (III), and (IV) oxidation states. The low preparation temperatures employed prevented further chromium oxidation to Cr(VI). Maximum surface areas of 439 m²/g were obtained. The materials efficiently removed AB (maximum experimental adsorption capacity of 44.4 mg/g) by means of electrostatic interaction caused by the positively charged distribution of the carbons. The adsorption capacity was not affected by temperature, but pH had a mixed effect due to the combination of a shift in surface charge distribution and dye speciation. The results demonstrated that it is possible to obtain a value-added product, i.e., carbons modified with chromium nanoparticles for dye removal, from a hazardous residue of the tanning industry.

Formation of trihalomethanes (THMs) through excessive chlorination in the supplied water and its carcinogenic nature is a public health concern in many parts of the world, including a couple of neighboring countries in Asia. However, the issue was not yet addressed either in the public health policy or in academia in Bangladesh. Therefore, the objectives of this study are to determine the THM concentration in supplied water, its multiple pathways to the human body, and an estimation of resultant carcinogenic risk to urban dwellers in six different regions of Dhaka city. Thirty-one supplied water samples were collected from 31 different water points located in Purana Paltan, Naya Paltan, Kallyanpur, Shyamoli, Malibagh-Rampura, and Panthapath regions in premonsoon time. Total chlorine and chlorine dioxide (ClO₂) and trihalomethane (THM) concentration were determined using UV-VIS spectrophotometer; total organic carbon (TOC), total inorganic carbon, and total carbon concentration were measured using TOC analyzer, and chloroform concentration was determined by applying gas chromatography-mass spectroscopy (GC-MS-MS) in the supplied water samples. Research findings indicate that THM concentration exceeded the USEPA acceptable limit (80 ppb) in all regions except Panthapath. Study results showed that carcinogenic risk via ingestion was higher than the USEPA acceptable limit of 10⁻⁶. Carcinogenic risk via dermal absorption and inhalation exposure was lower according to USPEA acceptable limit. To conclude, this study represents the current knowledge about THM concentration in supplied pipeline water and adverse health risk, which signifies that regulatory measures should be taken to reduce the THM concentration.

Inorganic and organic constituents present in textile effluents have a noticeable effect on the performance of Fenton processes. However, studies have been focused on simple wastewater matrices that do not offer enough information to stakeholders to evaluate their real potential in large-scale facilities. Chemical auxiliaries, commonly present in textile wastewaters (NaCl = 30 g/L, Na₂CO₃ = 5 g/L, and CH₃COONa = 1 g/L), affect both the economic and environmental performance of the process because they increase the treatment time (from 0.5 to 24 h) and the consumption of H₂SO₄ (657%) and NaOH (148%) during conditioning steps. The life cycle assessment (LCA) performed with the IPCC-2013 method revealed that dyeing auxiliaries increase from 1.06 to 3.73 (252%) the emissions of carbon dioxide equivalent (CO₂-Eqv/m³). Electricity consumption can be considered an environmental hotspot because it represents 60% of the carbon footprint of the Fenton process. Also, the presence of auxiliaries is critical for the process because it results in the increase of the relative impact (between 50 and 80%) in all environmental categories considered by the ReCiPe-2008 method. Chemical auxiliaries increased the costs of the treatment process in 178% (US$2.22/m³) due to the higher energy consumption and the additional reagent requirements. It is worthwhile mentioning that the technical simplicity of the Fenton process and its low economic and environmental costs turn this process into an attractive alternative for the treatment of textile effluents in emerging economies.

An acquisition of metal tolerance in cladocerans related to the historical exposure has been well documented for the genera Daphnia and Ceriodaphnia, which are frequently used in ecotoxicological studies. However, small-sized cladocerans are rarely investigated for the inter-clonal variation in metal sensitivity, whereas they often dominate zooplankton community in many lakes and ponds, and even in eutrophicated rivers. We investigated the influence of historical copper exposure on the copper sensitivity of Bosmina longirostris. Copper sensitivity was compared among three clones originating from a site (Lake Yanaka), which located at downstream of historically contaminated river (Watarase River) and clones from five different reservoirs. For reference, the background copper concentration (as Cu²⁺ activity) at each site and its toxicity to Daphnia magna were estimated by metal speciation and the biotic ligand model (BLM), respectively. Less copper-sensitive Bosmina clones were obtained only from Lake Yanaka, although the background copper concentrations were far below the lethal levels. The results suggested the variability in copper-sensitivity in B. longirostris and its association with historical copper contamination.

This study was conducted to assess the proximate analysis (protein, carbohydrate, lipid, and moisture content) and concentration levels of metals (Zn, Cu, Cd, Pb, and Cr) in the muscles of selected shellfish (Portunus reticulatus, P. segnis, P. sanguinolentus, Scylla olivaceae, Penaeus monodon, and P. indicus) species. The concentration of metals showed significant difference (p > 0.05) among species. The detected concentrations of the analyzed heavy metals were below the daily intake and legal limits set by national and international standards. The THQs and CR index were calculated to evaluate the risk estimation of the metal contamination associated with the human health. The THQ values of all metals were below 1 in all species, indicated that there is no risk of adverse health effect, but the risk of elevated intakes of heavy metals adversely affecting food safety for the studied species. The CR index indicated that Cd and Pb caused the greatest cancer risk. The correlation and multivariate (principle component analysis) among metal concentration and nutritional quality were also evaluated. The carbohydrate and moisture showed the positive correlation (p > 0.05) with metals. The biochemical results of the present work clearly indicate that there was a significant difference in the muscles of shellfish. It was concluded that more effective controls should be focused on Cd and Pb to reduce pollution for quality and seafood safety concern.

The intensity and frequency of cyanobacteria-dominated harmful algal blooms (cHABs) has been increasing. A key issue associated with cHABs is the potential to release cyanotoxins, such as microcystin. One of the primary methods for addressing cHABs in a reservoir is the application of algaecides. This research evaluated the impact of common environmental factors (i.e., Fe, total organic carbon) on the efficacy of a hydrogen peroxide-based algaecide to attain control of a targeted cyanobacterial population. The results found that sodium carbonate peroxydrate (SCP, trade name PAK®27) at half the manufacturer’s suggested application was effective at suppressing cyanobacteria for 2 weeks. For example, reactors that contained a full level of TOC and 1 mg/L Fe significantly decreased by 89% from 21,899 to 2437 ± 987 cells/mL (p < 0.05) by 2 days after treatment with half-dose SCP while reactors that contained the full-dose TOC and no SCP treatment depicted an increase in cyanobacteria population over the first week. Furthermore, as the cyanobacteria population decreased, the algal assemblage began to switch to being green algae dominant. Under the experimental conditions evaluated, Fe and total organic content did not interfere with the efficacy of SCP. SCP can provide effective control of cyanobacteria in a variety of environmental conditions.