Advances in Environmental Behaviors of Persistent Contaminants: Fate, Distribution, Risk, and Challenges

This study aims to assess the contents of different kinds of low-molecular-weight organic acids (LMWOAs) in reclaimed soil filled with fly ash in the Huainan mining area in China using high-performance liquid chromatography (HPLC). Using a mobile phase consisting of 0.1% phosphoric acid and acetonitrile in a volume ratio of 98:2, the detection was performed at a wavelength of 210 nm for 15 min. In addition, a cluster analysis was performed on the detected LMWOAs in the reclaimed soil. The correlations between the LMWOA and nutrient contents in the reclaimed soil were also analyzed. In total, eight and seven LMWOAs were detected in the reclaimed soil and filled fly ash, respectively. In contrast, no LMWOAs were detected in the fresh fly ash from a thermal power plant. The order of total LMWOA contents at different sampling points followed the order of farmland control soil > 1# (Triticum aestivum) > 4# (Phragmites australis) > 5# (Vigna radiata) > 2# (Sorghum bicolor) > 3# (Tamarix ramosissima) > fly ash-filled soil. The farmland control soil and fly ash-filled soil exhibited the highest and lowest LMWOA contents of 648.22 and 85.09 μg·g⁻¹, respectively. The LMWOA contents in the reclaimed soil followed the order of oxalic acid > tartaric acid > malonic acid > lactic acid > acetic acid > citric acid > propionic acid > succinic acid. Indeed, oxalic acids exhibited the highest total amount of 1445.79 μg·g⁻¹ and succinic acids exhibited the lowest total amount of 6.50 μg·g⁻¹. The LMWOA contents in the reclaimed soil decreased with increasing soil depth, showing statistically significant differences between the 0–10 and 10–40 cm soil layers (p < 0.05). According to the obtained clustering results, the detected LMWOAs can be divided into two categories. The first category consisted of oxalic acid, while the second category included the remaining LMWOAs. The soil LMWOA contents of 4# (Phragmites australis) and 5# (Vigna radiata) were significantly different from those at the other sampling points. According to the Pearson correlation analysis results, the occurrence and characteristics of the soil LMWOAs can be controlled by regulating the pH values and available nutrient contents in the soil, thereby improving the eco-environmental conditions of the reclaimed rhizosphere. Full article

Due to their significant environmental impact, there has been a gradual restriction of the production and utilization of legacy per- and polyfluoroalkyl substances (PFAS), leading to continuous development and adoption of novel alternatives. To effectively identify the potential environmental risks from crop consumption, the levels of 25 PFAS, including fourteen perfluoroalkyl acids (PFAAs), two precursor substances and nine novel alternatives, in agricultural soils and edible parts of various crops around a fluoride industrial park (FIP) in Changshu city, China, were measured. The concentration of ΣPFAS in the edible parts of all crops ranged from 11.64 to 299.5 ng/g, with perfluorobutanoic acid (PFBA) being the dominant compound, accounting for an average of 71% of ΣPFAS. The precursor substance, N-methylperfluoro-octanesulfonamidoacetic acid (N-MeFOSAA), was detected in all crop samples. Different types of crops showed distinguishing accumulation profiles for the PFAS. Solanaceae and leafy vegetables showed higher levels of PFAS contamination, with the highest ΣPFAS concentrations reaching 190.91 and 175.29 ng/g, respectively. The highest ΣAlternative was detected in leafy vegetables at 15.21 ng/g. The levels of human exposure to PFAS through crop consumption for various aged groups were also evaluated. The maximum exposure to PFOA for urban toddlers reached 109.8% of the standard value set by the European Food Safety Authority (EFSA). In addition, short-chained PFAAs and novel alternatives may pose potential risks to human health via crop consumption. Full article

Profenofos is a detectable insecticide in the environment with strong toxicity to non-targeted organisms. Photodegradation is a main transformation of profenofos in the environment. Myricetin is a flavonoid that strongly scavenges free radicals. The effect of myricetin on the photodegradation of profenofos was studied. The half-lives (T_1/2) of profenofos were 1.7–7.0 and 90 h under artificial light and sunlight. The photolysis rate of profenofos decreased by 1.87–4.72 and 7.62 times with the addition of 20 ratios of myricetin. Free radicals reacting with profenofos were •OH and ¹O₂, and the key free radical was •OH. Myricetin strongly scavenged •OH and ¹O₂ which rapidly reacted with profenofos. O-(2-Chlorophenyl)-O-ethyl-S-propyl phosphorothioate (M3) and O-(2-chlorophenyl)-O-ethyl phosphorothioate (M4) were major and new photoproducts of profenofos. According to the Ecological Structure Activity Relationships, photodegradation of profenofos was a detoxification process, but myricetin inhibited the photodegradation of profenofos and its photoproducts. These results highlight the implication of myricetin on the fate and potential risk of profenofos in the environment. Full article

The extensive use of the parabens triclosan (TCS) and bisphenol A (BPA) has potential adverse effects on human health and aquatic organisms. However, their monitoring information in freshwater lakes is still limited. This study simultaneously summarized the concentrations, spatial distribution characteristics, and correlations of four types of parabens, TCS, and BPA in the surface water and sediment of Baiyang Lake. Finally, the potential risks of target pollutants were evaluated from two aspects: human health risks and ecological risks. The average contaminations of target compounds in surface water and sediment—BPA, TCS, and ∑₄ parabens—was 33.1, 26.1, 0.7 ng/L and 24.5, 32.5, 2.5 ng/g, respectively. The total concentration of target compounds at the inlet of the upstream Fu River and Baigouyin River is significantly higher than that near Hunan and the outlet. In addition, Spearman’s correlation analysis showed a significant positive correlation between compounds. The health hazards of target compounds in surface water were all within safe limits. However, the risk quotient results indicate that in some locations in surface water, TCS poses a high risk to algae and a moderate risk to invertebrates and fish, and appropriate attention should be paid to these areas. Full article

In the present study, the developmental toxicity and endocrine-disrupting effects of fenpropathrin on Gobiocypris rarus during the early life stage were studied using a semi-static water exposure method. The results showed that the LOEC (lowest observed effect concentration) of fenpropathrin on the incubation of rare minnow embryos was above 2.5 μg·L⁻¹. The LOEC and NOEC (no observed effect concentration) of fenpropathrin on the developmental malformations and death indicators were 2.0 and 1.5 μg·L⁻¹, respectively. After exposure to 1.5 μg·L⁻¹ of fenpropathrin for 31 days, the expressions of androgen receptor genes (AR) and sex hormone-synthesis-related genes (CYP17 and CYP19a) were significantly decreased and the expressions of thyroid hormone receptor genes (TRβ) and aryl hydrocarbon receptor genes (AhR1a and AhR2) were significantly increased in juvenile Gobiocypris rarus. The expression levels of the androgen receptor gene (AR), estrogen receptor gene (ER1), and the sex hormone-synthesis-related genes (HMGR, CYP17, and CYP19a) were significantly decreased, while the estrogen receptor gene (ER2a), thyroid hormone receptor gene (TRβ), and aromatic hydrocarbon receptor genes (AhR1a and AhR2) were upregulated in juvenile Gobiocypris rarus under exposure to 2.0 μg·L⁻¹ of fenpropathrin. Relatively low concentrations of fenpropathrin can affect the expression of sex hormone receptor genes, genes related to sex hormone synthesis, thyroid hormone receptor genes, and aromatic hydrocarbon receptor genes, thus interfering with the reproductive system, thyroid system, and metabolic level in Gobiocypris rarus. Therefore, more attention should be paid to the endocrine-disrupting effect caused by the pyrethroid insecticides in the water environment. Furthermore, studies on the internal mechanism of the endocrine-disrupting effect of pyrethroid insecticides on fish is needed in the future. Full article

With rapid economic development, soil heavy metal (HM) pollution has emerged as a global environmental concern. Because the toxicity of HMs differs dramatically among various fractions, risk assessments based on these fractions are of great significance for environmental management. This study employed a modified Hakanson index approach to evaluate the possible ecological impacts of soil HMs in a gold mine tailings pond in Shaanxi Province, China. A modified Hakanson–Monte Carlo model was built to perform a probabilistic risk assessment. The results showed that: (1) the exceedance rates of chromium (Cr) and zinc (Zn) were 68.75% and 93.75%, respectively. Moreover, the overall concentrations of nickel (Ni), copper (Cu), arsenic (As), and lead (Pb) were higher than the background soil environmental values in China. (2) HMs with the lowest oxidizable fraction were mostly present in the residual fraction. The oxidizable portions of Cr, Cu, and Pb and the reducible and residual fractions of As were notably distinct. (3) The risk degrees of Cr, Ni, Cu, and Zn were low; those of As and Pb were very high and moderate; and the comprehensive ecological hazard index was very high. This study offers a solid scientific foundation for ecological risk notification and environmental management. Full article

Gaseous polycyclic aromatic hydrocarbons were measured in northern Thailand. No previous studies have provided data on gaseous PAHs until now, so this study determined the gaseous PAHs during two sampling periods for comparison, and then they were used to assess the correlation with meteorological conditions, other pollutants, and their sources. The total concentrations of 8-PAHs (i.e., NAP, ACY, ACE, FLU, PHE, ANT, FLA, and PYR) were 125 ± 22 ng m⁻³ and 111 ± 21 ng m⁻³, with NAP being the most pronounced at 67 ± 18 ng m⁻³ and 56 ± 17 ng m⁻³, for morning and afternoon, respectively. High temperatures increase the concentrations of four-ring PAHs, whereas humidity and pressure increase the concentrations of two- and three-ring PAHs. Moreover, gaseous PAHs were estimated to contain more toxic derivatives such as nitro-PAH, which ranged from 0.02 ng m⁻³ (8-Nitrofluoranthene) to 10.46 ng m⁻³ (1-Nitronaphthalene). Therefore, they could be one of the causes of local people’s health problems that have not been reported previously. Strong correlations of gaseous PAHs with ozone indicated that photochemical oxidation influenced four-ring PAHs. According to the Pearson correlation, diagnostic ratios, and principal component analysis, mixed sources including coal combustion, biomass burning, and vehicle emissions were the main sources of these pollutants. Full article

The concentrations of 14 polycyclic aromatic hydrocarbons (PAHs) in the sediment of the Tatar Trough were studied. Despite the increase in PAH concentrations over recent decades, which is likely the result of the handling and transportation of fossil fuels, PAH levels and ecological risk were found to be low. The spatial pattern revealed that higher PAH concentrations were mainly in the deeper water sites, suggesting that trough slope failure transported the PAHs to the deeper part of the basin. There was no correlation between the PAHs and grain size or the PAHs and organic carbon that is related to the PAH input from a variety of sources and the heterogeneity of organic matter. The PAH composition, isomer ratio, and PCA identified two areas with different PAH sources. The most northern part of the Tatar Trough received petrogenic PAHs that are probably transported downslope from the northern Tatar Strait where fossil fuels are handled in some ports. Another trough part was polluted by the PAHs from the combustion of coal and biomass and the exhaust of marine vehicles. The minor presence of genes responsible for aerobic PAH destruction can be explained by the anaerobic degradation of PAHs or the spontaneous creation of favorable conditions that promote bacterial PAH oxidation. Full article

One practice to reduce spray drift during pesticide application is the addition of certain chemical adjuvants to spraying solutions, which change their physicochemical properties and result in larger droplets. The environmental impact of these agrochemicals continues however also after application, depending on surface processes occurring upon treated surfaces. While the impact of anti-drift adjuvants has been studied regarding spray drift, their impact on the fate of deposited pesticides has received little attention. Here, the effect of a polymer-based adjuvant (polyacrylamide) on the photolysis and evaporation rates of pyrimethanil (common fungicide) from dry films were investigated under controlled laboratory conditions and during two field studies. The laboratory results indicate that the adjuvant enhances the volatilization and photolysis rate both on hydrophobic lemon leaves and hydrophilic glass substrates. These results can be attributed to an increase in the geometrical area of residual film and a widening of its circumference rim, where solutes are likely to concentrate, when generated from adjuvant-containing droplets. Such morphological differences may enhance the exposure of deposited pesticides to interact with the overlaying atmosphere and incident radiation. The field data was less conclusive, suggesting a small impact of the anti-drift adjuvant on the fungicide’s secondary drift from crops and an even lower effect on volatilization from bare soil. Full article

BTEX (benzene, toluene, ethylbenzene, and xylene), as characteristic pollutants in chemical plant sites, are widely present in the environment and pose a serious threat to the health and safety of nearby residents. Studying the spatial distribution characteristics and transport fluxes of BTEX in soil and air at contaminated sites and the health risks they pose to humans is of great significance for fine pollution control and environmental management. This study took a typical decommissioned steel plant as a case study. A total of 23 soil and air samples were collected from different locations to investigate the spatial distribution characteristics of BTEX in soil and air. The transport and fate of BTEX in soil and air were evaluated using the fugacity model, and finally, a human health risk assessment was conducted. The results indicate a relatively severe level of benzene pollution in both soil and air. The maximum exceedance factor of benzene in soil samples is 31.5, with the concentration exceedance depth at 1.5 m. The maximum concentration of benzene in air samples is 4.98 μg·m⁻³. Benzene, at 5.9% of the site, shows a low flux with negative values, while other components at various locations all exhibit a trend of transport from the soil phase to the atmospheric phase. Benzene is the pollutant that contributes the most to the transport flux from soil to air within the site. The coking area and sewage treatment area are key areas within the steel mill where BTEX accumulate easily in the soil. The non-carcinogenic risk values of the individual components of BTEX in the soil are below the acceptable risk level. However, the carcinogenic risk value of benzene in the children’s exposure scenario exceeds the carcinogenic risk level of 10⁻⁶. The carcinogenic risk range of various components of BTEX in the air is 2.63 × 10⁻⁶~3.88 × 10⁻⁵, with 28.6% of the locations exceeding the threshold of 10⁻⁶. The range of the total HI (hazard index) is 2.08 × 10⁻⁴~1.81 × 10⁻¹, all of which is below the safety threshold of 1. The results of this study will provide scientific support for the fine pollution control and environmental management of industrial contaminated sites with BTEX as their typical pollutants. Full article

The purpose of this study is to evaluate the bio-accumulation of different soil-crop systems (SCSs) for heavy metals (HMs) and the geo-accumulation of different agricultural growing regions. The ecological risk (ER) assessment was conducted to understand the impact of intensive agricultural production on the environment. To achieve this aim, four typical crops, wheat, corn, potatoes, and leeks grown in the Jiao River Basin (JRB), were selected as the research objects. The concentrations of eight HMs, including copper (Cu), lead (Pb), zinc (Zn), nickel (Ni), chromium (Cr), cadmium (Cd), arsenic (As), and mercury (Hg) in crop tissue and soil were detected. The statistical analysis, including the geo-accumulation index ($I_{geo}$), geostatistical analysis, correlation and cluster analysis were then used to evaluate soil contamination and determine the source types of HMs. The results show that the average concentrations of eight HMs in the soil follow the order: Zn > Cr > Ni > Pb > Cu > As > Cd > Hg and the calculated concentration coefficients (K) vary from 0.41–1.12, indicating relative scarcity in sources of HMs. All the $I_{geo}$ values of HMs are less than 0 except the $I_{geo}$ of Cr within potato-farmland is from 0 to 1, illustrating that the soil in JRB is uncontaminated. The correlation and cluster analysis reveal that Cu, Zn, and Cd have a strong relationship with each other and the relationship between Pb, Ni, and Cr is general. The content of eight HMs in different crops varies greatly and most of them are within the scope of National Food Safety Standards—Limit of Pollutants in food of China. The bioconcentration factors (BCF) indicate that wheat, corn, potato, and leek have strong bio-accumulation ability of Cu, Zn, and Cd. The ecological risk factor (Er) shows that JRB is in low risk of Cu, Pb, Zn, Ni, Cr, and As; however, the risk of Cr and Hg are mostly low, characterized by partially dotted moderate risk. The risk index (RI) is mainly moderate with partially low risk distributed in planar and high risk distributed in point. Full article

We found that the typical fluoroquinolone antibiotic enrofloxacin (ENR) and plasticizer di-(2-ethylhexyl) phthalate (DEHP) are often detected simultaneously and at high frequencies in the environment, but their combined exposure effects on soil animals are poorly understood. Here, oxidative stress, DNA damage and changes in digestibility of the earthworm were investigated to reflect the toxicological effects of single and combined exposure of DEHP and ENR on earthworms (Eisenia fetida). We found that the DEHP treatment group and the combined pollution treatment group showed significantly increased reactive oxygen species content of earthworms at 14 d and 28 d. ENR exposure alone had little effect on the antioxidant enzyme system, while DEHP and combined treatment showed a trend of inhibition and then activation. Addition of both pollutants caused a rise in the lipid peroxidation levels of earthworms. Malonaldehyde (MDA) was mainly scavenged by glutathione sulfur transferase (GST). ENR and DEHP caused more DNA damage to earthworm tissue than their combined pollution under the regulation of GST. Both single and combined pollution inhibited the digestive enzyme activity of earthworms, but the combined pollution had a stronger inhibitory effect. Cellulase, MDA and GST were the three most sensitive indicators on PCA. The toxicity was ENR + DEHP > DEHP > ENR according to the IBR index, and the combined toxicity showed a synergistic effect. The results showed that the combined pollution of phthalate esters and antibiotics in the actual environment was a significant ecological risk that deserves special attention. Full article

Spatiotemporal changes in the concentration of UV filters were investigated along the shore according to increasing distance from breakwaters, from the shoreline, as well as according to seasonality in three locations of different anthropogenic pressures, involving those from cosmetic products being released during touristic activity. Nine organic UV filters (benzophenone-1 (BP-1), benzophenone-2 (BP-2), benzophenone-3 (BP-3), octocrylene (OCR), 4-methoxy benzylidene camphor (4-MBC), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate (EHS), homosalate (HMS), and butyl methoxydibenzoylmethane (BMDM)) were determined in core sediments, and the range of determined concentrations above the limit of quantification was between 19.2 ng·kg⁻¹ d.w. (HMS) and 539.5 μg·kg⁻¹ d.w. (4-MBC). Unexpectedly, contrary to the level of anthropogenic pressure, the concentrations of four (BP-1, BP-2, BP-3, OCR) UV filters decreased in the following order: Darłówko > Ustka > Rowy. Higher concentrations of BP-1, BP-2, BP-3, and OCR were determined in spring than in summer and autumn. The maximal concentration of HMS and EHMC/EHS was found in the summer and in the autumn, respectively. BMDM was determined occasionally only in two samples collected in Ustka. The higher maximal concentration range of all UV filters was determined in core sediments taken from the eastern (539.5 μg·kg⁻¹ d.w.) rather than from the western (11.3 μg·kg⁻¹ d.w.) parts of the beaches. According to increasing distance from the breakwaters, higher concentrations of UV filters were determined in sites located up to 100 m away in all locations and seasons. Spatial variation in the concentration of UV filters was observed in profiles perpendicular to the water line. Typically, higher concentrations were determined at sites having contact with water, although incidentally, high concentrations were also noticed at sites located further into the beach. The Polish coast of the Baltic Sea is not free from organic UV filters, and expectations concerning the abundance of UV filters in a given location are far from recorded data due to the impact of hydro-technical treatments (i.e., stony and wooden breakwaters, artificial reefs, nourishment) and coastal littoral drift. Full article

Asbestos has been confirmed as a major pollutant in asbestos-mining areas that are located in western China. In general, asbestos-fibre dust will is released into the environment due to the effect of intensive industrial activities and improper environmental management, such that the health of residents in and around mining areas is jeopardised. A typical asbestos mining area served as an example in this study to analyse the content and fibre morphology of asbestos in soil and air samples in the mining area. The effects of asbestos pollution in and around the mining areas on human health were also assessed based on the U.S. Superfund Risk Assessment Framework in this study. As indicated by the results, different degrees of asbestos pollutions were present in the soil and air, and they were mainly concentrated in the mining area, the ore-dressing area, and the waste pile. The concentration of asbestos in the soil ranged from 0.3% to 91.92%, and the concentration of asbestos fibres in the air reached 0.008–0.145 f·cc⁻¹. The results of the scanning-electron microscope (SEM) energy suggested that the asbestos was primarily strip-shaped, short columnar, and granular, and the asbestos morphology of the soils with higher degrees of pollution exhibited irregular strip-shaped fibre agglomeration. The excess lifetime cancer risk (ELCR) associated with the asbestos fibres in the air of the mining area was at an acceptable level (10⁻⁴–10⁻⁶), and 40.6% of the monitoring sites were subjected to unacceptable non-carcinogenic risks (HQ > 1). Moreover, the waste pile was the area with the highest non-carcinogenic risk, followed by the ore dressing area, a residential area, and a bare-land area in descending order. In the three scenarios of adult offices or residences in the mining area, adults’ outdoor activities in the peripheral residence areas, and children’s outdoor activities, the carcinogenic-and non-carcinogenic-risk-control values in the air reached 0.1438, 0.2225 and 0.1540 f·cc⁻¹, and 0.0084, 0.0090 and 0.0090 f·cc⁻¹, respectively. The results of this study will lay a scientific basis for the environmental management and governance of asbestos polluted sites in China. Full article

The development of differentiated emission reduction strategies plays an important role in achieving carbon compliance targets. Each city should adopt carbon reduction strategies according to its carbon emission characteristics. China is a vast country, and there are significant differences between cities. Therefore, this study classifies 340 Chinese cities according to their carbon emission characteristics since 2020 and proposes differentiated emission reduction strategies accordingly. The results of the research show that Chinese cities can be divided into four categories, and they can strive to achieve their carbon peak targets by adopting differentiated emission reduction strategies. In the baseline scenario, Chinese cities will not be able to meet the peak carbon target by 2030. In the differentiated scenario, eco-agricultural cities, industry-led cities, and high-resource-availability cities will be able to achieve peak carbon by 2030. Unfortunately, resource-poor cities will not reach their peak. However, the extent to which their total carbon emissions contribute to the achievement of national goals is low, and their carbon emissions can be traded off for economic development by appropriately relaxing the constraints on carbon emissions. Therefore, in order to achieve China’s peak carbon goal, this study proposes emission reduction recommendations that should be adopted by different types of cities to form differentiated emission reduction strategies. Full article