A pilot-scale multistage constructed wetland-pond (MCWP) system with a "pre-ecological oxidation pond, two-stage horizontal subsurface flow constructed wetland (HSCW) and surface flow constructed wetland (SFCW) as the core and postsubmerged plant pond" as the process was used to treat actual polluted river water in the field, and the variation in nitrogen removal from summer to winter was investigated. The results showed that the average total nitrogen (TN) removal efficiency in the MCWP was approximately 40.74%. The significant positive correlation between the daily highest temperature and the TN removal efficiency of the whole system was fitted with a nonlinear curve (R² = 0.7192). The TN removal load rate in the HSCWs was 2.7-3.7 times that in the SFCW. The SFCW, which had high-density plants (35 plants/m²), increased the proportion of nitrogen removed by plant harvesting and microbial function. The TN transformed by Iris pseudacorus L. accounted for 54.53% in the SFCW. Furthermore, bacteria completed the nitrogen cycle in the SFCW through a variety of nitrogen removal pathways. This research not only investigated the TN removal performance in an MCWP system but also made it possible to predict the TN removal efficiency according to the daily highest temperature from summer to winter in the field.

Fuxin is located in the atmospheric channel around Bohai Bay, and its geographical location is very special. Few existing studies have investigated the pollution characteristics and health risk assessment of heavy metals in atmospheric PM_2.5 during the four seasons in Fuxin, so a total of 180 PM_2.5 samples were collected from four sampling sites in Fuxin from December 2021 to November 2022. The seasonal distribution characteristics of V, Cr, Mn, Co, Ni, Cu, Zn, Pb, As, Sb, Cd and Ba were analysed via inductively coupled plasma-mass spectrometry (ICP‒MS), and the source of the heavy metals was analysed via the enrichment factor (EF) and principal component analysis (PCA). A health risk model was used to assess the health risk of respiratory exposure in men, women and children in Fuxin. The results revealed that the annual average mass order of heavy metals in Fuxin PM_2.5 was Zn (0.2947 μg·m⁻³) > Pb (0.0664 μg·m⁻³) > As (0.0225 μg·m⁻³) > Ba (0.0205 μg·m⁻³) > Mn (0.0187 μg·m⁻³) > Cu (0.0140 μg·m⁻³) > Cr (0.0095 μg·m⁻³) > V (0.0067 μg·m⁻³) > Ni (0.0061 μg·m⁻³) > Sb (0.0024 μg·m⁻³) > Cd (0.0019 μg·m⁻³) > Co (0.0007 μg·m⁻³). The annual average concentration of As was 3.75 times the GB3095-2012 (China) secondary standard limit, and the concentration of hazard quotient (HQ) in PM_2.5 was lower than 1, but the concentration of incremental lifetime cancer risk (ILCR) in As was higher than the cancer risk threshold (10^–4). These findings indicate a certain risk of cancer in the urban population of Fuxin. Therefore, it is necessary to control the emissions created from coal burning to minimize the health risks to the people of Fuxin.

In order to solve the serious dust pollution problem in mining and loading process of burnt rock open-pit coal mines, a dust suppression technology was proposed to investigate the compound dust suppressant with four functions of wetting, coagulation, moisture absorption, and moisture retention, and improve the hydrophilicity and dust suppression efficiency of burnt rock. Through single-factor experiments, four functional reagents were selected. Determined the best mass concentration ratio by orthogonal test, and the optimum dilution ratio was determined through the contact angle verification test. Fourier infrared spectroscopy (FTIR) analysis of the functional group of the compound dust suppressant showed that the hydrophilic functional group was increased. The scanning electron microscopy (SEM) revealed that the dust surface formed a dense film after spraying the dust suppressant, and the effect of fine dust coagulation was obvious. The results of the wind tunnel simulation test revealed that the inhibitory efficiency of the compound dust suppressant on total dust and respirable dust could reach up to 81.90% and 87.06%, respectively, under a wind speed of 4.00 m/s. The field test data for mining and loading spray dust suppression in open-pit coal mines revealed that the dust suppression efficiency of whole dust and respirable dust was greater than 85.70%, which indicates that the compound dust suppressant can effectively suppress the dust of burnt rock, and effectively improve the working environment quality of mining and loading in open-pit coal mines. Implications: Open-pit coal mines located in arid areas will produce a large amount of dust during the mining and loading process, which will cause serious air pollution. In particular, the burnt rock is highly hydrophobic, and it is difficult to achieve effective removal by water spraying. The open-pit coal mine face advances faster and has strong mobility, There are few researches on dust reduction in this link. Therefore, in this study, in order to improve the dust suppression efficiency in the mining and loading process, a compound dust suppressant to improve the hydrophilicity of the burnt rock was developed through single-factor experiments and orthogonal experiments. Microscopic analysis using FTIR and SEM confirmed the wetting and coagulation effect of the dust suppressant. Then designed a spray dust suppression program for the mining and loading process and achieved good results.

Antibiotics are widely detected in the water environment, posing a serious threat to the health of humans and animals. The effect of levofloxacin (LOFL) on pollutant removal and the difference in the influence mechanisms at normal and low temperatures in constructed wetlands are worth discussing. A hydroponic culture experiment was designed with Iris pseudacorus L. at low and normal temperatures. LOFL (0-100 µg/L) was added to the systems. The results indicated that the removal of pollutants was affected most by temperature, followed by LOFL concentration. At the same concentration of LOFL, the pollutant removal rate was significantly higher at normal temperature than at low temperature. Low concentrations of LOFL promoted the degradation of pollutants except TN under normal-temperature conditions. Compared with the results at low temperature, the bacterial community richness was higher and the diversity of bacterial communities was lower under normal-temperature conditions. The genera and the function of bacteria were greatly affected by antibiotic concentration, temperature and test time. A series of microorganisms resistant to antibiotics and low temperature were identified in this study. The results will provide valuable information and a reference for our understanding of the ecological effects of LOFL.

Twelve samples of heavy metals were analyzed by using a 1108A-1 mid-current particle sampler in Dalian, Liaoning Province, for 31 days before and after the spring festival 2019. The results showed that the concentrations of heavy metals were decreased by more than 25% during the spring festival, which was probably due to the shutdown of the factories and the decrease in people’s travel. During the spring festival, the concentration of Ba was increased by 343.39% as compared to the concentration of Ba before the spring festival, which indicated that the fireworks had a great influence on the concentration of Ba. At the same time, this study also evaluated the health risk of heavy metals. For the heavy metals As, Cd, Co, Cr, and Ni, the lifetime cancer risk was found to be 2.13 × 10⁻⁴, 2.08 × 10⁻⁵, 8.64 × 10⁻⁷, 4.39 × 10⁻⁴ and 7.93 × 10⁻⁷, respectively. The lifetime cancer risk of As, Cd, and Cr exceeds the threshold range of cancer risk (10⁻⁶–10⁻⁴), indicating that they are carcinogenic to humans. Also, during the spring festival, the non-carcinogenic risk value of V exceeded the limit value of environmental protection agency (EPA), and the lifetime carcinogenic risk value of As, Cd, and Cr exceeded the threshold range of carcinogenic risk; hence, they need to be carefully monitored and controlled.