[Occurrence Characteristics of Microplastics in Baiyangdian Lake Water and Sediments].

In order to explore the occurrence characteristics of microplastics in the freshwater environment of Baiyangdian Lake in China, ten overlying water samples and ten sediment samples were collected in Baiyangdian Lake of Hebei Province in October 2021, and the abundance distribution, shape, particle size, and polymer type of microplastics in the samples were identified using laboratory pretreatment, microscope observation, and laser infrared spectroscopy. The sedimentation law of microplastics at the overlying water-sediment interface was studied using the Stokes sedimentation formula, and their pollution characteristics and potential sources were analyzed. The abundances of microplastics in the overlying water and sediments in Baiyangdian Lake ranged from 474-19382 n·m-3 and 95.3-29542.5 n·kg-1, respectively, with an average value of 6255.4 n·m-3 and 11088 n·kg-1. The main polymer of the microplastics in the overlying water was polyethylene terephthalate[PET, (17.20±0.26)%], and the microplastics in the sediments were mainly chlorinated polyethylene[CPE, (46.11±1.30)%]. The sedimentation velocities of microplastics in the sedimentation zone ranged from 0.0793-111.7547 mm·s-1. The particles with larger particle size had higher sedimentation velocity and easily settled and remained in the sediments. The main sources of microplastic pollution in the study area were the discharge of textile fibers from washing wastewater and the wear and tear of ship paint, ship rubber, and building materials.

[Spatial-temporal Variation in Water Quality and Its Response to Precipitation and Land Use in Baiyangdian Lake in the Early Stage of the Construction of Xiong'an New Area].

To assess the water quality of Baiyangdian Lake in the early stage of construction of the Xiong'an New Area, the water quality data in Baiyangdian Lake from December 2020 to November 2021 were collected from five typical monitoring stations. Using the remote-sensing interpretation of land use types, Pearson correlation analysis, comprehensive pollution index, and principal component analysis, the spatial-temporal variation characteristics of the water quality and its response to precipitation and land use structure at different spatial scales were explored in Baiyangdian Lake. The results showed that:① the water quality of Baiyangdian Lake was the best in spring and the worst in summer. Nutrient pollution was the heaviest at Nanliuzhuang, which was greatly affected by the Fuhe River. Organic pollution was the heaviest at Caiputai. ② The comprehensive pollution index of Nanliuzhuang was the highest, followed by that of Shaochedian, Guangdianzhangzhuang, Caiputai, and Quantou. The main excessive pollutant was TN, and the pollution index of 1.55 reached the level of severe pollution. The water quality of Baiyangdian Lake was significantly better than that before the construction of the Xiong'an New Area. ③ The construction land and cropland within the 1.5 km buffer zone had the greatest impact on turbidity, NH4+-N, and TP. While the reed wetland acted as the "sink" for intercepting and absorbing pollutants, it also released nitrogen into the 800 m buffer zone, which was the "source" of the pollutants. ④ The correlation between water quality indicators and land use structure in the rainy season was lower than that in the dry season. This was due to the dilution effect of the upstream reservoir discharging in the rainy season, which weakened the impact of pollutants in the rainfall runoff on the water quality of Baiyangdian Lake.

A Fast Hybrid Feature Selection Based on Correlation-Guided Clustering and Particle Swarm Optimization for High-Dimensional Data.

The "curse of dimensionality" and the high computational cost have still limited the application of the evolutionary algorithm in high-dimensional feature selection (FS) problems. This article proposes a new three-phase hybrid FS algorithm based on correlation-guided clustering and particle swarm optimization (PSO) (HFS-C-P) to tackle the above two problems at the same time. To this end, three kinds of FS methods are effectively integrated into the proposed algorithm based on their respective advantages. In the first and second phases, a filter FS method and a feature clustering-based method with low computational cost are designed to reduce the search space used by the third phase. After that, the third phase applies oneself to finding an optimal feature subset by using an evolutionary algorithm with the global searchability. Moreover, a symmetric uncertainty-based feature deletion method, a fast correlation-guided feature clustering strategy, and an improved integer PSO are developed to improve the performance of the three phases, respectively. Finally, the proposed algorithm is validated on 18 publicly available real-world datasets in comparison with nine FS algorithms. Experimental results show that the proposed algorithm can obtain a good feature subset with the lowest computational cost.

[Impact of Mainstream Backwater on the Water Environment of the Tributaries of the Three Gorges Reservoir at Low Water Level].

To prevent the eutrophication of tributaries and guarantee water quality and safety in the Three Gorges Reservoir, research on the impact of mainstream backwater on tributary water environments is of great significance. The investigation and sampling of the Yangtze mainstream and its major tributaries in the reservoir region were performed from August 7 to August 12, 2016, through which the overall hydrochemical environment of the Three Gorges Reservoir has been revealed, and the impact of mainstream backwater on the hydrochemical characteristics of main tributaries has been determined during the low water level operation period. The results showed the following:① The electrical conductivity of the mainstream varied from 291 µS·cm-1 to 336 µS·cm-1, whereas that of the mainstream backwater unaffected zone of the tributary varied from 183.7 µS·cm-1 to 518 µS·cm-1. The electrical conductivity of the mainstream backwater affected zone of the tributary varied from 267 µS·cm-1 to 330 µS·cm-1, which was close to the mainstream variation range. ② The variation range of the δD and δ18 O values of the mainstream were -81.60‰--75.16‰ and -11.57‰--0.26‰, whereas that of the mainstream backwater unaffected zone of tributaries were -59.94‰--43.67‰ and -9.00‰--6.04‰; those of the mainstream backwater affected zone of tributary were -77.85‰--50.75‰ and -11.06‰--7.33‰, which showed the same pattern as those of electrical conductivity and mass concentration of main anions and cations. This means that the mainstream affected the waterbody composition of tributaries through backwater as well as the chemical characterization of tributary water. The extent of mainstream backwater influence on tributaries was negatively correlated to the distance between the tributary estuary and Three Gorges Dam as well as tributary discharge. The hydrochemical characteristics of the mainstream backwater unaffected zone of the tributary were related to the tributary catchment properties. Tributaries with denser populations and higher proportions of cultivated land have poorer water quality. Mainstream backwater can pollute tributaries of better water quality and optimize those with poor water quality.

[Impact of Maximum Precipitation in 2017 on the Runoff Component of Reclaimed Water-Intaking River].

The hydrology of rivers recharged with reclaimed water is an important factor controlling its aquatic environment and biochemical processes, which change during the wet season. To understand the impacts of precipitation on hydrological conditions, water samples were collected from seven sites in three periods (before the wet season and during and after the maximum precipitation in July 2017, with 3.3 return periods) throughout a reclaimed water intake area of the Chaobai River in the Shunyi District, Beijing. The hydrogen-oxygen isotope characteristics and chloride content were measured. The results show that the hydrogen and oxygen isotopes of precipitation are mainly affected by the amount of the effect. The minor variation in the later period is due to changes in the sources of moisture. Within three days after precipitation, the slope runoff continues and the fraction of each section varies greatly. The reclaimed water reaches the downstream section through the preferred pathway. The water component ratio of the slope runoff increases from 2% to 85.6% in the direction of the flow, while the reclaimed water ratio decreases from 90% to 67%. The stream remains effluent from sections SY01 to SY05 that are recharged by the slope runoff, reclaimed water, and in-site river water, while the sections SY06 to SY07 are mainly recharged by the slope runoff and in-site river water within three days after the precipitation (the stream effluent is unremarkable).

Behavior, mass inventories and modeling evaluation of xenobiotic endocrine-disrupting chemicals along an urban receiving wastewater river in Henan Province, China.

Historically, the locations of cities mainly depend on the available water source and the urban river not only supplies the fresh water to city but also receives its wastewaters. To analyze the influences of urban zone on its receiving water river, the Jialu River in Henan Province, China, a typical urban river was chosen. Water and sediment samples were collected along the river in 2007 to analyze the concentrations of xenobiotic endocrine-disrupting chemicals (XEDCs) including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in surface water and sediment. The results showed that the concentrations of OP, NP and BPA in surface water were 20.9-63.2 ng L(-1) (mean 39.8 ng L(-1)), 75.2-1520 ng L(-1) (mean 645 ng L(-1)), 410-2990 ng L(-1) (mean 1535 ng L(-1)), respectively. The lowest and highest concentrations of XEDCs in surface water were found in the upper stream and downstream of Zhengzhou urban zone, which was regarded as the major discharge source of these chemicals to this river. The concentrations of OP, NP and BPA in the sediment were 15.9-31.1 ng g(-1), 145-349 ng g(-1) and 626-3584 ng g(-1) with the average concentrations of 21.4 ng g(-1), 257 ng g(-1) and 2291 ng g(-1), respectively. The results of in situ sediment-water partition of XEDCs showed that the partition coefficients (log K(oc)') in the downstream were higher than that in the upstream, which was mainly caused by the retransfer of surface sediment from the upper stream to the downstream. Comparison of measured and theoretical inventories of XEDCs in sediment indicated that the residual time of XEDCs in sediment in the river was about 5 years, which was in the same order of magnitude with its big flood frequency. In order to predict concentration variances of XEDCs in surface water, a fugacity-hydrodynamic model was developed according to the concept of in series completely stirred tank reactors (CSTR). The model results showed that about 29-65% of XEDCs derived from the urban zone (about 2.0 t yr(-1)) would finally dissipate from aqueous phase in the 170 km downstream of the river. Assuming the discharge amount of XEDCs from the urban zone remaining constant, the predicted concentrations of the total XEDCs in the over 90% river reach would be higher than 1.0 µg L(-1) under all normal, high water and low water season in 2007.

[Characteristics of soil water movement using stable isotopes in red soil hilly region of northwest Hunan].

Stable isotope techniques provide a new approach to study soil water movement. The process of water movement in soils under two kinds of plant types (oil tea and corn) were studied based on the observed values of hydrogen and oxygen isotopes of precipitation and soil water at different depths in red-soil sloping land. The results showed that stable isotopes of precipitation in this area had obvious seasonal effect and rainfall effect. The stable isotopes at 0-50 cm depth in oil tea forestland and at 0-40 cm depth in corn cropland increased with the increase in depth, respectively, but they had the opposite tendency after rainfall in arid time. The stable isotopes decreased with the increase in depth below 50 cm depth in oil tea forestland and below 40 cm depth in corn cropland where evaporation influence was weak. The infiltrate rate of soil in oil tea land was affected by precipitation obviously, and it was about 50-100 mm/d after 2-3 days in heavy rain, slowed sharply later, and soil water at 50 cm depth often became a barrier layer. The permeability of soil in corn land was poor and the infiltration rate was lower. The change of stable isotopes in soil water in red soil hilly region was mainly affected by the mixing water which was formed by the antecedent precipitation, and evaporation effect took the second place. The evaporation intensity in oil tea land was lower than that in corn land, but the evaporation depth was higher.

Behavior and fate of alkylphenols in surface water of the Jialu River, Henan Province, China.

The behavior and fate of alkylphenols (APs) were studied in surface water from the Jialu River, Henan Province, China. Located at its upper stream, Zhengzhou city is regarded as the major discharge source to this river with its annual effluents containing 726 kg for nonylphenol (NP) and 30.2 kg for octylphenol (OP). The concentrations of NP and OP in surface water ranged from 75.2 to 1520 ngL(-1) and from 20.9 to 63.2 ngL(-1), respectively. To assess the behavior of APs along the river, a mass balance equation based on chloride was adopted, due to its relative conservation. The results showed that dilution effect was prevailing in determining the APs concentrations in surface water along the river. The effect of potential biodegradation was also estimated with an assumption of the optimized biodegradation. The contributions of dilution and biodegradation to the decline of APs concentrations were 38.8%, 23.7% for NP and 57.8%, 24.3% for OP, respectively. The other contribution to the decline of APs concentrations along the river was considered as an integrated effect of adsorption and air-water exchange with the values of 37.5% for NP and 17.9% for OP. The decay half-lives of NP and OP from surface water bodies were 1.6 and 2.4d, respectively. About 70.2% of total NP and 24.1% of total OP were finally eliminated from water phase to surrounding matrix in the downstream. The results suggested that the downstream river channel served as the net sink of APs in the study area.