Large amounts of fracturing flowback and wastewater with complex compositions are produced during hydraulic fracturing. Characterization of hydraulic fracturing flowback and produced water (HF-FPW) is an important initial step in efforts to determine a suitable treatment method for this type of wastewater. In the present study, fracturing flowback and produced water samples were obtained from well CN-F and well CN-E in the prophase and anaphase stages of the Changning shale gas mining area. Chemical characterization of inorganic and organic substances was then conducted. Metal contents were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), and all inorganic anions involved were determined by ion chromatography. The organic pollutant components were analyzed in detail by combining Fourier transform infrared spectrometer (FTIR) and gas chromatography-mass spectrometer (GC-MS). Results showed that samples contained salt (TDS = 30,000–50,000 mg/L), metals (e.g., 650 ± 50 mg/L calcium), and total organic carbon (TOC = 32–178 mg/L). The organic substances detected in all samples could be divided into six categories, alkanes, aromatics, halogenated hydrocarbons, alcohols, esters, and ketones. C₆–C₂₁ straight-chain alkanes and C₇–C₁₃ naphthenes had the highest amount of organic matter, reaching more than 48%. The organic matter contained fracturing fluid additives, such as surfactants (e.g., ethylene glycol), and nitrotrichloromethane, which is a chlorinated product of some additives. These results provide information on the chemical composition of HF-FPW in Sichuan, China, as well as a basis for subsequent processing.

A particle size distribution (PSD) of particulate matter (PM) is a primary metric to examine PM transport and fate, as well as PM-bound chemicals and pathogens in urban waters. To facilitate physical interpretation and data sharing, a series of concise analytical models are examined to reproduce unit operation (UO) influent and effluent PSD data and indices. The models are a (1) single-parameter exponential and two-parameter (2) gamma, (3) lognormal, and (4) Rosin-Rammler distributions. Two-parameter models provide physical interpretations for the central tendency of PM diameters, and shape as an index of PSD hetero-dispersivity. Goodness-of-fit is used to test models and PSDs. For influent data from two disparate areas, a paved source area and a larger watershed delivering unique PSDs, lognormal and gamma models provide consistent representation of influent and effluent complexity. In these areas, contrasting UOs (a clarification basin and a volumetric filter), subject to type I settling, scour, and filter PM elution, are differentiated based on flow, surface area, volume, and residence time. Surface overflow rate (SOR) as a common heuristic design tool for only type I settling is used to further test PSD models by simulating effluent PSDs for a scaled basin design. Lognormal and gamma models of SOR-generated effluent PSDs were not statistically different. In conclusion, two-parameter PSD models have physical interpretations and lower errors compared to an exponential model. Gamma and lognormal distributions are physically-based models that reproduce actual complex influent or effluent or through SOR as a tool for PSD transformation. Results indicate that PSD models and parameters can be applied to evaluate behavior of common UOs.

Well-defined targets for nitrogen (N) release into the local environment are essential for water management in creeks, but difficulties often arise from working with data that are too sparse to achieve reliable evaluations. Here, a simulation–optimization approach based on the QUAL2K model was developed to put forward strategies for nitrogen pollution control in a creek with sparse data in Shixi Creek, southeast China. The model showed good agreement with field observations from 22 sampling sites sampled over the period from March 2017 to February 2019, with normalized objective function (NOF) less than 0.360. Based on this model, the water pollutant sources in the creek were distinguished and analyzed. Rural sewage discharge in Shixi Creek was the major factor threatening water quality in the stream. Seasonal variations may influence the transformation of riverine N. To make more than 80% of the area in Shixi Creek meet the water quality standard of grade III, an optimized approach is to reduce more than 55% of the N pollution from point source pollution and 10% from nonpoint source pollution. This study proposed an approach that can effectively evaluate strategies for water management in a creek watershed with sparse data.

The mechanism of the non-agricultural transfer of rural labor to agricultural production efficiency and their interrelationships is a problem worthy of further discussion at this stage in China. The mediating effect model is constructed, the least square method is used for regression, and the instrumental variable method is used to solve the possible endogeneity problem. Through the investigation of farmers in Loess Plateau region, this paper analyzes the effects of factor substitution and planting structure adjustment after agricultural labors work outside and its impact on agricultural land output from the theoretical and empirical aspects, as well as the impact of off-farm employment on agricultural land output under different constraints. Results showed that the negative influence of labor non-agricultural transfer on farmland land output rate is − 7.264, and farmers’ participation in returning farmland to forests can alleviate the negative impact of non-agricultural transfer on the agricultural land output. Labor substitution factor investment plays a part in the mediating effect, and part of the mediating effect is − 0.879. The adjustment of agricultural planting structure plays the whole mediating effect, that is to say, the larger the scale of labor non-agricultural transfer in Loess Plateau area, the more unfavorable for farmers to invest in labor substitution agricultural factors of production, and the more they are inclined to grow food crops. When the constraint conditions of factor substitution difficulty and planting structure adjustment space are considered, the higher the factor substitution difficulty is, the smaller the planting structure adjustment space; the negative effect of the non-agricultural transfer of labor on the agricultural land output rate is more obvious. It provides effective reference value to judge the development stage and trend of regional agriculture and puts forward relevant policy suggestions to guarantee the development of regional agriculture and farmers’ life.

Coal and its byproducts and mineral waste constitute complex mixtures, which contain a variety of chemical compounds that impact the ecosystems. For this reason, procedures are required to monitor coal-degraded areas, including the use of biomonitoring organisms. In this light, the aim of the present study was to evaluate the cytotoxicity, genotoxicity, mutagenicity, and phytotoxicity of the aerial part and root extracts from Eragrostis plana Nees collected in the surroundings of the Thermoelectric Power Plant President Médici-UTPM (Candiota, Brazil), through Allium cepa bioassay. Cytotoxicity, genotoxicity, and mutagenicity in the A. cepa meristematic cells were verified through the mitotic index (MI), chromosomal alterations, and micronucleus formation, respectively. In addition, the germination rate, vigor index, and morphological abnormalities were verified in A. cepa seedlings. Treatment with root extracts from E. plana (ACR) specimens collected in a coal-contaminated region resulted in the lowest MI values (8.9%, 12.7%, and 16.0%), representing the most cytotoxic effect when compared with the negative control—NC (dH₂O) (MI = 35.8%). ACR extract also was the most genotoxic and mutagenic sample compared with NC and other treatments. Phytotoxicity analyses corroborated the toxic action of ACR, presenting abnormal seedlings and change in vigor index. The high concentration of dissolved total chlorides and electrical conductivity presented in the root extracts of E. plana, which were grown in the carboniferous region, indicates an increase in the absorption of metallic ions and organic compound and supports the hypothesis that this species has bioaccumulator potential, being a new biomonitor model of coal-contaminated region.

Particulate matter (PM) is defined as a mixture of solid and/or liquid particles that remain separately dispersed in air. PM is not a pollutant by itself but a complex and dynamic combination of compound particles with biological and chemical origins. However, fine PM (PM₂.₅) seems to be incriminated in the respiratory system and poses a severe threat to human health. Several reviews focused on chemistry segments because they mainly contribute to fine PM concentration. Biological elements in PM₂.₅ should also be considered because they cause multiple allergies and respiratory illnesses. This review has selected articles by following predefined criteria and demonstrated that the biological and chemical parts of fine particles play a significant role in PM₂.₅ concentration. In addition, justification on the origin or sources of biological and chemical compositions and their effects on health become a concern in this review. Lastly, this review can provide knowledge that can be a useful tool for researchers, designers, engineers and policymakers to consider for further action.

The aim of this research was the investigation of the effectiveness of several extractants as possible assessment of pseudo-total As, Pb and Cu concentrations in moderately contaminated soils of Central Greece. In soils of 3 different land uses (forest, agricultural and industrial), various extraction procedures were performed using simple and low-cost extraction solutions, i.e. inorganic acids (HCl and H₃PO₄), salts (NH₄NO₃ and CH₃COONH₄), organic chelating agents (as ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA)) and an alkaline agent (NaOH). The findings were reported as percentages to their pseudo-total concentrations obtained using Aqua Regia. The species of As (III), As (V) and total As(T) were extracted. Higher percentages of As concentrations were extracted using H₃PO₄ concluding that this may be the most effective of the extractants used. On the other hand, the percentages of the EDTA-extracted Pb and Cu, in forest soils with high organic matter content, were the highest. In forest soils, also, satisfactory correlations between EDTA-extracted Pb and Cu versus their pseudo-total content were observed. Finally, significant correlations among As, Pb and Cu concentrations in some soil extracts and soil physicochemical parameters were obtained, suggesting that the extractability of As, Pb and Cu may depend upon soil characteristics in the study area.

The Lhasa River is the largest and most important tributary of the Yarlung Tsangpo River on the Tibetan Plateau, China. It is an important source of drinking water and irrigation for the inhabitants living in the watershed. Despite the increasing focus on water chemistry, the ecological risk assessment (ERA) caused by heavy metals to aquatic organisms in the Lhasa River has not been performed before. Based on the documented monitoring data for heavy metals, the species sensitivity distributions (SSDs) method was applied in this study. The potential ecological risks induced by eight major heavy metals (including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), lead (Pb), and zinc (Zn)) in the Lhasa River to four typical categories of freshwater organisms, including insects, crustaceans, fish, and mollusks, were assessed in different water periods (e.g., high, normal, and low water-periods). Results suggested that the downstream part of the Lhasa River and the Meldromarchu and Tölungchu tributaries are the principal zones for the high aquatic ecological risks. For most of the monitoring sites, the ecological risks decreased in the following order: high-water period > normal-water period > low-water period. During the high-water period, Cu had the highest ecological risks for all selected species. For the insects, the ecological risks were quite low (< 1%) throughout the year. These results suggested that particular attention should be paid to the contamination of certain heavy metals (e.g., Cu and Cr) in the future water management in the Lhasa River.

The present study explores the efficient management of non-degradable polystyrene foam wastes (PSFW) by transforming into a microbial responsive material for an effective biodegradation process. In brief, the study involves three steps, viz., (i) preparation of citrus fruit peel extract from peel wastes; (ii) dissolution of PSFW using the extract and transform to polystyrene sheet (PSS) and characterization of the sheet formed and (iii) finally the microbial adhesion and biofilm formation on PSS. Results revealed that the maximum yield of the peel extract identified as D-limonene was obtained from Citrus sinensis (8.2 ± 0.06 ml/100 g fresh waste). Characterization studies on PSS suggested that there are appreciable changes in the infrared spectrum, thermo gravimetric analysis, gel permeation chromatography analyses, and contact angle measurements in comparison with PSFW. Observations on significant variations in the glass transition temperature of PSFW (100 °C) and PSS (60 °C); decomposition temperature of PSFW (310.93 °C) and PSS (78.18 °C), and molecular weight distribution changes in PSFW (2.00 Mw/Mn) and PSS (1.03 Mw/Mn) suggested the occurrence of structural and molecular changes in PSS. Studies on microbial adhesion and biofilm formation on PSS suggested that amongst six microbial species isolated from the waste dump yard, WD03 strain identified as Lysinibacillus sp., displayed a maximum adhesion and biofilm formation on the surface of the PSS as evidenced through biofilm characterizations, SEM, and fluorescence microscopic analyses respectively. In conclusion, the transformation of PSFW to PSS and the appreciable microbial adhesion and biofilm formation suggested the possibility of the effective management of white nuisance (PSFW) wastes in the environment.

The intensive development of medical science has led to an increase in the availability and use of pharmaceutical products. However, nowadays, most of scientific attention has been paid to the native forms of pharmaceuticals, while the transformation products (TPs) of these substances, understood herein as metabolites, degradation products, and selected enantiomers, remain largely unexplored in terms of their characterization, presence, fate and effects within the natural environment. Therefore, the main aim of this study was to evaluate the toxicity of seven native compounds belonging to different therapeutic groups (non-steroidal anti-inflammatory drugs, opioid analgesics, beta-blockers, antibacterial and anti-epileptic drugs), along with the toxicity of their 13 most important TPs. For this purpose, an ecotoxicological test battery, consisting of five organisms of different biological organization was used. The obtained data shows that, in general, the toxicity of TPs to the tested organisms was similar or lower compared to their parent compounds. However, for example, significantly higher toxicity of the R form of ibuprofen to algae and duckweed, as well as a higher toxicity of the R form of naproxen to luminescent bacteria, was observed, proving that the risk associated with the presence of drug TPs in the environment should not be neglected.