Genome-Wide Identification of the 14-3-3 Gene Family and Its Involvement in Salt Stress Response through Interaction with NsVP1 in Nitraria sibirica Pall.

14-3-3 proteins are widely distributed in eukaryotic cells and play an important role in plant growth, development, and stress tolerance. This study revealed nine 14-3-3 genes from the genome of Nitraria sibirica Pall., a halophyte with strong salt tolerance. The physicochemical properties, multiple sequence alignment, gene structure and motif analysis, and chromosomal distributions were analyzed, and phylogenetic analysis, cis-regulatory elements analysis, and gene transcription and expression analysis of Ns14-3-3s were conducted. The results revealed that the Ns14-3-3 gene family consists of nine members, which are divided into two groups: ε (four members) and non-ε (five members). These members are acidic hydrophilic proteins. The genes are distributed randomly on chromosomes, and the number of introns varies widely among the two groups. However, all genes have similar conserved domains and three-dimensional protein structures. The main differences are found at the N-terminus and C-terminus. The promoter region of Ns14-3-3s contains multiple cis-acting elements related to light, plant hormones, and abiotic stress responses. Transcriptional profiling and gene expression pattern analysis revealed that Ns14-3-3s were expressed in all tissues, although with varying patterns. Under salt stress conditions, Ns14-3-3 1a, Ns14-3-3 1b, Ns14-3-3 5a, and Ns14-3-3 7a showed significant changes in gene expression. Ns14-3-3 1a expression decreased in all tissues, Ns14-3-3 7a expression decreased by 60% to 71% in roots, and Ns14-3-3 1b expression increased by 209% to 251% in stems. The most significant change was observed in Ns14-3-3 5a, with its expression in stems increasing by 213% to 681%. The yeast two-hybrid experiments demonstrated that Ns14-3-3 5a interacts with NsVP1 (vacuolar H+-pyrophosphatase). This result indicates that Ns14-3-3 5a may respond to salt stress by promoting ionic vacuole compartmentalization in stems and leaves through interactions with NsVP1. In addition, N. sibirica has a high number of stems, allowing it to compartmentalize more ions through its stem and leaf. This may be a contributing factor to its superior salt tolerance compared to other plants.

Integrated metabolome and transcriptome analysis unveils novel pathway involved in the fruit coloration of Nitraria tangutorum Bobr.

BACKGROUND: The desert shrub Nitraria tangutorum Bobr. is important for its resistance to salt and alkali in Northwest China. It is an ecologically important species in this region and provides edible and medicinal berries. This study showed a mutant of N. tangutorum (named Jincan, JC) that has a strong yellow pericarp vs red in a wild type (represented by NT). RESULTS: In this study, the secondary metabolic and molecular mechanisms responsible for Nitraria fruit coloration were investigated using LC-MS-based widely targeted metabolomics and transcriptomics data. As a result of our study, 122 and 104 flavonoid metabolites were differentially expressed throughout the mature and transition stages between JC and NT, respectively. Furthermore, two cyanidin derivatives (cyanidin 3-O-glucoside and cyanidin-3-O-(2''-O-glucosyl) glucoside) and one pelargonidin derivative (pelargonidin-3-O-glucoside) were identified only in the NT phenotype. The functional genes F3H (flavanone 3-hydroxylase), F3'H (flavonoid 3'-hydroxylase) and UFGT (flavonoid 3-O-glucosyltransferase) and the transcription factors MYB, bHLH, NAC and bZIP were significantly downregulated in JC. Meanwhile, the activity of UFGT was extremely low in both periods of JC, with a five-fold higher enzymatic activity of UFGT in RT than in YT. In summary, due to the lack of catalysis of UGFT, yellow fruit of JC could not accumulate sufficient cyanidin and pelargonidin derivatives during fruit ripening. CONCLUSION: Taken together, our data provide insights into the mechanism for the regulation of anthocyanin synthesis and N. tangutorum fruit coloration and provide a theoretical basis to develop new strategies for developing bioactive compounds from N. tangutorum fruits.

Selection and validation of appropriate reference genes for RT-qPCR analysis of Nitraria sibirica under various abiotic stresses.

BACKGROUND: Nitraria sibirica Pall. is a halophytic shrub with strong environmental adaptability that can survive in extremely saline-alkali and drought-impacted environments. Gene expression analysis aids in the exploration of the molecular mechanisms of plant responses to abiotic stresses. RT-qPCR is the most common technique for studying gene expression. Stable reference genes are a prerequisite for obtaining accurate target gene expression results in RT-qPCR analysis. RESULTS: In this study, a total of 10 candidate reference genes were selected from the transcriptome of N. sibirica, and their expression stability in leaves and roots under different treatment conditions (salt, alkali, drought, cold, heat and ABA) was evaluated with the geNorm, NormFinder, BestKeeper, comparative ΔCt and RefFinder programs. The results showed that the expression stability of the candidate reference genes was dependent on the tissue and experimental conditions tested. ACT7 combined with R3H, GAPDH, TUB or His were the most stable reference genes in the salt- or alkali-treated leaves, salt-treated roots and drought-treated roots, respectively; R3H and GAPDH were the most suitable combination for drought-treated leaves, heat-treated root samples and ABA-treated leaves; DIM1 and His maintained stable expression in roots under alkali stress; and TUB combined with R3H was stable in ABA-treated roots. TBCB and GAPDH exhibited stable expression in heat-treated leaves; TBCB, R3H, and ERF3A were stable in cold-treated leaves; and the three most stable reference genes for cold-treated roots were TBCB, ACT11 and DIM1. The reliability of the selected reference genes was further confirmed by evaluating the expression patterns of the NsP5CS gene under the six treatment conditions. CONCLUSION: This study provides a theoretical reference for N. sibirica gene expression standardization and quantification under various abiotic stress conditions and will help to reveal the molecular mechanisms that confer stress tolerance to N. sibirica.

Microfiber releasing into urban rivers from face masks during COVID-19.

Face masks play a crucial protective role in preventing the spread of coronavirus disease during the COVID-19 pandemic, but the improper disposal of used face masks also causes an emerging environmental problem, such as microplastic contamination. Here, the aim was to evaluate the improper disposal of used face masks and, subsequently, the potential contribution to microplastic contamination in urban rivers. First, we investigated the occurrence of discarded face masks in Qing River through continuously one-month collection on-site, and the disposable masks with a density of (8.28 ± 4.21) × 10-5 items/m2 with varying degrees of wear and tear were found. Next, the microfibers shedding from two popular types of new disposable masks were tested. The results showed that 50.33 ± 18.50 items/mask of microfibers, ranging from 301 µm to 467 µm in size, were released from the disposal face mask after immersion in ultrapure water for 24-h. It was significantly higher than the KN95 respirator of 31.33 ± 0.57 items/mask, ranging from 273 µm to 441 µm. Besides C and O elements only found in new face masks, some potentially toxic elements were also detected on the surface of discarded face masks, indicating that various environmental contaminations are easy to adsorb on the surface of discarded face masks. The results implied that these discarded face masks in an aquatic environment are emerging sources of microfibers and could act as transport vectors for contaminants, which would aggravate the present microplastic contamination. In conclusion, these findings were expected to raise public awareness of the proper disposal of used face masks to prevent microplastic contamination and the spread of COVID-19 in the environment.

Emission and spatial variation characteristics of odorous pollutants in the aerobic tank of an underground wastewater treatment plant (UWWTP) in southern China.

In this study, the spatial concentration of odorous pollutants in the aerobic tank of an underground wastewater treatment plant (UWWTP) in southern China is monitored. The odour activity value, odour contribution rate, and chemical concentration contribution rate are used to evaluate the degree of contribution of odorous substances. Computational fluid dynamics (CFD) simulations of odorous pollutant diffusion are also established. The study shows that the odorous substances detected in the aerobic tank mainly included ammonia (NH3), hydrogen sulfide (H2S), trimethylamine (C3H9N), and methanethiol (CH3SH), and their concentrations are 1.160, 0.778, 0.022, and 0.0006 mg/m3, respectively. The total odour activity value of the aerobic tank is 450.72 (dimensionless), of which the odour activity value of H2S is 432.22, and the contribution rate reaches 95.9%. H2S is the main contributor to odour and a key controlled substance. The air inlets and exhaust outlets in the aerobic tank are cross-arranged at the top of the space, and the CFD model of odorous pollutant diffusion shows that the gas flow organization determines the odorous pollutant diffusion. The spatial distribution of gas flow and odorous substances in the aerobic tank is relatively uniform, and the odour collection efficiency is higher. The production flux and production coefficient of H2S in the aerobic tank are calculated as 25.831 mg/(m2·h) and 14.149 mg/t, respectively. This study determines the reasonable air supply and exhaust design of the aerobic tank, the number of odour pollutants, and the key controlled substances. These findings offer guidance and serve as useful references for the prevention and control of odour pollution in aerobic tanks of the same type of UWWTPs.

Research on factors influencing Chinese parents' support for death education: a cross-sectional survey.

Objective: This study aims to explore the factors influencing Chinese parents' attitudes toward death education. Given the current lack of such education in China, this research is particularly significant. Death education is vital for shaping the values of young people and alleviating mental health issues, such as depression and suicidal tendencies. By identifying these influencing factors, this study seeks to provide guidance for policymakers and educators in promoting the development and widespread adoption of death education. Methods: To do so, a national cross-sectional quota sample of 12,435 Chinese parents was used. Borrowing from social-ecological theory, the researchers carried out multiple stepwise regression analyses to examine the individual, family, and social-level factors that shape the supportive attitudes of Chinese parents toward death education. Results: The findings revealed that at the individual level, parent (ß = 0.04, p < 0.001), education level (ß = 0.07, p < 0.001), and religious belief (ß = -0.02, p < 0.05) were significant predictors of Chinese parents' support for death education. Meanwhile, at the family and social level, average monthly household income (ß = 0.07, p < 0.001), family health (ß = 0.03, p < 0.05), family communication (ß = 0.02, p < 0.05), social support (ß = 0.15, p < 0.001), neighborhood relations (ß = 0.11, p < 0.001), and social network size (ß = 0.05, p < 0.001) were significant predictors of Chinese parents' supportive attitudes toward death education. Conclusion: Based on these findings, it is suggested that the relevant development, planning, publicity, and public welfare groups and government departments should promote death education, provide more social support, and encourage neighborhood harmony. As higher education and average monthly household income were found to significantly impact the support, the government should improve access to higher education and actively work to increase residents' income to facilitate the development of death education.

Occurrence of microplastics in commercially sold bottled water.

Microplastics are ubiquitous in all environmental compartments, including food and water. A growing body of evidence suggests the potential health impacts of continuous microplastic ingestion on humans. However, a lack of information on microplastic exposure to humans through drinking water and the high heterogeneity of available data limits advancements in health risk assessments. In the present study, laser direct infrared spectroscopy (LD-IR) was used to determine the occurrence of microplastics in bottled water sold in China. Then, the ingestion level of microplastics through drinking water was estimated. The results showed that the average microplastic abundance in bottled water was 72.32 ± 44.64 items/L, which was higher than that detected in tap water (49.67 ± 17.49 items/L). Overall, the microplastic structures were dominated by films and mainly consisted of cellulose and PVC. Their sizes were concentrated in the range of 10-50 µm, accounting for 67.85 ± 8.40 % of the total microplastics in bottled water and 75.50 % in tap water. The estimated daily intake of microplastics (EDI) by infants through bottled water and tap water was almost twice as high as that by adults, although adults ingested more microplastics. The present results provide valuable data for further assessing human health risks associated with exposure to microplastics.

Promising indicators for monitoring microplastic pollution.

Microplastic pollution is a global crisis. This requires a better understanding of microplastic abundance, distribution, and accumulation to prevent potential risks in the future. However, it is very difficult to accurately identify all polymers of microplastics due to the limits of present detection technologies, which might result in overestimation and underestimation of microplastic pollution. Moreover, it also doesn't meet the growing demand for regular monitoring. Herein, we propose an alternative approach to regularly monitoring microplastics in all environmental mediums. The results could meet the urgent need for understanding the spatiotemporal pattern of microplastic pollution. Environmental policy-makers can use it to monitor microplastic pollutants and then rapidly evaluate the environmental level of microplastic pollution.

Characterization of microplastics in the septic tank via laser direct infrared spectroscopy.

Microplastics (MPs) are emerging pollutants that have been widely detected in the atmosphere, hydrosphere, lithosphere, and biosphere. Such wide spread of MPs indicates that the effective control in different environmental sectors is in an urgent need, and the first step in meeting this need is to identify the occurrence of MPs in the relevant environment. However, research on MPs in septic tanks has not been reported so far. This study investigated the distribution characteristics of MPs in septic tanks with a size detection limit of as low as 20 µm detected by laser direct infrared spectroscopy. Results showed that the number of MPs in the septic tank was reached 2803 (1489-4816) particles/g dry sludge, and the amount detected in the sediments was one order of magnitude higher than that in the scums. A total of 36 types of MPs were found in the septic tank, and 26 types were found in both sediments and scums, but the type in the scums was 21% higher than that in the sediments. The size was mostly 20-100 µm, accounting for 86.3% and 91.2% in the sediments and scums, respectively. Four shapes of MPs were detected in the septic tank, namely, fiber, bead, granule, and fragment. Our study revealed that septic tanks are both sinks and sources of MPs, which are reflected in the fact that MPs are not only large in number but also abundant in types. Thus, significant attention should be paid to septic tank-based microplastic pollution, which may lead to environmental and health risks without proper control and management.

Full-Length Transcriptome Analysis of the Halophyte Nitraria sibirica Pall.

BACKGROUND: Nitraria sibirica Pall. is one of the pioneer tree species in saline-alkali areas due to its extreme salt tolerance. However, the lack of information on its genome limits the further exploration of the molecular mechanisms in N. sibirica under salt stress. METHODS: In this study, we used single-molecule real-time (SMRT) technology based on the PacBio Iso-Seq platform to obtain transcriptome data from N. sibirica under salt treatment for the first time, which is helpful for our in-depth analysis of the salt tolerance and molecular characteristics of N. sibirica. RESULTS: Our results suggested that a total of 234,508 circular consensus sequences (CCSs) with a mean read length of 2121 bp were obtained from the 19.26 Gb raw data. Furthermore, based on transcript cluster analysis, 93,713 consensus isoforms were obtained, including 92,116 high-quality isoforms. After removing redundant sequences, 49,240 non-redundant transcripts were obtained from high-quality isoforms. A total of 37,261 SSRs, 1816 LncRNAs and 47,314 CDSs, of which 40,160 carried complete ORFs, were obtained. Based on our transcriptome data, we also analyzed the coding genes of H+-PPase, and the results of both bioinformatics and functional analyses indicated that the gene prediction via full-length transcripts obtained by SMRT technology is reliable and effective. In summary, our research data obtained by SMRT technology provides more reliable and accurate information for the further analysis of the regulatory network and molecular mechanism of N. sibirica under salt stress.

Dual role of O2 concentration on the reducing gases produced and NO reduction during sewage sludge combustion in pilot scale cement precalciner.

The reducing gases produced and NO reduction by sewage sludge combustion were investigated in a self-made cement precalciner. The dual role of O2 concentration (0-5 vol%) in the production characteristics of reducing gases and the reduction efficiency of NO were evaluated experimentally. TG-FTIR analysis demonstrated that the key reducing gaseous species produced by sewage sludge combustion were HCN, NH3, CO, and CH4. And experiments demonstrated that O2 concentration had pronounced effects on NH3 distribution, the maximum production rate was obtained at an O2 concentration of 3 vol%. Meanwhile, the reducing gases NH3 and CO were the key species for NO reduction in the cement precalciner, and the reduction efficiency of NO, when reduced by NH3, increased with an increase in O2 concentration, while the reduction performance of NO by CO was limited by O2 concentration. Therefore, O2 concentration greatly influences NO reduction efficiency by sewage sludge combustion; the maximum NO reduction efficiency was 61.67% at an O2 concentration of 3 vol%. The difference in NO reduction by sewage sludge combustion under different O2 concentrations was primarily attributed to NH3 production rate and NO reduction by NH3 and CO, which is greatly affected by O2 concentration. Sewage sludge combustion can result in NO reduction in the cement kiln flue gas and resource utilisation of sewage sludge.

Three-dimensional distribution of vessels, passage cells and lateral roots along the root axis of winter wheat (Triticum aestivum).

BACKGROUND AND AIMS: The capacity of a plant to absorb and transport water and nutrients depends on anatomical structures within the roots and their co-ordination. However, most descriptions of root anatomical structure are limited to 2-D cross-sections, providing little information on 3-D spatial relationships and hardly anything on their temporal evolution. Three-dimensional reconstruction and visualization of root anatomical structures can illustrate spatial co-ordination among cells and tissues and provide new insights and understanding of the interrelation between structure and function. METHODS: Classical paraffin serial-section methods, image processing, computer-aided 3-D reconstruction and 3-D visualization techniques were combined to analyse spatial relationships among metaxylem vessels, passage cells and lateral roots in nodal roots of winter wheat (Triticum aestivum). KEY RESULTS: 3-D reconstruction demonstrated that metaxylem vessels were neither parallel, nor did they run directly along the root axis from the root base to the root tip; rather they underwent substitution and transition. Most vessels were connected to pre-existent or newly formed vessels by pits on their lateral walls. The spatial distributions of both passage cells and lateral roots exhibited similar position-dependent patterns. In the transverse plane, the passage cells occurred opposite the poles of the protoxylem and the lateral roots opposite those of the protophloem. Along the axis of a young root segment, the passage cells were arranged in short and discontinuous longitudinal files, thus as the tissues mature, the sequence in which the passage cells lose their transport function is not basipetal. In older segments, passage cells decreased drastically in number and coexisted with lateral roots. The spatial distribution of lateral roots was similar to that of the passage cells, mirroring their similar functions as lateral pathways for water and nutrient transport to the stele. CONCLUSIONS: With the 3-D reconstruction and visualization techniques developed here, the spatial relationships between vessels, passage cells and lateral roots and the temporal evolution of these relationships can be described. The technique helps to illustrate synchronization and spatial co-ordination among the root's radial and axial pathways for water and nutrient transport and the interdependence of structure and function in the root.

Microplastic characteristics in organisms of different trophic levels from Liaohe Estuary, China.

Microplastics are a growing concern globally due to their small size and easy ingestion by terrestrial and aquatic organisms, resulting in potential adverse impacts on wildlife. However, current data regarding microplastics in wild organisms in different trophic levels is limited. This study investigated microplastic characteristics, including their abundance, size, shape and polymer type, in estuarine invertebrates and vertebrates. Resultantly, polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) were the predominant microplastics found, as confirmed by a Fourier transform infrared spectrometer (FT-IR). An average microplastic abundance of 0.83 ± 0.99 to 3.87 ± 2.18 items/individual was detected across all species, including sandworm, mollusks, crustacean and fish, but they were not found in all individuals. Microplastics ranged from 52 µm to 5392 µm in size, and the shapes were consisted of fiber, fragment, and pellet. Moreover, the detection ratio (91.95%) and abundance (3.34 ± 2.17 items/individual) of microplastics in fish were significantly higher than in sandworm (42.86%, 0.88 ± 1.04 items/individual), mollusks (66.97%, 1.42 ± 1.41 items/individual) and crustaceans (66.66%, 1.33 ± 1.32 items/individual) (p < 0.05). Furthermore, a positive relationship was identified between microplastic abundance and the trophic level of organisms. These findings imply that microplastics might transfer along the food chain and accumulate at organisms in higher trophic levels.

A proposed nomenclature for microplastic contaminants.

Microplastics are emerging contaminants with a wide environmental distribution and potential to elicit adverse impacts on organisms. Despite this lack of consistency among reports, data obtained from different investigations are often compared, resulting in the potential for misrepresentation of global microplastic contamination. Major interlaboratory variability in quantification of microplastic levels stem from size-related differences in sampling and analysis with different density solutions to separate microplastics. Herein, we propose a nomenclature that provides key information relating to the microplastics abundance in samples. That is, the proposed nomenclature, MPsca, b, informs on mesh or filter size used in sampling, the density of flotation solution used to separate the microplastics, and the detection limit during the analysis progress of microplastics. This proposed nomenclature would facilitate comparisons among studies to avoid over- or under-estimation of global microplastic levels. Moreover, it would also facilitate the interpretation of meta-data in future assessments.

Single molecule real-time sequencing revealing novel insights on the response to estrogen and androgen exposure in freshwater snails.

The molecular mode of action underpinning the response of mollusks exposure to endocrine disrupting chemicals (EDCs) remains unclear due to a lack of available information regarding their genome. Single molecule real-time (SMRT) sequencing makes it possible to reveal molecular mechanisms by direct sequencing of full-length transcripts. In the present study, the transcriptome profile of the freshwater snail Parafossarulus striatulus after exposure to 17ß-estradiol (E2) or 17α-methyltestosterone (MT) was evaluated using SMRT sequencing strategy. In total, 216,598 non-redundant and full-length gene isoforms were generated and 106,266 isoforms were predicted with a complete open reading frame (ORF). Moreover, 60.36% of the isoforms were matched to known proteins in at least one of six databases. Differential gene expression analyses showed significantly different patterns in paired samples with different treatments. The expression levels of several membrane receptor isoforms of P. striatulus including dopamine receptor (DR), FMRFamide receptor (FMRFaR), neuropeptide Y receptor (NYR) and neuropeptide FF receptor (NFFR), but not estrogen receptor (ER) or estrogen-related receptor (ERR), were significantly affected by E2 and MT. These findings suggest that activation of membrane receptors, as well as other signaling pathways, might be critical for mediating the effects of endocrine disruption in mollusks. The transcriptome information obtained from the SMRT sequencing provides a significant contribution to the investigation of the molecular mode of action of endocrine disrupting chemicals on P. striatulus.

Study on the influencing factors of removal of NOX from cement kiln flue gas by sewage sludge as a denitration agent.

Experimental study on the influencing factors of using sewage sludge as a denitration agent for cement industry was carried out on a self-made laboratory-scale fluid-bed reactor. Results indicate that sludge combustion at 900 °C shows an ideal NOX (the sum of NO and NO2) removal activity under simulated working conditions of cement precalciner. The optimal removal efficiency of NOX can reach 70.36 ± 3.59% in the presence of cement raw meal (CRM) at a sludge particle size range of 0.18-0.25 mm and the sludge dosage of 0.75 g/min. Besides, the NOX removal efficiency increases to 76.94 ± 5.02% in the absence of CRM, indicating that cement raw meal inhibits the NOX removal. This phenomenon may be attributed to the fact that CRM has promotion effect on NH3 produced and obvious inhibitory effect on CO produced; while NH3 and CO play a leading role in NOX reduction, the combined effect leads to the decrease of NOX removal. Moreover, the relationship between the composition of CRM on the inhibition of NOX removal is MgO < CaCO3 < CRM < Al2O3

miRNA-mRNA Integrated Analysis Reveals Roles for miRNAs in a Typical Halophyte, Reaumuria soongorica, during Seed Germination under Salt Stress.

MicroRNAs (miRNAs) are endogenous small RNAs that play a crucial role in plant growth, development, and environmental stress responses. Reaumuria soongorica is a typical halophyte that is widely distributed in saline-alkali desert regions. Under salt stress, R. soongorica can complete germination, a critical biological process in the life cycle of seed plants. To identify miRNAs and predict target mRNAs involved in seed germination during salt stress, nine small-RNA libraries were constructed and analyzed from R. soongorica seeds treated with various concentrations of NaCl. We also obtained transcriptome data under the same treatment conditions. Further analysis identified 88 conserved miRNAs representing 25 defined families and discovered 13 novel miRNAs from nine libraries. A co-expression analysis was performed on the same samples to identify putative miRNA-mRNA interactions that were responsive to salt stress. A comparative analysis of expression during germination under 273 (threshold) and 43 mM (optimal) NaCl treatments identified 13 differentially expressed miRNAs and 23 corresponding target mRNAs, while a comparison between 43 mM NaCl and non-salt-stress conditions uncovered one differentially expressed miRNA and one corresponding target mRNA. These results provide basic data for further study of molecular mechanisms involved in the germination of salt-stressed R. soongorica seeds, and also provide a reference for the improvement of salt tolerance during plant germination.

Potential sources, influencing factors, and health risks of polycyclic aromatic hydrocarbons (PAHs) in the surface soil of urban parks in Beijing, China.

Urban parks are an important part of the urban ecological environment. The environmental quality of parks is related to human health. To evaluate sources of polycyclic aromatic hydrocarbons (PAHs) in soils of urban parks and their possible health risks, soil samples from 122 parks in Beijing, China, were collected and analyzed. The total content of 16 PAHs between 0.066 and 6.867 mg/kg. Four-ring PAHs were predominant, followed by 5-ring PAHs, while the fraction of 2-ring PAHs was the lowest. The dominant PAHs sources were found to be coal combustion and oil fuels such as gasoline and diesel. A conditional inference tree (CIT) was used to identify the key influencing factors for PAHs. Traffic emissions was the most important factor, followed by coal consumption, as well as the history and location of the park. Incremental lifetime cancer risk (ILCR) for urban park soil in Beijing were low under normal conditions. The soil PAHs exposure pathway risk for both children and adults decreased in the following order: ingestion > dermal contact > inhalation. The risk from soil in parks to children's health is slightly higher than that of adults, although the health risk due to exposure to PAHs was not extraordinary. Ecosystem risk was negligible.

Heavy metal(loid)s in the topsoil of urban parks in Beijing, China: Concentrations, potential sources, and risk assessment.

Urban parks play an important role in the urban ecosystem and are also used by residents for recreation. The environmental quality of urban park soils might influence human health following long-term exposure. To assess potential sources and pollution risks of heavy metal(loid)s in the topsoil of urban parks, we subjected metal concentrations in soil samples from 121 parks in the Beijing urban area to geostatistical analyses, conditional inference tree (CIT) analyses, ecological risk and human health risk assessment. CIT effectively explained the influence of human activity on the spatial variation and accumulation of soil metal(loid)s and identified the contributions of natural and anthropogenic inputs. The main factors influencing the accumulation of heavy metal(loid)s, including urbanization duration, park age, per capita GDP, industrial output, and coal consumption, were evaluated by CIT. Except for Cr and Ni, the average concentrations of the metal(loid)s tested (Cu, Pb, Zn, Hg, As, and Cd) were higher than the background values. In the urban parks, Ni and Cr derived mostly from soil parent materials. Concentrations of Cu, Zn, Pb, Cd, As, and Hg were strongly associated with human influences, including industrial, agricultural, and traffic activity. After assessing health and ecological risks, we conclude that heavy metal(loid)s in the soil of Beijing urban parks pose no obvious health risk to humans, and the ecological risk is also low.

Effect of Ca(OH)2 on the Release Characteristics of HCl during Sludge Combustion.

With the addition of Ca(OH)2, the effects of combustion temperature, moisture, sludge particle size, and chlorine-containing additives on the removal of HCl during sludge combustion were studied. The experimental results showed that combustion temperature and moisture content promoted the formation of HCl and Ca(OH)2 played a key role in the formation of HCl during sludge combustion. Under the best conditions of a sludge particle size of 380-250 µm, moisture content of 5%, temperature of 850 °C, and Ca(OH)2/sludge weight ratio of 3/10, the HCl capture efficiency was 79.81%. In addition, the effect of PVC on the production of HCl was greater than that of NaCl, probably because the lattice energy of NaCl was much higher, indicating that inorganic chlorine was not the main source of HCl. Ca(OH)2 can effectively inhibit the formation of HCl, which had practical guiding significance for the formation of HCl during the sludge combustion, especially the sludge containing chlorine.