Sites In Northern China Research Articles

Unraveling soil geochemical, geophysical, and microbial determinants of the vertical distribution of organic phosphorus pesticide pollutants

Pesticide contamination has emerged as a global threat to humans. Here, we investigate the soil distribution pattern of organic phosphorus pesticide contamination at a pesticide manufacturing site in northern China, exploring their relationships with soil properties and microbial communities. The concentrations of four organic phosphorus pesticides (i.e., phorate, terbuthion, fenitrothion, and parathion) decreased substantially with soil depths from the surface down to 2 m. However, terbuthion, fenitrothion, and parathion had second-peak concentrations at a depth of 8 m. The concentrations of those organic phosphorus pesticides were negatively correlated with soil water content, but positively correlated with sulfide, pH, and total phosphorus. The distribution patterns of organic phosphorus pesticides closely aligned with that of soil organic matter and clay minerals, especially in the presence of montmorillonite, kaolinite, and chlorite. Various bacterial genera known to degrade organic phosphorus pesticides, such as Flavobacterium, Bacillus, Acinetobacter, Lactobacillus, Pseudomonas, Sphingomonas, and Thiobacillus, were correlated with these pesticides. Since these genera were among the top 50 abundant genera in our samples, they might play a significant role in the degradation of organic phosphorus pesticides. Together, this study unveils previously unrecognized pesticide-soil-microbe interactions, thus providing an important knowledge basis for environmental remediation strategies.

Regional differences in molecular characteristics of atmospheric water-soluble organic carbon over northern China: Comparison of remote, rural, and urban environments

Atmospheric water-soluble organic carbon (WSOC) is a critical component of airborne particulates. It significantly affects the Earth's energy balance, air quality, and human health. Despite its importance, the molecular composition and sources of WSOC remain unclear, particularly in non-urban areas. In this study, we collected total suspended particulate (TSP) samples from three sites in northern China: Erenhot (remote site), Zhangbei (rural site), and Jinan (urban site). The WSOC components were analyzed using high-performance liquid chromatography coupled with high-resolution mass spectrometry. The results showed that the formula numbers of identified compounds exhibited a decreasing trend of Jinan (2647) > Zhangbei (2046) > Erenhot (1399). Among the assigned formulas, CHO compounds were the most abundant category for all three sites, accounting for 33 %–38 % of the identified compounds, followed by the CHON compounds with contributions of 27 %–30 %. In the remote site of Erenhot, CHO compounds were dominated by oxidized unsaturated organic compounds, and CHON compounds were mainly low-oxygenated aliphatic compounds, suggesting a significant influence of primary emissions. In contrast, the urban site of Jinan showed higher contributions of CHO and CHON compounds with elevated oxidation degrees, indicating the influence of more extensive secondary oxidation processes. Atmospheric WSOC in Erenhot and Zhangbei had abundant reduced sulfur-containing species, likely from coal or diesel combustion, while that in Jinan was characterized by aliphatic organosulfates and nitrooxy-organosulfates, which are mainly associated with traffic emissions and biogenetic sources, respectively. These findings reveal significant differences in the molecular composition of WSOC in different atmospheric environments and improve our understanding of the chemical properties, potential sources, and transformations of organic aerosols.

Evidence of Surface-Tension Lowering of Atmospheric Aerosols by Organics from Field Observations in an Urban Atmosphere: Relation to Particle Size and Chemical Composition.

Surface-active organics lower the aerosol surface tension (σs/a), leading to enhanced cloud condensation nuclei (CCN) activity and potentially exerting impacts on the climate. Quantification of σs/a is mainly limited to laboratory or modeling work for particles with selected sizes and known chemical compositions. Inferred values from ambient aerosol populations are deficient. In this study, we propose a new method to derive σs/a by combining field measurements made at an urban site in northern China with the κ-Köhler theory. The results present new evidence that organics remarkably lower the surface tension of aerosols in a polluted atmosphere. Particles sized around 40 nm have an averaged σs/a of 53.8 mN m-1, while particles sized up to 100 nm show σs/a values approaching that of pure water. The dependence curve of σs/a with the organic mass resembles the behavior of dicarboxylic acids, suggesting their critical role in reducing the surface tension. The study further reveals that neglecting the σs/a lowering effect would result in lowered ultrafine CCN (diameter <100 nm) concentrations by 6.8-42.1% at a typical range of supersaturations in clouds, demonstrating the significant impact of surface tension on the CCN concentrations of urban aerosols.

Different formation pathways of nitrogen-containing organic compounds in aerosols and fog water in northern China

Abstract. While aqueous-phase processing is known to contribute to the formation of nitrogen-containing organic compounds (NOCs), the specific pathways involved remain poorly understood. In this study, we aimed to characterize the NOCs present in both pre-fog aerosols and fog water collected at a suburban site in northern China. Fourier-transform ion cyclotron resonance mass spectrometry was utilized to analyze the molecular composition of NOCs in both negative and positive modes of electrospray ionization (ESI− and ESI+). In both pre-fog aerosols and fog water samples, NOCs constituted a significant portion, accounting for over 60 % of all assigned formulas in ESI− and more than 80 % in ESI+. By comparing the molecular composition of NOCs originating from biomass burning, coal combustion, and vehicle emissions, we identified that 72.3 % of NOCs in pre-fog aerosols were attributed to primary anthropogenic sources (pNOCs), while the remaining NOCs were categorized as secondary NOCs formed within the aerosols (saNOCs). Unique NOCs found in fog water were classified as secondary NOCs formed within the fog water (sfNOCs). Through a comprehensive “precursor–product pair” screening involving 39 reaction pathways, we observed that the nitration reaction, the amine pathway, and the intramolecular N-heterocycle pathway of NH3 addition reactions contributed 43.6 %, 22.1 %, and 11.6 % of saNOCs, respectively. In contrast, these pathways contributed 26.8 %, 28.4 %, and 29.7 % of sfNOCs, respectively. This disparity in formation pathways is likely influenced by the diverse precursors, the aqueous acidity, and the gas-phase species partitioning. Correspondingly, saNOCs were found to contain a higher abundance of carbohydrate-like and highly oxygenated compounds with two nitrogen atoms compared to pNOCs. Conversely, sfNOCs exhibited a higher content of lipid-like compounds with fewer oxygen atoms. These results underscore the distinct secondary processes contributing to the diversity of NOCs in aerosols and fog water, which may lead to their different climate effects.

Distribution and health risk of chromium in wheat grains at the national scale in China

Chromium (Cr) pollution may threaten food safety in China. In this study, the concentration, pollution level, distribution, and non-cancer risk of Cr in wheat grains grown in 186 areas across 28 provinces in China were investigated. Results indicated that mean concentration of Cr was 0.28 ± 2.5 mg/kg, dry mass (dm). Of the samples, 7.5 % were found to be polluted with Cr. The mean concentrations were in the following order: Northwest > Northeast > South > East > North > Southwest > Central China. Based on deterministic models, mean hazard quotient (HQ) values for adult males, adult females, and children were 0.11 ± 3.4, 0.11 ± 3.4, and 0.13 ± 3.5, respectively with < 6 % of HQ values ≥ 1. Eleven sites in northern China were identified as hotspots, whereas Gansu Province and Northwestern China were labeled as priority provinces and regions for risk control. The mean HQ values estimated by probabilistic risk assessment were two times greater than those estimated using deterministic models. The risk probabilities for adult males, adult females, and children were 4.81 %, 3.78 %, and 6.55 %, respectively. This study provides valuable information on Cr pollution in wheat grains and its risks at a national scale in China.

Changes in prehistoric wood procurement strategies in Northern China from 6500 – 2000 BP. Evidence for human preferential harvesting in the face of climatic change

In the past, humans have adapted their strategies of wood collection to shifts in the surrounding environment. Shifts in wood procurement strategies have been assumed to have been heavily influenced by changes in biomes due to shifts in climate. In these models, wood found on archaeological sites is interpreted as being representative of the surrounding environment. Around the world there is an increasing recognition that human preferences and management strategies impacted forest composition and species harvesting. We evaluated charcoal data gathered from 92 archaeological sites in northern China, with chronologies spanning the period from 6500 BP to 2000 BP. By combining the results of the analysis with published paleoenvironment records and archaeological evidence, we aimed to determine when and how there was an anthropogenic impact on wood procurement strategies. Our results indicated that a distinct spatiotemporal pattern of wood utilisation existed in northern China during the period 6500–2000 BP that could not be fully explained by changes in climate. Spatially, anthropogenically-collected woody assemblages showed remarkable differences in northern China. Northern China's climate gradually became colder and drier during the mid to late Holocene, especially during the period 4000–2000 BP. This appears to have led to a decreased use of Quercus L. in the Loess Plateau and the Guanzhong Basin. However, in the Central Plains and Shandong Peninsula, Quercus L. usage continued and increased in the late Holocene. During the same period, a striking shift in wood procurement occurred in the western part of China. In the northeastern Tibetan Plateau, wood procurement shifted from predominantly coniferous to broadleaved trees, and forest succession caused by anthropogenic collection played the significant role. Paleoclimatic information in Hexi Corridor suggests that some arbour trees in archaeological sites were not locally available, suggesting that human preference for certain wood types led them to engage in long distance transport. This finding indicates that starting after 4000 BP, climatically driven shifts in biomes were no longer a primarily influencing variable in human procurement of trees in north-western and eastern China. Key regional differences in strategy emerged. In Eastern China, wood species which humans preferred were still harvested even when climatic change reduced their availability. In North-western China, however, changes in biomes following 4000 BP meant that people needed to change the species on which they had previously relied and began to engage in long distance transport of wood.

New age of the Dingcun 54:100 hominin site in northern China

The Dingcun locality 54:100 site was first excavated in 1950 s and has since yielded abundant stone artefacts and the famous ‘Dingcun human’ fossils, including three teeth and a parietal fragment. The Dingcun teeth has been regarded as a potential evidence of early emergence and development of ‘modern’ anatomic characters, making them key to understanding the origin and evolution of our species. However, there has been considerable debate regarding the chronology of the Dingcun site. Here we establish a new chronology for the site, based on optical dating of the fossil-bearing sediments and U-series dating of fauna fossils from the cultural layers. Our study shows that the age of the Dingcun human fossil ranges from 298,000 to 225,000 years ago (at 95.4 % confidence interval). This new dating result suggest that the Dingcun hominins represent a Late Middle Pleistocene population in East Asia who had borne some modern dental traits.

Will large-scale forestation lead to a soil water deficit crisis in China's drylands?

Trading water for carbon has cautioned large-scale afforestation in global drylands. However, model simulations suggested that the consumption of soil water could be partially offset by increasing precipitation due to vegetation feedback. A systematic meta-analysis of long-term and large-scale field observations is urgently required to address the abovementioned limitations, and the implementation of large-scale afforestation since 1978 in northern China provides an ideal example. This study collected data comprising 1226 observations from 98 sites in northern China to assess the variation in soil water content (SWC) with stand age after afforestation and discuss the effects of tree species, precipitation and conversions of land use types on SWC. We found that the SWC has been decreased by coniferous forest and broadleaf forest at rates of 0.6 and 3.2 mm decade–1, respectively, since 1978. There is a significant declining trend of SWC with the stand age of plantations, and the optimum growth stage for plantation forest is 0–20 a in northern China. However, we found increases in SWC for the conversion from grassland to forest and in the low-precipitation region, both are corresponding to the increased SWC in coniferous forest. Our study implies that afforestation might lead to a soil water deficit crisis in northern China in the long term at the regional scale but depends on prior land use types, tree taxa and the mean annual precipitation regime, which sheds light on decision-making regarding ecological restoration policies and water resource management in drylands.

Geographical distribution and species variation of gut microbiota in small rodents from the agro-pastoral transition ecotone in northern China.

The gut microbiota of rodents is essential for survival and adaptation and is susceptible to various factors, ranging from environmental conditions to genetic predispositions. Nevertheless, few comparative studies have considered the contribution of species identity and geographic spatial distance to variations in the gut microbiota. In this study, a random sampling survey encompassing four rodent species (Apodemus agrarius, Cricetulus barabensis, Tscherskia triton and Rattus norvegicus) was conducted at five sites in northern China's farming-pastoral ecotone. Through a cross-factorial comparison, we aimed to discern whether belonging to the same species or sharing the same capture site predominantly influences the composition of gut microbiota. Notably, the observed variations in microbiome composition among these four rodent species match the host phylogeny at the family level but not at the species level. The gut microbiota of these four rodent species exhibited typical mammalian characteristics, predominantly characterized by the Firmicutes and Bacteroidetes phyla. As the geographic distance between populations increased, the number of shared microbial taxa among conspecific populations decreased. We observed that within a relatively small geographical range, even different species exhibited convergent α-diversity due to their inhabitation within the same environmental microbial pool. In contrast, the composition and structure of the intestinal microbiota in the allopatric populations of A. agrarius demonstrated marked differences, similar to those of C. barabensis. Additionally, geographical environmental elements exhibited significant correlations with diversity indices. Conversely, host-related factors had minimal influence on microbial abundance. Our findings indicated that the similarity of the microbial compositions was not determined primarily by the host species, and the location of the sampling explained a greater amount of variation in the microbial composition, indicating that the local environment played a crucial role in shaping the microbial composition.

Cultivation and morphology of jujube (Ziziphus Jujuba Mill.) in the Qi River Basin of Northern China during the Neolithic Period

This transition from gathering to cultivation is a significant aspect of studying early agricultural practices. Fruit trees are an essential component of food resources and have played a vital role in both ancient and modern agricultural production systems. The jujube (Ziziphus jujuba Mill.), with its long history of cultivation in northern China, holds great importance in uncovering the diet of prehistoric humans and understanding the origins of Chinese agricultural civilization. This paper focuses on the domestication of jujube by analyzing the morphology of jujube stones found in three Neolithic sites in northern China's Qi River basin, Zhujia, Wangzhuang, and Dalaidian. The measurements of these jujube kernels are compared with those found in other areas of northern China, as well as modern jujube kernels that were collected. The measurements revealed that the length-to-diameter (L/D) ratio of sour jujube kernels ranged from 1.36 to 1.78, whereas the L/D ratio of cultivated jujube stones varied between 1.96 and 4.23. Furthermore, jujube stones obtained from Zhujia and Wangzhuang sites exhibit pointed ends and possess an elongated oval or narrow oval shape overall, which is indicative of clearly artificial domestication traits. Therefore, this study suggests that jujube was selected and cultivated as an important food supplement in the Qi River basin no later than around 6200 BP.

Characteristics and origins of fine particulate amines at a coastal mountain site in northern China in spring

Low-molecular-weight amines are the most abundant amine compounds in the atmosphere and they affect new particle formation, aerosol properties, climate change and human health. To understand the chemical composition, diurnal variation, influences of terrestrial and marine emissions, and potential sources of fine particulate amines in the coastal area in northern China, field sampling and measurements was conducted at coastal Mt. Lao in the spring of 2021. The total concentration of amines in PM2.5 was around 60 ng m−3 on average. Dimethylamine was the most abundant compound with mean fraction of 27.2% in the quantified 16 amines, followed by diethylamine (19.6%) and ethanolamine (12.6%). Elevated concentrations of amines usually appeared with high levels of CO, SO2, NOx, and/or moderately high humidity. Amines exhibited higher concentrations during the daytime than nighttime at the mountain site, due to more intense anthropogenic activities at daytime. The concentration peak in the late afternoon is ascribed to relatively strong anthropogenic emissions and enhanced gas-to-particle partitioning. Furthermore, comparison between terrestrial- and marine-airmass dominated samples shows that most amines primarily came from terrestrial activities, while TMA was mainly from marine sources. Source apportionment with the positive matrix factorization model identified seven major sources including agricultural emissions, industrial production, biomass burning, coal combustion, marine emissions, traffic emissions and crustal dusts. Notably, high contributions from agricultural source and biomass burning were observed at this coastal mountain site, indicating differential compositions and origins of particulate amines in different seasons and locations.

Site-scale groundwater pollution risk assessment using surrogate models and statistical analysis

Petroleum pollution in soil and groundwater has emerged as a significant environmental concern worldwide. As a sustainable and cost-effective in-situ remediation technique, Monitored Natural Attenuation (MNA) exhibits significant promise in addressing sites contaminated by petrochemicals. This study specifically targets a typical petrochemical-contaminated site in northern China and employs GMS software to establish a comprehensive physical model. The model relies on time-series monitoring data of phenol concentrations spanning from 2018 to 2020, effectively simulating both the leakage and natural attenuation of phenol. Within this study, the adsorption coefficient and maximum adsorption capacity emerge as the foremost influential factors shaping the outcomes of the model. Given the inherent heterogeneity of the site and the variability of hydrochemical conditions, parameters such as dispersion, porosity, and adsorption coefficient exhibit significant uncertainties. Consequently, relying on traditional deterministic models to predict the feasibility of MNA technology is not reliable. Therefore, this study employs machine learning (ML) methods to construct stochastic parameter models based on physical processes. The Random Forest Regression (RFR) algorithm, after trained, demonstrates strong alignment with numerical model output, exhibiting an average Nash-Sutcliffe Efficiency (NSE) >0.96. Using a stochastic approach, RFR iteratively computes phenol concentration across 6000 sets of parameters. Applying probability statistics, the model shows a notable reduction in the likelihood of phenol concentrations exceeding a threshold, dropping from 64.0% to 15.7% before and after natural attenuation. In parameter uncertainty, the stochastic model emphasizes natural attenuation's efficacy in mitigating phenol pollution risk (porosity being the most influential factor). This case study proposed a novel method to quickly assess the pollution risks at petrochemical sites under the influence of the uncertainty of pollutant transport and reaction parameters. The results can provide a reference for the pollution risk assessment at petrochemical sites, especially in sites with high stratigraphic heterogeneity or insufficient transport parameter data.

Mapping vertical distribution of SOC and TN in reclaimed mine soils using point and imaging spectroscopy

Soil organic carbon (SOC) and total nitrogen (TN) contents in different soil horizons are essential for vegetation growth and crucial indicators to evaluate soil quality in reclaimed mining areas. Compared with conventional wet chemistry methods, soil spectroscopy, including imaging spectroscopy, can be used as a cost and time-efficient soil analysis technique. However, there is a great challenge in combining laboratory point spectra and laboratory hyperspectral imagery for mapping vertical distribution of SOC and TN (0–100 cm) in reclaimed soils. This is primarily because mixing of spectral data from different sources and technologies to improve soil models is still in its infancy. The main objective of this study is to provide a generic workflow to efficiently evaluate and map reclaimed mine soils in different horizons using imaging spectroscopy and machine learning approaches. A total of 65 soil samples (0–100 cm) were collected from three reclaimed mining lands and one natural site in northern China. Both point soil spectral information and hyperspectral images (350–2500 nm) were obtained under laboratory condition. In order to enhance the relationship between soil quality indicators and spectral features, the stacked feature selection algorithms and three-bands spectral indices were proposed for further modelling. Three machine learning methods (partial least squares regression; PLSR, random forest; RF, and radial basis function model; RBF) based on the point spectra were applied to calibrate and map continuous vertical distribution of SOC and TN. According to the results, thirty spectral bands were identified as important spectral features for SOC and eighteen bands for TN. With feature spectral bands and optimized three-bands spectral indices, the RF model yielded the best predictions for both SOC (R2 = 0.97, RMSE = 7.5 g kg−1) and TN (R2 = 0.78, RMSE = 0.33 g kg−1). It was concluded that imaging spectroscopy can be used to quantify and map soil quality indicators for better monitoring ecological restoration process in reclaimed soil of mining site.

Agricultural practices during the middle and late Yangshao periods (6000-4500 BP) in the Guanzhong Basin, North China

The middle and late Yangshao (6000–4500 BP) were important periods for the emergence of early social complexity in prehistoric China. While the way ancient people came over the challenges from both environmental changes and human society was unclear. Here, we use flotation and plant stable isotope analysis of the Chakou site in Guanzhong Basin, located in the southern margin of the Loess Plateau, to determine human adaptation strategies in the early times. The results demonstrated that early agriculture was dominated by common millet during 5700–4900 BP. Meanwhile, manuring was applied to meet the challenge of increasing population pressure. In the late Yangshao period (4900–4500 BP), the proportion of foxtail millet increased and became the main crop in the area. Although the archaeological centre moved northwards, the same intensity of manuring was maintained. The stable nitrogen isotope value (δ15N) of charred millet indicated that manuring was widely used during 6000–4500 BP in northern China, among which the manuring level in the Guanzhong Basin was the highest. Synthesized with 37 site studies, the millet weight percentage from archaeological sites in northern China showed that the proportion of foxtail millet in northern China was higher than that of common millet after 5000 BP, whereas the reverse was true before that. These adjustments in agricultural strategies implied an attempt by these middle-late Yangshao people to ensure the sustainable development of agriculture and provide the basis for the emergence of early civilizations and social complexity in northern China. The results of this study may also aid present-day efforts to address unprecedented climatic and social changes.

Characteristics of bacterial and fungal communities and their associations with sugar compounds in atmospheric aerosols at a rural site in northern China

Abstract. Bioaerosols play significant roles in causing health and climate effects. Sugar compounds in air have been widely used to trace the source of bioaerosols. However, knowledge about the association of sugar molecules and the microbial community at taxonomic levels in atmospheric aerosols remains limited. Here, microbial community compositions and sugar molecules in total suspended particles collected from a typical rural site, Gucheng, in the North China Plain were investigated by gas chromatography–mass spectrometry and high-throughput gene sequencing, respectively. Results show that fungal community structure exhibited distinct diurnal variation with largely enhanced contribution of Basidiomycota at night, while bacterial community structure showed no obvious difference between daytime and night. SourceTracker analysis revealed that fungi and bacteria were mainly from plant leaves and unresolved sources (presumably human-related emissions and/or long-distance transport). All the detected anhydrosugars and sugar alcohols and trehalose showed diurnal variations with lower concentrations in the daytime and higher concentrations at night, which may be affected by enhanced fungal emissions at night, while primary sugars (except trehalose) showed an opposite trend. Mantel's test showed that more sugar compounds exhibited significant associations with fungal community structure than bacterial community structure. Co-occurrence analysis revealed the strong associations between sugar compounds and a few saprophytic fungal genera with low relative abundances, e.g., Hannaella, Lectera, Peniophora, Hydnophlebia, Sporobolomyces and Cyphellophora. This study suggests that the entire fungal community, rather than specific fungal taxa, likely greatly contributes to sugar compounds in rural aerosols, while the contribution of bacteria is limited.

Optimized NPK fertilizer recommendations based on topsoil available nutrient criteria for wheat in drylands of China

The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers. Critical nutrient values can be used for evaluating the nutritional status of a crop, and they reflect the nutrient concentrations above which the plant is sufficiently supplied for achieving the maximum potential yield. Based on on-farm surveys of 504 farmers and 60 field experimental sites in the drylands of China, we proposed a recommended fertilization method to determine nitrogen (N), phosphorus (P), and potassium (K) fertilizer input rates for wheat production, and then validated the method by a field experiment at 66 different sites in northern China. The results showed that wheat grain yield varied from 1.1 to 9.2 t ha−1, averaging 4.6 t ha−1, and it had a quadratic relationship with the topsoil (0−20 cm) nitrate N and soil available P contents at harvest. However, yield was not correlated with the inputs of N, P, and K fertilizers. Based on the relationship (exponential decay model) between 95–105% of the relative yield and topsoil nitrate N, available P, and available K contents at wheat harvest from 60 field experiments, the topsoil critical nutrient values were determined as 34.6, 15.6, and 150 mg kg−1 for soil nitrate N, available P, and available K, respectively. Then, based on five groups of relative yield (>125%, 115–125%, 105–115%, 95–105%, and <95%) and the model, the five groups of topsoil critical nutrient levels and fertilization coefficients (Fc) were determined. Finally, we proposed a new method for calculating the recommended fertilizer input rate as: Fr=Gy×Nr×Fc, where Fr is the recommended fertilizer (N/P/K) input rate; Gy is the potential grain yield; Nr is the N(NrN), P(NrP), and K(NrK) nutrient requirements for wheat to produce 1,000 kg of grain; and Fc is a coefficient for N(Nc)/P(Pc)/K(Kc) fertilizer. A 2-year validated experiment confirmed that the new method reduced N fertilizer input by 17.5% (38.5 kg N ha−1) and P fertilizer input by 43.5% (57.5 kg P2O5 ha−1) in northern China and did not reduce the wheat yield. This outcome can significantly increase the farmers’ benefits (by 7.58%, or 139 US$ ha−1). Therefore, this new recommended fertilization method can be used as a tool to guide N, P, and K fertilizer application rates for dryland wheat production.

Bioaccumulation of novel brominated flame retardants in crucian carp (Carassius auratus): Implications for electronic waste recycling area monitoring

Bioaccumulation factor (BAF) of pollutants is an important parameter for evaluating their bioaccumulation potential and an important indicator for evaluating their environmental risks. However, little study exits on the BAF of novel brominated flame retardants (NBFRs). The present study determined 17 NBFRs in 24 water samples in dissolved phase and 93 crucian carp samples collected from an electronic waste recycling site in northern China, in order to examine their contamination, distribution and bioaccumulation. The results showed that the targeted NBFRs were widely detectable in the dissolved phase and crucian carps. In dissolved phase, allyl 2,4,6-tribromophenyl ether (ATE) had the highest detectable rate (100%) and concentration (mean: 1.3 ± 0.62 ng/L), but in crucian carp, hexachlorocyclopentenyl-dibromocyclooctane (HCDBCO) was the one with the highest detectable rate (89%) and concentration (mean: 16 ± 9.2 ng/g wet weight (ww)) among all 17 NBFRs. The discharge and water solubility of NBFRs determined their concentration in the dissolved phase, while the concentration of NBFRs in crucian carp was the results of their discharge and food exposure. The estimated BAFs exceeded 5000 L/kg for petabromoethylbenzene (PBEB), pentabromotoluene (PBT), HCDBCO, pentabromobenzyl acrylate (PBBA), 1,2,3,4,5-pentabromobenzene (PBBZ), 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), hexabromobenzene (HBBZ), and α-1,2,5,6-tetrabromocyclooctane (α-TBCO), suggesting that these compounds were above the hazard standard of bioaccumulation. Although the BAFs of 2,3,5,6-tetrabromo-p-xylene (p-TBX), 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE), α-/β-tetrabromoethylcyclohexane (α-/β-TBECH) and ATE were less than 5000, the potential of bioaccumulation cannot be ignored. The log BAF of tested NBFRs showed a pattern of first increasing and then decreasing with the increase of log KOW, the water solubility of NBFRs, the exposure to fish, the uptake and depuration of fish were the key factor to this pattern. To our knowledge, the BAF values of the most of NBFRs calculated in this study were not reported in the published work previously.

Sources and solubility of aerosol phosphorus at a coastal site in northern China: Coarse versus fine particles and spring versus winter

Atmospheric P is of great importance as it is a major source of phosphorus (P) in open oceans, which can limit the primary productivity of ocean ecosystems and indirectly affect global climate. However, the understanding on the sources of atmospheric P, especially water-soluble P in different particle size and the factors that dominate P solubility is limited. This study characterizes P in fine and coarse particles during winter and spring in Qingdao, a coastal city in North China. The average concentration of total P in fine particles was 23 ± 15 ng/m3 in winter and 28 ± 24 ng/m3 in spring, while in coarse particles it was 21 ± 15 ng/m3 in winter and 15 ± 12 ng/m3 in spring. In spring, fine particles had notably higher concentrations of total P than coarse particles, while in winter, the difference between the two particle sizes was not pronounced. Regardless of the concentration of total P, the sources of total P varied distinctly between fine and coarse particles in both seasons. The concentration of soluble P is obviously higher in spring than in winter for the fine particles but coarse particles show no significant difference between the two seasons. P solubility is always higher in spring compared to winter regardless of the particle size, which can be due to higher relative humidity. Both soluble P concentrations and P solubility were significantly higher in fine particles compared to coarse particles during winter and spring. A higher contribution of combustion emission and higher acidity can be the reasons for the higher P solubility in fine particles in winter. The findings suggest that a comprehensive evaluation of the ecological impacts of atmospheric phosphorus should consider its sources, aerosol acidity, humidity, and differences among fine and coarse particles.

Mechanisms of reproductive isolation between annual and perennial plants of Incarvillea sinensis

AbstractQuantifying the relative strength of isolating barriers is a major focus of research on plant speciation. Contrasting life histories and mating systems have the potential to limit gene exchange between closely related populations growing in sympatry. However, few studies have quantified reproductive isolating barriers between conspecific annual and perennial populations and their contributions to total reproductive isolation (RI). Incarvillea sinensis Lam. (Bignoniaceae) is an insect‐pollinated herb with largely allopatric annual and perennial populations that differ in mating systems. The perennial populations are primarily outcrossing whereas annual populations are predominantly selfing. At a rare sympatric site in northern China we estimated prezygotic and postzygotic barriers to gene exchange between annual and perennial plants and found complete RI between the two life histories. Annuals exhibited significantly higher ecogeographic isolation than perennials whereas perennials experienced more isolation through pollen–pistil interactions than annuals. Crosses between annuals and perennials demonstrated that postzygotic barriers influencing fruit and seed formation, F1 germination and survival were negligible for annuals but played a small role for perennials. However, F1 hybrids of crosses between annuals and perennials produced no pollen and their ovules were largely sterile. Our study provides insight into the relative importance of prezygotic and postzygotic isolating barriers between closely related annual and perennial populations of I. sinensis and some of these barriers could have been involved with speciation. Annuals and perennials of I. sinensis represent two biological species and thus deserve to be recognized as distinct taxonomic species.

Risk assessment of bolt-gasket-flange connection (BGFC) failures at hydrogen transfer stations based on improved FMEA

Failure Modes and Effects Analysis (FMEA) is an engineering technique widely used to identify, evaluate, and eliminate known or potential failures, problems, and errors and inform risk management decisions. Traditional FMEA uses the risk priority number (RPN) to identify potential failure modes and their levels. However, it displays shortcomings in determining risk factor weights, ranking risk priorities of failure modes, and dealing with uncertainties during the risk assessment process. To address these issues, this paper proposed an improved FMEA risk assessment method by integrating FMEA, the analytic hierarchy process (AHP), the technique for order preference by similarity to an ideal solution (TOPSIS), and the cloud model (CM) to determine a more reasonable failure mode level. First, the CM was used to improve the FMEA framework structure to comprehensively assess ambiguity and randomness during the evaluation process. Second, the cloud weights of the risk factor severity (S), occurrence (O), and detectability (D) were calculated using AHP and CM to determine the relative risk factor importance. Then, the cloud distance measurement algorithm and TOPSIS were combined into the TOPSIS-CM risk ranking method to objectively identify the failure modes requiring improvement. Finally, a case study of a flange connection system at a hydrogen blending transmission site in northern China was conducted to verify the adaptability of the proposed method in failure mode assessment. Compared with traditional FMEA methods, the decision scores obtained using the improved FMEA were more discriminating and distinguished the risk of each failure mode, providing more accurate information to decision makers (DMs).