Vertical distribution of Candidatus Methylomirabilis and Methanoperedens in agricultural soils.

Candidatus Methylomirabilis-related bacteria conduct anaerobic oxidation of methane (AOM) coupling with NO2- reduction, and Candidatus Methanoperedens-related archaea perform AOM coupling with reduction of diverse electron acceptors, including NO3-, Fe (III), Mn (IV) and SO42-. Application of nitrogen fertilization favors the growth of these methanotrophs in agricultural fields. Here, we explored the vertical variations in community structure and abundance of the two groups of methanotrophs in a nitrogen-rich vegetable field via using illumina MiSeq sequencing and quantitative PCR. The retrieved Methylomirabilis-related sequences had 91.12%-97.32% identity to the genomes of known Methylomirabilis species, and Methanoperedens-related sequences showed 85.49%-97.48% identity to the genomes of known Methanoperedens species which are capable of conducting AOM coupling with reduction of NO3- or Fe (III). The Methanoperedens-related archaeal diversity was significantly higher than Methylomirabilis-related bacteria, with totally 74 and 16 operational taxonomic units, respectively. In contrast, no significant difference in abundance between the bacteria (9.19 × 103-3.83 × 105 copies g-1 dry soil) and the archaea (1.55 × 104-3.24 × 105 copies g-1 dry soil) was observed. Furthermore, the abundance of both groups of methanotrophs exhibited a strong vertical variation, which peaked at 30-40 and 20-30 cm layers, respectively. Soil water content and pH were the key factors influencing Methylomirabilis-related bacterial diversity and abundance, respectively. For the Methanoperedens-related archaea, both soil pH and ammonium content contributed significantly to the changes of these archaeal diversity and abundance. Overall, we provide the first insights into the vertical distribution and regulation of Methylomirabilis-related bacteria and Methanoperedens-related archaea in vegetable soils. KEY POINTS: • The archaeal diversity was significantly higher than bacterial. • There was no significant difference in the abundance between bacteria and archaea. • The abundance of bacteria and archaea peaked at 30-40 and 20-30 cm, respectively.

The Relationship between Indoor and Outdoor Fine Particulate Matter in a High-Rise Building in Chicago Monitored by PurpleAir Sensors.

In urban areas like Chicago, daily life extends above ground level due to the prevalence of high-rise buildings where residents and commuters live and work. This study examines the variation in fine particulate matter (PM2.5) concentrations across building stories. PM2.5 levels were measured using PurpleAir sensors, installed between 8 April and 7 May 2023, on floors one, four, six, and nine of an office building in Chicago. Additionally, data were collected from a public outdoor PurpleAir sensor on the fourteenth floor of a condominium located 800 m away. The results show that outdoor PM2.5 concentrations peak at 14 m height, and then decline by 0.11 µg/m3 per meter elevation, especially noticeable from midnight to 8 a.m. under stable atmospheric conditions. Indoor PM2.5 concentrations increase steadily by 0.02 µg/m3 per meter elevation, particularly during peak work hours, likely caused by greater infiltration rates at higher floors. Both outdoor and indoor concentrations peak around noon. We find that indoor and outdoor PM2.5 are positively correlated, with indoor levels consistently remaining lower than outside levels. These findings align with previous research suggesting decreasing outdoor air pollution concentrations with increasing height. The study informs decision-making by community members and policymakers regarding air pollution exposure in urban settings.

Vertical variation in prokaryotic community composition and co-occurrence patterns in sediments of the Three Gorges Reservoir, China.

Archaea and bacteria are distributed throughout the sediment; however, our understanding of their biodiversity patterns, community composition, and interactions is primarily limited to the surface horizons (0-20 cm). In this research, sediment samples were collected from three vertical sediment profiles (depths of 0-295 cm) in the Three Gorges Reservoir (TGR), one of the largest reservoirs in the world. Through 16S rRNA sequencing, it was shown that sediment microbial diversity did not significantly vary across the sediment. Nevertheless, a decline in the similarity of archaeal and bacterial communities over distance along sediment vertical profiles was noted. Nonmetric multidimensional scaling (NMDS) analysis revealed that archaeal and bacterial communities could be clearly separated into two groups, located in the upper sediments (0-135 cm) and deep sediments (155-295 cm). Meanwhile, at the fine-scale of the vertical section, noteworthy variations were observed in the relative abundance of prominent archaea (e.g., Euryarchaeota) and bacteria (e.g., Proteobacteria). The linear discriminant analysis effect size (LEfSe) demonstrated that twenty-four bacterial and twenty-six archaeal biomarker microbes exist in the upper and deep sediment layers. Each layer exhibited distinctive microbial divisions, suggesting that microbes with diverse biological functions are capable of thriving and propagating along the sediment profile. Co-occurrence network analysis further indicated that the microbial network in the upper sediments was more complex than that in the deep sediments. Additionally, the newly discovered anaerobic methanotrophic archaeon Candidatus Methanoperedens was identified as the most abundant keystone archaeal taxon in both sediment layers, highlighting the significance of methane oxidation in material cycling within the TGR ecosystem. In summary, our study examined the biodiversity and coexistence patterns of benthic microbial communities throughout the vertical sediment profile, providing detailed insights into the vertical geography of archaeal and bacterial communities in typical deep-water reservoir ecosystems.

A land use regression model of nitrogen dioxide and fine particulate matter in a complex urban core in Lanzhou, China.

BACKGROUND: Land use regression (LUR) models have been widely used to estimate air pollution exposures at high spatial resolution. However, few LUR models were developed for rapidly developing urban cores, which have substantially higher densities of population and built-up areas than the surrounding areas within a city's administrative boundary. Further, few studies incorporated vertical variations of air pollution in exposure assessment, which might be important to estimate exposures for people living in high-rise buildings. OBJECTIVE: A LUR model was developed for the urban core of Lanzhou, China, along with a model of vertical concentration gradients in high-rise buildings. METHODS: In each of four seasons in 2016-2017, NO2 was measured using Ogawa badges for 2 weeks at 75 ground-level sites. PM2.5 was measured using DataRAM for shorter time intervals at a subset (N = 38) of the 75 sites. Vertical profile measurements were conducted on 9 stories at 2 high-rise buildings (N = 18), with one building facing traffic and another facing away from traffic. The average seasonal concentrations of NO2 and PM2.5 at ground level were regressed against spatial predictors, including elevation, population, road network, land cover, and land use. The vertical variations were investigated and linked to ground-level predictions with exponential models. RESULTS: We developed robust LUR models at the ground level for estimated annual averages of NO2 (R2: 0.71, adjusted R2: 0.67, and Leave-One-Out Cross Validation (LOOCV) R2: 0.64) and PM2.5 (R2: 0.77, adjusted R2: of 0.73, and LOOCV R2: 0.67) in the urban core of Lanzhou, China. The LUR models for the estimated seasonal averages of NO2 showed similar patterns. Vertical variation of NO2 and PM2.5 differed by windows orientation with respect to traffic, by season or by time of a day. Vertical variation functions incorporated the ground-level LUR predictions, in a form that could allow for exposure assessment in future epidemiological investigations. CONCLUSIONS: Ground-level NO2 and PM2.5 showed substantial spatial variations, explained by traffic and land use patterns. Further, vertical variation of air pollution levels is significant under certain conditions, suggesting that exposure misclassification could occur with traditional LUR that ignores vertical variation. More studies are needed to fully characterize three-dimensional concentration patterns to accurately estimate air pollution exposures for residents in high-rise buildings, but our LUR models reinforce that concentration heterogeneity is not captured by the limited government monitors in the Lanzhou urban area.

Vertical Displacement in Unilateral Extension Base Flexible Removable Dentures.

The need for flexible thermoplastic denture base materials has increased due to patient demand for better esthetic outcomes. Designs aimed at improving esthetic outcomes can cause difficulties for prosthodontists, however, from the viewpoint of function and maintenance. Therefore, the purpose of this study was to investigate vertical displacement in unilateral extension base denture models, comparing that obtained by flexible removable dentures with that by conventional metal clasp dentures. Models of unilateral extension base flexible removable dentures for mandibular defects were prepared. Periodontal ligament and jaw mucosa were simulated using a silicone impression material. Four types of flexible removable denture, with or without a metal rest, and two metal clasp dentures made of acrylic resin as a conventional design were used as dental prostheses. The amount of vertical displacement in the defect areas was measured under a load of 50 N at the first and second molars. Among the 6 types of dentures investigated, the amount of vertical displacement was greater with flexible removable dentures than with metal clasp dentures. This vertical displacement tended to decrease significantly, however, with the use of a metal rest with the flexible removable dentures. Esteshot with a metal rest, in particular, showed the smallest amount of displacement in the flexible removable dentures (first molar, 0.265±0.007 mm; second molar, 0.423±0.008 mm). These results indicate the importance of the application of rests in unilateral extension base flexible removable dentures. It may be useful to employ a metal rest in conjunction with a flexible removable denture to reduce load on the underlying mucosa, as is done with conventional partial dentures.

Variation with depth of the abundance, diversity and pigmentation of culturable bacteria in a deep ice core from the Yuzhufeng Glacier, Tibetan Plateau.

It has been suggested that the cryosphere is a new biome uniquely dominated by microorganisms, although the ecological characteristics of these cold-adapted bacteria are not well understood. We investigated the vertical variation with depth of the proportion of pigmented bacteria recovered from an ice core drilled in the Yuzhufeng Glacier, Tibetan Plateau. A total of 25,449 colonies were obtained from 1250 ice core sections. Colonies grew on only one-third of the inoculated Petri dishes, indicating that although the ice core harbored abundant culturable bacteria, bacteria could not be isolated from every section. Four phyla and 19 genera were obtained; Proteobacteria formed the dominant cluster, followed by Actinobacteria, Bacteroidetes and Firmicutes. The proportion of pigmented bacteria increased with depth from 79 to 95% and yellow-colored colonies predominated throughout the ice core, making up 47% of all the colonies. Pigments including α- and ß-carotene, diatoxanthin, peridinin, zea/lutein, butanoyloxy, fucoxanthin and fucoxanthin were detected in representative colonies with α-carotene being the dominant carotenoid. To the best of our knowledge, this is the highest resolution study of culturable bacteria in a deep ice core reported to date.

Temporal variation of per- and polyfluoroalkyl substances (PFASs) abundances in Shenzhen Bay sediments over past 65 years.

We examined the vertical distribution of per- and polyfluoroalkyl substances (PFASs) and total organic carbon in sediment cores located in Shenzhen Bay area. We investigated the 210Pbex specific activity of the sediments and calculated the flux of PFASs to understand the temporal variation of PFASs in the past 65 years. The results showed that the concentrations of PFASs generally decreased with depth, ranging from 13 to 251 pg/g dw. The highest PFASs detected were perfluorobutanesulfonic acid, perfluorooctanoic acid, and perfluorohexanoic acid, which correspond to raw materials used in fire-fighting foam and food packaging industries. The flux of PFASs in Shenzhen Bay showed varying growth after 1978 when China's GDP entered a rapid growth stage. Our findings suggest that the vertical distribution of PFASs in Shenzhen Bay is fluctuating with the changes in industrial types and economic development, with implications for studying the fate of other persistent pollutants in the oceans.

Genotype-Environment Interaction and Horizontal and Vertical Distributions of Heartwood for Acacia melanoxylon R.Br.

Acacia melanoxylon (blackwood) is a valuable wood with excellent-quality heartwood extensively utilized worldwide. The main aim of this study was to confirm the horizontal and vertical variation and provide estimated values of genetic gains and clonal repeatabilities for improving breeding program of A. melanoxylon. Six blackwood clones at 10 years old were analyzed in Heyuan and Baise cities in China. Stem trunk analysis was conducted for sample trees to explore the differences between heartwood and sapwood. The heartwood radius (HR), heartwood area (HA), and heartwood volume (HV) in heartwood properties decreased as tree height (H) in growth traits increased, and the HV = 1.2502 DBH (diameter at breast height)1.7009 model can accurately estimate the heartwood volume. Furthermore, G × E analysis showed that the heritabilities of the eleven indices, including DBH, DGH (diameter at ground height), H, HR, SW (sapwood width), BT (bark thickness), HA, SA (sapwood area), HV, HRP (heartwood radius percentage), HAP (heartwood area percentage), and HVP (heartwood volume percentage) were between 0.94 and 0.99, and repeatabilities of the eleven indices were between 0.74 and 0.91. Clonal repeatability of DBH (0.91), DGH (0.88), and H (0.90) in growth traits, HR (0.90), HVP (0.90), and HV (0.88) in heartwood properties were slightly higher than for SA (0.74), SW (0.75), HAP (0.75), HRP (0.75), and HVP (0.75). These data also implied that the growth characteristics of heartwood and sapwood of blackwood clones were less affected by the environment and had substantial heritability.

Characterization of the vertical variation in indoor PM2.5 in an urban apartment in China.

Indoor air pollution has aroused increasing concerns due to its significant adverse health impacts. Indoor PM2.5 exposure assessments often rely on PM2.5 concentration measured at a single height, which overlooks the vertical variation of PM2.5 concentrations accompanied by various indoor activities. In this study, we characterize the vertical profile of PM2.5 concentration by monitoring PM2.5 concentration at eight different heights in the kitchen and the bedroom, respectively, using low-cost sensors with high temporal resolution. The localized enhancement of PM2.5 concentration in elevated heights in the kitchen during cooking was observed on clean and polluted days, showing dominating contribution from cooking activities. The source contribution from cooking and outdoor penetration was semi-quantified using regression models. Stratified source contribution from cooking activities was evident in the kitchen during the cooking period. The contribution in elevated heights (above 170 cm) almost tripled the contrition in bottom layers (below 140 cm). In contrast, little vertical variation was observed during other times of the day in the kitchen or the bedroom. The exposure level calculated using the multi-height measurement in this study is consistently higher than the exposure level estimated from the single-height (at 110 cm) measurement. A more significant discrepancy existed for the cookers (17.8%) than the non-cookers (13.5%). By profiling the vertical gradient of PM2.5 concentration, we show the necessity to conduct multi-height measurements or proper breathing-height measurements to obtain unbiased concentration information for source apportionment and exposure assessment. In particular, the multi-height measuring scheme will be crucial to inform household cooking emission regulations.

A three-dimensional LUR framework for PM2.5 exposure assessment based on mobile unmanned aerial vehicle monitoring.

Land use regression (LUR) models have been widely used in epidemiological studies and risk assessments related to air pollution. Although efforts have been made to improve the performance of LUR models so that they capture the spatial heterogeneity of fine particulate matter (PM2.5) in high-density cities, few studies have revealed the vertical differences in PM2.5 exposure. This study proposes a three-dimensional LUR (3-D LUR) assessment framework for PM2.5 exposure that combines a high-resolution LUR model with a vertical PM2.5 variation model to investigate the results of horizontal and vertical mobile PM2.5 monitoring campaigns. High-resolution LUR models that were developed independently for daytime and nighttime were found to explain 51% and 60% of the PM2.5 variation, respectively. Vertical measurements of PM2.5 from three regions were first parameterized to produce a coefficient of variation for the concentration (CVC) to define the rate at which PM2.5 changes at a certain height relative to the ground. The vertical variation model for PM2.5 was developed based on a spline smoothing function in a generalized additive model (GAM) framework with an adjusted R2 of 0.91 and explained 92.8% of the variance. PM2.5 exposure levels for the population in the study area were estimated based on both the LUR models and the 3-D LUR framework. The 3-D LUR framework was found to improve the accuracy of exposure estimation in the vertical direction by avoiding exposure estimation errors of up to 5%. Although the 3-D LUR-based assessment did not indicate significant variation in estimates of premature mortality that could be attributed to PM2.5, exposure to this pollutant was found to differ in the vertical direction. The 3-D LUR framework has the potential to provide accurate exposure estimates for use in future epidemiological studies and health risk assessments.

Quantifying source contributions for indoor CO2 and gas pollutants based on the highly resolved sensor data.

Household air pollution is the dominant contributor to population air pollutant exposure, but it is often of less concern compared with ambient air pollution. One of the major knowledge gaps in this field are detailed quantitative source contributions of indoor pollutants, especially for gaseous compounds. In this study, temporally, spatially, and vertically resolved monitoring for typical indoor gases including CO2, CO, formaldehyde, methane, and the total volatile organic compounds (VOCs) was conducted to address pollution dynamics and major sources in an urban apartment. The indoor concentrations were significantly higher than the simultaneously measured outdoor concentrations. A new statistic approach was proposed to quantitatively estimate contributions of different sources. It was estimated that outdoor CO2 contributed largely to the indoor CO2, while main indoor sources were human metabolism and cooking. Outdoor infiltration and cooking contributed almost equally to the indoor CO. The contribution of outdoor infiltration to methane was much higher than that to formaldehyde. Cooking contributed to 24%, 19%, and 25% of indoor formaldehyde, methane, and VOCs, whereas the other unresolved indoor sources contributed 61%, 19%, and 35% of these pollutants, respectively. Vertical measurements showed that the uplifting of hot air masses led to relatively high concentrations of the pollutants in the upper layer of the kitchen and in the other rooms to a lesser extent.

First report on polybrominated diphenyl ethers in the Iranian Coral Islands: Concentrations, profiles, source apportionment, and ecological risk assessment.

Coral reefs are challenged by multiple stressors due to the growing industrialization. Despite that, data on their environment are still scarce, and no research is yet performed on polybrominated diphenyl ethers in the Persian Gulf area. Seeking to fill in this gap, the present study aims to determine spatio-vertical distributions, source apportionment and ecological risk of polybrominated diphenyl ethers in the sediment cores and seawater samples from ten coral reef Islands in the Persian Gulf, Iran. Σ12PBDEs concentrations ranged from 0.42 ± 0.04 to 47.14 ± 1.35 ng g-1 dw in sediments, and from 1.17 ± 0.06 to 7.21 ± 1.13 ng L-1 in seawater. The vertical polybrominated diphenyl ethers distribution varied significantly among the sampling stations and different depths with a decreasing trend towards the surface and peaks around 12-20 cm. Both in the seawater and sediment samples, elevated polybrominated diphenyl ethers loadings were observed in highly industrialized areas. Deca-bromodiphenyl ether-209 was the predominant congener along the sediment cores, whereas Tetra-bromodiphenyl ether-47 and Penta-bromodiphenyl ether-100 dominated in seawater samples. Commercial Deca-bromodiphenyl ether mixture was found to be the major source of polybrominated diphenyl ethers. Penta-bromodiphenyl ether was revealed to be the major ecological risk driver in the study area: it posed medium to high-risk quotient to sediment dwelling organisms. This study indicated that coral reefs are playing an important role in retaining polybrominated diphenyl ethers and highlighted the need to manage polybrominated diphenyl ethers contamination in the coral reef environment.

The spatial and vertical distribution of heavy metal contamination in sediments of the Three Gorges Reservoir determined by anti-seasonal flow regulation.

The contamination of heavy metals in sediments of the Three Gorges Reservoir (TGR) is increasingly concerned as a major issue for water quality since the full impoundment. In this study, the sediment profiles in the riparian and submerged areas from Fuling to Zigui in the middle-low TGR mainstream were collected to investigate the stratified distribution of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and assess their contamination and potential eco-risk. The results showed that the concentrations of these metals in the riparian sediments did not present a marked spatial trend except the concentrations of Cd that increased towards the dam. However, the metal concentrations (except Cd) in the submerged sediments were generally higher near the dam. The concentrations of heavy metals in the riparian sediments did not show marked vertical variation, while in the submerged sediments they fluctuated dramatically with depth, indicating the metal accumulation processes in last few years. Sediment grain sizes as an indicator of hydrodynamic regimes dominated the vertical distribution of heavy metals over organic matters and Fe/Mn oxide/hydroxides. The sediments from both riparian and submerged areas of the TGR were contaminated by anthropogenic metals of Cd, Cu and Pb that were mainly from the ore mining, fossil fuel combustion, agricultural pollution and atmospheric deposition. Cadmium was a major metal pollutant in the sediments with a high contamination and potential eco-risk level. The results of this study indicate that the sorting of sediments with the anti-seasonal flow regulation determines the spatial and temporal distribution of heavy metal contamination in the sediments, and the impoundment stages of the TGR in history regulate the accumulation processes of the metals.

Depth-Resolved Distribution of Particle-Attached and Free-Living Bacterial Communities in the Water Column of the New Britain Trench.

Particle-attached (PA) and free-living (FL) microorganisms play significant but different roles in mineralization of organic matter (OM) in the ocean. Currently, little is known about PA and FL microbial communities in bathyal and abyssal pelagic waters, and understanding of their diversity and distribution in the water column and their interactions with environmental factors in the trench area is limited. We investigated for the first time the variations of abundance and diversities of the PA and FL bacterial communities in the epi-, bathy-, and abyssopelagic zones of the New Britain Trench (NBT). The PA communities showed decreasing species richness but increasing relative abundance with depth, suggesting the increasing ecological significance of the PA bacteria in the deep ocean. The abundance and diversity of PA and FL bacterial communities in the NBT water column appeared to be shaped by different sets of environment factors, which might be related to different micro-niches of the two communities. Analysis on species distribution suggested that the differences between PA and FL bacteria communities mainly resulted from the different relative abundance of the "shared taxa" in the two types of communities. These findings provide valuable information for understanding the relative ecological roles of the PA and FL bacterial communities and their interactions with environmental factors in different pelagic zones along the vertical profile of the NBT water column.

Characteristics of phytoplankton communities and their biomass variation in a gas hydrate drilling area in the northern South China Sea.

We analyzed the data obtained from field observations on a gas hydrate drilling area in Dongsha of northern South China Sea (SCS) in middle May (before drilling) and early October (after drilling) in 2013. The variation in the phytoplankton communities and biomass as well as the impacts of environmental factors including dissolved methane was studied. Results indicated that the gas hydrate drilling area in Dongsha, SCS exhibited a typical low-nutrients low-chlorophyll a (LNLC) environment accompanied with low phytoplankton abundance. A total of 103 taxa belonging to 52 genera of 5 classes were identified, with diatoms and dinoflagellates dominating the community. Both phytoplankton abundance and chlorophyll a (Chl a) were highest at the subsurface maximum layer. The subsurface chlorophyll maximum (SCM) before and after drilling were stabilized at 75 m (0.30 ±â€¯0.06 mg/m3 and 0.51 ±â€¯0.29 mg/m3, respectively), while the subsurface maximum of abundance after drilling went deeper to 75 m (604.17 ±â€¯313.22 cells/L) from the surface (707.14 ±â€¯243.98 cells/L) before drilling. After drilling, phosphate and Chl a increased significantly, but no significant differences were observed on abundance. Dominant species of diatoms were basically constant with dinoflagellates becoming more apparent in higher occurrence and abundance, while Cyanophyta was diverse after drilling. Redundancy analysis (RDA) and Spearman's correlation analysis both indicated that temperature, pH and phosphates were major factors causing fluctuation in phytoplankton community structure, while dissolved methane had non-significant impact directly. We clearly found both abundance and Chl a increased in particular water layers (between 50 and 75 m) and at stations (DS06, DS08 and DS15) where dissolved methane concentrations were also abnormally high. This study appeared to partly coincide with the findings of natural oil seeps in the Gulf of Mexico, which assumed that the turbulence from the natural oil and gas leaking zone could raise the bottom water through the rising bubbles and bring cold nutrient rich waters to the thermocline from the deep seeps. This plume-generated upwelling could then fuel a bottom-up effect on the photosynthetic species in the upper pelagic waters within the euphotic zone.

Trophic-functional patterns of biofilm-dwelling ciliates at different water depths in coastal waters of the Yellow Sea, northern China.

Vertical variations in trophic-functional patterns of biofilm-dwelling ciliates were studied in coastal waters of the Yellow Sea, northern China. A total of 50 species were identified and assigned to four trophic-functional groups (TFgrs): algivores (A), bacterivorous (B), non-selective (N) and raptors (R). The trophic-functional structures of the ciliate communities showed significant variability among different water depths: (1) with increasing water depth, relative species numbers and relative abundances of groups A and R decreased sharply whereas those of groups B and N increased gradually; (2) in terms of the frequency of occurrences, group A dominated at depths of 1-3.5 m whereas group B dominated at 5 m, while in terms of the probability density function of the trophic-functional spectrum, group A was the highest contributor at 1 m and group B was highest at the other three depths; (3) distance-based redundancy analyses revealed significant differences in trophic-functional patterns among the four depths, except between 2 and 3.5 m (P > 0.05); and (4) the trophic-functional trait diversity increased from 1 to 3.5 m and decreased sharply at 5 m. Our results suggest that the biofilm-dwelling ciliates maintain a stable trophic-functional pattern and high biodiversity at depths of 1-3.5 m.

Vertical variation of a black soil's properties in response to freeze-thaw cycles and its links to shift of microbial community structure.

Soil freeze-thaw cycles (FTCs) change soil physical, chemical, and biological properties, however information regarding their vertical variations in response to FTCs is limited. In this work, black soil (silty loam) packed soil columns were exposed to 8 FTCs, and soil properties were determined for each of vertical layer of soil columns. The results revealed that after FTCs treatment, moisture and electrical conductivity (EC) salinity tended to increase in upper soil layers. Increments of ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) in top layers (0-10cm) were greater than those in other layers, and increments of water soluble organic carbon (WSOC) and decrease of microbial biomass carbon (MBC) in middle layers (10-20cm) were greater than those in both ends. Overall, microbial community structure was mainly influenced by soil physical properties (moisture and EC) and chemical properties (pH and WSOC). For bacterial (archaeal) and fungal communities, soil physical properties, chemical properties and their interaction explained 79.73% and 82.66% of total variation, respectively. Our results provided insights into the vertical variation of soil properties caused by FTCs, and such variation had a major impact on the change of structure and composition of soil bacterial and fungal communities.

[Characteristics of soil moisture variation in different land use types in the hilly region of the Loess Plateau, China]. / 黄土丘陵区不同土地利用类型土壤水分变化特征.

Soil water availability is a key factor restricting the ecological construction and sustainable land use in the loess hilly region. It is of great theoretical and practical significance to understand the soil moisture status of different land use types for the vegetation restoration and the effective utilization of land resources in this area. In this study, EC-5 soil moisture sensors were used to continuously monitor the soil moisture content in the 0-160 cm soil profile in the slope cropland, terraced fields, jujube orchard, and grassland during the growing season (from May to October) in the Yuanzegou catchment on the Loess Plateau, to investigate soil moisture dynamics in these four typical land use types. The results showed that there were differences in seasonal variation, water storage characteristics, and vertical distribution of soil moisture under different land use types in both the normal precipitation (2014) and dry (2015) years. The terraced fields showed good water retention capacity in the dry year, with the average soil moisture content of 0-60 cm soil layer in the growing season being 2.6%, 4.2%, and 1.8% higher than that of the slope cropland, jujube orchard, and grassland (all P<0.05). The water storage of 0-160 cm soil profile was 43.90, 32.08, and 18.69 mm higher than that of slope cropland, jujube orchard, and grassland, respectively. In the normal precipitation year, the average soil moisture content of 0-60 cm soil layer in jujube orchard in the growing season was 2.9%, 3.8%, and 4.5% lower than that of slope cropland, terraced fields, and grassland, respectively (all P<0.05). In the dry year, the effective soil water storage of 0-160 cm soil profile in the jujube orchard accounted for 35.0% of the total soil water storage. The grey relational grade between the soil moisture in the surface layer (0-20 cm) and soil moisture in the middle layer (20-100 cm) under different land use types was large, and the trend for the similarity degree of soil moisture variation followed terraced fields > grassland > slope cropland > jujube orchard. The slope cropland in this area could be transformed into terraced fields to improve the utilization of precipitation and promote the construction of ecological agriculture. Aiming at resolving the severe water shortage in the rain-fed jujube orchard for the sustainable development of jujube orchard in the loess hilly region, appropriate water management measures should be taken to reduce the water consumption of jujube trees and other inefficient water consumption.

[Spatial heterogeneity of soil moisture of mountain apple orchards with rainwater collection and infiltration (RWCI) system in the Loess Plateau, China]. / é»„åœŸé«˜åŽŸé›¨æ°´é›†èšæ·±å±‚å ¥æ¸—(RWCI)系统下山地果园土壤水分时空变异特征.

Water scarcity is a critical factor influencing rain-fed agricultural production on the Loess Plateau, and the exploitation of rainwater is an effective avenue to alleviate water scarcity in this area. This study was conducted to investigate the spatial and temporal distribution of soil moisture in the 0-300 cm under a 21-year-old apple orchard with the rainwater collection and infiltration (RWCI) system by using a time domain reflectometer (TDR) probe on the Loess Plateau. The results showed that there was a low soil moisture zone in the 40-80 cm under the CK, and the RWCI system significantly increased soil moisture in this depth interval. Over this depth, the annual average soil moisture under RWCI40, RWCI60 and RWCI80 was 39.2%, 47.2% and 29.1% higher than that of bare slope (BS) and 75.3%, 85.4% and 62.7% higher than that of CK, respectively. The maximum infiltration depth of water under RWCI40, RWCI60 and RWCI80 was 80 cm, 120 cm and 180 cm, respectively, and the soil moisture in the 0-60, 0-100 and 0-120 cm was more affected by RWCI40, RWCI60 and RWCI80, respectively. Over the whole growth period of apple tree, the maximum value of soil moisture content in the 0-300 cm existed in the RWCI80 treatment, followed by the RWCI40 and RWCI60 treatments. Overall, the RWCI system is an effective meaning of transforming rainwater to available water resources and realizing efficient use of agricultural water on the Loess Plateau.

Short-chain chlorinated paraffins in the soils of two different Chinese cities: Occurrence, homologue patterns and vertical migration.

UNLABELLED: Short-chain chlorinated paraffins (SCCPs) are candidate persistent organic pollutants (POPs) that are under review by the Stockholm Convention. China is currently the largest producer and consumer of chlorinated paraffins (CPs). To study the environmental behavior and fate of SCCPs in the soils of urban and suburban regions, the SCCP concentrations in 88 topsoils and 15 soil columns from land of different use types (e.g., woodland, vegetable field, paddy field and greenbelt) from Guangzhou and Chengdu have been determined. The SCCP concentrations in topsoils from Guangzhou (range: 1.45-25.5ngg(-1) dry weight (dw), average: 10.3ngg(-1) dw) were much higher than those from Chengdu (range: 0.218-3.26ngg(-1) dw, average: 1.43ngg(-1) dw). When compared to previously reported SCCP levels for topsoils from other areas, the SCCP concentrations measured in the present work were quite low. Much higher SCCP concentrations were observed in the greenbelt topsoils from Chengdu relative to the values measured from woodlands and vegetable and paddy fields. The composition profiles suggest that C10Cl6-10 and C11-13Cl6-8 were the major groups of SCCPs in topsoils from the woodlands and vegetable and paddy fields in Guangzhou and Chengdu. Vertical variations of the SCCP concentrations in the soil columns suggest that less chlorinated SCCPs (Cl5-6-SCCPs) are more capable of migrating to the deeper-layer soils than more chlorinated ones (Cl9-10-SCCPs). The SCCP concentrations displayed little dependence on organic matter (OM) for most topsoils (p>0.05), indicating that OM is not the controlling factor in the distribution of SCCPs in the soils. CAPSULE: This study analyzed the occurrence, homologue patterns and vertical migration of SCCPs in the topsoils of two Chinese cities with different industrial structures and climate conditions.