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The study investigated the wood mechanical properties of black alder [Alnus glutinosa (L.) Gaertn.], a widely distributed deciduous tree in Europe valued for its suitability in silviculture and wood industry applications. The aim was to compare these properties among selected half-sib families and assess the relationship between wood hardness and other characteristics. Experimental plantations of black alder progenies from Lithuanian populations were established in different forest regions in 1998. The study analyzed various parameters for different genetic families, including tree diameter, height, wood hardness, moisture content, wood density, and mechanical properties. The findings revealed significant variability in wood properties among half-sib families, highlighting a strong genetic influence. Although the static modulus of elasticity showed no notable difference across families, other properties showed significant variations. Furthermore, the analysis identified weak correlations between wood hardness and other mechanical properties like density, modulus of elasticity, and bending strength. This suggests that wood hardness may not reliably indicate wood quality for industrial applications. Consequently, the study recommends considering alternative non-destructive properties, such as the dynamic modulus of elasticity, in future genetic studies of black alder for more accurate assessments of wood quality. [ABSTRACT FROM AUTHOR]

The study investigated the wood mechanical properties of black alder [Alnus glutinosa (L.) Gaertn.], a widely distributed deciduous tree in Europe valued for its suitability in silviculture and wood industry applications. The aim was to compare these properties among selected half-sib families and assess the relationship between wood hardness and other characteristics. Experimental plantations of black alder progenies from Lithuanian populations were established in different forest regions in 1998. The study analyzed various parameters for different genetic families, including tree diameter, height, wood hardness, moisture content, wood density, and mechanical properties. The findings revealed significant variability in wood properties among half-sib families, highlighting a strong genetic influence. Although the static modulus of elasticity showed no notable difference across families, other properties showed significant variations. Furthermore, the analysis identified weak correlations between wood hardness and other mechanical properties like density, modulus of elasticity, and bending strength. This suggests that wood hardness may not reliably indicate wood quality for industrial applications. Consequently, the study recommends considering alternative non-destructive properties, such as the dynamic modulus of elasticity, in future genetic studies of black alder for more accurate assessments of wood quality.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Lake Shala, endorheic Soda Lake in the Ethiopian Riftvally Lake, supports an enormous biodiversity, with a large human population and economic development. However soda lakes are under several ecological changes, with unexpected shifts in biodiversity composition and physicochemical changes. This study focuses on assessing the community structure of zooplankton in Lake Shala. Samples were taken at monthly intervals from January to December 2018. A total of 32 zooplankton species were identified, of which 23 species were Rotifers and followed by Copepoda (6) and Cladocera (3). The community was dominated by Brachionus dimidiatus, B. dimidiatus inermis, B. plicatilis and B. calyciflorus. Their abundance exhibit significant seasonal and vertical variations (ANOVA, p < 0.05). Zooplankton community structure of Lake Shala has changed over time, benthic harpacticoids (Nitocra lacustris) have become replaced by small-bodied and generalist-feeder rotifers (genus Brachionus). Such ecological shifts may be driven mainly by partial atelomixis in this deep tropical lake. Overall, zooplankton species distribution and abundance are influenced by various environmental factors such as conductivity, salinity, Chl-a and nutrients. This study concludes that the composition and community structure of zooplankton in Lake Shala has changed over time with the change in physicochemical and internal limnological dynamics (atelomix). [ABSTRACT FROM AUTHOR]

Global warming has caused changes in various ecological processes and has potential to change ecosystems’ stability. In spite of comprehensive studies to investigate air temperatures under global warming, much less is known about changes in soil temperatures, particularly in deep layers. Herein, we used 30 years of soil temperature data from a temperate steppe region to assess vertical characteristics and their changes in soil temperature from the surface to a depth of 3.20 m. We determined, apparently for the first time, that the soil temperature is the lowest at 0.2 cm layer at an annual level. Furthermore, the vertical variation of soil temperature (temperature variation with soil depth) strictly conformed to composite exponential function curves, and there were two composite exponential function curves that are symmetric to each other, to represent soil temperature in a pair of months with a difference of 6 months. Parameters in the functions changed as the soil warmed over 30 years. This finding explored the pattern of soil temperature in deep layers depending on the mathematics model. Model building and understanding is beneficial for predicting vertical and temporal extensions of soil temperature and their impact on below-ground processes in regional ecosystem.

Diffuse attenuation coefficient of photosynthetically available radiation (PAR), KPAR, is a key product of ocean color remote sensing. Current ocean color algorithms generally detect only the average KPAR within one optical depth, K P A R R S . Due to the marked vertical variations of KPAR, knowledge of K P A R R S is insufficient to accurately evaluate the submarine light field. By using field in situ observations, a two-step approach, based on the development of an ocean color algorithm for K P A R R S and the relationships between K P A R R S and the average KPAR from the surface down to depth Z ( K ¯ P A R Z ), was developed to remotely estimate the vertical variations in K ¯ P A R Z in the North Pacific from the MODerate-resolution Imaging Spectrometer (MODIS) imagery. The root mean square difference of log( K ¯ P A R Z ) in depths within the euphotic zone was around ±0.059 (in unit of m−1 for K ¯ P A R Z ), which corresponded to a deviation of ±15% for the estimated K ¯ P A R Z and the penetration depths of PAR. Our study may provide a promising approach to detect the vertical variations of K ¯ P A R Z and underwater PAR distributions in the North Pacific Ocean. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

AbstractLake Shala, endorheic Soda Lake in the Ethiopian Riftvally Lake, supports an enormous biodiversity, with a large human population and economic development. However soda lakes are under several ecological changes, with unexpected shifts in biodiversity composition and physicochemical changes. This study focuses on assessing the community structure of zooplankton in Lake Shala. Samples were taken at monthly intervals from January to December 2018. A total of 32 zooplankton species were identified, of which 23 species were Rotifers and followed by Copepoda (6) and Cladocera (3). The community was dominated by Brachionus dimidiatus, B. dimidiatus inermis, B. plicatilis and B. calyciflorus. Their abundance exhibit significant seasonal and vertical variations (ANOVA, p

Vertical stratification in trees may respond to selective pressures to enhance light interception and utilization; therefore, the vertical functional variation in leaf traits may indicate niche partitioning within forests. In this study, vertical variations in leaf and crown structure traits of seven common tree species were analysed with respect to differences between species in different height groups, within the same height range, in the same species across tree height, and different parts of the individual tree crown to reveal coexistence mechanisms in subtropical forest tree species. There were multiple levels of trait variation in the vertical dimension, validating the existence of vertical niche differentiation in subtropical forest species. The functional trait differences arose among different height groups, among species co-occurring within the same height range, in the same species across tree height, and among different parts of the individual tree crown. Variation in comparative advantages, which was characterised by those traits between species across different height ranges, was also one of the manifestations of niche differentiation in the vertical dimension. Moreover, contrasting results between lower height ranges and higher ranges in the relationship between species' differences in functional traits and species' difference of abundance were found, further confirming that there was obvious vertical niche separation in the community. This study emphasised the importance of vertical variation in species' performances in elucidating the mechanisms of tree species coexistence in subtropical forests. [ABSTRACT FROM AUTHOR]

The migration and transformation of the petroleum hydrocarbons from sediments into water columns is an important basis for assessing the impact on marine environment. In this paper, a static release experiment of crude oils from the Bohai Sea was carried out to evaluate the temporal and spatial variation of petroleum hydrocarbons and microbial communities. The results showed C1 phenanthrene (C1-P) can be used as an evaluation index of different crude oils during static release of oil pollution sediments and their trends of the static release were similar. The crude oil with higher C1-P content released C1-P into the water body significantly higher. After 72 hours, the C1-P release degree of crude oil with a smaller viscosity was more obvious. In the crude oil with the smallest viscosity and the higher viscosity, the bacterial phyla abundance increase was greater. And more importantly, the top 10 abundance of the microbial communities in the water columns and sediments appeared partial (3 species) replacement phenomenon. The research results can deep understanding the migration and transformation of the petroleum hydrocarbons from oil pollution sediments and understanding of the interaction between extreme weather events and human activities by incorporating an eco-evolutionary perspective.

Diffuse attenuation coefficient of photosynthetically available radiation (PAR), KPAR, is a key product of ocean color remote sensing. Current ocean color algorithms generally detect only the average KPAR within one optical depth, KPARRS. Due to the marked vertical variations of KPAR, knowledge of KPARRS is insufficient to accurately evaluate the submarine light field. By using field in situ observations, a two-step approach, based on the development of an ocean color algorithm for KPARRS and the relationships between KPARRS and the average KPAR from the surface down to depth Z (K¯PARZ), was developed to remotely estimate the vertical variations in K¯PARZ in the North Pacific from the MODerate-resolution Imaging Spectrometer (MODIS) imagery. The root mean square difference of log(K¯PARZ) in depths within the euphotic zone was around ±0.059 (in unit of m−1 for K¯PARZ), which corresponded to a deviation of ±15% for the estimated K¯PARZ and the penetration depths of PAR. Our study may provide a promising approach to detect the vertical variations of K¯PARZ and underwater PAR distributions in the North Pacific Ocean.

Based on the ERA5 reanalysis dataset, this paper examines the vertical variation of tropical cyclone (TC) size in the western North Pacific during 1998–2018. The TC size is defined as the distance from the TC centre to the radius at which the azimuthally averaged relative vorticity decreases to 1 × 10−5 s−1 (Rvor). It is found that TCs with similar sizes at the surface can be significantly different in size at higher levels. The Rvor at 10 m height (Rvor10) and that at 200 hPa (Rvor200) are related to TC intensity categories, and Rvor10 and that at 700 hPa (Rvor700) correlate linearly with the relative sea surface temperature (RSST) averaged within a 500‐km radius. Further, a positive correlation is found between the 500‐km radius averaged rain rate and Rvor200, while Rvor10, Rvor700 and Rvor200 all decrease with an increasing vertical wind shear (VWS). The spatial distributions of Rvor10, Rvor700, Rvor200 and Vmax, RSST, and rain rate are all similar to one another, and the spatial correlation coefficient between any pair of variations is larger than 0.91, which is statistically significant at the 0.01 level. The monthly variations of Rvor10, Rvor700 and Rvor200 are generally larger in the months with strong TC activity (May–October) than in the other months, although a peak of Rvor10 during March has been identified for the more recent few TCs. No significant interannual trend is found during 1998–2018 for any of the three variables (Rvor10, Rvor700 and Rvor200). Statistically significant correlations between the ENSO (El Niño–Southern Oscillation) index and Rvor10 and Rvor200 are 0.54 and 0.47, respectively, while no statistically significant correlation is found between the ENSO index and Rvor700. The mechanisms that affect the TC size at different heights are complicated and will be explored in later studies. [ABSTRACT FROM AUTHOR]

Paddy soil is an important source of methane (CH 4) emissions, and the nitrite-driven anaerobic oxidation of methane (AOM) mediated by Candidatus Methylomirabilis bacteria is a crucial process for CH 4 mitigation. However, the vertical and temporal fluctuations in nitrite-driven AOM activity, as well as the abundance and composition of Methylomirabilis bacteria in paddy soil, remain poorly understood. We investigated the potential rate of nitrite-driven AOM and the composition of Methylomirabilis bacteria at varying depths (0–40 cm, at 10 cm intervals) within a paddy soil during different growth stages of rice, including tillering, jointing, flowering, and milky. The potential rate of nitrite-driven AOM ranged from 0.24 to 20.6 nmol CO 2 g−1 (dry soil) d−1, and the abundance of Methylomirabilis bacterial 16S rRNA genes varied from 5.8 × 106 to 4.4 × 107 copies g−1 dry soil. The 10–20 cm soil depth showed higher potential activity and bacterial abundance compared to other depths, and the tillering and jointing stages exhibited greater activity and abundance. The composition of Methylomirabilis bacteria showed significant variation across different soil depths but remained stable throughout the growth stages of rice. Soil organic carbon content was positively correlated with potential nitrite-driven AOM rate, and nitrite content was negatively correlated with the abundance of Methylomirabilis bacteria. Soil organic carbon and ammonium content had a significant impact on the composition of Methylomirabilis bacteria. The results underscore the substantial influence of soil depth and the growth stage of rice on nitrite-driven AOM in paddy ecosystems. • Nitrite-driven AOM activity and the bacterial abundance peaked at 10–20 cm soil depth. • Early rice growth stage exhibited higher activity and abundance than late stage. • Composition of Methylomirabilis bacteria varied significantly with soil depth. • Organic carbon content was significantly correlated with nitrite-driven AOM activity. [ABSTRACT FROM AUTHOR]

This study examines the vertical variations of cloud microphysical relationships and their implications to cloud microphysical processes in marine stratocumulus clouds using in‐situ aircraft observations during the Aerosol and Cloud Experiments in Eastern North Atlantic (ACE‐ENA) field campaign. A new diagram with a coordinate system based on cloud droplet liquid water content (Lc) and phase relaxation time scale is proposed to investigate mixing mechanisms. This new diagram analysis shows that the inhomogeneous mixing trait is dominant near the cloud top, but homogeneous mixing trait is stronger at lower altitudes. The relevant scale parameters (i.e., transition length scale and transition scale number) also indicate a high likelihood of inhomogeneous mixing. The relationship between Lc and standard deviation of droplet radius (σR) clearly shows the vertical transition: the correlation between Lc and σR is positive at lower cloud altitudes, but it becomes negative as altitude increases. Such a vertical transition is consistent with the vertical circulation mixing, modulating the cloud microphysical relationships to suggest homogeneous mixing at a significant depth from the cloud top. Plain Language Summary: Stratocumulus (Sc) clouds are climatically crucial as they cover large regions of Earth's surface and influence the radiative balance of the Earth. For these clouds, entrainment‐mixing of the air from above cloud top has been considered as one of the most important processes that modulates the relationships among cloud microphysical parameters. We investigate marine stratocumulus clouds observed at various altitudes. We propose a new mixing diagram based on the liquid water content and the phase relaxation time. Cloud microphysical relationships analyzed in this coordinate system suggest inhomogeneous mixing near cloud top, becoming more consistent with the character of homogeneous mixing at lower cloud altitudes. Such vertical variation of mixing signature is consistent with the vertical circulation hypothesis. Key Points: A new mixing diagram is proposed to analyze cloud microphysical relationshipsAnalysis shows a transition of cloud microphysical relationships with cloud altitudeVertical circulation mixing is suggested to explain a vertical variation of cloud microphysics [ABSTRACT FROM AUTHOR]

Vertical stratification in trees may respond to selective pressures to enhance light interception and utilization; therefore, the vertical functional variation in leaf traits may indicate niche partitioning within forests. In this study, vertical variations in leaf and crown structure traits of seven common tree species were analysed with respect to differences between species in different height groups, within the same height range, in the same species across tree height, and different parts of the individual tree crown to reveal coexistence mechanisms in subtropical forest tree species. There were multiple levels of trait variation in the vertical dimension, validating the existence of vertical niche differentiation in subtropical forest species. The functional trait differences arose among different height groups, among species co-occurring within the same height range, in the same species across tree height, and among different parts of the individual tree crown. Variation in comparative advantages, which was characterised by those traits between species across different height ranges, was also one of the manifestations of niche differentiation in the vertical dimension. Moreover, contrasting results between lower height ranges and higher ranges in the relationship between species’ differences in functional traits and species’ difference of abundance were found, further confirming that there was obvious vertical niche separation in the community. This study emphasised the importance of vertical variation in species’ performances in elucidating the mechanisms of tree species coexistence in subtropical forests.

Periodic submersion and exposure due to the operation of the Three Gorges Reservoir (TGR) alter the soil properties and plant characteristics at different elevations within the water level fluctuation zone (WLFZ), possibly influencing the soil detachment capacity (Dc), but the vertical heterogeneity of this effect is uncertain. Soil samples were taken from 6 elevation segments (5 m per segment) along a slope profile in the WLFZ of the TGR to clarify the vertical heterogeneity of Dc. Scouring experiments were conducted at 5 slope gradients (17.6%, 26.8%, 36.4%, 46.6%, and 57.7%) and 5 flow rates (10, 15, 20, 25, and 30 L min−1) to determine Dc. The results indicate that the soil properties and biomass parameters of the WLFZ exhibit strongly vertical heterogeneity. Dc fluctuates with increasing elevation, with maximum and minimum average values at elevations of 145–150 m and 165–170 m, respectively. Linear equations accurately describe the relationships between Dc and hydrodynamic parameters, for which the shear stress (τ), stream power (ω), and unit energy of water‐carrying section (E) perform much better than the unit stream power (U). Furthermore, a clear improvement is achieved when using a general index of flow intensity to estimate Dc. Furthermore, Dc is significantly and negatively correlated with the mean weight diameter (MWD, p < 0.05) and organic matter content (p < 0.01) but not significantly correlated with other soil properties (p > 0.05). The rill erodibility at elevations of 145–150 m and 170–175 m is greater than that at other elevations. The critical hydraulic parameters were highest in the 165–170 m segments. Both the rill erodibility and the critical parameters fluctuate vertically along the sloping surface. This research highlights the vertical heterogeneity of Dc and is helpful for better understanding the mechanisms responsible for soil detachment in the WLFZ of the TGR. [ABSTRACT FROM AUTHOR]

It is often assumed that a homogeneous distribution of soil properties occurs in the topsoil layer, but the vertical variation of soil properties in cultivated soils would mainly depend on the tillage system. In remote sensing, for example, only information strictly limited to the soil surface is accessible, although the interest of the user communities would concern the topsoil rootzone, i.e. until a depth of 30–40 cm. The present study provides an analysis of data collected from studies in which the vertical variation of the main soil properties was reported for four types of tillage systems: i) deep inversion ploughing (DP); ii) subsoiling (SUB); iii) minimum tillage (MT) and no-tillage (NT). To the best of our knowledge, a review about the effects of different tillage systems on soil vertical variation seems to be lacking in the current literature. A keyword-based search followed by a two-stage manual selection provided a total of 43 papers with data sets suitable for the analysis. The soil data, extracted by these papers, were standardized to avoid different measurement units and different site-specific baselines. This method allowed to obtain the soil data extracted by different papers worldwide, comparable to study the vertical gradient. A gradient of soil organic carbon (SOC) was reported in all the 43 selected papers, whereas total nitrogen (TN) in 20 papers, therefore reliable global models of vertical variation could be obtained for these properties. Linear models of SOC vertical variation were obtained for MT and SUB, whereas second order polynomial functions were calculated for DP and NT. The full cross-validation of the models provided R2 higher than 0.8 and errors (RMSE) from 1.55 to 3.23 g.kg−1, with similar efficiency for SOC and TN. Predictive models of vertical variation of C/N ratio and bulk density (BD) were also carried out, whereas data of pH, CEC, and textural fractions were found only in few papers and modelling was not possible. The models proposed by this analytical review might be employed to extend the estimation of surface soil properties to the whole topsoil layer of cultivated soil, according to the adopted tillage method. In addition, the results of the paper highlighted the impact of tillage system on the vertical gradient of SOC, TN, and BD, allowing a better quantification of the carbon and nitrogen stock in agricultural soils. • Predictive models for remote sensing are strictly limited to the soil surface. • Rootzone volume is commonly the layer of interest in most agronomic applications. • Tillage typologies influence the vertical gradients of soil features. • Inversion tillage tend to homogenize the soil features within A horizon. • Surface features can be extended to the A horizon according to the tillage type. [ABSTRACT FROM AUTHOR]

Heartwood is the most important part of the Tectona grandis tree. Although various equations for prediction of this tissue are available for this species, there are no models for prediction of its heartwood exclusively. The objective of the present study was to establish equations for predicting heartwood merchantable volume and tradable sawlog of teak trees growing in fast-growth plantations in Costa Rica. A total of 54 plantations were sampled from five regions of this country. Four equations were used to establish heartwood parameters using diameter at breast height (dbh), total height (H) and age as predictor variables. The equation selected for prediction of heartwood height (Hhw) and heartwood diameter (Dhw) included dbh and H. For Hhw, the equation proposed was Y = b1 + b2H + b3Age + b4dbh, with coefficients of determination (r²) of 0.87, while the stem profile equation to determine the different values of external diameter was dub = a0dbha1 Ha2XM with r = 0.94, and the equation to determine the Dhw was -4.83 + 0.190d, where d was any given external diameter of a tree. The selected equation could be used to predict total and commercial heartwood and quantity of sawlog of trees from plantation of T. grandis. [ABSTRACT FROM AUTHOR]

Accurate evaluation of the carbon release by stems is an important objective of many forest carbon cycling studies. However, few studies have assessed the applicability of different extrapolation methods of stem CO2 efflux. Therefore, a reliable estimation method that considers both temporal and vertical variations is required. To overcome this problem, we conducted a field experiment to measure the stem CO2 efflux rate of Abies fabri in subalpine forests, and evaluated the effect of three extrapolation methods (area-based estimation, volume-based estimation and integral method) on accurate estimation of stem respiration at the individual and stand levels. First, we calculated the stem carbon loss at the individual level using the three extrapolation methods, and discovered that the diameter at the breast height (DBH) played a major role in determining the magnitudes of stem respiration. Second, we summarized the relationship between the stem CO2 efflux rate (Es) and the DBH from previous studies. The Es for small diameter stems tended to increase with height, but remained constant in trees with large DBH, implying a role of DBH threshold in determination of the Es effect. Our calculations from three estimation methods supported the hypothesis that a threshold accounted for the different vertical variations in Es. Specifically, the vertical variation of Es primarily presented as two categories: Es decreased with the stem height for small diameters (DBH < 30 or 40 cm), or Es showed little change for stem height for large diameters (DBH > 60 cm). Based on these trends, we suggest a two-part approach to scale the individual tree stem CO2 efflux, in which a volume-based scaling method is recommended for trees with small DBH (0–30 or 40 cm) and an area-based estimation is suitable for stems with large DBH (> 30 or 40 cm). Using this approach, the annual amount of stem carbon release for an immature forest and a mature forest were estimated as 1.80 and 4.81 t C ha−1 year−1, respectively. [ABSTRACT FROM AUTHOR]

Urban lakes play an important role in urban residents' lives, but they are more vulnerable to nitrogen pollution due to the large number of pollution sources in urban areas. Analyzing the characteristic variation of nitrogen-related functional genes in sediments could improve our understanding of nitrogen removal from urban lakes. Based on field samples of lake sediments in Wuhan, China, the seasonal and vertical variations in the characteristics of seven genes were detected using metagenome sequencing and qPCR. The genes examined were the ammonia-oxidizing bacteria gene (AOB amoA), ammonia-oxidizing archaea gene (AOA amoA), anammox gene (anammox 16S rRNA), denitrification genes (narG , nirS , nosZ), and dissimilatory nitrate reduction to ammonium gene (nrfA). The sequencing results revealed that the strain types of nosZ and nrfA were more abundant than amoA , anammox 16S rRNA, narG , and nirS. The nitrogen-related genes' abundances were much lower in summer than in winter. In the vertical zones of the sediments, the abundances of the seven genes mainly decreased as the sediment depth increased. The abundances of ammonium-oxidizing microorganisms had no significant difference in the vertical direction (P > 0.05), but there were significant differences in the vertical direction for the abundances of narG , nirS , nosZ , and nrfA (P < 0.05). Canonical correspondence analysis (CCA) illustrated that the main environmental factors affecting the gene abundances were NH 4 +-N in the interstitial water, dissolved oxygen (DO) and electrical conductivity (EC) in the overlying water, and total nitrogen (TN) in the sediment. The anammox 16S rRNA abundances were significantly correlated with the nrfA abundances, while the narG abundances were also significantly correlated with nirS abundances. The results extend the knowledge of spatiotemporal variations of nitrogen-cycle microorganisms' characteristics in urban eutrophic lakes. • nosZ had most strain types in sediments, and dominant types were distinct in different lakes. • Abundances of anammox 16S rRNA were highest among nitrogen-related genes in sediments. • Abundances of nitrogen-related genes were higher in winter than in summer in sediments. • Abundances of seven nitrogen-related functional genes decreased with sediment depth. [ABSTRACT FROM AUTHOR]

Hydrodynamic conditions in the Bohai Sea (BS) play an important role in regulating variabilities in the regional climate and marine ecosystem. In the current study, wintertime current variations in the BS were investigated using continuous in situ observations at two sites in the western BS (S1) and southeastern BS (S2) from November/December 2020 to March 2021. The results indicated that residual currents and their variations were both stronger at S1 than at S2. Residual currents had notable vertical variations, with nearly opposite directions in the upper and lower layers. Upper layer residual currents were mostly southeastward at both sites, while lower layer residual currents were basically west-northwestward at S2 following the topography in the deep trough in the South BS but were north-northwestward at S1 up the slope to the coast. Upper layer residual currents were strongly subsurface-intensified and experienced significant intraseasonal variations. Subsurface currents in the upper layer shifted from being weak in December 2020 to strong in January–February 2021, especially in the western BS. Surface currents were directly driven by surface winds following the Ekman layer dynamics in shallow waters. Weak/strong subsurface currents occurred during/after sustained strong sea surface winds, implying that they experienced more complex dynamics than surface currents. This study provides new understanding to the wintertime circulation pattern in the BS. It is helpful for fully understanding the characteristics and underlying dynamics of the BS circulation variations in winter and their impacts on biogeochemical processes. • Observed currents flowed in opposite directions in the upper and lower layers. • Waters from the Yellow Sea entered the Bohai Sea only in the lower layer. • Currents in upper layer were subsurface-intensified and stronger than in lower layer. • Weak/strong subsurface currents occurred during/after sustained strong winds. • One possible mechanism was related to PV input by sea surface wind stress curl. [ABSTRACT FROM AUTHOR]

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. • The α-diversity of archaea and bacteria were insensitive to sedimental depths • Microbial communities could be clearly divided into two groups based on sediment depth • Community similarity tends to significant decrease with increasing depth distance • Candidatus Methanoperedens was identified as the most abundant keystone archaeal taxon [ABSTRACT FROM AUTHOR]

While the crucial roles of ozone (O 3) transport in the planetary boundary layer (PBL) have been acknowledged for some time, there is currently limited knowledge about this aspect primarily due to the limited availability of measurements to determine the characteristics of the PBL. In this study, measurements from a wind Light Detection and Ranging (LiDAR) system were taken to monitor vertical profile of wind pattern at an urban site in Hong Kong in September 2022, a period when the city was frequently impacted by tropical cyclones and experienced severe O 3 pollution levels. The PBL height was identified based on the vertical profile of wind speed shear. By combining information on the PBL height, vertical wind profile, and O 3 concentration, we performed a cross-sectional analysis to explore the total horizontal flux (THF) of O 3 across the PBL in Hong Kong. Throughout the entire study month, the THF of O 3 exhibited a predominant easterly component. However, during the O 3 pollution episodes, the THF of O 3 exhibited a predominant westerly component, indicating an increased regional transport from Greater Bay Area (GBA). The westerly winds between 240° and 300° contributed 61.2% to the total flux of O 3 in the PBL during these episodes. In addition, clockwise veering winds were observed from the ground to the top of the PBL, which can be attributed to the Ekman spiral. As a result, during the O 3 pollution episodes, the wind with the peak O 3 flux shifted from westerly to northwesterly as the height increased in the PBL. The northwesterly THF of O 3 between 290° and 300° reached its peak at 600 m above ground level during these episodes. These findings enhance our understanding of the 3D pollutant transports for both long-term averages and short-term pollution episodes in the GBA and Hong Kong. • Total horizontal flux (THF) of O 3 across the PBL was explored using a wind LiDAR. • The PBL height was identified based on the vertical profile of wind speed shear. • The THF of O 3 exhibited a predominant westerly component during O 3 episodes. • Clockwise veering flux of O 3 were observed from the ground to the top of the PBL. • Our results enhance our understanding of the 3D pollutant transports in the GBA. [ABSTRACT FROM AUTHOR]

Estuarine carbon cycle and biogeochemical studies usually focus on along-estuary variations and neglect cross-estuary variations. In a stratified middle reach of the Chesapeake Bay, we observed a counterclockwise circulation and upwelling of subsurface water with high partial pressure of carbon dioxide (p CO 2) on the eastern shoal during a down-estuary wind event from October 24 to 25, 2013. The average air-sea CO 2 gas exchange flux over the eastern one-third of this cross transect was approximately 20 to 40% higher, while the flux over the western 1/3 was lower by a similar amount, compared with the middle section. A statistically strong correlation between p CO 2 and salinity values was observed, suggesting the presence of a high CO 2 source from the higher salinity bottom water. The observations suggest that wind-driven lateral upwelling can enhance the release of respired CO 2 from subsurface water in stratified large estuaries by as much as 30% over a short time-scale of hours. • The p CO 2 and salinity were repeatedly measured in the cross-channel section. • Down-estuary winds drove the upwelling of high-salinity subsurface water. • Higher p CO 2 values were observed on the eastern than those on the western shoal. • Air-sea CO 2 exchange fluxes were 20–40% higher on the eastern shoal. [ABSTRACT FROM AUTHOR]

Abstract 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. Graphical abstract Unlabelled Image Highlights • Spatiotemporal variation of heavy metal contamination in TGR sediments was investigated. • Vertical variation of metal concentrations was related to impoundment stages of the TGR. • Sediment grain-sizes dominated metal distribution over OMs and Fe/Mn oxides. • Anti-seasonal flow regulation and human activities regulated metal accumulation processes. • Cd contamination and eco-risk need to be concerned. [ABSTRACT FROM AUTHOR]

Abstract Weighted mean temperature (T m) is a crucial parameter for retrieving precipitable water vapor (PWV) in Global Navigation Satellite System (GNSS) meteorology. The difference between the height of the GNSS receiver and the height of the derived T m may cause large uncertainty in the value of the retrieved PWV. In this study, we analyze the vertical variation of T m on a global scale and build a new vertical correction model using the operational reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF). Another dataset from ECMWF and the radiosonde data derived from 678 globally distributed stations are used to independently validate the performance of the newly built model and demonstrate its superiority compared with the existing vertical correction method. The results show that the lapse rate of T m has geographic and seasonal variations, and the T m has large nonlinear variation along the vertical direction in the high-latitude regions, especially in the polar regions. A performance improvement of 15%–35% compared with the existing vertical correction method is achievable for the newly built model when tested with the ECMWF data, and the improvement is 10%–25% when tested with the radiosonde data. Highlights • The vertical variation in weighted mean temperature is investigated on a global scale. • A global empirical model for vertical correction of weighted mean temperature is built. • The performance of vertical correction methods for weighted mean temperature is comprehensively evaluated. [ABSTRACT FROM AUTHOR]

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 210Pb ex 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. • PFBS, PFOA and PFHxA were the predominant PFASs detected in sediment core obtained from Shenzhen Bay area. • The primary sources of PFASs in this region were linked to food packaging, textiles, and firefighting foam. • Over the past 65 years (1955–2020), the concentration of PFASs in the sediment exhibited a fluctuating pattern. • The F of PFASs in Shenzhen Bay was positively correlated with the GDP and soil and water conservation measures. [ABSTRACT FROM AUTHOR]

Tectona grandis is a valuable timber species with heartwood that is used worldwide. Most of the previous studies on its heartwood and sapwood have focused on dominant or mean trees, while trees with different social status might show different vertical and horizontal distributions of heartwood and sapwood. Studies on their heartwood and sapwood properties could be conducive to increasing heartwood yield at stand level. In 31-year-old plantations of T. grandis in southwest Guangxi, China, the trees were divided into three groups including dominant, mean and suppressed trees. Stem analysis was conducted for sampled trees in each of these groups to explore the differences in the horizontal and vertical distribution of their heartwood and sapwood. The results indicated that the heartwood radius, heartwood and sapwood areas of T. grandis showed significant differences in horizontal and vertical directions among trees of different social status. Heartwood began to form when xylem radius was 2−3 cm, and the heartwood radius ratio tended to be stable when the xylem radius reached about 8 cm. Heartwood radius and area, sapwood area and section heartwood volume all decreased with increasing tree height. The ratios of heartwood radius and area were relatively stable for sections under 50% of tree height. The sapwood width did not vary largely in horizontal and vertical directions among the three social status tree groups, which mainly fluctuated in the range of 1−4 cm. The heartwood volume proportions for dominant, mean and suppressed trees were 60%, 55% and 51%, respectively. There was a significant exponential relationship between heartwood volume and diameter at breast height (DBH) regardless of social status. The model HV = 0.000011 × DBH2.9787 (R2 = 0.8601) could accurately estimate heartwood volume for all T. grandis with different social statuses at this age. These findings could provide evidence for stand management and high-quality and large-sized timber production of T. grandis.

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.

Concentrations of volatile organic compounds (VOCs) and inorganic pollutants including sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) were measured using passive samplers in both indoor and outdoor environments at 2, 5, 8, 13, 17, 24, and 29 m from the ground level at a high-rise building in the Middle East Technical University campus in Ankara, Turkey. The measured indoor concentrations of ∑24VOCs were highly variable, ranging from 98 μg m−3 (at the ground floor) to 235.3 μg m−3 (at the fourth floor), while the outdoor concentrations varied between 96.8 μg m−3 (at the seventh floor) and 189.8 μg m−3 (at the ground level). Outdoor concentrations of inorganic pollutants ranged between 58 μg m−3 at the ground floor and 26 μg m−3 at the ninth floor for SO2, and 59.9 μg m−3 at the ground floor and 31.2 μg m−3 at the ninth floor for NO2. A similar decreasing trend with altitude was also observed for indoor concentrations of these pollutants. Indoor and outdoor O3 concentrations did not change with altitude. Statistically significant correlations were found between indoor and outdoor concentrations of some of the measured NO2, SO2 toluene, octane, nonane and 1,2-dichlorobenzene, indicating moderate-to-strong relationships between their indoor and outdoor concentrations. The factor analysis revealed six factors for both indoor and outdoor data. Traffic was found to be the highest contributor to the measured VOCs, SO2, and NO2 concentrations, which was followed by painting activities. [ABSTRACT FROM AUTHOR]

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 ± 0.06 mg/m 3 and 0.51 ± 0.29 mg/m 3 , respectively), while the subsurface maximum of abundance after drilling went deeper to 75 m (604.17 ± 313.22 cells/L) from the surface (707.14 ± 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. [ABSTRACT FROM AUTHOR]

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 (NH 4 + -N) and nitrate nitrogen (NO 3 − -N) in top layers (0–10 cm) 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 (10–20 cm) 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Eddy correlation measurements have been carried out at six different heights above the urban canopy in three cities of China, that is, Nanjing, Changzhou, and Suzhou. Observations at these heights are used to evaluate the dependence of normalized standard deviations of velocity components σi/u*l ( i = u, v, w) and temperature σ T v / T v * l on local atmospheric stability ζ ( =(z − zd)/Λ), where u*l is the local friction velocity, Tv*l is the local temperature scale, zd is the displacement height, and Λ is the local Obukhov length. It is found that the universal functions ai(1 + bi| ζ| )1/3 and b T v ζ − 1 / 3, in which ai, bi, and b T v are empirical coefficients, are suitable for describing the behaviors of σi/u*l and σ T v / T v * l, respectively. Under neutral conditions ( |ζ| < 0.05), the value of σi/u*l (approximately equal to ai) decreases with height. On the other hand, bi increases with height under both unstable ( ζ <  − 0.05) and stable ( ζ > 0.05) conditions, suggesting that the thermal effect of stratification on the standard deviations of velocity components increases with height in the urban roughness sublayer. However, the behavior of σ T v / T v * l is different from that of σi/u*l. b T v remains constant with height under unstable conditions but increases with height under stable conditions. Vertical variations of these coefficients in the universal functions are consistent with the concept of local similarity, suggesting that the turbulence behavior in the urban roughness sublayer is different from that over the flat terrain. [ABSTRACT FROM AUTHOR]

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 β-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. [ABSTRACT FROM AUTHOR]

Cloud liquid water content (LWC) and droplet effective radius (re) have an important influence on cloud physical processes and optical characteristics. The microphysical properties of a three-layer pure liquid stratus were measured by aircraft probes on 26 April 2014 over a coastal region in Huanghua, China. Vertical variations in aerosol concentration (Na), cloud condensation nuclei (CCN) at supersaturation (SS) 0.3%, cloud LWC and cloud re are examined. Large Na in the size range of 0.1–3 μm and CCN have been found within the planetary boundary layer (PBL) below ~1150 m. However, Na and CCN decrease quickly with height and reach a level similar to that over marine locations. Corresponding to the vertical distributions of aerosols and CCN, the cloud re is quite small (3.0–6 μm) at heights below 1150 m, large (7–13 μm) at high altitudes. In the PBL cloud layer, cloud re and aerosol Na show a negative relationship, while they show a clear positive relationship in the upper layer above PBL with much less aerosol Na. It also shows that the relationship between cloud re and aerosol Na changes from negative to positive when LWC increases. These results imply that the response of cloud re to aerosol Na depends on the combination effects of water-competency and collision-coalescence efficiency among droplets. The vertical structure of aerosol Na and cloud re implies potential cautions for the study of aerosol-cloud interaction using aerosol optical depth for cloud layers above the PBL altitude.

Soil pollution of fluorine is a serious environmental problem in the world, and the fluorine pollution evaluation of spatial and vertical distribution study in the Karst region is quite limited. In this study, the farmland around lead-zinc mine in the Karst region was chosen as the study area. Ninety-one upper layer soil samples and two soil profiles (one in paddy field, the other one in aerated field) samples were taken. The average concentration of total fluorine of topsoil in the paddy fields is 378 mg/kg, whereas in the aerated field it is 508 mg/kg. The concentrations of total fluorine in all paddy soil samples and 97.87% aerated field soils are higher than that of the background value of Guangxi. The total fluorine contaminations in all aerated field soils are much higher than in paddy soil samples, so the aerated field is contaminated severely. The vertical distribution of fluorine is different in paddy field and aerated field. In paddy field, the content of fluorine increases from 20 to 40 cm, then it decreases rapidly from 40 to 60 cm in depth, and then increases gradually. However, in the aerated field, the content of fluorine rises gradually with the depth of the sampling point. The results of relative analysis and regression analysis between fluorine in soil and soil properties show that the spatial distribution and vertical variation of fluorine in this region are mainly affected by parent rock.

This study reports the spatial and temporal behavior of straight and coiled morphotypes of C. raciborskii in a reservoir in Brazil's semi-arid region as well as the main factors responsible for the variability. Two set of samples were collected from the subsurface and bottom in the central region of a reservoir in two seasonal periods (dry - January 2005; rainy - June 2005) over 20-hour sampling periods during daylight (8 am, 12 pm and 4 pm) and dark (8 pm, 12 am and 4 am) hours. Measurements of abiotic parameters were determined concurrently to the sampling of biotic variables. Two C. raciborskii morphotypes were found in the reservoir: straight and coiled. There was no difference in density of the straight and coiled C. raciborskii morphotypes between the different sampling times for either season. Vertical differences were found in the distribution of both morphotypes in both seasons, with greater densities recorded at the subsurface. Densities of the two C. raciborskii morphotypes were greater in the dry season, with the density of the coiled morphotype at the surface two-fold greater than that of the straight morphotype and that found in the rainy season. The ecological success of the coiled morphotype was due to thermal stratification, whereas a mixed condition was determinant in the success of the straight morphotype.O presente estudo reporta o comportamento espacial e temporal dos morfotipos reto e espiralado de C. raciborskii em um reservatório da região semi-árida do Brasil bem como os principais fatores responsáveis pela variabilidade. Dois conjuntos de amostras foram coletadas na subsuperfície e próximo ao sedimento, na região central do reservatório, em dois períodos sazonais (seco - janeiro 2005; chuvoso - junho 2005), sendo realizadas amostragens de 20 horas durante horários claros (08hs, 12hs e 16hs) e escuros (20hs, 00hs e 04hs). Medidas de parâmetros abióticos foram realizadas concomitantes as amostragens das variáveis bióticas. Dois morfotipos de C. raciborskii foram encontrados no reservatório: reto e espiralado. Não houve diferenças na densidade dos morfotipos reto e espiralado de C. raciborskii entre os diferentes horários amostrais em cada período sazonal. Diferenças verticais foram encontradas na distribuição de ambos morfotipos em ambos períodos sazonais, com maiores densidades registradas na subsuperfície. As densidades dos dois morfotipos de C. raciborskii foram maiores no período seco, com densidade do morfotipo espiralado na subsuperfície duas vezes maior que o morfotipo reto e o encontrado no período chuvoso. O sucesso ecológico do morfotipo espiralado foi devido à estratificação térmica, enquanto as condições de mistura foram determinantes no sucesso do morfotipo reto.

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: 1.45–25.5 ng g − 1 dry weight (dw), average: 10.3 ng g − 1 dw) were much higher than those from Chengdu (range: 0.218–3.26 ng g − 1 dw, average: 1.43 ng g − 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 C 10 Cl 6–10 and C 11–13 Cl 6–8 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 (Cl 5–6 -SCCPs) are more capable of migrating to the deeper-layer soils than more chlorinated ones (Cl 9–10 -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. [ABSTRACT FROM AUTHOR]

We measured size–resolved PNCs in the 5–560 nm range at two different types (4– and 3–way) of TIs in Guildford (Surrey, UK) at fixed sites (∼1.5 m above the road level), sequentially at 4 different heights (1, 1.5, 2.5 and 4.7 m), and along the road at five different distances (10, 20, 30, 45 and 60 m). The aims were to: (i) assess the differences in PNCs measured at studied TIs, (ii) identify the best fit probability distribution curves for the PNCs, (iii) determine vertical and horizontal decay profiles of PNCs, (iv) estimate particle number emission factors (PNEFs) under congested and free–flow traffic conditions, and (v) quantify the pedestrian exposure in terms of respiratory deposition dose (RDD) rates at the TIs. Daily averaged particle number distributions at TIs reflected the effect of fresh emissions with peaks at 5.6, 10 and 56 nm. Despite the relatively high traffic volume at 3–way TI, average PNCs at 4–way TI were about twice as high as at 3–way TI, indicating less favourable dispersion conditions. Generalised extreme value distribution fitted well to PNC data at both TIs. Vertical PNC profiles followed an exponential decay, which was much sharper at 4–way TI than at 3–way TI, suggesting ∼40% less exposure for people at first floor (4.7 m) to those at ground floor around 4-way TI. Vertical profiles indicated much sharper (∼132–times larger) decay than in horizontal direction, due to close vicinity of road vehicles during the along-road measurements. Over an order of magnitude higher PNEFs were found during congested, compared with free–flow, conditions due to frequent changes in traffic speed. Average RDD rate at 4–way TI during congested conditions were up to 14–times higher than those at 3–way TI (0.4 × 10 11 h −1 ). Findings of this study are a step forward to understand exposure at and around the TIs. [ABSTRACT FROM AUTHOR]

Influenced by climate, biology and soil properties, vertical soil profile showed stratification character in terms of basic physical properties. The research conducted measurement and analysis on basic physical properties of typical field in the Daxia irrigation area in Qinghai Province. The results showed that soil bulk density changed from decreasing to increasing upon soil horizon; the soil horizons in 0-40 and 90-150 cm were high porosity zones, and the others were low porosity area; the saturation moisture capacity, water retention of capillary porosity and field water retention all changed from decreasing to increasing upon soil horizon featured by arithmetic progression. In addition, the research area in Daxia irrigated area showed loose structure in soil horizon of 0-40 cm, compacted in 40-60 cm, and loose again in 60-200 cm vertically. [ABSTRACT FROM AUTHOR]

Indoor air pollution has aroused increasing concerns due to its significant adverse health impacts. Indoor PM 2.5 exposure assessments often rely on PM 2.5 concentration measured at a single height, which overlooks the vertical variation of PM 2.5 concentrations accompanied by various indoor activities. In this study, we characterize the vertical profile of PM 2.5 concentration by monitoring PM 2.5 concentration at eight different heights in the kitchen and the bedroom, respectively, using low-cost sensors with high temporal resolution. The localized enhancement of PM 2.5 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 PM 2.5 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. [Display omitted] • Cooking creates substantial local enhancement of indoor PM 2.5 in elevated heights. • Vertical variation was insignificant in the absence of cooking activities. • Multi-height measurement is recommended to avoid biases in household exposure assessments. [ABSTRACT FROM AUTHOR]

Water use efficiency (WUE) reflects the coupling of carbon and water cycles. Analyzing the spatial variability of WUE can improve our understanding on the interaction between carbon and water cycles at a large scale, which also provides a basis for improving the regional carbon budget assessment. Based on China's eddy covariance measurements, we examined the spatial variation of China's WUE and its affecting factors. WUE showed a decreasing trend with the increasing altitude, which was the result of ecosystem type distribution resulting from the climatic gradient. After fully considering the vertical variation of WUE, we found that not only mean annual air temperature (MAT), mean annual precipitation (MAP), and mean leaf area index (MLAI) but also mean annual total photosynthesis active radiation (MAR) affected the spatial variation of WUE. With the increasing MAT, MAP, and MLAI, WUE increased significantly but the increasing MAR decreased WUE. The spatial variation of WUE could be directly depicted by MLAI and altitude, the equation including which explained 65% of the spatial variation of WUE. The effects of MAT and MAP on the spatial variation of WUE may be achieved through altering MLAI, while the mechanism underlying the effect of MAR on the spatial variation of WUE was still unclear, which should be the subject of future investigations. This study reveals the vertical variation of WUE and provides a new approach to generate the spatial variation in WUE, which will benefit the regional carbon budget assessment. [ABSTRACT FROM AUTHOR]

This paper presents a novel triple-layer model, called VART DO-3L, for simulation of spatial variations in dissolved oxygen (DO) in fine-grained streams, characterized by a fluid mud (fluff or flocculent) layer (an advection-dominated storage zone) as the interface between overlying stream water and relatively consolidated streambed sediment (a diffusion-dominated storage zone). A global sensitivity analysis is conducted to investigate the sensitivity of VART DO-3L model input parameters. Results of the sensitivity analysis indicate that the most sensitive parameter is the relative size of the advection-dominated storage zones ( As/A), followed by a lumped reaction term ( R) for the flocculent layer, biological reaction rate ( μo) in diffusive layer and biochemical oxygen demand concentration ( L) in water column. In order to address uncertainty in model input parameters, Monte Carlo simulations are performed to sample parameter values and to produce various parameter combinations or cases. The VART DO-3L model is applied to the Lower Amite River in Louisiana, USA, to simulate vertical and longitudinal variations in DO under the cases. In terms of longitudinal variation, the DO level decreases from 7.9 mg l at the Denham Springs station to about 2.89 mg l−1 at the Port Vincent station. In terms of vertical variation, the DO level drops rapidly from the overlying water column to the advection-dominated storage zone and further to the diffusive layer. The DO level ( CF) in the advective layer (flocculent layer) can reach as high as 40% of DO concentration ( C) in the water column. The VART DO-3L model may be applied to similar rivers for simulation of spatial variations in DO level. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]