South Slope Research Articles

Variation in the physical properties of soil in relation to natural and anthropogenic factors in the hilly loess region of China

Soil particle size distribution (PSD), bulk density (BD), saturated hydraulic conductivity (Ks), soil water content (SWC) and generalized soil structure index (GSSI) are key physical properties for vegetation growth and are easily affected by natural and anthropogenic factors. However, how these soil physical properties respond to land use, slope aspect, slope position, and their interactions are less clearly understood. Here, an experiment with three land uses (cropland, grassland, and black locust [Robinia pseudoacacia L.] forests after 4, 9, 15, and 19 years of restoration), two slope aspects (south and north slope) and two slope positions (up and down slope) were conducted in the hilly loess region of China. The results showed the following: (1) The variation in different physical properties were driven by different factors of land use, slope aspect, slope position and their interactions. (2) The 9, 15 and 19 year old locust forests significantly decreased the BD by 6.75 %–19.32 % and increased the Ks by 69.96 %–195.97 % compared with grassland, while the cropland had higher SWC and GSSI values than the grassland and locust forests. (3) Soil physical properties were higher on the north slope than on the south slope and were larger on the down slope than on the up slope. (4) The BD, Ks, SWC, and GSSI of locust forests displayed different changes with the restoration year. (5) The key factor affecting forest growth and soil quality improvement varied with forest ages. Overall, 19 year old locust was the most effective at improving the BD and Ks. Furthermore, slope aspect, slope position and restoration time should be considered when evaluating the response of physical properties to land uses.

Initial Limnology of Laguna Pozo Verde, Costa Rica: Bathymetry, Water, Sediments, and Diatoms

Introducción : Costa Rica tiene cientos de lagos, muchos de los cuales nunca han sido estudiados científicamente. Objetivo: Conocer limnológia de la Laguna Pozo Verde en el Parque Nacional Juan Castro Blanco, Costa Rica (~1935 m de elevación), para proporcionar datos de referencia para estudiar cambios futuros. Métodos: Medimos la profundidad y temperatura del agua y la profundidad de Secchi; sedimentos superficiales analizados; y examinó mapas e imágenes de satélite. Resultados: Aunque algunos la describen como formada por procesos volcánicos, la Laguna Pozo Verde probablemente se formó en un deslizamiento de tierra, que ocurre con frecuencia en esta zona lluviosa en la empinada ladera sur del inactivo volcán Porvenir. Nuestros sondeos mostraron una profundidad máxima de 9,25 m cerca del centro del lago. El agua era moderadamente transparente (profundidad de Secchi 2,6 m), con pH circunneutro y temperaturas de 15,9 a 18,1 °C, con estratificación débil a 0,5 m. Los sedimentos superficiales contenían 27% de materia orgánica y tenían relaciones C/N y valores de isótopos de carbono estables consistentes con algas lacustres y plantas C 3 ; Surirella angusta compuso más del 90% de las diatomeas. Conclusión: La laguna es significativamente más omera de lo informado y los sedimentos superficiales albergar una combinación de diatomeas única entre los 88 lagos examinados en Costa Rica.

The control of turbidite deposition on pyrite sulfur isotopic composition in sediments on the continental slope of the South China Sea

Sulfate reduction is a commonly reported process in a variety of continental margin settings that affects the carbon (C), sulfur (S), and iron (Fe) marine sedimentary cycles. However, sulfate reduction in unstable environment (turbidite deposition) is easily ignored, which results in a lack of understanding of the C, S, and Fe biogeochemical cycle. Therefore, to elucidate the role of turbidite sedimentation in the global C, S, and Fe biogeochemical cycle, total organic carbon (TOC), total sulfur (TS), iron speciation, pyrite contents, and sulfur isotopic composition in sediments (CL94) on the South China Sea continental slope were analyzed, along with sediment grain sizes, calcium carbonate (CaCO3) content, and K/Al and Ti/Al ratios. Based on petrographic characteristics, grain size parameters, and element geochemistry (K/Al and Ti/Al ratio), it was concluded that the mid-section (322–350 cm) of Site CL94 is a turbidite layer. Compared with normal sedimentary environment, δ34SCRS (−39.7 ‰ on average) exhibits a high value in turbidite layer, which could be related to the high deposition rate and relatively closed environment caused by the turbidity current deposition. Furthermore, in situ deposition is virtually entirely unaffected by external influences, and this is the primary source of sulfide and reactive iron in the relatively closed environment. Thus, pyrite concentration in the turbidity layer fluctuates in conjunction with variations in sulfide and active iron. Moreover, the identification and data extraction of methane seeps were further complicated by the fact that the TS/TOC ratio and δ34SCRS features induced by the turbidity current were extremely similar to those of sediments around methane seeps. The examination of pyrite sulfur isotopic composition and TS/TOC ratios for detecting methane seepage requires further investigation.

A Quantitatively Divided Approach for the Vertical Belt of Vegetation Based on NDVI and DEM—An Analysis of Taibai Mountain

Vertical vegetation differentiation is the most important form of spatial pattern in mountainous areas. It is of great significance to accurately divide vegetation into vertical zones for the study of mountain ecosystems and ecological protection. In order to accurately divide the vertical zone of mountain vegetation and determine the spatial distribution of mountain vegetation, the relationship between the vegetation index of various vegetation types and altitude was examined using remote sensing and geographic information technology. Taking Taibai Mountain, the main peak of the Qinling Mountains in China, as the study area, based on the difference in NDVI between summer and autumn (DNSA), this work constructed a DEM-NDVI scatter plot and quantified the boundary of the vertical zone by the half-peak width calculation method. The findings showed that: (1) the vertical distribution pattern of mountain vegetation may very well be reflected in the scatterplot that NDSA and DEM created; (2) Six vertical belts could be accurately identified to the meter level on Taibai Mountain’s south slope. Up to the altitude, the oak forest zone from the bottom of the mountain to the elevation of 1919 m, the pine-oak mixed forest zone is distributed in 1919–2331 m, the birch forest is distributed in 2115–2585 m, the fir forest is distributed in 2516–3150 m, the redwood forest is distributed in 3109–3551 m, and the alpine scrub meadow is distributed in 3551 m to the peak. On the north slope, 1053–2087 m above sea level is oak forest, 2087–2693 is birch forest, 2562–3006 is fir forest, 2987–3513 m is redwood forest, and 3513 to the top of the mountain is alpine scrub meadow; and (3) the distribution pattern of the vegetation vertical belt on the DEM-NDVI scatter plot was essentially compatible with the vegetation classification results derived from remote sensing images. The DEM-NDVI scatter plot can reflect the average distribution of vegetation population and can more accurately express the characteristics of vegetation vertical zone changes with altitude.

Stability and probabilistic assessment of a large asymmetric bedding slope with a weak interlayer.

The mining of open-pit mines has a significant influence on the surrounding ecological environment and safety. Once the slope of an open pit is unstable, it will bring extremely severe disasters to the surrounding environment. The south slope of the Fushun West open-pit mine is a large bedding slope with weak interlayer and asymmetrical features between the eastern and western regions. The different deformation mechanisms are worth further discussion, and the deformation mechanism of the eastern region needs to be systematically investigated. In this study, a comprehensive method combining a numerical model, the limit equilibrium method, and a probabilistic approach is used. The different deformation mechanisms of the slope are explored. Thereafter, the sensitivity of the geometric and mechanical parameters of the slope is determined. Finally, the probability of failure (PF) and slope stability are evaluated. The results illustrate that the difference in geological characteristics and constraint conditions is the fundamental reason for the difference in deformation features of the slope. The sensitivity analysis results show that the friction angle of the weak layer exhibits the most sensitivity and that the unit weight is irrelevant to the slope stability. Taking the friction angle of the weak layer as a variable, when thethickness of the basalt layer is less than 140 m and the height of the slope is more than 360 m, the PF of the slope reaches a high value. When the inclination of the weak layer exceeds 30°, the PF of the slope increases to a high value. When the Ru coefficient exceeds 0.2, the slope presents a high PF. The results illustrate that decision-makers should pay attention to the strength degradation, transitional mining of the basalt layer, and establish a good drainage system. The comprehensive method can also provide an effective way to assess the stability and PF of similar large-scale bedding slopes under complex geological conditions.

Carbon and Phosphorus in Volcanic Soils of Mt. Kerinci (Sumatra) After Long Term Tea and Paddy Cultivation

ABSTRACT Volcanic soils are well-known to have a high agronomical value, and in Sumatra, Mt. Kerinci volcanic soils produce one of the highest quality tea and rice. Declining soil organic carbon (C) and high phosphorus (P) retention are two main issues in volcanic soils in the area. Thus, this study aimed to study the dynamic of C) and P content in volcanic soils and to find the main controls of their variation from geochemical signatures. The soils of Mt Kerinci present a unique environment as one part of the area was converted from forest to tea plantation for about 100 years, and a nearby field had been used for paddy rice cultivation for about 200 years. The study was conducted in the Mt Kerinci area covering 5,922 ha in the north comprise of paddy soils (ps) and north tea soils (nts) and the south slope (south tea soils= sts). Soil samples were collected on a grid of 500 × 500 m under tea and paddy (n = 206 samples) at 0–20 and 20–40 cm depth. All soils have similar pH in H2O, but pH in KCl paddy soils (ps) > north tea soils (nts) > south tea soils (sts). The average content of soil organic Carbon (SOC) in paddy soils was 50% less than in the soils of tea plantations. The labile organic carbon content in paddy soils were lower than in soils of tea plantations. Most C was chemically bound to the metal complex. Higher P retention occurred in all soils. The CaO/TiO2 index indicated a weathering sequence of ps > nts > sts. Soil weathering controlled P retention with an increasing P retention as the soils weathered. Overall, the study suggests that cultivation in volcanic soils influenced the geochemical properties of the soils and subsequently their C and P contents.

Retrieving Surface Deformation of Mining Areas Using ZY-3 Stereo Imagery and DSMs

Measuring surface deformation is crucial for a better understanding of spatial-temporal evolution and the mechanism of mining-induced deformation, thus effectively assessing the mining-related geohazards, such as landslides or damage to surface infrastructures. This study proposes a method of retrieving surface deformation by combining multi-temporal digital surface models (DSMs) with image homonymous features using China’s ZY-3 satellite stereo imagery. DSM is generated from three-line-array images of ZY-3 satellite using a rational function model (RFM) as the imaging geometric model. Then, elevation changes in deformation are extracted using the difference of DSMs acquired at different times, while planar displacements of deformation are calculated using image homonymous features extracted from multi-temporal digital orthographic maps (DOMs). Scale invariant feature transform (SIFT) points and line band descriptor (LBD) lines are selected as two kinds of salient features for image homonymous features generation. Cross profiles are also extracted for deformation in typical regions. Four sets of stereo imagery acquired in 2012 to 2022 are used for deformation extraction and analysis in the Fushun coalfield of China, where surface deformation is quite distinct and coupled with rising and descending elevation together. The results show that 21.60% of the surface in the study area was deformed from 2012 to 2017, while a decline from 2017 to 2022 meant that 17.19% of the surface was deformed with a 95% confidence interval. Moreover, the ratio of descending area was reduced to 6.44% between 2017 and 2022, which is lower than the ratios in other years. The slip deformation area in the west open pit mine is about 1.22 km2 and the displacement on the south slope is large, reaching an average of 26.89 m and sliding from south to north to the bottom of the pit between 2012 and 2017, but elevations are increased by an average of about 16.35 m, involving an area of about 0.86 km2 between 2017 and 2022 due to the restoration of the open pit. The results demonstrate that more quantitative features and specific surface deformation can be retrieved in mining areas by combining image features with DSMs derived from ZY-3 satellite stereo imagery.

High-quality wild barley genome assemblies and annotation with Nanopore long reads and Hi-C sequencing data

Wild barley, from “Evolution Canyon (EC)” in Mount Carmel, Israel, are ideal models for cereal chromosome evolution studies. Here, the wild barley EC_S1 is from the south slope with higher daily temperatures and drought, while EC_N1 is from the north slope with a cooler climate and higher relative humidity, which results in a differentiated selection due to contrasting environments. We assembled a 5.03 Gb genome with contig N50 of 3.53 Mb for wild barley EC_S1 and a 5.05 Gb genome with contig N50 of 3.45 Mb for EC_N1 using 145 Gb and 160.0 Gb Illumina sequencing data, 295.6 Gb and 285.35 Gb Nanopore sequencing data and 555.1 Gb and 514.5 Gb Hi-C sequencing data, respectively. BUSCOs and CEGMA evaluation suggested highly complete assemblies. Using full-length transcriptome data, we predicted 39,179 and 38,373 high-confidence genes in EC_S1 and EC_N1, in which 93.6% and 95.2% were functionally annotated, respectively. We annotated repetitive elements and non-coding RNAs. These two wild barley genome assemblies will provide a rich gene pool for domesticated barley.

Comparison of species composition and community characteristics of Quercus forests on south and north slopes of Taibai Mountain, China.

We examined species composition, community characteristics, diversity, and community similarity of five Quercus communities composed of three Quercus species (Q. variabilis, Q. aliena var. acutiserrata, Q. wutaishanica) on the altitudinal gradient on the south and north slopes of Taibai Mountain. The results showed that there was an altitudinal transition pattern from Q. variabilis pure forest to Q. variabilis-Q. aliena var. acutiserrata mixed forest, Q. aliena var. acutiserrata pure forest, Q. aliena var. acutiserrata-Q. wutaishanica mixed forest and Q. wutaishanica pure forest on the south and north slopes of Taibai Mountain. The main companion species of Quercus community on the north slope were Pinus armandii, Castanea seguinii, and Sorbus alnifolia, and were Pinus tabuliformis, C. seguinii, Carpinus cordata, and Q. spinosa on the south slope. Species richness, woody plant density, and Quercus species dominance on the north slope of Taibai Mountain were higher than those on the south slope. α diversity of tree layer in Quercus community on the south and north slopes of Taibai Mountain increased first, then decreased and then increased with altitude. α diversity of tree layer was higher in mixed forests than pure forests. α diversity of shrub layer was higher than that of tree layer and herb layer in Quercus community on south and north slopes. β diversity fluctuated greatly along the altitudinal gradient on the south and north slopes, indicating that species composition changed greatly with altitude. Results of redundancy analysis showed that mean warmest month temperature, altitude and tree height accounted for 79.0% of the community diversity on the north slope, and that soil water content, tree height, canopy density and mean annual temperature accounted for 79.6% of the community diversity on the south slope. Overall, Quercus dominance was higher on the north slope of Taibai Mountain, and the substitution distribution pattern of Quercus species was clearer than that on the south slope. Environmental factors related to temperature and precipitation jointly affected α diversity of Quercus communities.

Displacements of Fushun west opencast coal mine revealed by multi-temporal InSAR technology

ABSTRACT In this paper, the Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technology is adopted to monitor the Line of Sight (LOS) displacement of Fushun West Opencast Coal Mine (FWOCM) and its surrounding areas in northeast China using Sentinel-1 Synthetic Aperture Radar (SAR) images acquired from 2018 to 2022. The spatial-temporal evolution of urban subsidence and the south-slope landslide are both analyzed in detail. Comparison with ground measurements and cross-correlation analysis via cross wavelet transform with monthly precipitation data are also conducted, to analyze the influence factors of displacements in FWOCM. The monitoring results show that a subsidence basin appeared in the urban area near the eastern part of the north slope in 2018, with settlement center located at the intersection of E3000 and fault F1. The Qian Tai Shan (QTS) landslide on the south slope, which experienced rapid sliding during 2014 to 2016, presents seasonal deceleration and acceleration with precipitation, with the maximum displacement in vicinity of the Liushan paleochannel. The results of this paper have fully taken in account for the complications of large topographic relief, geological conditions, spatial distribution and temporal evolution characteristics of surface displacements in opencast mining area. The wide range and long time series dynamic monitoring of opencast mine are of great significance to ensure mine safety production and geological disaster prevention in the investigated mining area.

Experimental study on the influence of embankment slope direction on near-surface thermal conditions in permafrost region, Qinghai-Tibet Plateau

Heterogeneous ground thermal conditions caused by slope orientation are significant in Qinghai-Tibet Plateau because of the high altitude and strong solar radiation. Variation in solar radiation may result in contrasting thermal and upper boundary conditions, causing engineering problems at infrastructure with sloped embankments. Quantitative research on conditions on different man-made slopes is insufficient in permafrost regions, and consequently, planning for long-term effects on linear infrastructure is challenging. Net radiation, heat flux, near-surface temperature, soil moisture content, were recorded for one whole year (2021) at a field platform with eight slopes. Slope orientation affected net radiation (Rn) and ground heat flux (G), resulting in different energy balances between slopes. The north facing slope had a lowest Rn (174 W m-2), while the south slope had a maximum (239.8 W m-2). The north slope had a negative annual heat flux (-0.7 W m-2), while a maximum positive flux (1.5 W m-2) was recorded on the southeast slope. The annual mean surface temperature (Ts) was highest on the south slope and lowest on the north slope. The maximum difference of ground temperatures (within 30 cm depth) (Tg), was close to differences in Ts of over 4 °C. The maximum difference in soil moisture content during the thawing season (May–October) was 11% between the W and E slopes. Due to the different ground temperatures and soil moisture conditions, the annual number of freeze-thaw cycles was variable, and the maximum freeze-thaw cycles were 106 times in south slope and the minimum were 18 times in west slope. Those different thermal conditions between different slope orientations were significant, and pertinent to planning and maintenance of infrastructure. The results provide accurate boundary conditions for modeling to support development of new infrastructure that have embankment slopes in any direction, and for ensuring the stability of existing structures on Qinghai-Tibet Plateau.

Precipitation Variations in China’s Altay Mountains Detected from Tree Rings Dating Back to AD 1615

As the primary mountain range in Central Asia, the Altay Mountains receive water vapor carried by westerly circulation, resulting in relatively abundant local precipitation and lush pastures in all seasons. Consequently, it has become one of the important transportation routes between Asia and Europe. The exploration of long-term variations in precipitation is meaningful for understanding the ebb and flow of the Asia–Europe steppe trade routes. However, previous dendroclimatological studies of the Altay Mountains focused more on temperature changes than precipitations variations. We carried out a 404-year precipitation reconstruction based on the tree rings of Siberian larch growing on the south slopes of the Altay Mountains, which could explain 45.9% of the variance observed in the February–October precipitation. Our reconstruction demonstrated some severe drought events which could be found in the historical documents, such as the drought in the late Ming Dynasty (1640s) and the Ding-Wu Disaster (1870s). The spatial correlation analysis, cross-wavelet spectrum and wavelet coherency analysis indicated that the precipitation variations in the study area may be related to the ENSO and NAO. This study presents a robust precipitation reconstruction of the southern Altay Mountains, serving as a reference for future research on large-scale climatic forces acting on Altay precipitation.

Prediction of CO pollutant in Mashhad metropolis, Iran: Using multiple linear regression

AbstractGiven the importance of carbon monoxide (CO) in acute health threats, studies have been conducted in different countries and cities (272 cities in China and 337 cities on a global scale) on the relationship between daily mortality and CO while the spatial analysis of factors affecting CO pollutant in cities, especially in developing countries, has rarely been done. Accordingly, this research has measured the effect of five environmental‐social variables (ESVs) on the spatial distribution of CO pollutants in the metropolis of Mashhad, Iran. CO concentration data were collected in 23 air pollutant monitoring stations in an area of 356 km2 in 2019. Then, the relationship between five variables and CO pollutant were measured using linear and multiple regression by Sentinel 2A and 3 satellite images in ArcGIS and TerrSet software. The results show that the mean CO concentration averages at 1.56 ppm in the whole city. But its range varies between 0.171 and 2.907 ppm, which is a low figure compared with presented standards and does not indicate a critical situation. The results of multiple regression indicate that 42% of the variance in CO concentration is explained by independent variables. Among five independent variables, the beta value of the land surface temperature (LST) and digital elevation model (DEM) variables is negative and positive for the other three variables, including population density, normalised difference vegetation index (NDVI) and normalised difference built‐up index (NDBI). It should be noted that the strongest correlating variable is population density. Prediction of the spatial distribution of CO pollutants shows the division of the city into three areas: (1) the south and southwest slopes of the city with a low concentration; (2) central areas with a medium concentration; and (3) northern and northeastern areas of the city with a high concentration where low‐income groups reside and there are more worn‐out vehicles, motorcycles and industrial workshops. Areas with high CO concentration need more attention from urban managers.

Spatial and Temporal Variation of Soil Conservation on The Southern Slopes of Qilian Mountains, China

Soil is essential to human survival, and soil health directly impacts human production and life; therefore, monitoring soil erosion has been the primary concern for scientists worldwide. Using the Revised Universal Soil Loss Equation (RUSLE), we analyzed soil conservation, actual soil erosion, and potential soil erosion on the south slope of the Qilian Mountains in China from 2000 to 2015. We drew the following conclusions: (1) The spatial distribution characteristics of soil conservation (Ac) and potential soil erosion (Ap) in the study area remained highly consistent, with a decreasing trend in the northwest and an increasing trend in the southeast. (2) The soil conservation capacity of the study area is increasing while the LSCA area is decreasing significantly. (3) The influence of R and Ap on Ac is powerful, whereas the influence of Ar on Ac is moderate. (4) The change in soil conservation decreases as DEM increases but increases as NDVI increases.

Breadcrust Bomb Merapi: Geological-Inspired Culinary Art and Socio-Cultural Empowerment in Merapi Region

This scientific article explores the creation of Breadcrust Bomb Merapi, a culinary art inspired by the geological features of Mount Merapi in Yogyakarta, Indonesia. The study aims to promote socio-cultural empowerment and geology education while supporting local communities surrounding Mount Merapi. The research methodology involved direct interviews with residents of the South Slope of Mount Merapi to identify the most popular products among tourists and the feasibility of their development. The selection process led to the production of Breadcrust Bomb Merapi, a cake resembling the explosive eruptions of Merapi, featuring a crust-like texture with a soft interior filled with melted cheese, symbolizing hot lava. The legal aspects of the creation were ensured through copyright registration. The results demonstrate the successful integration of geological inspiration into culinary art, providing a unique Merapi culinary experience for visitors and offering socio-cultural and economic opportunities for the local community. The implication of this study lies in its contribution to geotourism, ecotourism, and the preservation of local cultural heritage while fostering socio-economic development in the Merapi region.
 Highlight:
 
 Natural beauty and geological evolution of Mount Merapi
 Breadcrust Bomb Merapi: Culinary art inspired by explosive eruptions
 Socio-cultural empowerment through local culinary development
 
 Keyword:
 Mount Merapi, Breadcrust Bomb Merapi, Geology-Inspired Culinary Art, Socio-Cultural Empowerment, Tourism

The role of terrain-mediated hydroclimate in vegetation recovery after wildfire

Throughout communities and ecosystems both within and downstream of mountain forests, there is an increasing risk of wildfire. After a wildfire, stakeholder management will vary depending on the rate and spatial heterogeneity of forest re-establishment. However, forest re-establishment and recovery after a wildfire is closely linked to interactions between the temporal evolution of plant-available water (PAW) and spatial patterns in available energy. Therefore, we propose a conceptual model that describes spatial heterogeneity in long-term watershed recovery rate as a function of topographically-mediated interactions between available energy and the movement of water in the subsurface (i.e. subsurface hydrologic redistribution). As vegetation becomes re-established across a burned landscape in response to topographic and subsurface controls on water and energy, canopies shade the ground surface and reduce wind speed creating positive feedbacks that increase PAW. Furthermore, slope aspect differentially impacts the spatial patterns in regrowth and re-establishment. South aspect slopes receive high solar radiation, and consequently are warmer and drier, with lower standing biomass and greater drought stress and mortality compared to north aspect slopes. To date, most assessments of these impacts have taken a bulk approach, or an implicitly one-dimensional conceptual approach that does not include spatial heterogeneity in hydroclimate influenced by topography and vegetation. The presented conceptual model sets a starting point to further our understanding of the spatio-temporal evolution of PAW storage, energy availability, and vegetation re-establishment and survival in forested catchments after a wildfire. The model also provides a template for collaboration with diverse stakeholders to aid the co-production of next generation management tools to mitigate the negative impacts of future wildfires.

Characteristics of Nitrate Pollution in Shallow Groundwater on the South Slope of Mount Merapi, Yogyakarta, Indonesia

Groundwater is the primary clean water source for most Indonesian society. The increasing use of groundwater is inevitable due to the rapid development in Indonesia, particularly in Yogyakarta. Shallow aquifers are vulnerable to contamination due to anthropogenic influences. Therefore, this research aims to determine shallow groundwater's physicochemical and chemical characteristics on the southern slope of Mount Merapi, specifically focusing on nitrate and chloride concentrations in groundwater. This research collected monthly data from eighteen dug wells or springs and rainfall data in the study area during the rainy and dry seasons from August 2022 to January 2023. The analyzing sample used argentometry to determine chloride concentration and ultraviolet spectrophotometric to determine nitrate concentration in Yogyakarta Environmental Health and Disease Control Technical Center (BBTKLPP) laboratory. The physicochemical parameters were tested directly in the field using Hanna instruments. The results indicate that a significant portion of shallow groundwater has high nitrate concentrations, corresponding to the growing settlements in the research area. Furthermore, according to the comparison graph between nitrate and chloride, the nitrate source was indicated as anthropogenic. Fecal matter from sanitation practices using septic tanks will likely influence the nitrate increase.

Response of soil N dynamics to land‐use change and topographic position in a semiarid hilly grassland

AbstractLand‐use changes through grazing exclusion (GE) or grassland afforestation (GA) are common restoring practices in semiarid ecosystems, but whether GE and GA exert similar or distinct effect on soil nitrogen (N) dynamics in certain ecosystem is still unclear, particularly in areas with complex terrain. Here, seasonal patterns of soil net N mineralization rates and mineral N contents were characterized in a hilly grassland on the Loess Plateau, China. A fenced grassland, an afforested shrubland and a grazing grassland (reference) with three topographic positions (the top, the north slope, and the south slope) were selected. Results showed that GE decreased soil net N mineralization rates but increased mineral N contents, while GA did not affect these metrics. Furthermore, topographic positions changed the effects of GE, with greater increase of soil total mineral N and nitrate N on the north slope than those on the top and the south slop. Soil layers also changed the effects of GE, with greater decrease in soil net N mineralization rates and greater increase in total mineral N and nitrate N contents at 0–10 cm than those at 10–20 cm. However, there was no difference among three topographic positions or between two soil layers under GA. These results demonstrated that GE was a better restoration practice than GA in respective of soil N dynamics.

Soil Fungal Community Characteristics at Timberlines of Sejila Mountain in Southeast Tibet, China.

Soil fungal community characteristics of alpine timberlines are unclear. In this study, soil fungal communities in five vegetation zones across timberlines on the south and north slopes of Sejila Mountain in Tibet, China were investigated. The results show that the alpha diversity of soil fungi was not different between the north- and south-facing timberlines or among the five vegetation zones. Archaeorhizomyces (Ascomycota) was a dominant genus at the south-facing timberline, whereas the ectomycorrhizal genus Russula (Basidiomycota) decreased with decreasing Abies georgei coverage and density at the north-facing timberline. Saprotrophic soil fungi were dominant, but their relative abundance changed little among the vegetation zones at the south timberline, whereas ectomycorrhizal fungi decreased with tree hosts at the north timberline. Soil fungal community characteristics were related to coverage and density, soil pH and ammonium nitrogen at the north timberline, whereas they had no associations with the vegetation and soil factors at the south timberline. In conclusion, timberline and A. georgei presence exerted apparent influences on the soil fungal community structure and function in this study. The findings may enhance our understanding of the distribution of soil fungal communities at the timberlines of Sejila Mountain.

Impacts of Anthropogenic Emissions over South Asia on East Asian Spring Climate: Two Possible Dynamical Pathways

Abstract Both South Asia and East Asia are the most polluted regions of the world. Unlike East Asia, the aerosol optical depth (AOD) over South Asia keeps increasing for all recent years, which calls for more attention. This study investigates the impacts of anthropogenic emissions over South Asia on the downstream regional climate during spring with the Community Earth System Model 2 (CESM2). The model results suggest that South Asian pollutants have significant impacts on East Asian spring climate, and the impacts could be even larger than locally emitted aerosols. Two possible dynamical pathways (i.e., the northern and the southern pathways) bridging South Asian aerosol forcing and East Asian climate are proposed, and both ways are associated with the black carbon (BC)-induced climate feedbacks surrounding the Tibetan Plateau (TP). The northern pathway is mainly due to the TP warming induced by the BC snow darkening effect (SDE), which significantly reduces the surface air temperature (SAT) over northern East Asia. BC-induced TP warming increases the meridional thermal gradient and accelerates the midlatitude jet stream, which favors the cold-air advection over northern East Asia. The southern pathway is associated with the BC “elevated heat pump” hypothesis, which mainly affects the precipitation in southern East Asia. BC from South Asia accumulates near the south slope of TP, inducing an abnormal ascending motion near the Bay of Bengal. A compensating anomalous sinking motion is then forced in South China, which suppresses the precipitation there. A primary observational analysis is also performed to verify both dynamical pathways. Significance Statement The intensified air pollution over South Asia and its impacts on local climate have been extensively investigated, but its impacts on the climate of remote regions have not been well recognized. Two possible dynamical pathways bridging South Asian air pollutants and East Asian spring climate are proposed, and the black carbon (BC)-induced climate feedbacks surrounding the Tibetan Plateau (TP) are emphasized for both pathways. The findings of this study favor the projection of East Asian future climate under the background of Third Pole/TP warming.