Bedrock Type Research Articles

Rare earth elements distribution in topsoil from Ditrău Alkaline Massif area, eastern Carpathians, Romania

This paper gives an overview of the REEs distribution in topsoil from Ditrău Alkaline Massif area under influence of basic natural factors (parent material and soil acidity). Seventy-six soil samples were collected in accord with the most representative bedrock types and concentrations of the elements were determined using inductively coupled plasma mass spectrometry. The ΣREEs contents in soil developed on alkaline rocks ranges from 52.59 to 579.20 μg/g, with an average value of 235.76 μg/g, significantly higher than the average value of Earth's crust (179.7 μg/g). Y content varies between 5.50 and 58.80 μg/g with an average of 21.67 μg/g. The soils are enriched in LREEs (La to Eu) and depleted in HREEs (Gd to Lu) and Y. This trend is expressed by the wide variations of the LREEs/HREEs, (La/Yb)ch, (La/Sm)ch and (Gd/Yb)ch ratios. The REE chondrite - normalized plots show for most soils strongly negative anomalies for cerium and europium and positive anomalies for gadolinium and dysprosium. The pH of soils is generally acidic to weakly acidic and has an insignificant role in REEs fractionations in soil. The spatial distribution of REEs is strongly related to the lithology of the study area, displaying minor to negligible effects of enrichment factors and a low geoaccumulation index, corresponding to the lack of anthropic contamination. The distribution of the elements in topsoil tends to mimic elemental accumulation in the parental bedrock, with a potential to highlight mineralized zones.

Canopy buffering effects against climatic extremes of deciduous broad‐leaved forests are higher on calcareous than siliceous bedrocks

Forest ecosystems can buffer understorey microhabitats and provide refuges for understorey species in a warming world. These effects are dependent on forest complexity and management. However, the roles of soils and bedrock types are less known although they also may affect forest complexity. We assessed differences in buffering effects of deciduous broad‐leaved forests from calcareous and siliceous soils in the temperate climate of south‐west France predicted to become dryer with climate change. We transplanted during dry and wet years, without and with neighbours (herbaceous and shrubs from forest understories and gaps), six species in gaps and dense forests of the two soil types. Target species originated from contrasting light availabilities and the two soil types. We measured transplant survival, light transmission, air temperature and vapour pressure deficit (VPD) in all treatments. Forest structure and soil parameters were also quantified on both bedrocks. Forest structure complexity was higher and light transmission lower on calcareous than siliceous soils. Relative air humidity was higher and maximum air temperature and VPD lower in the understorey of calcareous than siliceous forests, while soil nutrients and moisture were lower in siliceous soils. We found strong direct facilitation of transplants from shaded habitats by calcareous forest canopies during dry years. Facilitation of forest canopies was much weaker on siliceous bedrocks, during wet years and for species from sunny habitats. Facilitative responses were less obvious but still observed in the presence of understorey neighbours. Calcareous forests showed a stronger buffering ability than siliceous ones due to both higher facilitative effects of calcareous woody dominants and lower survival in calcareous gaps during dry years. Considering that the two forest types were old forests with similar management histories, differences in buffering ability between them were likely due to differences in forest complexity and composition induced by differences in soil types.

Application of Pb Isotopes and REY Patterns in Tracing Heavy Metals in Farmland Soils from the Upper-Middle Area of Yangtze River.

Farmland heavy metal pollution-caused by both human activity and natural processes-is a major global issue. In the current study, principal component analysis (PCA), cluster analysis (CA), rare earth elements and yttrium (REY) analysis, and isotope fingerprinting were combined to identify sources of heavy metal pollution in soil from different farmland types in the upper-middle area of the Yangtze River. The concentrations of Zn and Cu were found to be higher in the vegetable base and tea plantation soil compared with their concentrations in the orangery soil. On the other hand, greater accumulation of Cd and Pb was observed in the orangery soil versus the vegetable base and tea plantation soils. Influenced by the type of bedrock, REY was significantly enriched in the orangery soil and depleted in the vegetable base soil, as compared with the tea plantation soil. The Pb isotopic compositions of the tea plantation (1.173-1.193 for 206Pb/207Pb and 2.070-2.110 for 208Pb/206Pb) and vegetable base (1.181-1.217 for 206Pb/207Pb and 2.052-2.116 for 208Pb/206Pb) soils were comparable to those of coal combustion soil. The compositions of 206Pb/207Pb (1.149-1.170) and 208Pb/206Pb (2.121-2.143) in the orangery soil fell between those observed in soils obtained from coal combustion and ore smelting sites. Using the IsoSource model, the atmospheric Pb contributions of the vegetable base, tea plantation, and orangery soils were calculated to be 66.6%, 90.1%, and 82.0%, respectively, and the bedrock contributions of Pb were calculated to be 33.3%, 9.90%, and 18.1%, respectively. Based on the PCA, CA, and REY results, as well as the Pb isotope model, it appears that heavy metals in the orangery soil may be derived from atmospheric deposition and bedrock weathering, while heavy metals in the vegetable base and tea plantation soils may be derived from mining and the use of fertilizer.

The influence of geological setting and land use on the physical and chemical properties of the soil at the Fruska Gora Mountain

Soil erosion is a problem that affects the landscape at different scales and represents a serious challenge for land management and soil conservation in both natural forests and meadows. The aim of this study was to determine how the parent material and land use affect the physical and chemical properties of the soil in the area of the Fruska Gora Mountain. The soils were separated into five bedrock types: serpentinite, marl, trachyte, shale, loess and two land use types: forest and meadow. Twenty-three forest soil and 24 meadow soil from a depth of 0?20 cm were sampled from the Fruska Gora Mt. The following properties were determined: pH, electrical conductivity, oxidationreduction potential, content of organic carbon, sodium adsorption ratio, aggregate size and stability. There is no statistically significant difference in pH values, redox potential (Eh), electrical conductivity (EC) and sodium adsorption ratio (SAR) values between the analysed forest and meadow soils, but there is a statistically significant difference in the content of organic carbon (Corg). It can be concluded that both the parent material, and to a slightly less extent, land use have a great influence on physico-chemical properties of the soil.

Revealing the sources of arsenic in private well water using Random Forest Classification and Regression.

Exposure to arsenic through private drinking water wells causes serious human health risks throughout the globe. Water testing data indicates there is arsenic contamination in private drinking water wells across New Jersey. To reduce the adverse health risk due to exposure to arsenic in drinking water, it is necessary to identify arsenic sources affecting private wells. Private wells are not regulated by any federal or state agencies through the Safe Drinking Water Act and therefore information is often lacking. To this end, we have developed machine learning algorithms including Random Forest Classification and Regression to decipher the factors contributing to higher arsenic concentration in private drinking water wells in west-central New Jersey. Arsenic concentration in private drinking water wells served as a response variable while explanatory variables were geological bedrock type, soil type, drainage class, land use/cover, and presence of orchards, contaminated sites, and abandoned mines within the 152.4-meter (500 ft) radius of each well. Random Forest Classification and Regression achieved 66 % and 55 % prediction accuracies for arsenic concentration in private drinking water wells, respectively. Overall, both models identify that bedrock, soil, land use/cover, and drainage type (in descending order) are the most important variables contributing to higher arsenic concentration in well water. These models further identify bedrock subgroups at a finer scale including Passaic Formation, Lockatong Formation, Stockton Formation contributing significantly to arsenic concentration in well water. Identification of sources of arsenic contamination in private drinking water wells at such a fine scale facilitates development of more targeted outreach as well as mitigation strategies to improve water quality and safeguard human health.

Tracing the geographical origin of bottled water collected in South Korea via isotopic and elemental analyses.

The production of bottled water requires a forensic discriminant technique that enables the identification of the brands or accidents caused by intended contaminants. The bottled water poisoning crimes have drawn much attention, and such crimes may recur in the future. The water is colorless and odorless, and thus it is difficult to detect contaminated water through visual observation. Thus, bottled water can be easily exploited for poisoning, and a method for tracing their origin is currently required. In this study, a total of 27 brands of bottled water samples were analyzed to determine stable oxygen isotopes, strontium isotopes, major and trace elements. The geographical origin of the water was traced based on the climatic and geographical characteristics of the location from where water was sourced, which was assumed to be reflected in the bottled water. Furthermore, we investigated whether this method can be applied to identify bottled water products. The results demonstrated that the characteristics of the bottled water, including the oxygen stable isotope ratios, reflect the latitude and altitude of bottled water source in South Korea, from the high-latitude region to the coastal regions. In addition, the results indicated that excellent discrimination was achieved using strontium isotopes to identify source areas with different types of bedrock, complex underlying lithologies, and ocean areas in South Korea. A statistical method based on discriminant analysis was applied to measure trace elements, and the results effectively reflected the characteristics of water-rock interactions (cross-validated classification probability: ≥92%). These data suggest that the geographical characteristics of the source area are well reflected in commercial bottled water in South Korea. The proposed analytical methods can be utilized to trace the geographical origin of different bottled water samples and identify bottled water products used in poisoning crimes.

ANALISIS TIPE BATUAN DASAR PEMBENTUK NIKEL LATERIT PADA BLOCK X KABUPATEN BANGGAI, PROVINSI SULAWESI TENGAH

Nickel is an important strategic resource and has become a key material for the development of modern aerospace and defense industries, infrastructure and technology. The research area is located in block X, Banggai Regency, Central Sulawesi. The purpose of this study is to analyze the type of bedrock using petrographic analysis based on the research location. The research method used is direct observation in the field and laboratory analysis. The morphology of the research site belongs to the geomorphological unit of denudational origin, divided into two topography, namely denudational hills with gentle slopes (4-8° or 7-15%) and denudational hills with moderate-sloping slopes (8-16° or 15-30%). The bedrock that has been successfully analyzed at the research site is a cretaceous serpentinized peridotite unit.

EPIPACTIS SPECIES AND THEIR HABITAT PREFERENCES IN THE WESTERN PART OF HUNGARY

With 22 taxa reported from the country so far, Epipactis is the most species-rich orchid genus in Hungary. Many of them are rare, threatened species. To protect endangered species effectively, it is crucial to explore their ecology. Our work aimed to select and examine factors that are influencing the distribution of Epipactis species. Our data collection (2014–2018) was carried out in the Keszthely Hills, in the northeastern part of the Zala Hills and the Southern Bakony Mountains. We assigned ecologically relevant data from databases of local forestries, terrain models and geological maps to each occurrence. We examined the factors that result in the best differentiation between the studied species. At 1,261 localities, a total of 5,223 individuals of 15 taxa were found. We found three factors (tree species composition of the forest, genetic soil type, bedrock type) that significantly influenced the distribution of Epipactis species. Our results can help understand the distribution patterns of these species and allow for more effective, targeted protection of their potential habitats on a regional level.

VESTA – resurvey of natural, non-forest vegetation (Central Europe)

“VESTA - resurvey of natural, non-forest vegetation (Central Europe)” is a thematic, resurvey database focused on documentation of changes in natural, non-forest communities. Currently, the database includes 549 relevés (231 replots for 84 sites) corresponding to the classes Asplenietea trichomanis (incl. Polypodietea), Koelerio-Corynephoretea (rocky grasslands), Loiseleurio-Vaccinietea and Betulo carpaticae-Alnetea viridis. The project is continuous in character. It is based on the phytosociological relevés from own field studies which have been carried out in the Sudetes Mts. and their foothills since 1989. The subject of research have been all types of rocky communities (chasmophytic, grasslands, thickets), mountain and submountain tall-herb communities, subalpine thickets and heathlands. Relevés are collected according to the standard Braun-Blanquet method (species coverage scale: r, +, 1, 2, 3, 4, 5) and on rectangular or square-shaped surfaces with possible adjustment to the shape of the rocky outcrops. Initially (until 2008), the location of plots was marked on maps and field sketches. However, the fact that all relevés were collected by the owners of the database made it easier to revisit all plots and assigned a location compatible with GPS with SiRFstar III chipset. The accuracy of position measurements varies between 2 and 15 meters (on average 10 meters). Aspect is determined using electronic compass linked to GPS. Altitude is obtained from Google Earth and corrected with landmarks from topographical maps if necessary. The shading of the plots has been visually assessed so far. The bedrock type is derived from a Detailed Geological Map of the Sudetes (http://sudety.pgi.gov.pl/). Subsequent resurveys of the plots are conducted during field visits planned specifically for this purpose or during other research carried out in the same area.

Groundwater evaluation of northern Jazmourian (south Iran) for drinking, agriculture, and associated health risks of nitrate and fluoride contamination

To investigate groundwater quality in the north of Jazmourian (Roudbar plain), 30 samples were collected and analyzed for evaluating drinking and irrigation status and associated health risks. In addition to major anions and cations, the fluoride and nitrate content of samples were analyzed using standard procedures. Nitrate levels range between 6.6 and 131 mg/L and exceed the WHO permissible limit in more than 23% and 80% of samples for adults and children, respectively. Fluoride amounts ranged from 0.4 to 4.8 mg/L in samples. The F- level exceeded the WHO standard limit in 10% of samples. The EC level increases in fine-grained deltaic deposits toward the south. The concentrations of major ions (HCO3, Cl, SO4, Mg, Na, K) increase southwards, following the flow direction. There are, however, lateral (east-west) differences in water quality due to the influence of such factors as the rate of recharge and the type of bedrock. Wherever the redbeds comprise the bedrock and the recharge rate is weaker, the dissolved salts are higher in amount. The water quality index (IWQ) indicated that 13, 13, and 4 samples are in “good,” “poor,” and “very poor” quality classes, respectively. By using the irrigation water quality index (IWQI), eight samples were at “low restriction,” nine samples at “moderate restriction,” twelve samples at “high restriction,” and one sample at “severe restriction” classes. The acquired findings revealed that the mean oral hazard quotient of nitrate was 1.14, 1.0, and 0.84, and for fluoride, it was 0.82, 0.72, and 0.61 for children, females, and males, respectively. The total hazard index for cumulative NO3 - and F- toxicity exceeded the acceptable level in 76.67%, 66.67%, and 56.67% of samples for children, females, and males, respectively.

Assessment of soil erosion risk using an integrated approach of GIS and Analytic Hierarchy Process (AHP) in Erzurum, Turkiye

Assessing soil erosion hazards and mapping the spatial distribution of soil erosion have an essential role in sustainable forest management. In this study, the potential soil erosion risk was evaluated through the Analytical Hierarchy Process (AHP) and Geographic Information Systems (GIS) in the Oltu forest planning unit, Erzurum. Seven erosion-related criteria, including slope, bedrock type, relative relief, drainage density and frequency, rainfall, and land use/land cover (LULC) were used for the present assessment. According to the AHP analysis, the slope was the most influential factor (21%) followed by bedrock type (19%), land cover (17%), and relative relief (14%) in the soil erosion process. The soil erosion risk in the study area was strongly influenced by the LULC where 59.46% is bare land with high erosion risk and 12.07%, with the lowest risk, is in an area with any forest cover. The estimated soil erosion risk was classified into five different classes namely very low, low, moderate, high, and very high. The results showed that this study area is highly prone to soil erosion. The larger proportion of the area (39.16%) is exposed to high to very high erosion, mainly determined by forest cover and geomorphology. To analyze the accuracy of the soil erosion risk map, 40 points were selected randomly in this study area. In these points, predicted values were compared to the real values obtained by Google Earth-colored images. The area under the ROC curve (AUC) method was applied to validate the efficiency of the AHP which showed a satisfactory accuracy of 81.00%. Findings presented that including the more influencing factors with a slope instead of including only the slope contributes to a more accurate erosion risk map. This study highlighted that GIS-based multi-criteria decision-making is a valuable and practical tool for decision-makers and land managers in creating soil erosion susceptibility maps and determining high-priority areas that require conservation measures for sustainable land use management by reducing the economic and ecological impacts of soil loss. Also, this approach can be practically applied in other planning units.

Concentration and mobility of trace elements (Li, Ba, Sr, Ag, Hg, B) and macronutrients (Ca, Mg, K) in soil-orchid system on different bedrock types.

The mobility of chemical elements in the soil-orchid system has been poorly studied. The aim of this study is to evaluate the uptake and mobility of several trace (Li, Ba, Sr, Ag, Hg, and B) and macronutrients (Ca, Mg, and K) in the orchid Anacamptis morio (L.) R.M.Bateman, Pridgeon & M.W.Chase from soils in western Serbia. The sampling sites are characterized by three different bedrock types-cherts, limestones, and serpentines, which are the source of the significant chemical differences in the elemental status of the soil and plant tissues. The four-step Community Bureau of Reference sequential extraction procedure was used to determine the distribution of fractions and predict their potential phytoavailability. The orchid and soil samples were analyzed for total elemental content analysis using ICP-OES. The greatest potential for plant availability was determined for Ba and Sr, representing about 80% of the total soil content. More than 40% of Li in the soils was found to be potentially phytoavailable. Significant correlations were found between the total content of Li, B, and Sr in soils. Between 38 and 60% of Li content and more than 80% of Ba and Sr content were determined to be potentially phytoavailable by sequential analysis. The highest bioconcentration factor (> 1) was determined in the case of B and Sr for all orchid organs, while translocation factor for Li was highest in tubers and leaves. The studied elements were mainly stored in tubers and roots, indicating the exclusion strategy of A. morio as a metal tolerance mechanism. The data obtained showed significant differences in metal content in soils and plants originating from sites with different parent materials, suggesting that bedrock type and associated soil properties are important factors that determine chemical element mobility and uptake.

Morphology of Dome- and Tepee-Like Landforms Generated by Expansive Hydration of Weathering Anhydrite: A Case Study at Dingwall, Nova Scotia, Canada

The gypsum-anhydrite rocks in the abandoned quarry at Dingwall (Nova Scotia, Canada) are subjected to physical and chemical weathering, including hydration of the anhydrite, i.e., its transformation into secondary gypsum under the influence of water. This process is known to lead to the localized volume increase of the rock and the formation of spectacular hydration landforms: domes, tepees and ridges. Cavities appearing in the interior of these domes are often unique hydration caves (Quellungshöhlen in German). For the first time, this paper gives detailed geomorphometric characteristics of the 77 dome- and tepee-like hydration landforms growing today at Dingwall based on their digital surface models and orthophotomaps, made with the method of photogrammetry integrated with direct measurements. The length of hydration landforms varies from 1.86 to 23.05 m and the relative height varies from 0.33 to 2.09 m. Their approximate shape in a plan view varies from nearly circular, through oval, to elongated with a length-to-width ratio rarely exceeding 5:2. Length, width and relative height are characterized by moderate mutual correlation with proportional relations expressed by linear equations, testifying that the hydration landforms generally preserve the same or very similar shape independent of their sizes. The averaged thickness of the detached rock layer ranges from 6 to 46 cm. The size of the forms seems to depend on this thickness—the forms larger in extent (longer) generally have a thicker detached rock layer. Master (and other) joints and, to a lesser extent, layering in the bedrock influence the development of hydration landforms, particularly by controlling the place where the entrances are open to internal cavities or caves. Three structural types of the bedrock influencing the growth of hydration forms were recognized: with master joints, with layering and with both of them. The latter type of bedrock has the most complex impact on the morphology of hydration landforms because it depends on the number of master joint sets and the mutual orientation of joints and layering, which are changeable across the quarry. The durability of the hydration forms over time depends, among others, on the density of fractures in the detached rock layer.

Different components of interconnected karst environment select for highly distinct microbial communities

Karst environments, formed by dissolution of rocks, present a unique opportunity to study groundwater and surface water as a single dynamic system. We aimed to explore the hydrological connections and identify shared microbiome between different components of this complex landscape (terrestrial, surface-subsurface freshwater networks and two different lake strata) on example of karst landscape at north shore of Lake Thun (CH). 52 samples from soil and 87 from the freshwater network were collected during low hydrological conditions. Additionally, 43 samples from 13 different lakes across Europe were included in the analysis. A 16S rRNA gene amplicon analysis revealed highly homogenous lake communities dominated by typical lake microbes represented by members of Alphaproteobacteria, Gammaproteobacteria and Actinobacteria. On the contrary, communities in soils and surface and subsurface water were observed to be highly heterogenous within the karst landscapes. Soil samples built two robust groups that corresponded to alkaline and acidic pH values associated with two types of bedrocks. Alkaline soils had higher abundance of Gammaproteobacteria and Alphaproteobacteria, while acidic soils were dominated by Acidobacteria. Alkaline cluster was better connected with aquatic environments and shared genotypes from the families Nitrosomonadaceae and Nitrospiraceae with cave sediments and lake hypolimnia, that implied ammonia and nitrite oxidation as important chemotrophic processes in light depleted environments. Rhodoferax, Limnohabitans and Sediminibacterium were shared within subsurface network and lakes. Single Rhodoferax genotype was detected in all aquatic environments. Additionally, we observed that lineages from the families Pirellulaceae and Gemmataceae (phylum Planctomycetota) were alternatively distributed in both soil clusters and lakes. A similar pattern was observed in subsurface aquatic components and deeper lake strata within family Methylophilaceae, where Methylotenera was extensively replaced by Methylopumilus. This indicates that despite high hydrological connectedness between different karst landscape components, deterministic selective factors seem to prevail in the community assemblies.

Analisis Karakteristik Mineralogi dan Geokimia Berdasarkan Zona Profil Endapan Nikel Laterit (Studi Kasus: Blok X PT Ang and Fang Brother, Site Lalampu, Kecamatan Bahodopi, Kabupaten Morowali, Provinsi Sulawesi Tengah

Regionally, the study area is located in the Ophiolite Belt of East Sulawesi, particularly in the Tomata Formation (Tmpt), and is composed of igneous rock distribution in the Ultramafic Complex (Ku). The exposed of ultramafic rocks, caused the study area to contain elements of economic value such as nickel. The study aims to identify the constituent minerals, determine the abundance of elements and compounds, as well the correlation of major and minor elements and compounds based on the profile zone of laterite nickel deposits. Study data were in the form of soil and rock samples, and drilling data as many as 59 points. The mineral content of the study results was obtained based on the analysis of X-ray Diffraction and Petrography, while the univariate and bivariate statistical analysis was carried out on the drilling data. The results of the analysis obtained assemblages of minerals in the form of goethite, hematite, chlorite, and quartz in the limonite zone; antigorite, enstatite, chlorite, quartz, and magnetite in the saprolite zone; and lizardite, enstatite, spinel, and magnetite in the bedrock zone, with the bedrock type being serpentinized harzburgite. The results of the descriptive analysis showed the grade of major elements and compounds, which are Fe, SiO2, MgO, and Al, as well as minor elements, which are Ni, Cr, Co, Ca, and Mn which varied in each zone, where grade of SiO2, MgO, and Ca increased to the bottom of the profile, and the grade of Fe, Al, Cr, Mn, and Co decreased towards the bottom of the profile, while Ni increased to the saprolite zone. The results of the correlation of elements and compounds in the limonite zone are Cr vs Mn; SiO2 vs MgO and Ca; Ni vs Co and Cr; Fe vs Co positive is very strong to strong correlation, while Fe vs SiO2, MgO vs Al; Al vs Ni is strong negative correlation. Saprolite zone Fe vs Al, Cr, and Co; Cr vs Mn and Co; Mn vs Co; SiO2 vs MgO; Fe vs Mn; Al vs Cr, Mn, and Co were very strong to strong positive correlation, while Fe vs SiO2 and MgO; SiO2 vs Co; MgO vs Cr and Co; SiO2 vs Al, Cr, and Mn; MgO vs Al and Mn were very strong to strong negative correlation. Bedrock zones of Fe vs Cr, Mn, and Co; Cr vs Mn; Fe vs Al; Co vs Al, Cr, and Mn were very strong to strong positive correlation, while MgO vs Fe and Cr were strongly negative correlation.

Soil meets stream: Vertical distribution of soil phosphorus in streambanks

Characterizing the vertical distribution of total phosphorus (P) and P forms in streambanks can improve estimates of P loads to streams via bank erosion. Using a systematic literature review, this meta-analysis evaluated the vertical distribution of total P (Ptot), Bray-1 test P (PBray1), oxalate-extractable P (Pox), degree of P saturation (DPSox), and soil P storage capacity (SPSC) at 161 streambank locations encompassing diverse soil orders and riparian land covers. Across studies, maximum soil sampling depth (125 cm) was on average half that of streambank height (250 cm on average), and water quality-related P fractions such as water-extractable P (Pw) were not generally reported. Slightly weathered Entisols and Inceptisols collectively accounted for 84% of observations, likely reflecting alluvial deposition environments along stream corridors, and exhibited decreasing Ptot (820 to 400 mg kg−1) with increasing depth to 200 cm. Irregular changes in Ptot at depth > 200 cm of Entisols and Inceptisols suggested burial of organic-rich A horizons by alluvial deposition. Changes in riparian land cover mainly affect Ptot in the upper 60 cm, with depth-weighted mean Ptot increasing as grassland (217 mg kg−1) < forest (628 mg kg−1) ≈ wetland (624 mg kg−1) < developed (684 mg kg−1) < agriculture (739 mg kg−1), consistent with expected anthropogenic P enrichment of surface soils and posing increased P loading risk. Effect size analysis showed that riparian land cover had a large influence on Ptot within the top 30 cm depth whereas soil order and bedrock type had large influences on subsurface Ptot, suggesting depth-divergent drivers of P in streambank soils. Additionally, Ptot and Pox were positively correlated with silt, clay, carbon, cation exchange capacity (CEC), oxalate-extractable iron (Feox) and aluminum (Alox), and total Fe (Fetot) contents. This work helps advance understanding of the vertical variation of streambank soil P across diverse soil types, land covers, and soil properties, and their implications for P loading from bank erosion. We also identify gaps in sampling approaches (insufficient depth) and analysis (Pw) that may be hindering comprehensive assessment of bank erosion P loading and risk to water quality. Finally, we illustrate how fluvial erosion and deposition may generate complex vertical P distributions in streambanks, with implications for estimating erosional P loading that can benefit from a pedologically explicit approach.

Characterization of legacy landfills with electrical resistivity tomography; a comparative study

Historic landfills that were constructed to standards that would not meet current regulations represent environmental and human-health risks. The adequate characterization of legacy landfills is paramount to manage the risks they pose effectively. In this study, the non-invasive geophysical technique of electrical resistivity tomography has been used to characterize two sites that have been identified as posing risks to the local environment. The sites are significantly different in the type of waste present, moisture content, type of bedrock and shape and distribution of the waste; although they have in common that neither site is lined.The results of the resistivity imaging have allowed defining the boundaries of the landfill and the depth of the waste. Different types of waste and their distribution have been identified. Additionally, a relationship between the resistivity distribution and the release of residual gas from the landfill has been described; where the presence of saturated clay in the waste prevents the release of said gasses. This is be associated with locations with higher resistivity and lower clay content. That relationship is not observed when the clay is dry.When interpreting the results, the heterogeneous nature of the waste can lead to misinterpretations due to resistivity overlap between the bedrock and the waste materials. Therefore, comparison of the resistivity models with direct information like borehole logs can significantly improve the reliability of the interpretations. However, the resistivity survey should predate the installation of bores to identify the most suitable locations for them.

Cirque Floor Altitude of the Gangdise Mountains and its Controlling Factors

The cirque floor altitude (CFA) was used to indicate the patterns of paleoprecipitation, paleocloudiness, palaeoglaciation, and paleo-equilibrium line altitude (ELA). However, CFA is also affected by non-climatic factors, which limits its efficacy of being a paleoclimatic indicator. This study focuses on the Gangdise Mountains with an aim to investigate the controlling factors on CFA and test the CFA efficiency as an indicator of paleoclimate. A total of 1652 cirques were identified, and their CFAs were analysed in this study. The results show that the lowest CFA is in the eastern part of the Gangdise Mountains, followed by the western and central parts. This spatial distribution is in contrast with that of precipitation. This means that the development of the cirque is favoured by high precipitation. The high CFA values on southern and western slopes are due to effects of solar radiation and wind. The weak correlation between the cirque height and CFA and their different spatial distributions imply that cirque deepening is not the main factor affecting CFA. Various bedrocks of cirques manifest different CFA values, while the spatial patterns of the CFAs in the western, central and eastern parts can be partly explained by their bedrock types. The CFA values of the Gangdise Mountains are higher than those of the central Tibetan Plateau (TP). The CFA spatial distribution of the central TP is in contrast with that of precipitation, highlighting that precipitation is the primary control of the CFA. The relief and glacier type significantly control the CFAs. These findings lead to the conclusion that CFA is not always an actual indicator of paleoclimate on a large regional scale.

Geodiversity and biodiversity on a volcanic island: the role of scattered phonolites for plant diversity and performance

Abstract. Oceanic islands are cradles of endemism, contributing substantially to global biodiversity. A similarity in magmatic origin translates into high global comparability of substrates of volcanic islands on the oceanic crust with, however, slightly chemically or physically differentiated petrography in some places. Phonolites are examples of rare localities with intermediate chemical characteristics between felsic and mafic and with diverse textures. They contribute to habitat heterogeneity and offer specific growth conditions in a significantly different matrix of basaltic substrates. The explicit contribution of geodiversity to island biodiversity has been little studied, despite growing evidence of its importance on continents. On the island of La Palma, Canary Islands, isolated phonolitic rocks are conspicuous due to their light colour and specific shape. Although these outcrops only cover small areas, their unique form and composition increase within-island geodiversity. To investigate how this affects biodiversity on La Palma, we sampled all vascular plant species in 120 plots on four sets of paired sites in order to test if plant diversity and performance is enhanced on phonolitic rocks compared to basaltic rocks. We recorded species number and abundance as well as individual plant height and diameter as proxies for aboveground resource allocation and tested for differences in vegetation cover and species composition between the bedrock types. We found higher species richness and abundance on phonolites than neighbouring basaltic substrates, and individuals of the same species were larger (in height and diameter) on phonolites compared to neighbouring basalt. An endemic woody species with two distinct varieties even appears almost exclusively on the small surfaces of phonolitic rock. Despite extremely limited spatial extent, phonolitic rocks can play an important role in plant biodiversity on islands.

Predicting natural hyperdense regeneration after wildfires in Pinus halepensis (Mill.) forests using prefire site factors, forest structure and fire severity

Postfire Pinus halepensis (Aleppo pine) regeneration is often hyperdense. The overstocked stands created by this hyperdense regeneration considerably increase the risk of biotic and abiotic disturbances, especially fires, by increasing the potential for widespread forest losses. Our aim was to understand the relation between prefire site factors (climate, geographical position, topography, soil), prefire forest structure variables and fire severity with regeneration density after fire. We specifically wondered: (1) what are the general drivers of natural regeneration in these forests after fire?; (2) what are the necessary prefire conditions for establishing Aleppo pine hyperdense regenerations (>4,000 plants/ha)? To answer these questions, we sampled 147 plots in 15 wildfires located in the Comunitat Valenciana, which were representative of Aleppo pine Mediterranean forests. We used full and partial redundancy analyses (RDAs) for variance partitioning, and a decision tree analysis to look for the key site factors that drive regeneration density after fire. We found that all the site factors measured in the study explained 34.4 % of total variation in regeneration density. Prefire site factors and fire severity together explained 28.4 % of total variability, while the measured postfire factors explained only 7.5 %. Forest structure and climate explained 8.3 % and 6.7 % of variation, respectively. Five specific site factors drove regeneration density after fire: average minimum temperature, tree density before fire, resprouting shrubs coverage before fire, soil depth and bedrock type. The conclusions of this study were: (i) the average minimum temperature was the main significant variable that classified regeneration density and split data into three significant groups of Aleppo pine burned sites; (ii) the prefire forest structure (overstorey density and understorey coverage) controls regeneration density at colder burned sites, but soil depth and bedrock can be more important at warmer sites; (iii) fire severity relates positively to pine regeneration density, but negatively to resprouting vegetation coverage after fire; (iv) overstocked stands are not expected if prefire stand density is below 100 trees/ha at colder burned sites. These results may facilitate the planning of forest management and restoration actions because it may be used to identify those areas more likely to regenerate overstocked stands when faced with a changing fire regime.