Parent Material Type Research Articles

Stoichiometry of base cations and silicon during weathering of a deep soil profile derived from granite

Evaluation of the stoichiometry of base cations (BCs, including K+, Na+, Ca2+, and Mg2+) and silicon (Si) (BCs:Si) during soil mineral weathering is essential to accurately quantify soil acidification rates. The aim of this study was to explore the differences and influencing factors of BCs:Si values of different soil genetic horizons in a deep soil profile derived from granite with different extents of mineral weathering. Soil type was typic acidi-udic Argosol. Soil samples were collected from Guangzhou, China, which is located in a subtropical region. To ensure that the BCs and Si originated from the mineral weathering process, soil exchangeable BCs were washed with an elution treatment. The BCs:Si values during weathering were obtained through a simulated acid rain leaching experiment using the batch method. Results showed that soil physical, chemical, and mineralogical properties varied from the surface horizon to saprolite in the soil profile. The BCs:Si values of soil genetic horizons during weathering were 0.3–3.7. The BCs:Si value was 1.7 in the surface horizon (A), 1.1–3.7 in the argillic horizon (Bt), and 0.3–0.4 in the cambic (Bw) and transition (BC) horizons, as well as in horizon C (saprolite). The general pattern of BCs:Si values in the different horizons was as follows: Bt > A > Bw, BC, and C. Although BCs:Si values were influenced by weathering intensity, they did not correlate with the chemical index of alteration (CIA). The release amounts of Si and BCs are the joined impact of soil mineral composition and physical and chemical properties. A comprehensive analysis showed that the BCs:Si values of the soil derived from granite in this study were a combined result of the following factors: soil clay, feldspar, kaolinite, organic matter, pH, and CIA. The main controlling factors of BCs:Si in soils of different parent material types require extensive research. The wide variance of BCs:Si values in the deep soil profile indicated that H+ consumed by soil mineral weathering was very dissimilar in the soils with different weathering intensities derived from the same parent material. Therefore, the estimation of the soil acidification rate based on H+ biogeochemistry should consider the specific BCs:Si value.

Excellent source rocks found along the margin of a large lacustrine basin: Case study from the Ordos Basin, China

Whether the Chang 6 oil pools of the Triassic Yanchang Formation in the Ansai-Yanchang (AY) oil province on the Yishan slope of the Ordos Basin formed from near source rock or far source rock has long been debated. An understanding of the source rock's position will impact the formation mode and distribution of accumulations in this area. Based on the geochemical data of the Chang 7 source rock in six wells and 18 crude oil samples, the geochemical characteristics of Chang 7 source rock and its relationship with Chang 6 crude oil were studied. There are two types of source rocks, namely, black shales and dark mudstones, present in the AY area. The gross thickness of the Chang 7 black shale is 3.0–19.7 m, with a distribution area of 5500 km2. It has an average total organic carbon (TOC) content of 3.34%, with a chloroform bitumen “A" content of 0.512%, indicating good to excellent source rock potential. The kerogen assessment with core samples shows mixed type I-II1, and has reached peak oil generation, maximum pyrolysis temperatures (Tmax) ranging from 445 to 458 °C. In contrast, the average TOC content of the dark mudstone in Chang 7 is 0.91%, chloroform bitumen “A” is 0.079%, the main type of kerogen is type II2-II1, and Tmax varying from 446 to 461 °C, indicating only fair source rock potential overall. The Chang 7 source rocks in the AY area have a gammacerane index of 0.07–0.38, with an average value of 0.21, which reflects a low-salinity fresh to brackish water environment. The relative abundances of C27, C28, and C29 steranes are 29.7%, 23.1% and 47.2%, respectively, indicating that terrestrial higher plants and aquatic organisms provide similar contribution in the Chang 7 source rocks. Oils produced from the AY area of the Chang 6 member have similar geochemical signatures, but are significantly different from the Chang 6 crude oils in the Daozhen (DZ) area of Ganquan County and the Huaishuzhuang (HSZ) area of Fuxian County, which are located in the center of the lacustrine basin. They differ in terms of the maturity of the oil samples and the microscale composition of the parent material type. The closer the wells are to the center of the lacustrine basin, the higher the maturity of the source rock and the greater the contribution of aquatic organisms. The variation of carbon isotopic composition of Chang 6 crude oil in AY area is consistent with that of Chang 7 shale locally, but opposite to that of Chang 6 crude oil in DZ area. The ratios of nC21-/nC22+, tricyclic terpane/hopane and C29 sterane ββ/(ββ+αα) biomarker parameters of Chang 6 crude oils in AY area are similar to those of Chang 7 shale in local area, but deviate from those of DZ and HSZ area. These data results reveal that the Chang 6 crude oils in the AY oil province are dominated by the local Chang 7 excellent source rocks rather than by the long-distance migration of oils from the basin center.

Urban soil properties distinguished by parent material, land use, time since urbanization, and pre-urban geomorphology

The typically high lateral and vertical variation of urban soil properties challenges the interpretation and prediction of their spatial patterns. The aim of this study was to investigate physico-chemical properties of, and pedogenesis in urban soils with different parent materials, and to evaluate whether information on land use, time since urbanization, and pre-urban geomorphology can help to better understand and spatially predict urban soil properties in the historic city of Ghent, Belgium. Sixteen soils were collected from sites with various land uses in three quarters that were urbanized at different times. They were described and characterized by laboratory methods (soil pH, electrical conductivity, soil organic carbon content, black carbon content, equivalent calcium carbonate content, soil particle size distribution, coarse fragments content) and portable X-ray fluorescence (total Cr, Ni, Cu, Zn, and Pb content). Site history and pre-urban geomorphology were deducted from archeological reports and historical imagery. Our results revealed that human-transported materials (HTMs) are common in soils in Ghent. Decalcification, eluvation or illuvation in HTM were only evidenced in soils for which landfill occurred >100 years ago, which had not been disturbed recently. Hence, soil properties were strongly influenced by compositional differences (e.g., nature or type of artifacts) between (native or human-transported) parent material types. In contrast to land use, time since urbanization and pre-urban geomorphology were indicative of parent material type, soil properties, and human soil modifications. More specifically, soils in the old, medieval quarter Inner City consisted mainly of urbic or spolic parent material and had a lower sand content, and a higher content of silt, coarse fragments, and heavy metals (Ni, Cu, Zn, Pb) compared to the young quarter Wondelgem, where soils mainly developed in native parent material or lithic HTM. Furthermore, soils situated in raised, former floodplains had a higher soil pH, electrical conductivity, calcium carbonate content, silt content, and coarse fragments content, and a lower sand content compared to soils of the periglacial plain. Multidisciplinary data sources (e.g., historical maps) can be integrated to better comprehend the complex urban soilscape, where past and current human interventions, pre-urban geomorphology and hydrography are all at play.

Effects of Soil Quality on the Microbial Community Structure of Poorly Evolved Mediterranean Soils.

Physical and chemical alterations may affect the microbiota of soils as much as the specific presence of toxic pollutants. The relationship between the microbial diversity patterns and the soil quality in a Mediterranean context is studied here to test the hypothesis that soil microbiota is strongly affected by the level of anthropogenic soil alteration. Our aim has been to determine the potential effect of organic matter loss and associated changes in soil microbiota of poorly evolved Mediterranean soils (Leptosols and Regosols) suffering anthropogenic stress (i.e., cropping and deforestation). The studied soils correspond to nine different sites which differed in some features, such as the parent material, vegetation cover, or soil use and types. A methodological approach has been used that combines the classical physical and chemical study of soils with molecular characterization of the microbial assemblages using specific primers for Bacteria, Archaea and ectomycorrhizal Fungi. In agreement with previous studies within the region, physical, chemical and biological characteristics of soils varied notably depending on these factors. Microbial biomass, soil organic matter, and moisture, decreased in soils as deforestation increased, even in those partially degraded to substitution shrubland. Major differences were observed in the microbial community structure between the mollic and rendzic Leptosols found in forest soils, and the skeletic and dolomitic Leptosols in substitute shrublands, as well as with the skeletic and dolomitic Leptosols and calcaric Regosols in dry croplands. Forest soils displayed a higher microbial richness (OTU’s number) and biomass, as well as more stable and connected ecological networks. Here, we point out how human activities such as agriculture and other effects of deforestation led to changes in soil properties, thus affecting its quality driving changes in their microbial diversity and biomass patterns. Our findings demonstrate the potential risk that the replacement of forest areas may have in the conservation of the soil’s microbiota pool, both active and passive, which are basic for the maintenance of biogeochemical processes.

Distribution characteristics, influencing factors and releasing risk evaluation of phosphorus in the sediment of water-level-fluctuating zone in Lake Nansi

南四湖是南水北调东线最大的调蓄湖泊，周期性水位涨落会形成大面积消落带，认知消落带底泥磷形态赋存特征、影响因素及释放潜能，对于保障东线调水水质具有重要的科学意义.本研究分析了南四湖消落带底泥磷形态分布特征，探讨了各形态磷与土地利用、母质类型及底泥理化因素之间的关系，评价了南四湖消落带底泥磷的污染程度并分析了其释放风险.结果发现，消落带底泥中总磷（TP）、无机磷（IP）、NaOH提取态磷（NaOH-P）、HCl提取态磷（HCl-P）和有机磷（OP）含量的平均值分别为745.37、510.51、50.42、460.09和234.86 mg/kg，以HCl-P为主的IP占比较高.南四湖消落带底泥各形态磷含量具有较高的空间异质性，TP、IP、OP、HCl-P和NaOH-P含量的变异系数分别为30.7%、36.9%、29.6%、37.6%和51.2%.自然湿地、乔木林地和水浇地等土地利用方式下的底泥NaOH-P、HCl-P、IP、OP和TP含量差异不显著.土壤类型对消落带底泥OP含量影响明显，但对TP、IP、NaOH-P和HCl-P含量则影响不大.NaOH-P含量与HCl-P含量具有显著正相关，与OP含量则具有极显著正相关.南四湖周边30多km²消落带底泥磷污染程度相对较高，轻度、中度和重度污染底泥分别占5.9%、76.5%和17.6%，部分区域底泥磷释放潜能较高.研究结果可为南四湖消落带内源磷释放控制以及水质保障提供科技支撑.;As an important storage hub of the Eastern line of the South-to-North Water Transfer Project, the periodic fluctuation of water level in Lake Nansi leads to the formation of a large-area water-level-fluctuating zone (WLFZ), which affects the water quality of Lake Nansi. Understanding the distribution characteristics, influencing factors and release potential of phosphorus in the sediment of the WLFZ of Lake Nansi is of great scientific significance to ensure the water quality of the Eastern line of South-to-North Water Transfer Project. In this work, the distribution characteristics, influencing factors and releasing risk evaluation of phosphorus in the sediment in the WLFZ of Lake Nansi were investigated. The results showed that the average contents of total phosphorus (TP), inorganic phosphorus (IP), NaOH-extractable phosphorus (NaOH-P), HCl-extractable phosphorus (HCl-P) and organic phosphorus (OP) in the sediment of the WLFZ of Lake Nansi were 745.37, 510.51, 50.42, 460.09 and 234.86 mg/kg, respectively. The percentages of IP to TP in the sediments of the WLFZ of Lake Nansi were higher than those of OP to TP. The contents of different P species in the sediments of the WLFZ of Lake Nansi had great spatial heterogeneity, with TP, IP, OP, HCl-P and NaOH-P at 30.7%, 36.9%, 29.6%, 37.6% and 51.2% respectively. There was no significant difference in the contents of NaOH-P, HCl-P, IP, OP and TP in the sediments of natural wetland, arbor forest land and irrigated land. The type of sediment parent material could affect the content of OP in the sediment, but it had a negligible effect on the contents of TP, IP, NaOH-P and HCl-P in the sediment. There was a significant positive correlation between NaOH-P content and HCl-P content, and a very significant positive correlation between NaOH-P content and OP content. The pollution evaluation results showed that 5.9% of the sediment samples were slightly contaminated with phosphorus, 76.5% were moderately contaminated with phosphorus, and 17.6% were heavily contaminated with phosphorus. On the whole, the phosphorus pollution in the sediments of the 30 km² WLFZ of Lake Nansi was relatively serious. The results can provide scientific and technical support for the control of phosphorus release from sediments and the protection of water quality in the WLFZ of Lake Nansi.

Global patterns and drivers of soil total phosphorus concentration

Abstract. Soil represents the largest phosphorus (P) stock in terrestrial ecosystems. Determining the amount of soil P is a critical first step in identifying sites where ecosystem functioning is potentially limited by soil P availability. However, global patterns and predictors of soil total P concentration remain poorly understood. To address this knowledge gap, we constructed a database of total P concentration of 5275 globally distributed (semi-)natural soils from 761 published studies. We quantified the relative importance of 13 soil-forming variables in predicting soil total P concentration and then made further predictions at the global scale using a random forest approach. Soil total P concentration varied significantly among parent material types, soil orders, biomes, and continents and ranged widely from 1.4 to 9630.0 (median 430.0 and mean 570.0) mg kg−1 across the globe. About two-thirds (65 %) of the global variation was accounted for by the 13 variables that we selected, among which soil organic carbon concentration, parent material, mean annual temperature, and soil sand content were the most important ones. While predicted soil total P concentrations increased significantly with latitude, they varied largely among regions with similar latitudes due to regional differences in parent material, topography, and/or climate conditions. Soil P stocks (excluding Antarctica) were estimated to be 26.8 ± 3.1 (mean ± standard deviation) Pg and 62.2 ± 8.9 Pg (1 Pg = 1 × 1015 g) in the topsoil (0–30 cm) and subsoil (30–100 cm), respectively. Our global map of soil total P concentration as well as the underlying drivers of soil total P concentration can be used to constraint Earth system models that represent the P cycle and to inform quantification of global soil P availability. Raw datasets and global maps generated in this study are available at https://doi.org/10.6084/m9.figshare.14583375 (He et al., 2021).

Factors affecting cadmium accumulation in the soil profiles in an urban agricultural area

Soil Cd pollution is a serious environmental issue associated with human activities. However, the factors determining exogenous Cd dynamics in the soil profile in a complex environment are not well understood. Based on regional observations from 169 soil profiles across the Chengdu Plain, this study explored the key factors controlling Cd accumulation in the soil profile under actual field conditions. Results showed that total soil Cd contents decreased from 0.377 to 0.196 mg kg−1 with increasing soil depth. The effects of phosphate fertilizer rates, road density and precipitation on the difference in total soil Cd content were only observed in topsoil, while agricultural land-use type and topography had no impact. In contrast, significant differences in the total soil Cd content among different parent material types were found in the 0–20, 40–60 and 60–100 cm soil depths. One sample t-tests showed that significant Cd accumulation occurred in the whole soil profile in soils formed from Q4 (Quaternary Holocene) grey alluvium, while soils formed from Q3 (Quaternary Pleistocene) old alluvium and Q4 grey-brown alluvium showed significant Cd accumulation only in the 0–40 cm soil layers. In the topsoil, acid soluble Cd accounted for the largest proportion of the total Cd in soils formed from Q4 grey alluvium, reducible Cd was the main fraction in soils formed from Q4 grey-brown alluvium, while reducible Cd and residual Cd contributed the largest proportion of the total soil Cd in soils formed from Q3 old alluvium. The above results indicated that parent material was the decisive factor determining the magnitudes and depths of exogenous Cd accumulation in the soil profile due to its impacts on the Cd fraction distributions. These findings suggested that the parent material-induced Cd fraction distributions and accumulation should be considered for effectively exploring targeted remediation strategies for Cd pollution.

Physicochemical properties of selected soils formed on cretaceous sediments, shales and quaternary alluvium in Edo State, Nigeria

Physicochemical properties of some selected soils formed on three varied parent materials in Edo State, Nigeria, were evaluated for their physicochemical properties. Soil samples were collected from profile pits sunk on each parent material type. The collected soil samples were air-dried and analyzed for physicochemical properties and analyzed in the laboratory using standard methods. Results showed that the soils were low in plant nutrient elements, as revealed by their estimated levels of availability. Organic carbon, phosphorus and nitrogen were deficient in the soils. Soils formed on the three-parent materials were sufficient in Mg (1.11, 1.54, 0.88 cmol kg-1), Na (1.32, 1.39, 1.35 cmol kg-1) and K (0.20, 0.37, 0.28 cmol kg-1) while Ca was higher in soils formed on cretaceous sediment (3.08 cmol kg-1) and shale (5.22 cmol kg-1) than in quaternary alluvium (2.05 cmol kg-1). There was a significant positive correlation among the various soil properties of the different parent materials. In order to improve the productive capacity of these soils to obtain high crop yields; it is recommended that the soils be limed to increase pH levels to near neutral and optimum fertilization (organic and inorganic) for nitrogen, phosphorus and basic cations in the different parent materials.

Interrelationships among phosphorus and some soil properties in soils derived on cretaceous sediments, shale and quaternary alluvium in Edo state, Nigeria

Interrelationships among phosphorus and some soil properties in soils derived from Cretaceous Sediments, Shale and Quaternary Alluvium in Edo State, Nigeria was evaluated to understand likely soil constraints to increase crop yields. For each parent material type, soil samples were collected from the profile pits sunk. The soil samples collected were air-dried and were analyzed for physicochemical properties and various P-forms in the laboratory using standard methods. Results showed that in soils derived on cretaceous sediment, clay had significant negative relationship with total P, organic P and available P while in soils formed on shale, clay had significant negative relationship with total P and available P. Soil pH had a significant positive relationship with total P (r = 0.771*), indicating that the soil pH has a greater influence on total P in soils derived from quaternary alluvium. Organic carbon had significant positive relationship with total P (r = 0.913*), organic P (r = 0.984**), Ca-P (r =0.907*) and available P (r = 0.980**) in soils derived from shale. In order to boost the productive potential of these soils to achieve high yields of viable crops, remedial steps are taken to correct deficiencies. The availability of phosphorus and other nutrients to plant crops on these soils would be enhanced by the use of organic manure, with or without the use of inorganic P-fertilizer.

Pedogenic or anthropogenic? An approach to evaluate fragipan and redox features in paleosols of NE China

Archaeological studies are usually based on human-made artifacts or other remains of human activities. Where no such materials are preserved, soil properties can be used to detect past human activities. Archaeologists found some conspicuous features formed in a loess-paleosol succession comprising a sequence of Luvisol Bt horizons at the Shenyang Agriculture University Paleolithic Archaeological Site. The purpose of this study was to analyze the soil properties inside these features and in the surrounding soil material, to judge whether the soil features were related to human activities or not. Particle size distribution, major element composition and rare earth element contents inside the soil features and in the surrounding material were used to test the uniformity of the material inside and around the features. Soil organic carbon content, magnetic susceptibility and available phosphorus at the soil depth where the features occurred were used as indicators of potential human influence. Results showed that the conspicuous features had the same type of loess-like parent material as the surrounding soil, and also their chemical properties did not point to any human activities. We found two genetically different types of features. One type represents an initial stage of fragipan formation, whereas the other resulted from redox processes caused by perched water. In conclusion, this study proved that the soil features were not formed by human activities but by pedogenesis. Our approach is generally applicable to similar cases and research questions.

PARENT MATERIAL AS A KEY DETERMINANT OF SOIL PROPERTIES IN SOUTHERN PART OF NATIONAL PARK KRKA, CROATIA

Parent material is an important factor in soil formation, especially in soils formed in Mediterranean region dominated by calcareous sedimentary rocks. Their basic properties (mineralogical composition, coherence, and permeability for water) influence the resistance to weathering and type of weathering products, its amount, particle size distribution, as well as the intensity of physicochemical transformations within the original rock residue. Thus, the aim of this study was to investigate the impact of parent material on soil properties in southern part of Krka National Park, Croatia. Weathering of carbonate parent material (limestones, dolomites, conglomerates, marls) along with other soil forming factors was the base for soil development in this area. Thus, Calcocambisols and Terra rossa, typical and ilimerized are the most widespread soil types, while Calcomelanosols, Colluvium and Rendzinas are as well represented, but in much lesser extent. Soil depth, presence of coarse fragments and carbonate content in these soils vary considerably depending on parent material, although factors such as relief, vegetation and anthropogenic impact cannot be neglected. In general, shallow soils ( 35 cm) were formed on limestones and conglomerates, while medium deep soils (35-70 cm) were formed on marly substrates. The content of coarse fragments of variable size in soils (fine gravel 2-6 mm to boulders 60-200 cm) is related to different weathering processes of parent material. The presence of carbonate nodules on soil surface and within soil profile also indicates pedogenetic processes related to different types of carbonate parent material.

Soil Phosphorus Speciation and Availability in Meadows and Forests in Alpine Lake Watersheds With Different Parent Materials

In the Lake Tahoe Basin in California and Nevada (USA), managing nutrient export from watersheds into streams and the lake is a significant challenge that needs to be addressed to improve water quality. Leaching and runoff of phosphorus (P) from soils is a major nutrient source to the lake, and P loading potential from different watersheds varies as a function of landscape and ecosystem properties, and how the watershed is managed. In this research, P availability and speciation in forest and meadow soils in the Lake Tahoe Basin were measured at two watersheds with different parent material types. Soils developed on andesitic parent materials had approximately twice as much total P compared to those developed on granitic parent materials. Regardless of parent material, organic P was 79–92% of the total P in the meadow soils, and only 13–47% in the forest soils. Most of the soil organic P consisted of monoester P compounds, but a significant amount, especially in meadow soils, was diester P compounds (up to 30% of total extracted P). Water extractable P (WEP) concentrations were ~10 times greater in the granitic forest soils compared to the andesitic forest soils, which had more poorly crystalline aluminosilicates and iron oxides that retain P and thus restrict WEP export. In the meadow soils, microbial biomass P was approximately seven times greater than the forest soils, which may be an important sink for P leached from upland forests. Results show that ecosystem and parent material are important attributes that control P speciation and availability in the Lake Tahoe Basin, and that organic P compounds are a major component of the soil P and are available for leaching from the soils. These factors can be used to develop accurate predictions of P availability and more precise forest management practices to reduce P export into Lake Tahoe.

Bacterial community tolerance to Cu in soils with geochemical baseline concentrations (GBCs) of heavy metals: Importance for pollution induced community tolerance (PICT) determinations using the leucine incorporation method

PICT (Pollution Induced Community Tolerance) to Cu is a useful and sensitive tool to assess the effects of Cu pollution in soils under laboratory conditions. However, in field situations, the absence of reference values, i.e. bacterial community tolerance to Cu baseline from non-polluted soils, make the method uncertain when we want to know if a soil is or is not polluted from a microbiological point of view. In order to shed some light on this topic, the PICT (Pollution Induced Community Tolerance) concept was used to determine the bacterial community tolerance to Cu in uncontaminated soils developed on five different parent materials, using log IC50 as a tolerance index. IC50 was calculated as the amount of Cu that inhibit 50% of bacterial growth (estimated via the leucine incorporation method) in a bacterial suspension extracted from soil. With physico-chemical soil characteristics and type of parent material, a linear multiple regression equation was fitted explaining 80% of the variance in log IC50 values. This equation provides a useful tool to estimate the bacterial community tolerance to Cu baseline in a soil using the general soil characteristics, allowing for the more general use of PICT without the need of reference soils.

Quantitative analysis of the main sources of pollutants in the soils around key areas based on the positive matrix factorization method.

Quantitative identification of the main sources of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in soils around multiple types of key areas is of great significance for blocking pollution sources. However, there is a lack of more comprehensive relevant research. In this study, Beijing was taken as the research area and four main sources were identified using the positive matrix factorization (PMF) method. The concentration of Pb, PAHs, Cr, and Hg in soils was significantly affected by the presence of landuse type, road traffic, natural factor, and industrial production, respectively, and the farmland, distance to main road, Proterozoic Changcheng-Jixian parent material and cinnamon soil type, and the gross industrial production make greater contributions to these four factors respectively than other variables. Moreover, the uncertainty of the PMF indicates that this four-factor PMF solution is stable and appropriate. These results provide support for the comprehensive control of soil environmental risks.

Characteristics of phosphorus fractions and their driving factors in forest soils with different parent materials in the mid-subtropics, China

With the aim to understand the influence degree and mechanism of parent material and forest type on soil phosphorus component, we analyzed soil P fractions, iron and aluminum oxides, microbial biomass, and phosphatase activity in Castanopsis carlesii and Cunninghamia lanceolata forest soils developed from two types of parent materials, sandstone and granite, in Sanming, Fujian Province. The results showed that both parent material and forest type significantly affected the contents of different P fractions. The contents of total P, labile inorganic/organic P, moderately labile inorganic/organic P, and non-labile P from sandstone-developed soils were significantly higher than those from granite-developed soils. Moreover, soil labile organic P, moderately labile inorganic/organic P and non-labile P fraction in sandstone-developed soils of C. carlesii forest were significantly higher than those of C. lanceolata forest, while the corresponding soil P fractions in granite-deve-loped soils had no significant difference between the two types of forests. The activity of acid phosphatase (ACP) in granite-developed soils was significantly higher than that in sandstone-developed soils under two types of forest, while soil microbial biomass carbon (MBC) and P (MBP) in sandstone-developed soils were significantly higher under C. carlesii forest than under C. lanceolata fo-rest. The content of soil P fractions was significantly positively correlated with the content of different forms of iron and aluminum oxides, MBP, and MBC, but negatively correlated with soil pH and acid phosphatase activity (ACP). Our results indicated that parent material and forest types might affect soil P fractions and characteristics mainly through altering soil iron and aluminum oxides, ACP, MBP in mid-subtropical forest soils.

Accurate Determination and Comprehensive Evaluation of Heavy Metals in Different Soils from Jilin Province in Northeast China

To provide technical support and theoretical guarantee for the prevention and control of soil heavy metal pollution, the main types of topsoil and parent material in Jilin Province were systematically collected, accurately tested by atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry, and comprehensively evaluated through five indexes. By principal component analysis, it was initially judged that there were 2 or 3 major heavy metal sources in topsoil, which could be attributed to the parent material, soil-forming process, and/or anthropogenic factor. The pH of surface soil mainly depended on its parent material, and changed to a certain extent during its formation. The contents of heavy metals As, Hg, Cd, Cr, Cu, Ni, Pb, and Zn in surface soils were both significantly influenced by parent materials and soil-forming processes. Here the geo-accumulation index calculated by corresponding background value of parent material was more suitable for pollution assessment than the other four indexes, and the heavy metal contamination degree in each type of soil basically followed the order: Hg > Cd > Cu, Pb, Zn, As > Cr, Ni. Furthermore, the heavy metal contamination level in the types of soils was ranked as follows: cambisol, phaeozem > podzol, planosol > chernozem. The health risk assessment indicated that the soil in the study area had no significant carcinogenic or non-carcinogenic risks. Excluding the influence of parent material and soil-formation process, the comprehensive evaluation of soil heavy metal pollution will be more reasonable.

Soil selenium transformation across different parent materials in Pothwar uplands of Pakistan

Selenium (Se) is an essential trace element for humans but non-essential for plants. Selenium bioavailability depends on selenium forms in soil. Selenium contents may vary with the source of parent material, and pedogenesis controls its vertical distribution. The objectives of this study were to determine the variation in Se fractions with parent material and pedogenesis in Pothwar uplands of Pakistan. Triplicate soil profiles at different development stages from selected parent materials (sandstone, alluvium, loess, and shale) were sampled at different genetic horizons level. The soils were characterized for pH, dissolved organic carbon, total organic carbon, dithionite extractable amorphous iron, and cation exchange capacity. Soil selenium was fractioned into ion-exchangeable, metal oxides, organic, humic, sulfide, and residual selenium. Selenium in the soil extract was measured using HVG-AAS after centrifuge and passing through a 0.45-μm cellulose free filter. The distribution of total selenium content and selenium fractions varied with the type of parent material and soil genesis. Total selenium contents differed significantly across the different parent material. The highest total selenium was in shale followed by loess, alluvium, and sandstone, respectively. Exchangeable ion, metal oxides, and organic matter selenium were more in loess or the same level as of shale. Evaluation of the distribution of selenium fractions enabled us to estimate the occurrence of potential selenium deficiency and toxicity to humans and animals based on the parent materials and pedogenesis.

Conditions favoring local podzolization in soils developed from flysch regolith – A case study from the Bieszczady Mountains in southeastern Poland

Podzolization occurs mainly in soils developed from highly leached and coarse-textured parent materials in areas that remain under the influence of humid climate conditions and where forest or heath vegetation supply enough organic matter to form organic horizons on the surface of mineral soils. However, in certain environmental conditions Podzol development was found also in extremely unfavorable types of parent material, e.g. ultramafic rocks or even regoliths containing carbonates. Flysch rock regolith found in many geographic regions is an example of soil parent material considered to be unfavorable for podzolization in its major part due to its high clay, Ca, and Mg contents. Areas formed of materials considered to be rather unfavorable to Podzol development but characterized by very local occurrence of podzolized soils may be helpful in assessing the factors which favor the occurrence of this process and its thresholds. The main objective of the present study was to determine an optimal combination of conditions that trigger podzolization in soils in the uppermost part of mid-mountain slopes formed of flysch rocks in the Bieszczady Mountains in southeastern Poland. At the same time, an attempt was made to determine pedogenic thresholds of local podzolization in soils in the studied area. The studied soils showed large variability in soil processes and were classified according to the WRB as four different Reference Soil Groups: Podzols, Cambisols, Umbrisols and Leptosols. Two out of the eight soil profiles exhibited well-developed spodic horizons, while the properties of the two other profiles may be explained by either cryptopodzolization and/or formation of andic properties in non-volcanic soil material. Evidence of podzolization was observable in changes in soil morphology (i. e. color and consistence of soil material), vertical distribution of labile C and Fe and Al pedogenic forms, changes in mineral composition (mainly dissolution of chlorite, formation of mixed layered clay minerals and the redistribution of various amorphous phases), and also micromorphological features (presence of monomorphic fine coatings consisting of Fe- and Al-organic compounds). However, the occurrence of Podzols was strongly limited across the study area and determined by a combination of environmental conditions such as the co-occurrence of four key factors: (1) humid and cool climate, (2) sandy texture and mineral composition of parent material dominated by quartz, (3) location on the uppermost part of consequent slopes (ridge crests) and (4) predominance of berry (Vaccinium sp.) thickets in the vegetation cover in tandem with the occurrence of mosses (Polytrichum strictum and Sphagnum sp.). Moss cover facilitated a pedogenic feedback setup by increased water storage which promoted more advanced weathering and increase in dissolved organic carbon content in the soil. In the consequence the pedogenic threshold of podzolization was crossed.

Effectiveness of a soil mapping geomatic approach to predict the spatial distribution of soil types and their properties

A soil map (1:50,000 scale) was recently produced in Sardinia (Italy) using a cost-effective GIS approach. In this study we aimed to verify, in two pilot areas and by means of statistical analysis, the effectiveness of the adopted methodology in representing and predicting the spatial distribution of soil types and properties. We focused on evaluation of 1) the influence of landforms and parent materials on soil types (WRB Reference Soil Groups) and selected soil properties and 2) the suitability of the adopted methodology for calibrating a model to predict land unit composition in terms of different soil types.Leptosols, Regosols and Cambisols were prevalent on slopes, with Leptosols being more frequent on convex slopes and Regosols and Cambisols on concave slopes. In flat areas, soil types mainly depended on the type and age of parent material, with Regosols and Cambisols prevailing on Holocene deposits and highly developed soils (mainly Luvisols) largely prevailing on Pleistocene deposits. On hard rock, Leptosols were very frequent on terrigenous metamorphic rock and frequent on granite. Besides Leptosols, Regosols occurred more frequently than Cambisols on both parent materials. Landforms strongly influenced soil depth and available water capacity. Soils on plains were deeper than those on slopes, where convex forms had shallower soils than concave forms. A similar trend applied to the available water capacity. The parent material had a significant effect on topsoil properties (thickness, texture, pH and organic carbon content) of soils belonging to the same WRB Reference Soil Group (analysis done on the most relevant WRB Reference Soil Groups, i.e. Leptosols, Regosols and Cambisols).We calibrated and tested stepwise multiple linear regressions (MLR) and general linear models (GLM) to predict the composition of map units in terms of different WRB Reference Soil Groups. The two models gave very similar results, with distinct distribution patterns that were coherent with the relationships observed between soil groups and specific combination of terrain attributes and parent materials. Results showed that both models were more reliable in predicting the absence rather than presence of a given soil type.

Geochemical characteristics of crude oil and oil-source correlation in the western Qaidam Basin, China

The Cenozoic in the western Qaidam Basin is rich in oil and gas resources and has good prospects for exploration. The maturity, sedimentary environment, and biological source of the crude oil in the western Qaidam Basin are discussed based on the composition characteristics of biomarkers in crude oil and source rocks. The above is performed to classify the genetic types of crude oil and determine the oil source relationship. It is found that the crude oil shows the characteristics of low mature–mature and is formed in the reducing environment with high salinity. The organic matter is from the mixed source with dominant aquatic plants input. According to the sedimentary environment, parent material types, and maturity characteristics, the crude oil in the western Qaidam Basin can be classified into four types. (1) Type I is from the Shizigou-Yuejin areas, which have a high content of gammacerane, a low value of Pr/Ph, C27 sterane predominance, and “tail-upwarping” phenomenon. (2) Type II is from the Qiekelike-Zhahaquan and Nanyishan-Youquanzi areas, which have C27 sterane predominance and no “tail-upwarping” phenomenon. Its content of gammacerane is lower than type I. (3) Type III is from the Dafengshan and Huangguamao areas, which have C29 sterane predominance and no “tail-upwarping” phenomenon. (4) Type IV is from the Kaitemilike area, which has a C27 sterane predominance, no “tail-upwarping” phenomenon, and lower content of gammacerane than that of others. The result of the oil-source correlation shows that the crude oil is dominantly derived from source rocks of the lower Ganchaigou Formation (E3) and the upper Ganchaigou Formation (N1).