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Soil organic carbon (SOC) forms the largest terrestrial organic carbon (C) pool, which is regulated by complex connections between exogenous C input, microbial activity, and SOC conversion. Few studies have examined the changes in natural abundance C due to microbial activity after exogenous C inputs in karst lime soils in China. In this research, the 13C isotope tracer technique was employed to investigate the priming effect of SOC on typical lime soil (0~20 cm) of 13C_litter and 13C_calcium carbonate (CaCO3) through a mineralization incubation experiment. Samples were collected at 5, 10, 20, 40, 60, and 80 days of incubation and analyzed for SOC mineralization, SOC distribution across fractions (>250 μm, 53~250 μm, and <53 μm), and soil microbial diversity. A control consisting of no exogenous C addition was included. SOC mineralization and SOC priming were considerably higher (15.48% and 61.00%, respectively) after litter addition compared to CaCO3. The addition of either litter or CaCO3 reduced the total organic C (TOC) and macroaggregate (>250 μm) and microaggregate (53~250 μm) C fractions by 2150.13, 2229.06, and 1575.06 mg C kg−1 Cbulk on average and increased the mineral particulate C fraction (<53 μm) by 1653.98 mg C kg−1 Cbulk. As the incubation time extended, a significantly positive correlation was apparent between SOC priming and soil fungal diversity, as well as between the mineral particulate C fraction and soil bacterial diversity. The effect of soil fungal diversity on SOC priming (R = 0.40, p = 0.003) significantly exceeded that of bacterial diversity on SOC sequestration (R = 0.27, p = 0.02). Our results reveal that after adding litter or CaCO3, soil fungi stimulate SOC mineralization and decomposition and soil bacteria enhance SOC sequestration, with the effects of fungi being more pronounced. These findings can provide a theoretical basis for understanding C sequestration and emission reduction in karst lime soils. [ABSTRACT FROM AUTHOR]

In this paper, the engineering characteristics of the soft soil in Guan-Yun section of Lian-Yan railway were evaluated based on the CPTU test. The soil layer and classification of soil were performed by using the multi-functional CPTU test. On the basis of results of the CPTU test, the in-situ state parameters including the over consolidation ratio and the undrained shear strength were provided. Simultaneously, the consolidation and permeability characteristics were studied. The results showed that the silt and mucky soil was slightly overconsolidated and the clay was overconsolidated. Moreover, the coefficient of permeability was small and the rate of settlement consolidation was slow. The results revealed that the site engineering conditions were evaluated more accurately by the multi-function CPTU test technology. [ABSTRACT FROM AUTHOR]

The standard penetration test (SPT) and cone penetration test (CPT) are the two most commonly used in-situ tests. In this paper, SPT-CPT correlation is investigated using statistical and regression method based on a database of in-situ tests. Two correlation equations of the SPT N-value and the CPT cone tip resistance qcare proposed. The equations are applied for the liquefaction potential evaluation. Three effect factors including the soil type, mean particle size, and fine content are investigated for SPT-CPT correlation. The simple correlation can be used for the preliminary site investigation with least data and information. The comprehensive one can give more accurate result with detailed data. These two correlation equations are useful for different purposes with different accuracies. The liquefaction evaluations using the proposed correlation method are compared with those from the Chinese code method. It is shown that the proposed correlation can be helpful for site investigation and geotechnical design in practice. [ABSTRACT FROM PUBLISHER]

The Chinese government initiated a massive conservation program called 'Grain-for-Green' in 1999 to reduce soil erosion and improve ecosystem function. Implementing practical sustainable development in the loess plateau still remains problematic, particularly in its eco-fragile areas. Here we discussed an approach for sustainable development at the watershed scale by integrating land use suitability, ecosystem services and public participation in the loess hilly area. We linked land use scenario analysis and economic modeling to compare the outcomes of three scenarios, CLU (Current Land Use), GOLU (Grain-production Oriented Land Use) and PSLU (Potential Sustainable Land Use). The results indicated that compared to PSLU, GOLU may provide a higher economic productivity in the short-term, but not in the long-term. CLU ranked lowest in terms of economic benefits and did not meet the daily needs of the local farmers. To reconcile the land use adjustments with farmers' basic needs, a labor-saving land use strategy is necessary. Since the PSLU scenario assumes that slope cropland should be converted to pastures or orchards, more time may be available for off-farm work and for more public participation in integrated ecosystem management. Financial support to the local farmers for environmental conservation should be modulated in function of their positive contribution to ecosystem management. [ABSTRACT FROM AUTHOR]

Abstract: Shear wave velocity (V s) measurements from seismic piezocone penetration (SCPTU) soundings have been increasingly used for site characterization and liquefaction potential assessments. Several sites in Tangshan region, China liquefied during the Tangshan earthquake, M w =7.8 in 1976 and these sites were characterized recently using the SCPTU device. Other sites in the same region where liquefaction was not observed are also included in the present field investigations. Three liquefaction assessment models-based on measured shear wave velocity, shear modulus and tip resistance parameters of SCPTU are evaluated in this paper for their accurate predictions of liquefaction or non-liquefaction at the test sites. Analyses showed that the shear wave velocity—liquefaction resistance model with normalized overburden vertical stress have yielded a success rate of 78% in predicting liquefied site cases and another similar approach with mean stress based normalization has a success rate of 67%. The correlation of q c /G o-CRR 7.5 based on geological age has correctly assessed the liquefaction potential at most sites considered in this research. Overall, all three models based on shear wave velocity, shear modulus and cone tip resistance are proven valuable in the assessments of liquefaction at the present test sites in the Tangshan region. [Copyright &y& Elsevier]

Abstract: This paper focuses on the piezocone (CPTU) test results and the related interpretation procedures to predict ultimate pile load capacities of driven and jacked piles for the Jiangsu soft soil deposits in China. The pile foundation data including pile load tests on twenty six piles from several field sites are compiled and presented. A comparison was made to explain the advantages and fallacies of various CPT based interpretation methods. A modified CPTU-based method has been proposed, which was used to predict the ultimate capacity from effective cone tip resistance and excess pore water pressure. Comparison of the calculated pile capacities to the measured pile capacities showed that the modified CPTU method''s predictions showed a better agreement with the ultimate load capacities determined from static loading tests. Also, there was less scatter in this method''s predictions than other CPTU methods for deep foundations of soft clay deposits, indicating a higher reliability in the proposed methodology. [Copyright &y& Elsevier]

The coefficient of consolidation ( c or c) is an important parameter in both geotechnical and geo-environmental engineering, measuring the flow characteristics of soils. In China, conventionally it is obtained from the oedometer test, which is time consuming and of limited accuracy due to inevitable sample disturbance. These difficulties can be overcome by in situ pizeocone dissipation tests which provide continuous measurements of pore water pressure with time. In this paper, existing methods for interpreting coefficient of consolidation in clays from piezocone dissipation tests are briefly reviewed. Piezocone tests were undertaken at different sites in the Jiangsu province of China and piezocone dissipation tests conducted at different penetration depths. Based on the reference c values determined from the laboratory oedometer tests, comparisons with existing interpretation methods were undertaken. It is shown that the Teh and Houlsby's interpretation method has a much higher accuracy for determining the coefficient of consolidation of Quaternary clay deposits while the values of c obtained by the CPTU method are in the range of back-analyzed field values. [ABSTRACT FROM AUTHOR]

Abstract: Geotechnical engineers worldwide practice a variety of in-situ techniques to classify soils in order to obtain their physical and engineering properties. An electric piezocone, which is an advanced version of the cone penetrometer, is capable of measuring cone resistance, sleeve friction and pore pressure. The piezocone testing data not only provide valuable information on soil types but are also useful in deriving correlations with the engineering properties of soil for the purposes of analysis and design of foundations. In a view to establish a region-specific correlation between piezocone penetration resistance and soil properties, piezocone penetration tests (PCPT or CPTu), borings, and other in situ tests were carried out at seven locations in Jiangsu Province, China. PCPT data were first used for classifying soil; thus the data were fully analyzed and validated for providing a reasonable soil classification. Several available CPT based classification charts are used to determine soil types; these results are further validated with the soil classification determined from the field samples and basic soil test results. This paper summarizes these analysis results, including description of the available charts and their performance in soil classification. [Copyright &y& Elsevier]

This article mainly focuses on the piezocone test results and the related interpretation procedures to predict ultimate pile load capacities of driven and jacked piles for the Jiangsu soft soil deposits. First, the available literature on the evaluations of CPTU methods was collected and reviewed. The new CPTU-based method has been proposed to predict the ultimate capacity from effective cone tip resistance to excess pore water pressure. Second, this article presents an analysis of these pile load tests and correlations to neighboring piezocone data. Four CPTU-based methods are evaluated using the ultimate pile load capacities, shaft friction, and end bearing capacity. The results of a comparison of the calculated pile capacities to the measured pile capacities are very favorable to the new CPTU method, which shows better agreement with the capacity determined in a static loading test and less scatter than other CPTU methods. [ABSTRACT FROM AUTHOR]

Due to rapid population growth and infrastructure demand in China, more effective use of existing land is required. Infrastructure construction in coastal regions has driven rapid economic development. With increasing numbers of port facilities, cross-sea bridges and offshore engineering projects, large diameter and super-long cast-in-place piles are increasingly needed in these regions. The p-y curves of piles are key to evaluating their horizontal bearing characteristics, which is critical to the risk evaluation, design and construction of large infrastructural supports. In the present study, a p-y curve analysis method based on piezocone penetration test (CPTu) data is proposed, which uses the Matlock and hyperbolic p-y models. The relationship between CPTu cone tip parameters (q t , u 2 and q e) and p-y curve parameters (p u and y 50) is established. Moreover, the deformation and mechanical characteristics of large diameter and super-long cast-in-place piles in the Yangtze River floodplain are analysed thoroughly. The feasibility and reasonability of the proposed p-y curve method based on CPTu test data are verified through numerical simulation and horizontal load field tests. A hyperbolic p-y model based on CPTu test data is applicable to sandy soils, while a Matlock p-y curve model based on CPTu test data is applicable to cohesive soils. [ABSTRACT FROM AUTHOR]

Changes in humidity can influence the mechanical performance of embankments and the bearing capacity of pavement structures. Investigating the characteristics of embankment humidity fields is important in assessing the safety and stability of highways built on embankments. This study conducted long-term monitoring of the humidity within an embankment constructed from recycled construction waste on the Xi'an-Xianyang Highway, China. Humidity field dynamics beneath the road axis, lane, soil shoulder, hard shoulder, and slope at the barricade and arc-shaped protective slope sections are analyzed in detail. The embankment humidity field distribution was uneven due to differences in the initial humidity. Areas around the road axis, sides, and top of the embankment were readily affected by rainfall. Compared with the arc-shaped protective slope section, the barricade section had good water isolation. Damaged or improper drainage components of the pavement and slope can rapidly increase the humidity in areas of water infiltration. The effect of external water infiltration on water migration within the embankment at the barricade and arc-shaped protective slope sections is investigated comprehensively. [ABSTRACT FROM AUTHOR]

• Change in moisture and settling velocity of recycled construction waste are analyzed. • Influence of moisture on the settling velocity is mainly within a depth of 3 m. • Settling velocity of the arc-shaped protective slope section contains two peaks. • Prediction model for settling velocity of recycled construction waste is obtaind. Variation in moisture can influence the mechanical performance of embankments, and affect the bearing capacity of pavement structures. Therefore, it is necessary to constrain the relationship between the moisture and the settling velocity of embankments, to assess the safety and stability of highways built on the embankments. This research includes a long-term study of monitoring the moisture and deformation of an embankment on the Xi'an-Xianyang Highway, China. The influence of moisture on the settling velocity of barricade and arc-shaped protective slope sections were analyzed in detail. The results show that changes to the moisture and settling velocity followed similar trends. The influence of moisture on the settling velocity were mainly observed within a depth of 3 m from the road surface. The settling velocity of the arc-shaped protective slope section was bimodal. A model to predict the influence of moisture on the settling velocity of embankments made from recycled construction wastes was developed, based on the probability density function defined by the Weibull distribution. A formula to describe the cumulative effects of moisture on the settling velocity was devised, based on data measured at the barricade sections. [ABSTRACT FROM AUTHOR]

A comprehensive genetic diversity analysis of 87 Passiflora germplasm accessions domesticated and cultivated for several years in the karst region of Guizhou, China, was conducted utilizing simple sequence repeat (SSR) fluorescent markers. These Passiflora species, renowned for their culinary and medicinal value, could bring significant economic and ecological benefits to the region. This study aimed to assess the genetic resources of these species and facilitate the selection of superior cultivars adapted to the karst environment. Our analysis revealed an abundance of SSR loci within the Passiflora transcriptome, with single-base repeats being the most prevalent type. Through rigorous primer screening and amplification, we successfully identified 27 SSR primer pairs exhibiting robust polymorphisms. Further interrogation at eight microsatellite loci revealed 68 alleles, underscoring the high level of genetic diversity present in the cultivated accessions. The average expected heterozygosity was 0.202, with the ssr18 locus exhibiting the highest value of 0.768, indicating significant genetic variation. The mean polymorphic information content (PIC) of 0.657 indicates the informativeness of these SSR markers. Comparative analyses of the cultivated and potential wild progenitors revealed distinct genetic variations among the different Passiflora types. Genetic structure and clustering analyses of the 87 accessions revealed seven distinct groups, suggesting gene flow and similarities among the resources. Notably, a DNA fingerprinting system was established using eight SSR primer pairs, effectively distinguishing the selected cultivars that had adapted to the karst mountainous region. This study not only deepens our understanding of Passiflora genetic resources in the karst environment but also provides a valuable reference for conservation, genetic improvement, and cultivar selection. The rich genetic diversity of the Passiflora germplasm underscores their potential for sustainable utilization in breeding programs aimed at enhancing the economic and ecological viability of these valuable plant species., Competing Interests: The authors declare no conflicts of interest.

Phytoplankton communities are crucial components of aquatic ecosystems, and since they are highly interactive, they always form complex networks. Yet, our understanding of how interactive phytoplankton networks vary through time under changing environmental conditions is limited. Using a 29-year (339 months) long-term dataset on Lake Taihu, China, we constructed a temporal network comprising monthly sub-networks using "extended Local Similarity Analysis" and assessed how eutrophication, climate change, and restoration efforts influenced the temporal dynamics of network complexity and stability. The network architecture of phytoplankton showed strong dynamic changes with varying environments. Our results revealed cascading effects of eutrophication and climate change on phytoplankton network stability via changes in network complexity. The network stability of phytoplankton increased with average degree, modularity, and nestedness and decreased with connectance. Eutrophication (increasing nitrogen) stabilized the phytoplankton network, mainly by increasing its average degree, while climate change, i.e., warming and decreasing wind speed enhanced its stability by increasing the cohesion of phytoplankton communities directly and by decreasing the connectance of network indirectly. A remarkable shift and a major decrease in the temporal dynamics of phytoplankton network complexity (average degree, nestedness) and stability (robustness, persistence) were detected after 2007 when numerous eutrophication mitigation efforts (not all successful) were implemented, leading to simplified phytoplankton networks and reduced stability. Our findings provide new insights into the organization of phytoplankton networks under eutrophication (or re-oligotrophication) and climate change in subtropical shallow lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Litter is an important component of forest ecosystems and plays an important eco-hydrological function. Many studies have been carried out on litter at present, but less research has been carried out on the eco-hydrological service functions of litter in different plant communities in Karst, especially in the area of Karst peak-cluster depressions in southwest China. To reveal the characteristics of the hydrological function of the litter layer of the plant community in the area of Karst peak-cluster depressions around FAST (Five-hundred-meter Aperture Spherical Radio Telescope), three typical plant community litter layers of the broad-leaved forest, coniferous forest, and shrub were selected as research objects, and the hydrological function of the litter layer of different plant community types was studied using the immersion method. The results indicated: 1) The litter layer of the broad-leaved forest plant community has the strongest function of intercepting and regulating precipitation (Mlmax = 24.17±0.33 t/ha, Msv = 19.93±0.21 t/ha), and its hydrological service function is the best. 2) The higher the decomposition degree of litter, the stronger the interception function. 3) The fitted equations for both the litter water-absorption capacity (Qct) and time (t) for plant communities were Qct = b + alnt, and the fitted equations for both the litter water-release capacity (Qst) and time (t) were Qst = a t b. 4) The fitted equations for both the water absorption and release rates (vc and vs) and time (t) of the litter were v = a t -b. The water absorption rates of litter were the fastest within 5 min (15529.01~22634.43 g/kg·h), with the greatest interception and storage function for short-term rainfall., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Understanding the extent of contamination, sources and various carcinogenic and non-carcinogenic risks associated with different heavy metals in soil-crop systems is crucial for the prevention of heavy metal pollution. A survey was undertaken to determine heavy metal concentrations and degree of pollution in soil-crop systems (rice, wheat, and corn) using various indices such as pollution factor ( CF ), geo-accumulation index ( I geo ), enrichment coefficients and transfer coefficient, and to determine the source of heavy metals pollution in the Wanjiang Economic Zone, Anhui Province, China. A total of 308 pairs of soil-crop samples were collected in this study, comprising 245 pairs of soil-rice samples, 53 pairs of soil-wheat samples, and 10 pairs of soil-corn samples. The concentrations of cadmium (Cd) and nickel (Ni) in the soil of the study area exceeded the national limitation of heavy metals in the soil of China (GB 15618-2018, Soil Environmental Quality: Risk Control Standard for Soil Contamination of Agricultural Land. Ministry of Environmental Protection of China. Beijing. China ). The concentrations of copper (Cu), zinc (Zn) and lead (Pb) were also above the national limits to a lesser extent. All eight heavy metals (Cd, Cu, Ni, Pb Zn, arsenic (As), chromium (Cr), and mercury (Hg)) exceeded the background values in the study area. The enrichment coefficients of rice, wheat and maize to Cd, Cu and Zn were higher than those to other elements. On the basis of I geo , it can be indicated that the rhizosphere soil of rice was slightly polluted by Cd and Hg, while the concentrations of the other heavy metals were below the safety limits. The CF and pollution load index ( PLI ) indicated that the soil in the study area was heavily contaminated with heavy metals. A principal component analysis identified different sources of soil heavy metal pollution, that is, Cu, Pb, Zn and Cd from industrial sources, Cr and Ni from natural sources, and As and Hg from agricultural sources. The carcinogenic risk of heavy metals was related to the intake of crops. Residents in the study area ingest rice, wheat, and corn on a daily basis. On the basis this study, it is suggested that local governments should pay attention to the carcinogenic risk of heavy metals in rice.