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The Lijiang River Basin is a humid, subtropical, karst landform in China and is listed as a World Heritage Site. However, with the rapid development of urbanization and tourism activities in recent years, it faces increasingly severe non-point source pollution. To understand the temporal and spatial variations in nitrogen and phosphorus pollution discharge and the changes in river water quality, the Jingui Small Basin, in the upper reaches of the Lijiang River, was chosen as a representative system. Changes in nitrogen and phosphorus concentrations were continuously monitored in the main river channel and the river water quality was evaluated using the comprehensive water quality identification index method. The results indicated that there were obvious seasonal changes in nitrogen and phosphorus discharge loads in the basin. Both nitrogen and phosphorus discharge loads were higher in the crop-growing season than in the non-growing season. No significant difference in nitrogen and phosphorus discharge load between different scales was found, and the scale was not the key factor affecting the nitrogen and phosphorus discharge load of Jingui River. As the river flowed from the initial water source to the outlet of the basin, water quality was characterized by the spatial pattern of the upper reaches > the middle reaches > the lower reaches. Except for the water quality at the outlet of the basin in November and December, which reached Class V, the comprehensive water quality of each sub-basin reached the target water quality of the water function zoning from May to December. The elucidation of the nitrogen and phosphorus pollution discharge patterns in the Jingui River and the changes in water quality provide a reference for the control and management of agricultural non-point source pollution in the Lijiang River Basin. [ABSTRACT FROM AUTHOR]

The remobilization, migration, precipitation, and enrichment of ore-forming elements are closely related to structures. Therefore, detailed regional and ore-field structural analyses are critical for determining the genesis of a mineral deposit. The Jiangnan Orogenic Belt (JOB) is an important gold polymetallic metallogenic belt in South China, which is characterized by multiple periods of gold mineralization in the Paleozoic and Mesozoic. However, the genesis of these gold polymetallic deposits is still not well understood due to a lack of systematic research on the regional geology, ore-controlling structures and metallogenic mechanism. In this study, a detailed structural survey at the surface and in the subsurface tunnels was conducted on the Woxi Au-Sb-W deposit, the genesis of which is relatively controversial among the gold polymetallic deposits in the JOB due to poor structural constraints. In addition, a wolframite U-Pb dating was carried out to further constrain the relationship between structures and mineralization. Based on the results of these studies, together with those from previous studies, it is proposed that the Woxi deposit and surrounding areas likely underwent six periods of regional deformation, which are constrained in time and geodynamic setting. Furthermore, we present a systematic discussion on the roles of ore-controlling structures in the transportation, distribution, and deposition of ore-forming elements and localization of orebodies. According to the wolframite dating results, structural analyses, and previous data, we propose that the Woxi Au-Sb-W deposit was formed in two stages during the Yanshanian: a W (wolframite)-Au mineralization stage at ca. 140 Ma and an Au-Sb-W (scheelite) mineralization stage at <130 Ma. These mineralizing events are interpreted to have a tight relationship with tectonic reactivation, and the ore-forming fluids were derived from deep sources, including those of magmatic or metamorphic origins. The Woxi deposit can therefore be classified as an "intracontinental reactivation-type", and the mineralization is related to lithospheric extension caused by plate retreat, retention, and delamination following the cessation of westward subduction of the Paleo-Pacific Plate beneath the East Asian continent. [ABSTRACT FROM AUTHOR]

The objective of this work was to modify the HEC-HMS flood prediction for the karstic watershed of the Lijiang River, South China, through the quantitative inclusion into the model of the available reservoir capacity of karst (ARCK) as a case study. Due to the complexities caused by hidden drainage networks in karst hydrology, as a new approach, soil moisture accounting loss was used to reflect the ARCK in flood forecasting. The soil moisture loss was analyzed against daily rainfall runoff data across 1.5 years by using an artificial neural network via phyton programming. Through the correlations found among the amounts of soil moisture and river flow fluctuations in response to precipitation and its intervals, coefficients were introduced to the model for output modifications. ARCK analysis revealed that while heavy rainfalls with longer intervals (i.e., 174 mm/2d after 112 days of the dry season) may not cause considerable changes in the river flow magnitude (0.1–0.64 higher owing to high ARCK), relatively small rainfalls with higher frequency (i.e., 83 mm/4d during the wet season) can cause drastic raise of river flow (10–20 times greater at different stations) due to lower ARCK. Soil moisture accounting loss coefficients did enhance the model's simulated hydrographs accuracy (NSE) up to 16% on average as compared to the initial forecasting via real data. However, the modifications were valid for flood events within a few years from the soil moisture observation period. Our result suggested that the inclusion of ARCK in modeling through soil moisture accounting loss can lead to increased prediction accuracy through consistent monitoring. [ABSTRACT FROM AUTHOR]

The Uragen giant sandstone-hosted Zn–Pb deposit has a proven reserve of 5.90 Mt metals in the southern ore zone and potentially 10 Mt metals for the whole deposit, and orebodies are strictly confined to the bleached clastic rocks of the Lower Cretaceous red beds. The bleaching has been used to guide lead–zinc exploration; however, its nature and origin, as well as the relationship with Zn–Pb mineralization, remains unclear, although it is closely related to regional oil–gas infillings. Detailed field investigation and petrographic observation, TESCAN-integrated mineral analyzer (TIMA), and X-ray fluorescence (μ-XRF) analysis of the red and bleached sandstone at the same sedimentary layer demonstrate that the bleaching is mainly caused by the reductive dissolution of hematite pigment, which probably resulted from the interaction with H2S formed by in situ sulfate reduction during hydrocarbon migration. The calcite cements in the bleached sandstones show δ13C and δ18O values of −5.36~−5.94‰ and 20.94~27.91‰, respectively, and these samples fall close to the evolution line of decarboxylation of organic matter in δ13C-δ18O diagram, also suggesting a genetic relationship between the bleaching and hydrocarbon-bearing fluids. Petrol–mineral composition changes and sulfide characteristics of red, bleached, mineralized zones, as well as pyrite locally replaced by coarse-grained galena in the mineralized zone, imply that the bleaching may occurred before Zn–Pb mineralization. Mass balance calculation and μ-XRF analysis indicate that large amounts of Fe and minor Zn were extracted from red beds with little or no sulfates; however, the red beds with abundant sulfates may be a sink for leached ore metals during the bleaching process. We therefore propose that the former accumulations of iron sulfides and reduced sulfur in the bleached zones may provide an ideal chemical trap for later Zn–Pb mineralization, and the bleached zones with high ∑S contents are the favorable prospective targets of the Uragen-style sandstone-hosted Zn–Pb deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Woxi deposit is featured by coenriched Au-Sb-W elemental association. • The Au, Sb, and W occurred mainly as invisible gold, stibnite, and scheelite. • Transition of fluid-rock interaction to phase separation caused ore precipitation. • Dissolution-reprecipitation process facilitate coenriched Au-Sb-W metallogenesis. It is well-known that tungsten and antimony are commonly enriched in the gold deposit and occur as Au-Sb or Au-W deposits. However, the Woxi deposit, located in the West Jiangnan Orogen of South China, is remarkably co-enriched in the Au-Sb-W elemental association. This deposit is characterized by multistage Au mineralization and reactivation of structures developed in the Neoproterozoic metamorphic rocks, but the detailed mechanism of its co-enriched Au-Sb-W metallogeny is still unclear. Here, we perform detailed petrographic observations and ore mineral textural and pyrite compositional analyses by using SEM and LA-ICP-MS to constrain ore-forming physiochemical conditions and to decipher the Au-Sb-W metallogenic mechanism in the Woxi deposit. The Woxi deposit consists of nine auriferous quartz lodes in the shape of stratiform, tabular, and lenticular, which are surrounded by alteration halos in the Neoproterozoic slate. These orebodies are distributed along the bedding-parallel fracture zones of the EW-striking and N -dipping in the purplish red slate of the Madiyi Formation, below the regional EW-striking Woxi fault. Four stages of hydrothermal mineralization and alteration processes could be recognized in the Woxi. Stage 1 occurs in bleached slate, and consists of euhedral, porous, and coarse auriferous pyrite (Py1), with slight arsenopyrite, siderite, and rutile. Stage 2 mainly consists of subhedral to euhedral and compositional zoning auriferous pyrite (Py2) and scheelite (Sch1), with slight wolframite and apatite hosted in quartz veinlets and native gold enclaved in Sch1. Stage 3 is characterized by scheelite (Sch2) and stibnite, with slight native gold and dendritic-shaped anhedral auriferous pyrite (Py3) hosted in quartz veins. Stage 4 features a quartz-calcite-barite-chlorite mineral assemblage that occurred as veinlets, or in the pressure shadows of Py1. Gold is mainly incorporated in the three stages (S1 to S3) of arsenian pyrite (Py1to Py3) as invisible gold and, to a lesser extent, formed visible native gold at late S2 and S3, tungsten mineralization occurs mainly as scheelite (Sch1) and wolframite at S2, with a minor amount of scheelite (Sch2) at S3, and antimony mineralization is mainly occurred as stibnite at S3. Furthermore, invisible gold most likely occurs as nanoscale particles of Au-Bi-Pb-bearing tellurides in Py1, and may be hosted in the structurally bounded lattice of Py2 and Py3.The SEM study presents highly developed dissolution-reprecipitation microstructures in hydrothermal minerals, such as pyrite, arsenopyrite, wolframite, scheelite, and apatite. Mineral paragenesis and pyrite trace element signatures suggest the ore fluid is characterized by elevated f O2 , low pH and high temperature in S1, decreased f O2 , medium pH and medium temperature in S2, and elevated f O2 , high pH and low temperature in S3. The evolution of the physicochemical condition may be induced by penetration of multipulse ore-forming fluids and the transition of the ore-forming mechanism from fluid-rock interaction in S1 and early S2 to phase separation in late S2 and S3, as suggested by textural and LA-ICP-MS analyses. This study highlighted that coupled dissolution-reprecipitation reactions might facilitate the association of the Au-Sb-W elemental that successively mineralized and co-enriched in the Woxi deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Woxi deposit is an orogenic Au-Sb-W deposit. • U-Pb dating on apatite and wolframite yielded a robust gold mineralization age of ca. 141 Ma. • Pyrite in situ S-Pb isotopic signatures suggest the ore-forming metals and fluids mainly derived from a metasomatized lithospheric mantle. • This study provides a new example of orogenic gold deposit that was controlled by translithospheric processes in a back-arc environment far from the plate subduction zone. The majority of gold mineralization in the Jiangnan Orogenic Belt (JOB) of South China share similarities with the orogenic type, but the nature of mineralization remains controversial, especially in terms of intracrustal versus subcrustal origin of ore fluids and metals and their relationships with the subduction of the Paleo-Pacific plate. This paper reports results of in situ analyses of minerals closely related to gold mineralization, including U-Pb ages of apatite and wolframite, and S-Pb isotopes of pyrite, from the Woxi Au-Sb-W deposit in the western Jiangnan Orogen, and use them to address the above problems. The Woxi deposit, which consists of several auriferous quartz lodes hosted by ductile–brittle shear zones in the Neoproterozoic slate. The hydrothermal mineralization and alteration processes are divided into four stages. Early-ore stage (S1) is characterized by disseminated, euhedral, porous, coarse auriferous pyrite (Py1) with minor amounts of arsenopyrite, siderite, and rutile in the bleached slate. Main-ore stage (S2) is characterized by subhedral to euhedral, auriferous pyrite (Py2) with compositional zoning, with small amounts of wolframite and apatite in quartz veinlets. Late-ore stage (S3) is represented by scheelite and stibnite with minor amounts of native gold and anhedral, dendritic auriferous pyrite (Py3) in quartz veinlets. Post-ore stage (S4) features a quartz-calcite-barite-chlorite mineral assemblage that occurs as veinlets or in pressure shadows of Py1. Apatite and wolframite associated with Py2 yield a consistent U-Pb age of ca. 141 Ma, which is corresponded to a time when the Paleo-Pacific plate started to roll back, and a Basin-and-Range style tectonic regime began to developing in South China. The different stages of pyrite have variable S isotopes, with the δ34S CDT values (mainly between −6‰ and +1 ‰) largely overlapping with those of the metasomatized mantle (−5‰ ∼ + 5 ‰), and Pb isotope ratios between crustal and mantle values. Taking these results together, we proposed that the Woxi deposit and many other gold deposits in the JOB formed from subcrustal processes involving the metasomatized upper mantle above the subduction zone. Given the extended distance from JOB to the Paleo-Pacific plate boundary, the metasomatized mantle underneath the JOB is likely initially formed during the plate subduction leading to the formation of the JOB during the Neoproterozoic, which is further fertilized by upwelling asthenosphere due to rollback of the Paleo-Pacific plate in the Mesozoic. [ABSTRACT FROM AUTHOR]

Aboveground Biomass (AGB) in the grassland senescence period is a key indicator for assessing grassland fire risk and autumnal pasture carrying capacity. Despite the advancement of remote sensing in rapid monitoring of AGB on a regional scale, accurately monitoring AGB during the senescence period in vast arid areas remains a major challenge. Using remote sensing, environmental data, and 356 samples of grassland senescence period AGB data, this study utilizes the Gram-Schmidt Pan Sharpening (GS) method, multivariate selection methods, and machine learning algorithms (RF, SVM, and BP&#95;ANN) to construct a model for AGB during senescence grassland, and applies the optimal model to analyze spatio-temporal pattern changes in AGB from 2000 to 2021 in arid regions. The results indicate that the GS method effectively enhances the correlation between measured AGB and vegetation indices, reducing model error to some extent; The accuracy of grassland AGB inversion models based on a single vegetation index is low (0.03 ≤ |R| ≤ 0.63), while the RF model constructed with multiple variables selected by the Boruta algorithm is the optimal model for estimating AGB in arid regions during the senescence period (R 2  = 0.71, RMSE = 519.74 kg/ha); In the span of 22 years, the annual average AGB in the senescence period of arid regions was 1413.85 kg/ha, with regions of higher AGB primarily located in the northeast and southwest of the study area. The area experiencing an increase in AGB during the senescence period (79.97 %) was significantly larger than that with decreased AGB (20.03 %)., Competing Interests: Declaration of competing interest We claim that any of the material in the manuscript has not been published or is under consideration for publication otherwhere. All authors declare that there is no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Di(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer known to pose health risks to humans upon exposure. Recognizing the toxic nature of DEHP, our study aimed to elucidate the response mechanisms in Brassica chinensis L. (Shanghai Qing) when subjected to varying concentrations of DEHP (2 mg kg -1 , 20 mg kg -1 , and 50 mg kg -1 ), particularly under tissue stress. The findings underscored the substantial impact of DEHP treatment on the growth of Brassica chinensis L., with increased DEHP concentration leading to a notable decrease in chlorophyll levels and alterations in the content of antioxidant enzyme activities, particularly superoxide dismutase (SOD) and peroxidase (POD). Moreover, elevated DEHP concentrations correlated with increased malondialdehyde (MDA) levels. Our analysis detected a total of 507 metabolites in Brassica chinensis L., with 331 in shoots and 176 in roots, following DEHP exposure. There was a significant difference in the number of metabolites in shoots and roots, with 79 and 64 identified, respectively (VIP > 1, p < 0.05). Metabolic pathway enrichment in Brassica chinensis L. shoots revealed significant perturbations in valine, leucine, and isoleucine biosynthesis and degradation, aminoacyl-tRNA, and glucosinolate biosynthesis. In the roots of Brassica chinensis L., varying DEHP levels exerted a substantial impact on the biosynthesis of zeatin, ubiquinone terpenoids, propane, piperidine, and pyridine alkaloids, as well as glutathione metabolic pathways. Notably, DEHP's influence was more pronounced in the roots than in the shoots, with higher DEHP concentrations affecting a greater number of metabolic pathways. This experimental study provides valuable insights into the molecular mechanisms underlying DEHP-induced stress in Brassica chinensis L., with potential implications for human health and food safety., 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. Published by Elsevier B.V.)

Potentially toxic elements (PTEs) pollution in lake sediments is a serious threat to the ecological safety of lake water and human health, owing to anthropogenic activities. Studies on the distribution of pollution, the differences in lake types, and the influencing factors in China as a whole are lacking. This study collected data on PTEs (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in Chinese lake sediments published from 2005 to 2021, and aimed to evaluate pollution levels and spatial distribution characteristics of PTEs in lake sediments, differences in pollution in different types of lakes, and influencing factors. The results showed that (1) All metals in the lake sediments accumulated to different degrees, when compared to the background values. (2) The lake type pollution levels were ranked: urban lakes > reservoirs > plateau lakes > natural lakes. (3) The geoaccumulation and potential ecological risk indexes both indicated that Cd and Hg are the main pollutants, and that the overall ecological risk level of lake sediments in China is high. (4) The degree of economic and population growth is highly correlated with the concentrations of eight PTEs; the amount of fertilizer and pesticide used in agricultural activities are the main factors affecting As and Hg; industrial activities and traffic pollution emissions are the predominant factors affecting Cu and Ni. (5) In the interaction detection analysis, the Cr content was mainly influenced by natural factors; Cd, Pb, and Zn contents were affected more by human activities. This study provides a reference for understanding the current status and influencing factors of PTE pollution in Chinese 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 © 2023 Elsevier B.V. All rights reserved.)