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Phosphate‐solubilizing microbes (PSMs) drive the biogeochemical cycling of phosphorus (P) and hold promise for sustainable agriculture. However, their global distribution, overall diversity and application potential remain unknown. Here, we present the first synthesis of their biogeography, diversity and utility, employing data from 399 papers published between 1981 and 2017, the results of a nationwide field survey in China consisting of 367 soil samples, and a genetic analysis of 12986 genome‐sequenced prokaryotic strains. We show that at continental to global scales, the population density of PSMs in environmental samples is correlated with total P rather than pH. Remarkably, positive relationships exist between the population density of soil PSMs and available P, nitrate‐nitrogen and dissolved organic carbon in soil, reflecting functional couplings between PSMs and microbes driving biogeochemical cycles of nitrogen and carbon. More than 2704 strains affiliated with at least nine archaeal, 88 fungal and 336 bacterial species were reported as PSMs. Only 2.59% of these strains have been tested for their efficiencies in improving crop growth or yield under field conditions, providing evidence that PSMs are more likely to exert positive effects on wheat growing in alkaline P‐deficient soils. Our systematic genetic analysis reveals five promising PSM genera deserving much more attention. [ABSTRACT FROM AUTHOR]

Nitrogen isotope (δ15N) analysis has been used to evaluate depositional redox conditions in well-preserved sedimentary systems; however, fewer N-isotope studies have been performed to reconstruct the redox conditions in lacustrine shales. In this paper, we report the δ15N data from the Upper Triassic Chang 7 Shale of the Ordos Basin, North China. Sedimentary δ15N values are significantly higher in the Chang 7 3 and the lower part of the Chang 7 2 submembers (Zone A; average = 9.4 ± 1.3‰) than in the upper part of the Chang 7 2 and the Chang 7 1 submembers (Zone B; average = 5.4 ± 1.5‰). Previous geochemical measurements (i.e., U and TOC/P) of both zones show wide redox variation, however, the average values of these redox proxies are relatively higher in Zone A than those of Zone B. Combined with lithological aspects of the Chang 7 Shale, our study suggest that Zone A was mainly deposited under suboxic bottom water conditions, whereas Zone B deposits accumulated within an oxygenated water column. Stable organic carbon isotopes (δ13C org) and total nitrogen (TN) values of the two zones display little variation that could be attributed to changing organic matter sources and/or post-depositional alteration of δ15N. Thus, we suggest that variations in δ15N throughout the Chang 7 Shale primarily reflect differences in depositional redox conditions and δ15N values of the shale that can provide important details regarding the depositional history of unconventional resource plays. • Provide the first δ15N records of the Chang 7 Shale, Ordos Basin. • Differences in δ15N are primarily influenced by water column redox conditions. • Organic-rich intervals accumulated under suboxic conditions. • Tectonic events drove redox changes during deposition. [ABSTRACT FROM AUTHOR]

• We summarized and discussed about antimony pollution in water environment and its sources. • Research on toxicity of antimony was documented. • Occurrence and biogeochemistry of antimony in water environment were discussed. Antimony, the compounds of which exhibit toxicity, finds extensive usage in industrial processes for flame retardants, plastics, batteries, electronic components, and mechanical bearings. Consequently, mining and industrial activities contribute to the continuous migration of antimony into aquatic environments, influencing the Earth's biogeochemical cycle. Given China's status as the primary global exporter of antimony, the country confronts the challenge of water pollution arising from intensive antimony mining operations. This paper focuses on the latest advances in research concerning antimony toxicity, identifies potential sources of antimony water pollution, and explores its migration pathways and biogeochemistry. Moreover, the study provides estimations of antimony quantities in different compartments. Finally, we discuss the prospects for enhancing our comprehension of antimony's biogeochemical behavior. [ABSTRACT FROM AUTHOR]

Global management of wetlands to suppress greenhouse gas (GHG) emissions, facilitate carbon (C) sequestration, and reduce atmospheric CO2 concentrations while simultaneously promoting agricultural gains is paramount. However, studies that relate variability in CO2 and CH4 emissions at large spatial scales are limited. We investigated three-year emissions of soil CO2 and CH4 from the primary wetland types of the Liaohe Delta, China, by focusing on a total wetland area of 3287 km2. One percent is Suaeda salsa, 24% is Phragmites australis, and 75% is rice. While S. salsa wetlands are under somewhat natural tidal influence, P. australis and rice are managed hydrologically for paper and food, respectively. Total C emissions from CO2 and CH4 from these wetland soils were 2.9 Tg C/year, ranging from 2.5 to 3.3 Tg C/year depending on the year assessed. Primary emissions were from CO2 (~98%). Photosynthetic uptake of CO2 would mitigate most of the soil CO2 emissions, but CH4 emissions would persist. Overall, CH4 fluxes were high when soil temperatures were >18°C and pore water salinity <18 PSU. CH4 emissions from rice habitat alone in the Liaohe Delta represent 0.2% of CH4 carbon emissions globally from rice. With such a large area and interannual sensitivity in soil GHG fluxes, management practices in the Delta and similar wetlands around the world have the potential not only to influence local C budgeting, but also to influence global biogeochemical cycling. [ABSTRACT FROM AUTHOR]

Abstract: Submarine groundwater discharge (SGD) with inputs of nutrients in certain regions may play a significant role in controlling water quality in the coastal regions. In this paper, we have determined four naturally occurring radium isotope (223Ra, 224Ra, 226Ra and 228Ra) activities and nutrient concentrations in surface water, coastal groundwater and river water in the mixing zone of Laoye Lagoon to estimate the fluxes of SGD by several models. The activities of the four radium isotopes of ground water were considerably greater than those in surface water samples. Using a 224Ra/228Ra activity ratio (AR) model, we estimated the average lagoon water age to be 3.2days, which was comparable with the flushing time of 4.0days. Based on the excess radium isotopes and the water age of the lagoon, the estimated fluxes of SGD (in 106 m3/d) ranged from 2.64 to 5.32 with an average of 4.11. Moreover, we used Si balance to evaluate the flux of SGD (4.8×106 m3/d) which was close to the result calculated by radium. The SGD-derived nutrient fluxes (in mol/d) were DIN=1.7×105, PO4 3− =5.2×102, and SiO3 =5.3×104. Furthermore, we applied the biogeochemical budget approach using SiO3 as a tracer to evaluate the impact of SGD. The differences between the results estimated by radium and SiO3 may indicate different pathways for the input of nutrients. [Copyright &y& Elsevier]

Soil organic carbon (SOC) is of great importance in the global carbon cycle. Distribution patterns of SOC in various regions of China constitute a nation-wide baseline for studies on soil carbon changes. This paper presents an integrated and multi-level study on SOC stock patterns of China, and presents baseline SOC stock estimates by great administrative regions, river watersheds, soil type regions and ecosystem. The assignment is done by means of a recently completed 1: 1,000,000 scale soil database of China, which is the most detailed and reliable one in China at the present time. SOC densities of 7292 soil profiles collected across China in the middle of the 1980s were calculated and then linked to corresponding polygons in a digital soil map, resulting in a SOC Density Map of China on a 1: 1,000,000 scale, and a 1km×1km grid map. Corresponding maps of administrative regions, river watersheds, soil types (ST), and ecosystems in China were also prepared with an identical resolution and coordinate control points, allowing GIS analyses. Results show that soils in China cover an area of 9.281×106 km2 in total, with a total SOC stock of 89.14Pg (1Pg=1015 g) and a mean SOC density of 96.0tC/ha. Confidence limits of the SOC stock and density in China are estimated as [89.23Pg, 89.08Pg] and [96.143tC/ha, 95.981tC/ha] at 95% probability, respectively. The largest total SOC stock (23.60Pg) is found in South-west China while the highest mean SOC density (181.9tC/ha) is found in north-east China. The total SOC stock and the mean SOC density in the Yangtze river watershed are 21.05Pg and 120.0tC/ha, respectively, while the corresponding figures in theYellow river watershed are 8.46Pg and 104.3tC/ha, respectively. The highest total SOC stocks are found in Inceptisols (34.39Pg) with SOC density of 102.8tC/ha. The lowest and highest mean SOC densities are found on Entisols (28.1tC/ha), and on Histosols (994.728.1tC/ha), repectively. Finally, the total SOC stock in shrub and forest ecosystem classes are 25.55 and 21.50Pg, respectively; the highest mean SOC density (209.9tC/ha) was recorded in the wetland ecosystem class and the lowest (29.0tC/ha) in the desert ecosystem class. Among five forest ecosystem types, Evergreen conifer forest stores the highest SOC stock (6.81Pg), and Deciduous conifer forest shows the highest SOC density (225.9tC/ha). Figures of SOC stocks stratified by Administrative regions, river watersheds, soil types and ecosystem types presented in the study may constitute national-wide baseline for studies of SOC stock changes in various regions in the future. [Copyright &y& Elsevier]

The Cretaceous Era has always been a focus of geologic and palaeoenvironmental studies. Previous researchers believed that the impact of the global carbon cycle represents significant short-term global biogeochemical fluctuations, leading to the formation of a large number of organic rich sediments in the marine environment. During the Turonian, a large number of organic-rich oil shales were deposited in the lakes of the Songliao Basin in the Qingshankou Formation. How the depositional environment affected the formation of oil shales in continental lakes and the characteristics of these oil shales remain controversial. In this paper, through sampling of Qingshankou Formation strata, various testing methods are used to provide a variety of new data to study the characteristics of oil shales and palaeoenvironment evolution history in the Songliao Basin. The research of the sediments in the Qingshankou Formation in the Fuyu oilfield, Songliao Basin, via result analysis revealed that the oil shales possess an excellent oil-generation potential with moderate-high total organic carbon (TOC) levels (0.58–9.43%), high hydrogen index (HI) values (265–959 mg hydrocarbons (HC)/g TOC), high extractable organic matter (EOM) levels (2.50–6.96 mg/g TOC) and high hydrocarbon fractions (48–89%). The sources of the organic matter were mainly zooplankton, red algae and higher plants (including marine organisms). The aqueous palaeoenvironment of the Qingshankou Formation was a saline water environment with a high sulfate concentration, which promoted an increase in nutrients and stratification of the water density in the lake basin. Oxygen consumption in the bottom water layer promoted the accumulation and burial of high-abundance organic matter, thus forming the high-quality oil shales in the Qingshankou Formation. The global carbon cycle, warm-humid palaeoclimate, dynamic local biogeochemical cycling and relative passive tectonism were the most likely reasons for the TOC increase and negative δ13Corg deviation. [ABSTRACT FROM AUTHOR]