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101. 题目: Erosion effects on soil carbon and nitrogen dynamics on cultivated slopes: A meta-analysis
文章编号: N21040227
期刊: Geoderma
作者: Maire Holz, Jürgen Augustin
更新时间: 2021-04-02
摘要: Soil carbon (C) redistribution within cultivated landscapes is strongly controlled by soil erosion and sedimentation and it is widely appreciated that C is preferentially transported during erosion. In contrast, it remains elusive whether erosion induced transport of C and N is coupled although changes in the balance between C and N strongly affect soil C and N dynamics. We therefore reviewed the literature on carbon and nitrogen redistribution by erosion. Twenty-nine studies reported results on C and N enrichment of freshly eroded sediments after erosion events. Thirty-nine studies reported results on C and N contents and stocks along eroded slopes. Eroded sediments were enriched in C and N by 51.3% and 50.6% indicating that both elements are stored in soil fractions that are preferentially eroded. Slope gradient and soil texture strongly affected C and N enrichment. Decreasing C and N enrichment in fine-textured soils was counterbalanced by increasing erosion rates in these soils. This suggests similar SOM losses independent of textural class. The C/N ratio increased by 9.9%, pointing to preferential movement of C-rich particulate organic matter (POM) compared to N-rich mineral associated organic matter (MAOM). Breakdown of aggregates by rainfall energy possibly released POM which is then preferentially eroded. Soil C and N contents and total stocks showed similar percentage increases from upslope to depositional sites, indicating that downslope C and N stocks were largely driven by enrichment, rather by than increases in depth or bulk density. Altogether, our findings confirm that quantification of soil loss alone is not sufficient to estimate erosion-induced changes in soil fertility, because soil organic matter and plant nutrients are selectively moved during erosion. This leads to a shift in C and N dynamics in different slope positions and thus to an increase in the spatial variability of the C and N along the slope.

102. 题目: New insights into organic carbon stabilization in soil macroaggregates: An in situ study by optical microscopy and SEM-EDS technique
文章编号: N21040226
期刊: Geoderma
作者: Patrizia Guidi, Gloria Falsone, Clare Wilson, Luciano Cavani, Claudio Ciavatta, Claudio Marzadori
更新时间: 2021-04-02
摘要: The purpose of this study was to investigate the in situ characterization of organic matter (OM) within soil macroaggregates, and to assess the relationships between OM characteristics and macroaggregate size indicating different OM stabilization mechanisms. Optical micro-morphological investigations, coupled to SEM-EDS (scanning electron microscopy and energy X-ray spectroscopy) technique, were carried out on thin sections of 1–4 and 0.25–1 mm soil aggregates (coarse and fine macroaggregates, respectively) from 0 to 20 cm soil layer corresponding to A horizon of four different sites in which soil structure were not disturbed by tillage. The intraggregate porosity, measured by image analysis of four different size classes (<50, 50–100, 100–200, >200 µm), showed that fine macroaggregates were significantly less porous (3.70–6.71% of total porosity) and had higher presence of the finest pore class (<50 μm) compared to coarse macroaggregates (5.93–9.08% of total porosity), independently from sites. The percentage of organic matter forms (OMFs) identified by optical investigation was significant higher in fine (13.5–17.7%) than in coarse (4.19–8.27%) macroaggregates. In particular, fine macroaggregates were richer in red and black amorphous organic forms, which were characterized by the highest values of Al:C, Fe:C and Ca:C molar ratios. These findings suggested thus an accumulation of OM in fine macroaggregates than in coarse macroaggregates occurred. It was probably due to a more efficient OM stabilization in fine than in coarse macroggregates related to both physical occlusion (lower porosity and smaller pore size) and organo-minerals interaction (higher presence of OMFs characterized by the highest Al:C, Fe:C and Ca:C ratios), The OM exposure index (EI), a measurement of the OM surface exposed to pores and thus potentially available for microbial activity, was unexpectedly higher in fine than in coarse macroaggregates (EI: 0.48–0.79 and 0.25–0.58 mm−1 in fine and coarse macroaggregates, respectively). However, the accessibility of OM defined by the EI seemed to facilitate neither the oxidative transformation nor the damage of enzyme activities, being the EI positively related to C:N ratio (r = 0.66), negatively to δ13C values (r = -0.74) and positive to the geometric mean of the five assayed enzyme activities related to C-cycle (r = 0.79). Therefore, even more potentially exposed, in fine macroaggregates the OM was not accessible to microorganisms due to the effective physical occlusion, and thus both accumulation of few transformed OM and maintenance of functionality related to C-cycle occurred. The OM stabilization in macroaggregates thus involved both physical occlusion and organo-metals/mineral phase interactions processes. Both these processes are often related to microaggregates rather than macroaggregates. Our findings thus seem to provide a new insight for studying the potentiality of OM stabilization and C sequestration in soil macroaggregates.

103. 题目: Water dispersible colloids and related nutrient availability in Amazonian Terra Preta soils
文章编号: N21040225
期刊: Geoderma
作者: Qian Zhang, Roland Bol, Wulf Amelung, Anna Missong, Jan Siemens, Ines Mulder, Sabine Willbold, Christoph Müller, Aleksander Westphal Muniz, Erwin Klumpp
更新时间: 2021-04-02
摘要: Amazonian Dark Earths (or terra preta de índico) are known as highly fertile soils that can maintain elevated crop yields for centuries. While this fertility was frequently ascribed to the presence of black carbon, the availability and colloidal binding of major nutrients received limited attention. We examined the size distribution and the elemental compositions of water-dispersible colloids (WDC) in both forested and cultivated Terra Preta topsoils (0–10 cm, Anthrosols), as well as in their adjacent non-Terra Preta controls (Acrisols) via asymmetric flow field-flow fractionation (FFF). Liquid-state 31P-nucelar magenetic resonance (NMR) spectra, black carbon content, and scanning electron microscope (SEM) images were also obtained. We found that WDC in Terra Preta soils contained a significant proportion of organo-mineral associations in the size range 30–300 nm, whereas, in contrast, water-dispersible nanoparticles with a diameter < 30 nm were dominant in the adjacent Acrisols. The shifts to larger WDC sizes in the Terra Preta soils went along with elevated pH values, as well as with elevated contents of Si, Al, Fe, Ca and organic matter-containing particles. Also P concentrations were enriched in both the water-extractable phase (WEP) and WDC extracts of Terra Preta soils relative to the adjacent Acrisols. We assume that the higher pH values and Ca ion concentrations promoted the involvement of soil organic matter (SOM) into the formation of larger-sized colloids consisting of kaolinite-like clay minerals, iron oxides and Ca ions in the Terra Preta soils. The elevated content of Ca in Terra Preta soil colloids may also contribute to the retention of P, likely via bridging of anionic P like orthopohosphate to SOM. Preventing soil acidification is thus not only to be recommended for Acrisols, but also for maintaining colloidal structures and related fertility in Terra Preta soils.

104. 题目: Cryptogams build up a living microcosm: Geoecological effects of biocrusts on volcanic tephra (Haleakalā, Maui, Hawai’i)
文章编号: N21040224
期刊: CATENA
作者: Francisco L. Pérez
更新时间: 2021-04-02
摘要: This study analyzes data of moss/lichen biocrusts on volcanic tephra at 2335 m in Haleakalā Crater (Maui, Hawaiʻi). Samples were compared among three adjacent positions: rolling crusts, pinnacled crusts, and bare tephra; two profiles contrasted substrate variation in crust and tephra areas. Field experiments assessed soil shear- and compressive-strength, infiltration rates, and diurnal soil temperatures; a lab experiment measured evaporation from crust specimens for 9 days. Biocrusts significantly affected physical, chemical, and structural soil properties. Fine particles, organic matter, and water storage were appreciably greater in biocrusts. Microsampling indicated upper-pinnacle sections accumulated more fine grains due to capture of volcanic ash, and also contained greater organic matter, than lower-pinnacle portions. Crust areas experienced infiltration rates ~2.8 times faster than tephra; mean diurnal temperatures were 12.1 °C (26.9 vs 39.0 °C) cooler in crusts than in tephra. Saturated crust specimens stored ~2.7 times more moisture than tephra soils; slower evaporation in biocrusts significantly lengthened the period over which poikilohydric cryptogams are able to maintain metabolic activity. Soil shear- and compressive-strength were higher on crusts than on tephra. Biocrust soils showed greater fertility, as available Ca2+, Mg2+, K+, P, NH4+-N, and cation-exchange capacity were higher than in tephra. NH4+-N was more concentrated under rolling crusts than in pinnacled ones; this is mainly ascribed to sampling methodology. Buried profile horizons suggest the site experienced additional tephra deposition during episodic volcanic eruptions. A developmental model assesses interactions among soil and environmental processes, and provides an integrated geoecological view of linkages that influenced biocrust genesis.

105. 题目: Constraining the conditions of phosphogenesis: stable isotope and trace element systematics of Recent Namibian phosphatic sediments
文章编号: N21040223
期刊: Geochimica et Cosmochimica Acta
作者: Kaarel Lumiste, Kaarel Mänd, Jake Bailey, Eva E. Stüeken, Kärt Paiste, Liisa Lang, Holar Sepp, Aivo Lepland, Kalle Kirsimäe
更新时间: 2021-04-02
摘要: Modern phosphogenesis occurs on continental margins influenced by upwelling and high primary productivity. The formation of phosphatic sediments is coupled to global climate fluctuations, biological cycling of phosphorus and local redox conditions. Although the processes involved in phosphogenesis are well described, high-resolution data on the redox and stable isotope systematics in Recent in-situ phosphorites are scarce. In this contribution, we investigate the trace element and sulfur, nitrogen and organic carbon stable isotope composition of Recent in-situ phosphatic sediments off the coast of Namibia. Also, we examine the reliability of different widely used geochemical proxies in phosphatic sediments. Our results suggest a shift from sulfidic to suboxic conditions, coinciding with the maximum in solid calcium phosphate mineral concentration. This shift is accompanied by unidirectional changes in Mo and Re enrichments and TOC abundance. Relatively low pyrite δ34S values (ca -20‰) of phosphatic sediments indicate open system fractionation during phosphogenesis. The initiation of phosphogenesis is also accompanied by negative shifts in sedimentary δ13Corg and δ15N values. Phosphate associated sulfate (PAS) δ34S values are lower than modern seawater sulfate values, suggesting the involvement of chemolithotrophic sulfur oxidation. Our results show a shift in redox conditions from sulfidic to (sub)oxic, coupled with active sulfur cycling are prerequisites for phosphogenesis. Phosphatic sediments show substantial enrichments in U and V highlighting the complexity of using these elements, as well as V/(V+Ni) and V/Cr, as redox proxies particularly in phosphorites and phosphatic sediments.

106. 题目: Adsorption characteristics and the removal mechanism of two novel Fe-Zn composite modified biochar for Cd(II) in water
文章编号: N21040222
期刊: Bioresource Technology
作者: Tingting Yang, Yingming Xu, Qingqing Huang, Yuebing Sun, Xuefeng Liang, Lin Wang, Xu Qin, Lijie Zhao
更新时间: 2021-04-02
摘要: In this study, adsorbents (Fe/Zn-RBC and Fe/Zn-DBC) for the removal of Cd(II) in water were successfully prepared by iron/zinc composite modified biochar derived from the branches of Robinia pseudoacacia biochar (RBC) and durian shells biochar (DBC). The results revealed that the iron and zinc ions were successfully loaded onto the biochar. The adsorption data of Cd(II) on Fe/Zn-BC conformed to the models of pseudo-second-order kinetic, Langmuir isothermal, and Redlich-Paterson. According to the results of batch experiments, the maximum sorption capacities of Fe/Zn-RBC and Fe/Zn-DBC for Cd(II) were approximately five times and three times higher than RBC and DBC, respectively. As the most dominant adsorption mechanisms, Cd(II) and CO32-, Fe-O, Zn-O, and oxygen-containing functional groups on the Fe/Zn-BC surfaces precipitated CdCO3, Cd(OH)2, and CdO. Therefore, Fe/Zn-BC is an excellent adsorbent that removes Cd(II) from aqueous solutions, and also can be used in waste resource utilization, which has potential applications prospects.

107. 题目: Effect of oil palm biomass cellulosic content on nanopore structure and adsorption capacity of biochar
文章编号: N21040221
期刊: Bioresource Technology
作者: Abubakar Abdullahi Lawal, Mohd Ali Hassan, Mohd Rafein Zakaria, Mohd Zulkhairi Mohd Yusoff, Mohd Nor Faiz Norrrahim, Mohd Noriznan Mokhtar, Yoshihito Shirai
更新时间: 2021-04-02
摘要: The influence of biomass cellulosic content on biochar nanopore structure and adsorption capacity in aqueous phase was scarcely reported. Commercial cellulose (100% cellulose), oil palm frond (39.5% cellulose), and palm kernel shell (20.5% cellulose) were pyrolyzed AT 630 °C, characterized and tested for the adsorption of iodine and organic contaminants. The external surface area and average pore size increased with cellulosic content, where commercial cellulose formed biochar with external surface area of 95.4 m2/g and average pore size of 4.1 nm. The biochar from commercial cellulose had the largest adsorption capacities: 371.40 mg/g for iodine, 86.7 mg/L for tannic acid, 17.89 mg/g for COD and 60.35 mg/g for colour, while biochar from palm kernel shell had the least adsorption capacities. The cellulosic content reflected the differences in biochar nanopore structure and adsorption capacities, signifying the suitability of highly cellulosic biomass for producing biochar to effectively treat wastewater.

108. 题目: Change in soil water deficit and soil organic matter consumption over time in rain-fed apricot orchards on the semi-arid Loess Plateau, China
文章编号: N21040220
期刊: Agriculture, Ecosystems & Environment
作者: Kaiqi Yang, Ke Wang, Xiaoyuan Zhang, Xiaofeng Chang, Gangshuan Bai, Jiyong Zheng, Gao-Lin Wu
更新时间: 2021-04-02
摘要: The impacts of massive reforestation on soil water and soil organic matter (SOM) in the ecosystem are attracting increasing attention worldwide. However, the response of the soil water content (SWC) and SOM after the conversion of agricultural land to economic forestland have not been sufficiently clarified in semi-arid areas. To investigate the influence of land-use change on the SWC and SOM dynamics, we examined the SWC (0–400 cm depth) and SOM (0–60 cm depth) and growth status of fruit trees in three apricot (Armeniaca vulgaris Lam.) orchards of different ages (7, 12, and 22 years) under extensive management, together with those of adjacent cropland (control) on the Loess Plateau, China. The results showed that SWC significantly decreased with increasing stand age, and strong soil desiccation occurred in the 12-year-old apricot orchard after conversion from cropland. The annual growth rate of the dried soil layer between the 12th and 22nd years (12.00 cm y−1) was higher than that between the 1st and 12th years (6.67 cm y−1). The soil water deficit was 498.81 mm over 22 years in the 0–400 cm soil profiles. SOM stock was improved in the short term (7 y) compared with the cropland, and was consumed thereafter. Only the topsoil (0–20 cm soil profiles) experienced SOM consumption in the 12-year-old orchard, but the SOM of all soil layers was consumed in the 22-year-old orchard. In the 0–60 cm soil profiles over 22 years, the SOM consumption was 26.53 Mg ha−1. The length and diameter of peripheral branches generally decreased with increasing stand age; where those of the 22-year-old orchard were 83.87 % and 39.13 % lower than those of the 7-year-old orchard (P < 0.05). These results indicate that long-term planting of apricot trees under extensive management could aggravate soil water deficit and SOM consumption, and further limit apricot growth. Therefore, appropriate management measures should be implemented to maintain and improve the SWC and SOM conditions and enhance the productivity and vigour of the orchard over ten years of cultivation.

109. 题目: Greenalite and its role in the genesis of early Precambrian iron formations – A review
文章编号: N21040219
期刊: Earth-Science Reviews
作者: B. Rasmussen, J.R. Muhling, B. Krapež
更新时间: 2021-04-02
摘要: Iron formations are marine sedimentary rocks comprising Fe-rich and Si-rich bands that were most widely deposited before ~2.45 Ga, prior to the Great Oxidation Event (GOE). They host most of the world's iron resources but their scientific importance lies in their potential for tracking the evolution of ancient seawater chemistry. Most models of their deposition (see reviews by Bekker et al., 2010, Bekker et al., 2014; Konhauser et al., 2017) assume that iron oxides in iron formations were derived from original Fe(III)-oxides/hydroxides that were precipitated in the photic zone from Fe(II)-rich seawater via biologically mediated oxidation, the Fe(II) ultimately being derived from hydrothermal vent plumes. In this review, we present an alternative model for the origin of iron formations centred on petrographic observations that indicate that the depositional (original) iron phase was an Fe(II)-silicate (greenalite) that precipitated in vent plumes as nanometer-sized particles and silt-sized flocs. The greenalite was deposited throughout the oceans and, in times of increased mafic-ultramafic volcanism, on continental shelves. Paragenetic studies indicate that the bulk of the iron oxides in iron formations formed by replacement of Fe(II)-rich precursors during metamorphism, deformation and exhumation. The origin of early Precambrian iron formations by precipitation of greenalite from vent plumes implies that iron deposition was largely an abiotic chemical process that did not require biologically driven oxidation, consistent with the lack of microfossils and indigenous organic matter.

110. 题目: Adsorption and reduction of Cr(VI) by a novel nanoscale FeS/chitosan/biochar composite from aqueous solution
文章编号: N21040218
期刊: Journal of Environmental Chemical Engineering
作者: Yan Yang, Yuhao Zhang, Guiyin Wang, Zhanbiao Yang, Junren Xian, Yuanxiang Yang, Ting Li, Yulin Pu, Yongxia Jia, Yun Li, Zhang Cheng, Shirong Zhang, Xiaoxun Xu
更新时间: 2021-04-02
摘要: The purpose of this study was to synthesize FeS/chitosan/biochar composite (FSBC) to remove Cr(VI). Results indicate that the modification of FeS particles and chitosan to biochar provided large specific surface area and more active adsorption sites. FSBC(1:1:1) have an enhanced Cr(VI) adsorption capacity of 103.93 mg g-1 at 0.01 g per 50 mL Cr(VI) solution compared with 19.97 mg g−1 for FeS particles and 22.45 mg g−1 for biochar. Increasing temperature promote Cr(VI) removal. By contrast, increasing Cl- and SO42- concentrates and solution pH prevented Cr(VI) adsorption. Cr(VI) removal could attribute to surface adsorption, reduction and precipitation. XPS results indicated that 76.07% of Cr(VI) removal was due to reduction or precipitation, and 23.93% could be ascribed to surface adsorption. After adsorption-desorption cycle, Cr(VI) removal capacities are 70.42, 65.33 and 11.67 mg g−1 for FSBC(1:1:1), FSBC(1:1:5) and FSBC(5:5:1), respectively. The study demonstrated that FSBC were high-effective adsorbents for Cr(VI) removal in the water environment.

111. 题目: Reaction of DMS and HOBr as a Sink for Marine DMS and an Inhibitor of Bromoform Formation
文章编号: N21040217
期刊: Environmental Science & Technology
作者: Emanuel Müller, Urs von Gunten, Sylvain Bouchet, Boris Droz, Lenny H. E. Winkel
更新时间: 2021-04-02
摘要: Recently, we suggested that hypobromous acid (HOBr) is a sink for the marine volatile organic sulfur compound dimethyl sulfide (DMS). However, HOBr is also known to react with reactive moieties of dissolved organic matter (DOM) such as phenolic compounds to form bromoform (CHBr3) and other brominated compounds. The reaction between HOBr and DMS may thus compete with the reaction between HOBr and DOM. To study this potential competition, kinetic batch and diffusion-reactor experiments with DMS, HOBr, and DOM were performed. Based on the reaction kinetics, we modeled concentrations of DMS, HOBr, and CHBr3 during typical algal bloom fluxes of DMS and HOBr (10–13 to 10–9 M s–1). For an intermediate to high HOBr flux (≥10–11 M s–1) and a DMS flux ≤10–11 M s–1, the model shows that the DMS degradation by HOBr was higher than for photochemical oxidation, biological consumption, and sea–air gas exchange combined. For HOBr fluxes ≤10–11 M s–1 and a DMS flux of 10–11 M s–1, our model shows that CHBr3 decreases by 86% compared to a lower DMS flux of 10–12 M s–1. Therefore, the reaction between HOBr and DMS likely not only presents a sink for DMS but also may lead to suppressed CHBr3 formation. This article has not yet been cited by other publications.

112. 题目: Non-covalent doping of carbon nitride with biochar: Boosted peroxymonosulfate activation performance and unexpected singlet oxygen evolution mechanism
文章编号: N21040216
期刊: Chemical Engineering Journal
作者: Huazhe Wang, Wanqian Guo, Qishi Si, Banghai Liu, Qi Zhao, Haichao Luo, Nanqi Ren
更新时间: 2021-04-02
摘要: A noncovalent functionalization approach was implemented using graphitic biochar (BC) as dopant to manipulate electronic properties of polymeric carbon nitride (PCN) while preserving its robust geometric skeleton. By fine-tuning the mass proportions of precursors during copolymerization, the carbonization of corncob was successfully confined in the PCN interlayers. An electron transport highway from PCN to BC was built owing to the π-electron delocalization. As a result, the non-covalent assembled PCN/BC composite rivaled popular nitrogen-doped carbon materials in activating peroxymonosulfate (PMS), and meanwhile exhibited superior durability. Singlet oxygen (1O2) was identified as the primary reactive oxygen species. Combining theoretical calculations and in-situ detections, a novel 1O2 evolution route with respect to the dissociation of PMS at the S/O site and the formation of superoxide radical was decoded. This work offers a new idea for the synthesis of durable PMS activators and enriches mechanistic understanding of PMS decomposition over metal-free catalysts.

113. 题目: Revealing horizontal and vertical variation of soil organic carbon, soil total nitrogen and C:N ratio in subtropical forests of southeastern China
文章编号: N21040215
期刊: Journal of Environmental Management
作者: Jiaqi Dong, Kangning Zhou, Peikun Jiang, Jiasen Wu, Weijun Fu
更新时间: 2021-04-02
摘要: Soil organic carbon (SOC) and total nitrogen (STN) are crucial soil quality indicators in a forest ecosystem. Their cycling processes and interactions have a key impact on the plants productivity, potential carbon sequestration and stability of the terrestrial ecosystem. In this study, soil profile samples (0–100 cm) were collected from 906 plots of typical subtropical forest in Zhejiang Province, southeastern China. Moran's I, geostatistics and geographic information system (GIS) techniques were used to study the vertical and horizontal heterogeneity of SOC, STN and C:N ratio. The results indicated that the contents of SOC and STN clearly decreased with the soil depth increasing (from 0 to 10 cm layer to 60–100 cm layer). The spatial distributions of SOC and STN were consistent with the topography, showing a decreasing trend from southwest to northeast of Zhejiang Province. The results of ANOVA and correlation analyses indicated that the dominant tree species, elevation and Normalized Difference Vegetation Index (NDVI) were the key factors affecting SOC and STN contents. For the total 0–100 cm soil layer, the mean densities of SOC and STN were 108.53 Mg ha−1 and 0.08 Mg ha−1, respectively. The total stocks of SOC and STN were 877.19 Tg and 84.42 Tg. Approximately 65% SOC and 45% STN were belonged to the upper 30 cm soil layer, which was strongly related to the actual soil thickness. The results could provide critical information for forestry and environmental management related to C and N accumulations in subtropical forests of China.

114. 题目: Organic carbon accumulation in oligotrophic coastal lakes in southern Brazil during the last century
文章编号: N21040214
期刊: Journal of Paleolimnology
作者: Carolina Bueno, Christian J. Sanders, Felipe Hax Niencheski, Carlos Andrade, William Burnett, Isaac R. Santos
更新时间: 2021-04-02
摘要: We report organic carbon (OC) accumulation rates in three freshwater ecosystems in southern Brazil, along the largest shallow coastal lagoon ecosystem in the world, the Patos-Mirim-Mangueira. After European colonisation in the seventeenth century, regional wetlands started being replaced by agricultural fields (mostly rice). We used excess 210Pb to develop chronologies for lagoon sediment cores and quantify bulk sediment and OC accumulation rates. In the past 120 years, OC accumulation rates in Mirim and Mangueira Lagoons, which are influenced by rice paddies, averaged 14.9 ± 8.5 and 6.4 ± 3.7 g C m−2 year−1, respectively. Greater accumulation rates were estimated for macrophyte-dominated Nicola Lake (69.9 ± 38.5 g C m−2 year−1) located within the protected Taim Wetland with no direct influence of rice plantations. Starting in the early twentieth century, the construction of dams and drainage canals altered regional hydrology. Despite these anthropogenic changes, only a mild increase in OC accumulation was observed in Mirim Lagoon (15% only in site MIR2) after 1970. Mangueira Lagoon experienced the lowest OC burial rates despite increasing sedimentation rate and OC burial after the mid-1970s. This is probably because these large lakes (> 500 km2) have great nutrient-dilution potential, and their well-mixed water columns prevent nutrients from accumulating in the sediments over time.

115. 题目: Crop yield and soil organic carbon under ridge‐furrow cultivation in China: A meta‐analysis
文章编号: N21040213
期刊: Land Degradation & Development
作者: Yunqi Wang, Fuli Gao, Lixin Wang, Tongji Guo, Liuran Qi, Huanyu Zeng, Yuexin Liang, Kai Zhang, Zhikuan Jia, Rui Zhang
更新时间: 2021-04-02
摘要: Ridge‐furrow cultivation (RF) is a popular emerging technique that can increase crop productivity in dry areas. However, the efficacy of RF on crop yield and soil organic carbon (SOC) remains uncertain under different climate and management conditions. Here, we compiled data from 48 publications to evaluate the response of yield and SOC to RF in China. Overall, our meta‐analysis showed that RF increased yield by 30.2%, but it had no effects on SOC. When differentiated based on different categories, yield and SOC varied by crop species, climate, soil textures, mulching management and ridge‐furrow patterns. RF increased the yield of wheat, maize, soybean, rape, linseed, potato, and SOC under soybean cultivation. Yield increase with RF was also consistent across temperature and precipitation. Yield increase was observed in all the soil textures. There were no RF effects on SOC under different soil textures. RF enhanced yields under no mulching, straw mulching and plastic film mulching, but increased SOC only in combination with straw mulching. A higher yield increase was observed under alternating small and large ridges (ASLR) than alternating ridges and furrows (AR). RF decreased SOC by 11.7% under AR, but had no effects on SOC under ASLR. Together, ASLR with straw mulching could increase yield and SOC in coarse soil texture regions with annual mean temperature > 10°C and annual mean precipitation >400 mm. This study showed the importance of considering local environmental conditions with management practices in identifying appropriate RF practices for improving crop productivity and soil carbon sequestration. This article is protected by copyright. All rights reserved.

116. 题目: Organic manure induced soil food web of microbes and nematodes drive soil organic matter under jackfruit planting
文章编号: N21040212
期刊: Applied Soil Ecology
作者: Lanxi Su, Tingyu Bai, Xiaowei Qin, Huan Yu, Gang Wu, Qingyun Zhao, Lehe Tan
更新时间: 2021-04-02
摘要: Partial substitution of chemical fertilizers by organic manure is essential for improving the soil quality and crop production. However, there is limited information regarding the complex microbial-microfaunal interactions derived from different organic or inorganic fertilizer application rate in the rhizosphere of jackfruits. Therefore, the objective was to compare the effects of organic/inorganic fertilizers on the soil food web of microbes and nematodes. Filed and greenhouse studies were set up with six treatments, including CK (no fertilizer), 100CF (100% chemical fertilizer), 30OM (30% organic manure plus 70% chemical fertilizer), 50OM (50% organic manure plus 50% chemical fertilizer), 70OM (70% organic manure plus 30% chemical fertilizer) and 100OM (100% organic manure). After 4 years application of organic manure under field conditions, there was higher soil organic matter (SOM), microbial biomass carbon (MBC), nematode diversity and jackfruit yield. Moreover, the number of total nematode, microbivorous nematodes and omnivores-predators were positively correlated with organic manure, while plant-parasites did the opposite in greenhouse experiment. Organic manure increased the abundance, richness and Shannon diversity of bacteria and fungi as well as maturity indices (MI), Shannon index (H′), Pielou evenness index (J), enrichment index (EI), structural index (SI) and nematode channel ratio (NCR) of the nematode community in greenhouse experiment. Soil pH and SOM were significantly correlated with the variation of soil microbial-microfauna. Network analysis indicated that soil amended with organic manure presented more positive correlation between beneficial nematodes and microorganisms, but a negative correlation between plant-parasites Pratylenchus and dominant fungal taxon Chytridiomycota. These results indicated the feasibility of organic manure for soil quality improvement with high SOM and pH, suggesting that the correlation between microbes and nematodes constructed by organic fertilizer may play a key role in the improvement of soil quality.

117. 题目: Microorganisms and their metabolic activities affect seepage through porous media in groundwater artificial recharge systems: a review
文章编号: N21040211
期刊: Journal of Hydrology
作者: Yuesuo Yang, Yuhui Wu, Ying Lu, Min Shi, Wenfang Chen
更新时间: 2021-04-02
摘要: Groundwater artificial recharge has been widely utilised throughout the world as an effective measure for solving groundwater overdraft. Many microorganisms are present in both recharging water and porous media, and their metabolic activities inevitably have complicated effects on the recharge process. Bioclogging is attributable to the growing population of bacteria and their extracellular polymer substances secreted on the medium. The formation mechanism of microbial clogging and the impact of microbial organisms on seepage were further reviewed. The major factors that influence microbial clogging in the process of recharge are also discussed based on a literature review. Considering these problems, the activities of microorganisms in different seepage conditions and the role of microbial extracellular polymeric substances (EPSs) in the recharging process are particularly addressed.

118. 题目: Coagulation removal of phosphorus from a southern China reservoir in different stages of algal blooms: Performance evaluation and Al-P matching principle analysis
文章编号: N21040210
期刊: Science of The Total Environment
作者: Xi Wang, Hui Xu, Ruyuan Jiao, Gefei Ma, Dongsheng Wang
更新时间: 2021-04-02
摘要: Due to excessive nutrient discharge, many reservoirs in southern China suffer from eutrophication and harmful algal blooms. Several methods for phosphorus (P) removal have been proposed, including coagulation, adsorption, and biological methods. Among these methods, coagulation is preferable because of its quick effect, simple operation, and low cost. To investigate the effect and mechanism of coagulation on dephosphorization in reservoir water, the performances of Al-based (AlCl3 and polyaluminum chloride (PACl)) and Fe-based coagulants (FeCl3 and FeSO4) were evaluated in this work. For reservoir water with a total phosphorus (TP) concentration of approximately 0.080 mg/L, aluminum salts showed stable advantages in dephosphorization. AlCl3 reduced the TP level by over 90% when treating the water sample collected at the initial stage of algal blooms, and PACl reduced by over 80% during the blooming stage. To reveal the dephosphorization mechanism and Al-P matching principle, synthesized water samples were prepared and treated with AlCl3 and [AlO4Al12(OH)24(H2O)12]7+ (Al13). While simulating the water quality characteristics of reservoir water, important influencing factors were considered. The factors include P content (dissolved phosphorus (DP) and particulate phosphorus (PP)), pH, and extracellular organic matter (EOM). The pH was set to 7.66 and 8.29, with PP proportion set to 20%, 50%, and 80%. Simulated water treatment results indicated that, except for the coagulants species, pH significantly affected the dephosphorization efficiency. Moreover, the effects of P speciation and EOM were confirmed. Based on the coagulation performance and coagulation product characterization, chemical precipitation and inner-sphere complexation were estimated to be the most predominant way that DP and PP match with Al and were efficiently removed by Al-based coagulants.

119. 题目: Different storm responses of organic carbon transported to Lake Taihu by the eutrophic Tiaoxi River, China
文章编号: N21040209
期刊: Science of The Total Environment
作者: Dong Liu, Shujie Yu, Hongtao Duan
更新时间: 2021-04-02
摘要: Low-frequency high-magnitude storms can flush disproportionate amounts of terrigenous dissolved organic carbon (DOC) and particulate organic carbon (POC) into rivers during a short period. However, previous studies focused on the impacts of storms on organic carbon transport in headwater streams that are minimally influenced by human activities and are far from lakes. To better estimate the lake carbon budget and manage lake water environments, we need to understand the transport of storm-induced organic carbon into lakes by eutrophic rivers. Based on daily and hourly time-series monitoring data, this paper systematically studied the influences of storm precipitation on DOC and POC transport in the eutrophic Tiaoxi River entering Lake Taihu, the 3rd largest freshwater lake in China. The results showed that seven storms transported 59% of the annual total organic carbon into Lake Taihu in 2019, and all storms resulted in transport peaks. During the storm period on August 9–16, 2019, DOC was negatively related to the water level (r = −0.44, p < 0.05), but POC responded positively (r = 0.52, p < 0.05); allochthonous organic carbon contents were elevated, but the autochthonous components were diluted. Moreover, the storm-induced input of riverine organic carbon influenced the lake water environment across a large region, and the impacts lasted more than ten days. These findings have important implications for accurately estimating riverine organic carbon fluxes into lakes and making better-informed decisions about when to pump drinking water from lakes.

120. 题目: Climate-driven fluxes of organic-bound uranium to an alpine lake over the Holocene
文章编号: N21040208
期刊: Science of The Total Environment
作者: Pierre Lefebvre, Pierre Sabatier, Arnaud Mangeret, Alkiviadis Gourgiotis, Pierre Le Pape, Anne-Lise Develle, Pascale Louvat, Olivier Diez, Jean-Louis Reyss, Jérôme Gaillardet, Charlotte Cazala, Guillaume Morin
更新时间: 2021-04-02
摘要: Uranium (U) isotopic signatures and concentration in sediments are widely used as paleo-redox proxies, as the behavior of U is often controlled by bottom water oxygenation. Here, we investigated the processes controlling U accumulation in the sediments of Lake Nègre (Mediterranean Alps, South-East France) over the past 9200 years. Exceptionally high natural U concentrations (350–1250 μg.g−1) allowed the measurement of U along with other elements by high-resolution X-Ray Fluorescence core-scanning. Weathering and erosion proxies (Ti content, Zr/Al and K/Ti ratios) indicate that sedimentary inputs were controlled by Holocene climatic variations. After a period of low erosion during the Holocene Climatic Optimum, a major regime shift was recorded at 4.2 kyr BP when terrigenous fluxes consistently increased until present with high sensitivity to centennial-scale climatic events. Sedimentary organic matter (OM) inputs were dominated by terrigenous OM from the catchment soils until 2.4 kyr BP, as attested by carbon to nitrogen (C/N) and bromine to organic carbon (Br/TOC) ratios. From 2.4 kyr BP to present, lake primary production and soils equally contributed to sedimentary OM. Uranium fluxes to the sediments were well correlated to terrigenous OM fluxes from 7 kyr BP to present, showing that U supply to the lake was controlled by U scavenging in the soils of the watershed followed by transport of U bound to detrital organic particles. Higher U/OM ratios before 7 kyr BP likely reflect the development of the upstream wetland. The fluctuations of U sedimentary inputs appear to be independent of bottom water oxygenation, as estimated from constant Fe/Mn ratios and δ238U isotopic signatures, and rather controlled by the production, erosion and sedimentation of terrigenous OM. This finding confirms that the use of U (and potentially other metals with high affinity to OM) concentrations alone should be used with caution for paleo-redox reconstructions.