摘要：
Background and aimsIntercropping is known to have low fertilizer input but high production efficiency. However, only few studies have explored the nutrient stoichiometry of soil and microbiome under intercropping patterns to understand the mechanisms underlying the improvement in crop production by intercropping.MethodsA field-based experiment (started in 2013) was conducted to explore the effects of intercropping of maize with peanut, soybean, gingelly, and sweet potato on soil microbial resource limitation, and the factors controlling the resource limitation were investigated by exploring functional gene abundance and soil C-N-P stoichiometry.ResultsVector angle (indicator of microbial P limitation) was > 45 & DEG; in all soil samples. Compared with monocropping, intercropping significantly decreased the vector length and angle. The RC:N-TERC:N was < 0 and the RC:P-TERC:P was > 0 in all soil samples. The RC:P-TERC:P of the monocropping was significantly higher than that of the intercropping soil. Compared with monocropping, the abundances of most of functional genes related to C degradation and fixation, N fixation, nitrification, denitrification, and P activation increased in intercropping soil. Microbial P limitation was associated more with the C-N-P stoichiometric ratios of soil and microbiome than with functional gene abundance. Soil microbial P limitation was notably related to plant N and P uptake and maize yield, regulating by soil microbial N:P, available P:C and P:N ratio.ConclusionsThis study demonstrated the mitigation of microbial P limitation by intercropping and highlighted the importance of understanding the promotion of microbial metabolisms by soil resource stoichiometry, which can help in improving maize productivity.
摘要：
Biochar and organic fertilizer are widely supported to maintain crop production and sustainable development of agroecosystems. However, it is unclear how biochar and organic fertilizer alone or in combination regulate soil functional microbiomes and their relationships to ecosystem multifunctionality (EMF). Herein, a long-term (started in 2013) field experiment, containing five fertilization treatments, was employed to explore the effects of biochar and organic fertilizer applications on the EMF (based on 18 functional indicators of crop productivity, soil nutrient supply, element cycling, and microbial biomass) and the functional microbiomes of bulk soil and rhizosphere soil [normalizing the abundances of 64 genes related to carbon (C), nitrogen (N), phosphorus (P), and sulphur (S) cycles]. Compared with single-chemical fertilization, biochar and organic fertilizer inputs significantly enhanced most ecosystem-single functions and, in particular, the EMF significantly increased by 18.7-30.1%; biochar and organic fertilizer applications significantly increased the abundances of soil microbial functional taxa related to C-N-P-S cycles to varying degree. The combined application of biochar and organic fertilizer showed a better improvement in these indicators compared to using them individually. Most functional microbial populations in the soil, especially the taxa involved in C degradation, nitrification, nitrate-reduction, organic P mineralization, and S cycling showed significantly positive associations with the EMF at different threshold levels, which ultimately was regulated by soil pH and nutrient availability. These results highlight the strong links between soil microbiomes and agroecosystem functions, as well as providing scientific support for inclusion of biochar in agricultural production and services with organic amendments. 8-year field evidence revealed impacts of biochar and pig manure on soil functional microbiome and ecosystem functions.Biochar and pig manure inputs notably enhanced most ecosystem-single functions and the EMF increased by 18.7-30.1%.Biochar and pig manure inputs notably enriched soil functional microbes related to C-N-P-S cycles to varying degree.Increase in EMF was related to microbe-driven soil processes such as C degradation, nitrification, and Po mineralization.Inclusion of biochar in crop production with organic amendments could enhance agro-ecosystem functions and services.
摘要：
Biological soil crusts (BSCs) widely exists in mudflat environment, which is known to be efficient in capturing heavy metals from aqueous solutions; However, their ability to adsorb cadmium (Cd(II)) is limited due to low capacity and selectivity. To address this limitation, manganese ethylenediamine phosphates (MEPs) nanomaterial were incorporated into the BSCs to enhance Cd(II) uptake. The MEPs nanomaterials attached to BSC significantly improved the adsorption capacity, rate, and selection for Cd(II). The adsorption kinetics of Cd(II) by BSCs and BSCs-MEPs was well described by a pseudo-second-order model, with BSCs-MEPs exhibiting a much higher adsorption capacity for Cd(II) (77.00 mg/g) compared to BSCs (55.44 mg/g). The Cd(II) removal by BSCs-MEPs has been accelerated to 2 stages, in which the film diffusion/intraparticle diffusion/chemical reaction participated in the 1st stage. And another stage was dynamic equilibrium process. The adsorption isotherm of BSCs-MEPs demonstrated superior performance for Cd(II) compared to BSCs across a pH range from 2 to 9. Most importantly, even in the presence of high concentration of Na+ or Ca2+ ions, BSCs-MEPs exhibited preferential adsorption for Cd(II), a result not observed with BSCs alone. Analysis of X-ray photoelectron spectroscopy spectra demonstrated that functional groups (-NH2/-COOH/-OH) played an important role in Cd(II) adsorption, while the MEPs attach to BSCs leading to the -NH3+ deprotonation, thus enhanced the BSCs' affinity toward Cd(II). Furthermore, molecular dynamics simulation clearly showed that diffusion coefficients (D) of Cd(II) were much higher than those of Ca2+ in EPS with abundant -NH2, which were responsible for selective adsorption. These findings might provide a valuable approach for treating Cd-contaminated water bodies.
摘要：
Microplastics (MPs) and heavy metals often coexist in soil, however their interactions and effects on the soil-plant system remain largely unclear. In this study, ramie (Boehmeria nivea L.) was exposed to soil contaminated with lead (Pb) and polystyrene (PS) of different sizes, dosages, and surface-charged functional groups. This design aimed to simulate the effects of MPs on phytoremediation. The experimental results revealed that PS exacerbated the damaging effects of Pb on ramie. Compared to the effect of Pb alone, PS-COOH had a greater influence on root vigor, leading to a 15.6% reduction in the active absorption ratio. Laser scanning confocal microscope showed PS entered the roots. Adsorption/desorption experiments demonstrated that PS had a weaker adsorption capacity for Pb than soil but a greater desorption rate than soil when simulating rhizosphere secretion. Moreover, PS reduced soil pH and increased the reducible state of Pb by 6-12%. After 100days of phytoremediation, Pb content in the soil with PS-5μm was 150μgg(-1) less than that in the soil without PS. These results demonstrated that PS improved Pb bioavailability and enhanced the efficiency of Pb uptake by ramie. The redundancy analysis demonstrated that PS mitigated the toxicity of Pb to rhizosphere microorganisms, potentially via its effects on metal chemical fractions, dehydrogenase activity (S-DHA), cation exchange capacity (CEC), and soil organic matter (SOM). This study indicates that the presence of PS could potentially enhance the phytoremediation efficiency of ramie in Pb-contaminated land by influencing soil microenvironmental properties. This study provides insights into the complex interactions of MPs with soil-plant-microbial systems during metal remediation, thereby enhancing our understanding of their environmental impacts.
摘要：
Intercropping-driven changes in nitrogen (N)-acquiring microbial genomes and functional expression regulate soil N availability and plant N uptake. However, present data seem to be limited to a specific community, obscuring the viewpoint of entire N-acquiring microbiomes and functions. Taking maize intercropped with legumes (peanut and soybean) and non-legumes (gingelly and sweet potato) as models, we studied the effects of intercropping on N transformations and N-acquiring microbiomes in rhizosphere soil across four maize growth stages. Meanwhile, we compiled promising strategies such as random forest analysis and structural equation model for the exploitation of the associations between microbe-driven N dynamics and soil-plant N trade-offs and maize productivity. Compared with monoculture, maize intercropping significantly increased the denitrification rate of rhizosphere soils across four maize growth stages, net N mineralization in the elongation and flowering stages, and the nitrification rate in the seedling and mature stages. The abundance of most N-acquiring microbial populations was influenced significantly by intercropping patterns and maize growth stages. Soil available N components (NH(4)(+)-N, NO(3)(-)-N, and dissolved organic N content) showed a highly direct effect on plant N uptake, which mainly mediated by N transformations (denitrification rate) and N-acquiring populations (amoB, nirK3, and hzsB genes). Overall, the adaptation of N-acquiring microbiomes to changing rhizosphere micro-environments caused by intercropping patterns and maize development could promote soil N transformations and dynamics to meet demand of maize for N nutrient. This would offer another unique perspective to manage the benefits of the highly N-effective and production-effective intercropping ecosystems.
摘要：
【目的】按土壤剖面发生层分析水稻土有机碳剖面分布特征及其影响因素。【方法】通过测定湖南省58个水稻土剖面各发生层土壤有机碳含量,分析水稻土剖面有机碳分布特征,并利用地理探测器解析水稻土有机碳含量空间分异的影响因素。【结果...展开更多 【目的】按土壤剖面发生层分析水稻土有机碳剖面分布特征及其影响因素。【方法】通过测定湖南省58个水稻土剖面各发生层土壤有机碳含量,分析水稻土剖面有机碳分布特征,并利用地理探测器解析水稻土有机碳含量空间分异的影响因素。【结果】①湖南省水稻土剖面土壤有机碳平均含量为9.30 g kg−1,其在发生层上的分布表现为耕作层(22.94 g kg−1)>犁底层(15.09 g kg−1)>底土层(6.93 g kg−1)。②不同成土母质发育的土壤中,石灰岩风化物发育的水稻土发生层有机碳含量最大;不同质地的土壤中,水稻土各类发生层有机碳含量整体上表现为随粉粒含量的增加而增大。③各发生层有机碳空间分布均呈现西南高,东北低的格局。④地理探测器结果显示,容重对各发生层水稻土有机碳含量空间分异解释程度最高,且与其他因子交互之后解释力显著增强。【结论】湖南省水稻土有机碳含量在不同剖面发生层存在显著性差异,其空间分布是由多因子交互作用形成的,容重对各发生层有机碳解释力最高。收起
摘要：
Biological nitrogen fixation and nitrification inhibitor applications contribute to improving soil nitrogen (N) availability, however, free-living N fixation affected by nitrification inhibitors has not been effectively evaluated in soils under different weed management methods. In this study, the effects of the nitrification inhibitors dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate (DMPP) on the nitrogenase, nifH gene，and diazotrophic communities in soils under different weed management methods (AMB, weeds growth without mowing or glyphosate spraying; GS, glyphosate spraying; MSG, mowing and removing weeds and glyphosate spraying; and WM, mowing aboveground weeds) were investigated. Compared to the control counterparts, the DCD application decreased soil nitrogenase activity and nifH gene abundance by 4.5% and 37.9%, respectively, under the GS management method, and the DMPP application reduced soil nitrogenase activity by 20.4% and reduced the nifH gene abundance by 83.4% under the MSG management method. The application of nitrification inhibitors significantly elevated soil NH(4)(+)-N contents but decreased NO(3)(-)-N contents, which had adverse impacts on soil nifH gene abundance and nitrogenase activity. The nifH gene abundances were also negatively impacted by dissolved organic N and Geobacter but were positively affected by available phosphorus and diazotrophic community structures. Nitrification inhibitors significantly inhibited Methylocella but stimulated Rhizobiales and affected soil diazotrophic communities. The nitrification inhibitors DCD and DMPP significantly altered soil diazotrophic community structures, but weed management outweighed nitrification inhibitors in reshaping soil diazotrophic community structures. The non-targeted effects of the nitrification inhibitors DMPP and DCD on soil free-living N fixation were substantially influenced by the weed management methods.
摘要：
In order to explore the response mechanism of Passiflora edulis Sims to drought stress, the changes in morphological and physiological traits of Passiflora edulis Sims under different drought conditions were studied. A total of 7 germplasm resources of Passiflora edulis Sims were selected and tested under drought stress by the pot culture method under 4 treatment levels: 75%-80% (Control, CK) of maximum field water capacity, 55%-60% (Light Drought, LD) of maximum field water capacity, i.e., mild drought, 40%-45% (Moderate Drought, MD) of maximum field water capacity, i.e., moderate drought and 30%-35% (Severe Drought, SD) of maximum field water capacity, i.e., severe drought. On the 40th day of drought treatment, 13 indices, including seedling growth morphology, physiology, and biochemistry, were measured. The results showed that under drought stress, the height and ground diameter of P. edulis Sims gradually decreased with increasing drought stress, and there were significant differences in seedling height and ground diameter among the treatments. Drought stress significantly inhibited the growth of seven P. edulis Sims varieties. The contents of soluble sugar (SS), soluble protein (SP), proline (Pro), and other substances in P. edulis Sims basically increased with increasing drought stress. With the aggravation of drought stress, the malondialdehyde (MDA) content of P. edulis Sims tended to increase to different degrees, the superoxide dismutase (SOD) activity and peroxidase (POD) activity both tended to increase at first and then decrease, and the change in catalase (CAT) activity mostly showed a gradual increasing trend. The contents of endogenous hormones in P. edulis Sims significantly differed under different degrees of drought stress. With the aggravation of drought stress, the abscisic acid (ABA) content of P. edulis Sims tended to increase, whereas the contents of gibberellin (GA), indoleacetic acid (IAA), and zeatin nucleoside (ZR) exhibited a downward trend. A comprehensive evaluation of the drought resistance of seven P. edulis Sims varieties was conducted based on the principal component analysis method, and the results showed that the drought resistance decreased in the order XH-BL > XH-TWZ > TN1 > GH1 > ZJ-MT > LP-LZ > DH-JW.
摘要：
Soil is the basis of bamboo growth and quality formation of bamboo shoots and has an important contribution to the sustainable development of agriculture. To this end, We studied the soil properties and microbial communities of Dendrocalamus brandisii by collecting twenty-one soil samples from its seven typical geographic provenances in Yunnan Province, China. Bacterial 16S rRNA gene amplicons were used to detect soil bacteria and predict bacterial functions using Tax4Fun. The results indicated that the soil bacterial diversity indices (ACE, Chao1, Simpson, and Shannon) were significantly different among different geographical provenances. The dominant bacterial groups at the phylum level in all seven regions were Proteobacteria (19.78 similar to 29.06%), Actinobacteria (13.53 similar to 30.01%), Chloroflexi (8.03 similar to 31.47%), and Acidobacteria (7.12 similar to 19.17%), with markedly different constitution proportions. Total phosphorus, available potassium, and pH were the main environmental factors affecting soil bacterial communities. There were significant differences in the secondary metabolic pathways and phenotypes of soil bacterial functions, exhibiting a diversity of functions. The geographical variables of the soil bacterial community in D. brandisii varied with spatial scales. Environmental factors such as available potassium (AK), pH, and total nitrogen (TN) have an impact on soil bacterial communities.
期刊：
Global Change Biology,2024年30(2):e17158- ISSN：1354-1013
通讯作者：
Wang, JJ
作者机构：
[Wang, Jianjun; Wen, Shuailong; Jiang, Shuyu; Han, Lei; Hu, Ang; Zhong, Jicheng] Chinese Acad Sci, Nanjing Inst Geog & Limnol, Key Lab Lake & Watershed Sci Water Secur, Nanjing, Peoples R China.;[Jiang, Shuyu] Nanjing Normal Univ, Coll Life Sci, Nanjing, Peoples R China.;[Han, Lei] Hunan Agr Univ, Coll Resources & Environm, Changsha, Peoples R China.;[Jang, Kyoung-Soon] Korea Basic Sci Inst, Biochem Anal Team, Cheongju, South Korea.;[Tanentzap, Andrew J.] Univ Cambridge, Dept Plant Sci, Cambridge, England.
通讯机构：
[Wang, JJ ] C;Chinese Acad Sci, Nanjing Inst Geog & Limnol, Key Lab Lake & Watershed Sci Water Secur, Nanjing, Peoples R China.
关键词：
carbon quality temperature hypothesis;carbon-climate feedback;chemodiversity;functional traits;geography;global warming;greenhouse gas;lake ecosystems
摘要：
The mean value of temperature sensitivity of organic carbon decomposition in lake sediments is 1.78 ± 0.62. The quantity of sediment organic carbon determines the absolute rate of decomposition, while the quality of organic carbon determines the sensitivity of decomposition to warming. At both molecular and compositional levels, functional traits of DOM revealed the positive correlation between Q10 and biochemical recalcitrance, thus supporting the carbon quality temperature hypothesis. Abstract Organic carbon decomposition in lake sediments contributes substantially to the global carbon cycle and is strongly affected by temperature. However, the magnitude of temperature sensitivity (Q10) of decomposition and the underlying factors remain unclear at the continental scale. Carbon quality temperature (CQT) hypothesis asserts that less reactive and more recalcitrant molecules tend to have higher temperature sensitivities, but its support is challenged by complex composition of organic matter and environmental constraints. Here, we quantified Q10 of the sediments across 50 freshwater ecosystems along a 3500 km north–south transect, and characterized the quality of sediment dissolved organic carbon with chemodiversity reflected in molecular richness, functional traits (i.e., molecular weight, bioavailability, etc.) and composition. We further included classic environmental variables, such as climatic, physicochemical and microbial factors, to explore how Q10 is constrained by these factors or carbon quality. We found that Q10 varied greatly across lakes, with the mean value of 1.78 ± 0.62, but showed nonsignificant latitudinal pattern. Q10 was primarily predicted by chemodiversity and showed an increasing trend with the biochemical recalcitrance indicated by traits such as aromaticity and standard Gibb's Free Energy at both molecular and compositional levels. This suggests that carbon quality is the crucial determinant of Q10 in lakes, supporting the CQT hypothesis. Moreover, Q10 decreased linearly with the increase of molecular richness, implying that the resistance of decomposition to warming is associated with higher molecular diversity. Compared with the structural equation model containing only environmental variables, inclusion of chemodiversity increased 32.8% of the explained variation in Q10, and chemodiversity was the only driver showing direct effects. Collectively, this study illustrates the importance of chemodiversity in shaping the pattern of Q10, and has significant implications for accurately predicting the carbon turnover in lake ecosystems in the context of global warming.
摘要：
Hydrochar serves not only as a fuel source but also as a versatile carbon material that has found extensive application across various domains. The application performance of hydrochar, e.g., energy recovery and carbon stability, is substantially influenced by its mass yield, higher heating value (HHV), and compositions (C, H, O, N, S, and ash), so the prediction and engineering of these properties is promising. In this study, two machine learning algorithms, namely gradient boosting regression (GBR) and random forest (RF), were used to predict the hydrochar properties mentioned above. The GBR models (with test regression coefficient (R2) values of 0.87-0.98 for single-target prediction and average test R2 of 0.93 for multi-target prediction) exhibited superior predictive capabilities to the RF models (with test R2 of 0.78-0.97 for single-target and average test R2 of 0.90 for multi-target prediction). The interpretation of ML models revealed the importance ranking of features for all targets. Then, engineering hydrochar was carried out through three different optimizations to the as-built multi target prediction model: i) optimizations of HTC conditions for given biomass samples; ii) optimization of biomass mixture recipes; iii) simultaneous optimization of both biomass mixing recipes and HTC conditions.
作者机构：
[Xia, Yongqiu; Han, Haojie; Li, Xiaohan; Yan, Xiaoyuan; Yan, Xing] Chinese Acad Sci, Inst Soil Sci, State Key Lab Soil & Sustainable Agr, Changshu Natl Agroecosyst Observat & Res Stn, Nanjing 210008, Peoples R China.;[Han, Haojie; Li, Xiaohan; Yan, Xing] Univ Chinese Acad Sci, Beijing 100049, Peoples R China.;[Wen, Jiong] Yueyang Agr Res Acad, Yueyang 414215, Peoples R China.;[Rong, Xiangmin] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Peoples R China.
通讯机构：
[Xia, YQ ] C;Chinese Acad Sci, Inst Soil Sci, State Key Lab Soil & Sustainable Agr, Changshu Natl Agroecosyst Observat & Res Stn, Nanjing 210008, Peoples R China.
关键词：
N removal kinetics;Small water bodies;Dissolved organic carbon;Intensive agricultural areas
摘要：
Small water bodies are extensively distributed and play critical roles in nitrogen (N) removal, primarily through sediment denitrification. However, our comprehension understanding of the N removal rate constant in these systems, particularly within the first-order kinetics model, remains limited. To address this gap, a one-year field study was conducted to investigate the N removal rate and N removal rate constant in various small water bodies within a typical intensive agricultural area. We observed a decrease in N removal rates in the downstream direction, from ditches to downstream ponds and streams, potentially due to upstream water bodies receiving higher nutrient inputs. Moreover, our findings revealed that the N removal process in small water bodies generally follows a first-order kinetics reaction model, with the N removal rate constant varying from 0.22 d-1 in streams and 0.48 d-1 in vegetated ditches. Both water dissolved organic carbon (DOC) and dissolved oxygen (DO) concentrations collectively influenced the N removal rate constants. By leveraging the relationship between the N removal rate constant and these environmental factors, we further estimated that, on average, small water bodies remove 68% of the N loading in the Dongting Lake Basin. We recommend implementing artificial management measures, such as vegetation, to enhance the N removal capacity of water bodies. However, the caution must be exercised in measures like concrete linings in ditches, as they can hinder N removal. These findings not only offer methods for estimating N removal in small water bodies, but also provide an insight into enhancing the N removal capacity of these systems to effectively mitigate non-point N pollution.
关键词：
Intercropping;Soil C pool;Carbon use efficiency;Microbial growth;Microbial diversity;Core microbiota
摘要：
Intercropping is a powerful practice to alter the allocation of photosynthetic carbon (C) to belowground ecosystems via promotion of diversified plant communities. The feedback of soil C stability to intercropping is controlled by microbial C use efficiency (CUE). Despite its significance, there is currently insufficient evidence to decipher how soil microbial CUE reacts to intercropping. By combining a 10-year-long intercropping experiment with a substrate-independent 18O-H2O labelling approach and high-throughput sequencing, we elucidated the performance of intercropping on soil C pool and microbial metabolic traits as well as their relationships with soil microbial communities. Compared with monoculture, maize intercropping with peanut and soybean significantly increased soil C storage, soil mineral-associated organic C (MAOC), soil dissolved organic (DOC), and soil microbial biomass (MBC) contents at maize four growth stages. Soil microbial CUE increased significantly, especially at maize flowering and mature stages, as a consequence of enhanced microbial growth and biomass turnover rate after maize intercropping with peanut and soybean. Soil C storage and accessibility indicators (e.g., MAOC, DOC, and MBC contents) could significantly predict the changes of soil microbial diversity and core taxa. Meanwhile, the beta-diversity (community composition) of soil bacteria, fungi, saprotroph and protists, as well as rare fungal taxa were positively correlated with soil microbial CUE, and these indicators showed a high prediction of the microbial CUE. Soil C storage and accessibility indicators directly and indirectly influenced soil microbial CUE by regulating microbial diversity and key taxa. Soil microbial diversity and core taxa directly and indirectly influenced microbial CUE by mediating microbial respiration, growth, biomass, and enzyme activity, which mediated by soil C storage and accessibility. These findings provide an evidence for the associations between microbial diversity, CUE, and soil C stability, highlighting the importance of intercropping-driven soil microbiome to enhance soil microbial CUE.
摘要：
Understanding how phytoplankton interacts with local and regional drivers as well as their feedbacks is a great challenge, and quantitative analyses of the regulating role of human activities and climate changes on these feedback loops are also limited. By using monthly monitoring dataset (2000-2017) from Lake Taihu and empirical dynamic modelling to construct causal networks, we quantified the strengths of causal feedbacks among phytoplankton, local environments, zooplankton, meteorology as well as global climate oscillation. Prevalent bidirectional causal linkages between phytoplankton biomass (chlorophyll a) and the tested drivers were found, providing holistic and quantitative evidence of the ubiquitous feedback loops. Phytoplankton biomass exhibited the highest feedbacks with total inorganic nitrogen and ammonia and the lowest with nitrate. The feedbacks between phytoplankton biomass and environmental factors from 2000 to 2017 could be classified into two groups: the local environments (e.g., nutrients, pH, transparency, zooplankton biomass)-driven enhancement loops promoting the response of the phytoplankton biomass, and the climate (e.g., wind speed)-driven regulatory loops suppressing it. The two counterbalanced groups modified the emergent macroecological patterns. Our findings revealed that the causal feedback networks loosened significantly after 2007 following nutrient loading reduction and unsuccessful biomanipulation restoration attempts by stocking carp. The strength of enhancement loops underwent marked decreases leading to reduced phytoplankton responses to the tested drivers, while the climate (decreasing wind speed, warming winter)-driven regulatory loops increased- like a tug-of-war. To counteract the self-amplifying feedback loops, the present eutrophication mitigation efforts, especially nutrient reduction, should be continued, and introduction of alternative measures to indirectly regulate the critical components (e.g., pH, Secchi depth, zooplankton biomass) of the loops would be beneficial.
摘要：
Arsenic is a ubiquitous environmental pollutant. Microbe-mediated arsenic biotransformations significantly influence arsenic mobility and toxicity. Arsenic transformations by soil and aquatic organisms have been well documented, while little is known regarding effects due to endophytic bacteria. An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil. P. putida ARS1 shows high tolerance to arsenite (As(III)) and arsenate (As(V)), and exhibits efficient As(V) reduction and As(III) efflux activities. When exposed to 0.6 mg/L As(V), As(V) in the medium was completely converted to As(III) by P. putida ARS1 within 4 hr. Genome sequencing showed that P. putida ARS1 has two chromosomal arsenic resistance gene clusters ( arsRCBH ) that contribute to efficient As(V) reduction and As(III) efflux, and result in high resistance to arsenicals. Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation, which takes up As(III) more efficiently than As(V). Co-culture of P. putida ARS1 and W. globosa enhanced arsenic accumulation in W. globosa by 69%, and resulted in 91% removal of arsenic (at initial concentration of 0.6 mg/L As(V)) from water within 3 days. This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium. (c) 2023 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
摘要：
Biochar application has received much attention because biochar can be used as an organic amendment. The nutrient release patterns and interactions in straw biochar produced at different temperatures are not well understood. In this study, we observed the release patterns of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) and the interaction between released C, N, P, and K from straw biochar prepared from 225 to 600 degrees C through a 180-day degradation experiment. The results showed that the degradation rate of the two kinds of straw biochar was faster in the first 30 days at different temperatures, and that of the straw biochar prepared before 300 degrees C was more rapid, indicating that 300 degrees C is an important turning point. The rule of nutrient release in the straw biochar showed that the K release rate was the highest and most rapid and was more than 60% in the first 30 days. The nutrient release rates for the two kinds of straw biochar were in the order K > N > P > C. The release of nutrients accompanied the decomposition of the straw biochar, and there was an exponential relationship between the amount of nutrients released from straw biochar and its degradation mass. There were collaborative or similar release processes indicated by significant positive correlations between the released C and N (R-2 = 0.96) and P and K (R-2 = 0.94) in the tobacco straw biochar and an obvious correlation between the released C and N (R-2 = 0.76) in the rice straw biochar. These results indicated that the released C and N, P, and K in tobacco straw biochar, as well as C and N in rice straw biochar, have synergistic effects and the same degradation path. The application of straw biochar can provide a source of P and N in the short term and a source of P and C in the long term. This study suggests that returning straw biochar to the soil could appropriately reduce the input of K fertilizer in the early stage.
通讯机构：
[Liang, T ; Yan, XL] C;Chinese Acad Sci, Key Lab Land Surface Pattern & Simulat, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China.;Univ Chinese Acad Sci, Coll Resources & Environm, Beijing 100190, Peoples R China.
关键词：
Back propagation neural network algorithm;Hydrogeological features;Industrial site contamination;Integrated modeling;Three-dimensional spatial analysis
摘要：
Intensive industrial activities cause soil contamination with wide variations and even perturb groundwater safety. Precision delineation of soil contamination is the foundation and precondition for soil quality assurance in the practical environmental management process. However, spatial non-stationarity phenomenon of soil contamination and heterogeneous sampling are two key issues that affect the accuracy of contamination delineation model. Taking a typical industrial park in North China as the research object, we constructed a random forest (RF) model for finely characterizing the distribution of soil contaminants using sparse-biased drilling data. Results showed that the R2 values of arsenic and 1,2-dichloroethane predicted by RF (0.8896 and 0.8973) were greatly higher than those of inverse distance weighted model (0.2848 and 0.2908), indicating that RF was more adaptable to actual non-stationarity sites. The back propagation neural network algorithm was utilized to establish a three-dimensional visualization of the contamination parcel of subsoil-groundwater system. Multiple sources of environmental data, including hydrogeological conditions, geochemical characteristics and anthropogenic industrial activities were integrated into the model to optimize the prediction accuracy. The feature importance analysis revealed that soil particle size was dominant for the migration of arsenic, while the migration of 1,2-dichloroethane highly depended on vertical permeability coefficients of the soil. Contaminants migrated downwards with soil water under gravity-driven conditions and penetrated through the subsoil to reach the saturated aquifer, forming a contamination plume with groundwater flow. Our findings afford a new idea for spatial analysis of soil-groundwater contamination at industrial sites, which will provide valuable technical support for maintaining sustainable industry.
