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：
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：
Phytoplankton taxa are strongly interconnected as a network, which could show temporal dynamics and non-linear responses to changes in drivers at both seasonal and long-term scale. Using a high quality dataset of 20 Danish lakes (1989-2008), we applied extended Local Similarity Analysis to construct temporal network of phytoplankton communities for each lake, obtained sub-network for each sampling month, and then measured indices of network complexity and stability for each sub-network. We assessed how lake re-oligotrophication, climate warming and grazers influenced the temporal dynamics on network complexity and stability of phytoplankton community covering three aspects: seasonal trends, long-term trends and detrended variability. We found strong seasonality for the complexity and stability of phytoplankton network, an increasing trend for the average degree, modularity, nestedness, persistence and robustness, and a decreasing trend for connectance, negative:positive interactions and vulnerability. Our study revealed a cascading effect of lake re-oligotrophication, climate warming and zooplankton grazers on phytoplankton network stability through changes in network complexity characterizing diversity, interactions and topography. Network stability of phytoplankton increased with average degree, modularity, nestedness and decreased with connectance and negative:positive interactions. Oligotrophication and warming stabilized the phytoplankton network (enhanced robustness, persistence and decreased vulnerability) by enhancing its average degree, modularity, nestedness and by reducing its connectance, while zooplankton richness promoted stability of phytoplankton network through increases in average degree and decreases in negative interactions. Our results further indicate that the stabilization effects might lead to more closed, compartmentalized and nested interconnections especially in the deeper lakes, in the warmer seasons and during bloom periods. From a temporal dynamic network view, our findings highlight stabilization of the phytoplankton community as an adaptive response to lake re-oligotrophication, climate warming and grazers.
关键词：
Controlled-release nitrogen fertilizer;Double-cropping rice;Nitrogen losses;Nitrogen uptake;Productivity;Soil nitrogen pool
摘要：
Considerable literature has demonstrated the advantage of controlled-release nitrogen (CRN) fertilizer in improving crop productivity. However, few researches have explored the long-term impacts of using CRN fertilizers as alternative to common urea on production and N utilization in double-cropping paddy. To address this gap, our study utilized a database derived from a 10-year field experiment from 2013 to 2022. During early and late rice seasons, compared to common urea (early rice, 150kg hm(-2); late rice, 180kg hm(-2)), CRN fertilizer (150kg hm(-2); 180kg hm(-2)) input significantly increased yield by 7.4%, and 11.7%, as well as N use efficiency (NUE) from 23.0% and 24.6% to 33.0% and 37.5%, respectively. CRN application significantly reduced N losses, evidenced by decrease in runoff (23.1% and 19.4%), leaching (12.7% and 12.1%), ammonia volatilization (28.9% and 30.2%), and N(2)O emissions (10.4% and 16.1%). A reduction of 10% in CRN fertilizer input maintained yield. Compared with normal amount, reducing 10, 20, and 30% CRN input increased NUE by 7.0-7.6%, 7.3-7.4%, and 11.6-12.6%; reduced runoff loss by 16.1-17.9%, 27.9-30.7%, and 35.0-37.2%; decreased leaching loss by 7.6-12.8%, 18.1-22.6%, and 26.5-31.4%; decreased ammonia volatilization by 9.9-12.3%, 16.3-22.7%, and 23.2-29.3%, and decreased N(2)O loss by 7.8-13.3%, 12.8-32.8%, and 20.3-36.9%, respectively. Soils with CRN input showed higher total and inorganic N contents than the soils with common urea, and the content increased in parallel with CRN fertilizer input. Soil N content and N runoff loss were significantly related to yield and N uptake, and N runoff and leaching losses were significantly related to NUE. These results support the sustainable use of CRN fertilizers as a viable alternative to common urea, indicating that application rate of 135 and 162kgN hm(-2) of early and late rice, respectively, maintain yield and enhance N utilization in double-season paddy of southern China.
摘要：
Utilizing an acid-resistant biological soil crust (BSC) species that we discovered, we developed a device capable of efficiently removing cadmium (Cd) from mine wastewater with varying levels of acidity. Our research has demonstrated that this particular BSC species adapts to acidic environments by regulating the balance of fatty acids and acid-resistant enzymes. At a Cd concentration of 5 mg/L, the BSC grew well. When the initial Cd concentration was 2 mg/L, and the flow rate was set at 1 mL/min (at pH levels of 3, 4, and 5), BSC had a high removal rate of Cd, and the removal rate increased with the increase of pH (from 90% to 97%). Chemisorption is the primary removal mechanism in the initial stage, where the functional groups and minerals on the surface of the BSC play a significant role. In addition, BSC also adapts to Cd stress by changing bacterial community structure. It was discovered through infrared spectroscopy and two-dimensional correlation analysis that hydrophilic groups, specifically phosphate and carboxyl groups, exhibited the highest reactivity during the Cd binding process. Protein secondary structure analysis confirmed that as the pH increased, the adsorption capacity of the BSC increased; making biofilm formation easier. This study presents a novel approach for the treatment of acidic wastewater.
摘要：
Bio-drying is a practical approach for treating food waste (FW). However, microbial ecological processes during treatment are essential for improving the dry efficiency, and have not been stressed enough. This study analyzed the microbial community succession and two critical periods of interdomain ecological networks (IDENs) during FW bio-drying inoculated with thermophiles (TB), to determine how TB affects FW bio-drying efficiency. The results showed that TB could rapidly colonize in the FW bio-drying, with the highest relative abundance of 5.13%. Inoculating TB increased the maximum temperature, temperature integrated index and moisture removal rate of FW bio-drying (55.7 degrees C, 219.5 degrees C, and 86.11% vs. 52.1 degrees C, 159.1 degrees C, and 56.02%), thereby accelerating the FW bio-drying efficiency by altering the succession of microbial communities. The structural equation model and IDEN analysis demonstrated that TB inoculation complicated the IDENs between bacterial and fungal communities by significantly and positively affecting bacterial communities (b = 0.39, p < 0.001) and fungal communities (b = 0.32, p < 0.01), thereby enhancing interdomain interactions between bacteria and fungi. Additionally, inoculation TB significantly increased the relative abundance of keystone taxa, including Clostridium sensu stricto, Ochrobactrum, Phenylobacterium, Microvirga and Candida. In conclusion, the inoculation of TB could effectively improve FW bio-drying, which is a promising technology for rapidly reducing FW with high moisture content and recovering resources from it.
通讯机构：
[Bingyu Li] C;College of Resource & Environment, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Hunan Engineering & Technology Research Center for Irrigation Water Purification, Changsha 410128, China<&wdkj&>Key Laboratory of Southern Farmland Pollution Prevention and Control, Ministry of Agriculture, Changsha 410128, China
摘要：
The retention and fate of Roxarsone (ROX) onto typical reactive soil minerals were crucial for evaluating its potential environmental risk. However, the behavior and molecular-level reaction mechanism of ROX and its substituents with iron (hydr)oxides remains unclear. Herein, the binding behavior of ROX on ferrihydrite (Fh) was investigated through batch ex-periments and in-situ ATR-FTIR techniques. Our results demonstrated that Fh is an effective geo-sorbent for the retention of ROX. The pseudo-second-order kinetic and the Langmuir model successfully described the sorption process. The driving force for the binding of ROX on Fh was ascribed to the chemical adsorption, and the rate-limiting step is simultaneously dominated by intraparticle and film diffusion. Isotherms results revealed that the sorption of ROX onto Fh appeared in uniformly distributed monolayer adsorption sites. The two-dimensional correlation spectroscopy and XPS results implied that the nitro, hydroxyl, and arsenate moiety of ROX molecules have participated in binding ROX onto Fh, signifying that the predominated mechanisms were attributed to the hydrogen bonding and surface com-plexation. Our results can help to better understand the ROX-mineral interactions at the molecular level and lay the foundation for exploring the degradation, transformation, and remediation technologies of ROX and structural analog pollutants in the environment.(c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
通讯机构：
[Manyun Zhang] C;College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Centre for Planetary Health and Food Security, Griffith University, Nathan, Brisbane, QLD 4111, Australia
关键词：
Carbendazim residues;Co-occurrence network;Nitrogen-cycling inhibitors;Soil and endophytic bacteria;Yield
摘要：
Applying nitrogen (N)-cycling inhibitors is an effective measure to improve N fertilizer utilization efficiency, but the effects of N-cycling inhibitors on fungicide residues in soil-crop systems are unclear. In this study, nitrification inhibitors dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate (DMPP) and urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) were applied into agricultural soils with fungicide carbendazim applications. The soil abiotic properties, carrot yields, carbendazim residues, bacterial communities and their comprehensive relationships were also quantified. Compared to the control treatment, the DCD and DMPP significantly decreased soil carbendazim residues by 96.2% and 96.0%, and the DMPP and NBPT significantly reduced carrot carbendazim residues by 74.3% and 60.3%, respectively. The nitrification inhibitor applications also generated significant and positive effects on carrot yields and soil bacterial community diversities. The DCD application significantly stimulated soil Bacteroidota and endophytic Myxococcota and modified soil and endophytic bacterial communities. Meanwhile, the DCD and DMPP applications also positively stimulated the co-occurrence network edges of soil bacterial communities by 32.6% and 35.2%, respectively. The linear correlation coefficients between soil carbendazim residues and pH, ETSA and NH(4)(+)-N contents were -0.84, -0.57 and -0.80, respectively. The nitrification inhibitor applications generated win-win effects on the soil-crop systems by decreasing carbendazim residues but promoting soil bacterial community diversities and stabilities and crop yields.
期刊：
Environmental Monitoring and Assessment,2023年195(12):1-17 ISSN：0167-6369
通讯作者：
Wan, DJ
作者机构：
[Wan, Da-juan; Huang, Jun-lin; Wang, Chen-ran; Chen, Jia-qi; Xiang, Yi-fan] Hunan Normal Univ, Coll Geog Sci, Changsha 410081, Peoples R China.;[Cao, Xue-ying] Changsha Univ, Rural Vitalizat Res Inst, Changsha 410022, Peoples R China.;[Ouyang, Ning-xiang] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Peoples R China.
通讯机构：
[Wan, DJ ] H;Hunan Normal Univ, Coll Geog Sci, Changsha 410081, Peoples R China.
关键词：
Hunan Province;Paddy soil;Lead;Zinc;Spatial distribution characteristics;Parent materials
摘要：
This study aimed to investigate the distribution and migration characteristics of lead (Pb) and zinc (Zn) in paddy soils in Hunan Province, China. A total of 343 soil samples from 63 profiles were collected from typical regions. The concentration, spatial distribution, and migration behaviors of Pb and Zn in the paddy soils were examined. The results showed that (1) the concentration ranges of Pb and Zn in the surface layer were 17.62-114.07 mg/kg and 44.98-146.84 mg/kg, respectively. (2) The content was higher in the middle and lower reaches of the Xiangjiang River basin horizontally and exhibited shallow enrichment characteristics vertically. (3) Pb migration was weaker than Zn migration, and the parent material had the most significant influence on Pb and Zn content in the bottom soil layer. The research results will clarify the characteristics of Pb and Zn contents in paddy soils in Hunan Province, further understand the horizontal distribution and vertical migration and transformation characteristics of Pb and Zn contents in paddy soils, and provide basic data for scientific rice cultivation and safe food production.
摘要：
Allelopathy has been considered a good explanation for the successful invasion of some invasive plants. However, the real latitudinal and longitudinal allelopathic effects on native species have rarely been documented since many exotics have spread widely. We conducted a Petri dish experiment to determine the latitudinal and longitudinal allelopathic patterns of an invasive alligator weed (Alternanthera philoxeroides) on a common crop (Lactuca sativa) in China, and find what determines the allelopathic intensity. The results showed that the allelopathic effects of A. philoxeroides increased with the latitude while decreased with the longitude. This indicated that A. philoxeroides used its allelopathy to gain competitive advantages more in its recent invaded communities than that in its early invaded ones as A. philoxeroides is expanding from southeast China to northwest China. Furthermore, we found that the allelopathic intensity of A. philoxeroide was negatively correlated to the leaf contents of soluble carbohydrate (SC), carbon (C) and nitrogen (N), but that was positively correlated to the leaf contents of soluble protein (SP), free amino acids (FAA), plant polyphenol (PP), phosphorus (P) and potassium (K). These results suggested that the allelopathic intensity of A. philoxeroide was more determined by the limited P and K nutrients as well as the intermediate allelochemicals (SP, FAA, PP) rather than the unlimited C, N and SC. Thus, we can speculate that the negative or positive effects of plant aqueous extracts are a function of not only the extract concentrations but also the trade-offs between inhibition and promotion of all components in the extracts. Then we could reduce the allelopathic effects of A. philoxeroide by controlling the component contents in the plant tissues, by fertilization or other managements, especially in the plant recent invaded communities.
作者机构：
[Hu, Ang] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Peoples R China.;[Wang, Jianjun; Hu, Ang; Meng, Fanfan] Chinese Acad Sci, Nanjing Inst Geog & Limnol, State Key Lab Lake Sci & Environm, Nanjing 210008, Peoples R China.;[Wang, Jianjun; Meng, Fanfan] Univ Chinese Acad Sci, Beijing 100049, Peoples R China.;[Tanentzap, Andrew J.] Trent Univ, Sch Environm, Ecosyst & Global Change Grp, Peterborough, ON K9L 0G2, Canada.;[Tanentzap, Andrew J.] Univ Cambridge, Dept Plant Sci, Ecosyst & Global Change Grp, Cambridge CB2 3EA, England.
通讯机构：
[Jianjun Wang] S;State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academic of Sciences, Nanjing210008, China<&wdkj&>University of Chinese Academy of Sciences, Beijing100049, China
关键词：
dark matter;microbes;dissolved organic matter;global change
摘要：
Electrontransfer (ET) is the essence of most biogeochemical processesrelated to element cycling and contaminant attenuation, whereas ETbetween different minerals and the controlling mechanism remain elusive.Here, we used surface-associated Fe-(II) as a proxy to explore ET betweenreduced nontronite NAu-2 (rNAu-2) and Fe (hydr)-oxides in their coexistingsystems. Results showed that ET could occur from rNAu-2 to ferrihydritebut not to goethite, and the ET amount was determined by the numberof reactive sites and the reduction potential difference between rNAu-2and ferrihydrite. ET proceeded mainly through the mineral-mineralinterface, with a negligible contribution of dissolved Fe2+/Fe3+. Control experiments by adding K+ andincreasing salinity together with characterizations by X-ray diffraction,scanning electron microscopy/energy-dispersive spectrometry, and atomicforce microscopy suggested that ferrihydrite nanoparticles insertedthe interlayer space in rNAu-2 where structural Fe-(II) in rNAu-2 transferredelectrons mainly through the basal plane to ferrihydrite. This studyimplicates the occurrence of ET between different redox-active mineralsthrough the mineral-mineral interface. As minerals at differentreduction potentials often coexist in soils/sediments, the mineral-mineralET may play an important role in subsurface biogeochemical processes. Electron transfer from Fe-(II)-bearingclay minerals to Fe(hydr)-oxides proceeds mainly through the mineral-mineral interface,with the interior structural Fe-(II) and expandable interlayer spacein clay minerals serving as the major electron reservoir and reactionsite, respectively.
摘要：
In recent years, carbon-based materials catalyzing peroxymonosulfate (PMS) for green degradation of persistent or-ganic pollutants have attracted increasing attention. However, PMS activation by hydrochar composite (e.g. hydrochar-montomorillonite) has rarely been investigated. Herein, a simple preparation, low-cost and eco-friendly catalyst of hydrochar-montmorillonite composite (HC-Mt) was prepared to firstly catalyze PMS for the degradation of dicamba (DIC). The as-prepared HC-Mt showed a remarkably better catalyzing performance for PMS than pure hydrochar (HC) due to its good physicochemical characteristics and abundant oxygen-containing groups. Further-more, the electron spin resonance (ESR) and quenching tests revealed that active species such as SO4 center dot-, center dot OH and O2 center dot- all participated in the degradation process. DIC sites on C6, Cl 10, and O15 exhibited higher reactivity according to the density functional theory (DFT) calculation, which were easily attacked by active species. The DIC degradation mainly occurred via hydroxyl substitution, decarboxylation, oxidation and ring-cleavage and finally most of the inter-mediates were mineralized into CO2 and H2O. Finally, the phytotoxicity assessment was measured by the germination growth situation of tobacco and mung beans in the presence of DIC (with or without treatment by HC-Mt/PMS). The result showed that HC-Mt/PMS could significantly reduce the phytotoxicity of DIC to crops, suggesting that catalyzing PMS using HC-Mt was environmentally friendly. Therefore, this work did not only provide a novel catalyzing PMS strategy using hydrochar composite for wastewater treatment, but also give a new idea for herbicide phytotoxicity management.
作者机构：
[Li, Junchun] Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China;[Li, Junchun] Guangdong Key Laboratory of Contaminated Environmental Management and Remediation, Guangdong Provincial Academy of Environmental Science, Guangdong, 510045, China;[Yang, Xiao] Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China. Electronic address: yanxl@igsnrr.ac.cn;[Tong, Xuejiao] Yuhuan Enviromental Technology Co.Ltd, Shijiazhuang, Hebei, 050000, China;[Peng, Yutao] School of Agriculture, Sun Yat-sen University, Shenzhen, Guangdong, 518107, China
通讯机构：
[Xiao Yang; Xiulan Yan] K;Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
关键词：
Cd accumulation;Intercropping;Potentially toxic elements;Safe production;Sustainable agriculture
摘要：
The utilization of Cd-contaminated soil in vegetable crop production can lighten the food crisis and improve the soil environmental resilience. Intercropping is a reliable technology in safety production from contaminated soil. A field-scale experiment was carried out to unravel how plant species and pattern affect the growth and Cd uptake of Chinese cabbage from Cd contaminated land. Among all the intercropping systems designed in this study, one row of Chinese cabbage intercropping with one row of Solanum nigrum L. is the best planting mode (high yields (2.78kg/m(2)) and low Cd accumulation (0.02mg/kg) of Chinese cabbage). Combined with the in-depth joint analysis of diverse soil physicochemical features (soil nutrient characteristics and microbial community structure), biomass yield and quality, and soil microbiological properties, we elaborated that two measures (screening hyperaccumulation types and controlling planting strip width) were the major factors in determining the growth of the aboveground and underground parts of Chinese cabbage respectively, thus directly regulating the application effectiveness of intercropping technology. The intertwined mechanisms (interspecific and intraspecific relationship) of different intercropping systems are summarized, which include better utilization of space, light and other resources in the aboveground part, bioavailability of nutrient, drive of soil bacteria and alleviated soil Cd stress in the underground part, etc. Our research outputs indicate the effectiveness and feasibility of intercropping can be improved by optimizing the streamline configuration and plant mode, which provide theory of reference and practical evidence for warranting the food safety and agricultural soil remediation simultaneously.
摘要：
Although increasing attention has been paid to agronomic measures for reducing the heavy metal load in rice grain, the effects of duckweed-paddy co-cropping technology on the accumulation of cadmium (Cd) in rice grains remain unclear. To investigate its specific effects on Cd accumulation in paddy fields, three types of duckweed-like hydrophyte (DH), Azolla imbricata, Spirodela polyrrhiza, and Lemna minor were chosen for study. Their use resulted in a reduction of Cd content in rice grains from 0.40mg/kg to <0.20mg/kg, with A. imbricata yielding the best results (0.15mg/kg). The three types of DH reduced the available Cd content in the soil by 10% to 35% after the paddy tillering stage. The reduction of available Cd content was attributed to the absorption, high pH, and increase of relative abundance of special bacteria of immobilizing Cd. In addition, DH could regulate soil nitrogen leading to ammonium nitrogen increased from 75mg/kg to 100mg/kg, while nitrate nitrogen decreased from 0.55 to 0.1-0.3mg/kg. The increase of ammonium nitrogen content might induce the low Cd transfer ability in rice plant and then low Cd content in rice grain. This study demonstrated that DH has a good effect on the reduction of the Cd concentration in rice grains. Consequently, duckweed-paddy co-cropping technology offers a potential solution to heavy metal pollution and agricultural non-point source pollution, as it not only reduces Cd levels in rice plants, but also fixes nitrogen, reducing the need for nitrogen application.
期刊：
Science of The Total Environment,2023年859(Pt 1):160215 ISSN：0048-9697
通讯作者：
Lifeng Zhu
作者机构：
[Hu, Ting; Jiang, Shuyu; Zhu, Lifeng; Zhao, Wenqian] Nanjing Normal Univ, Coll Life Sci, Nanjing 210046, Peoples R China.;[Hu, Ting; Wang, Jianjun; Jiang, Shuyu; Hu, Ang; Zhao, Wenqian] Chinese Acad Sci, Nanjing Inst Geog & Limnol, State Key Lab Lake Sci & Environm, Nanjing 210008, Peoples R China.;[Wang, Jianjun] Univ Chinese Acad Sci, Beijing 100049, Peoples R China.;[Hu, Ang] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Peoples R China.
通讯机构：
[Lifeng Zhu] C;College of Life Sciences, Nanjing Normal University, Nanjing 210046, China
关键词：
Acidification;Alpha and beta diversity;Biotic homogenization;Environmental recovery;Plankton communities;Spatiotemporal variations
摘要：
Determining biodiversity responses to environmental change, such as acidification, is critical for ecosystem projections under future global change scenarios. Here, we analyzed three plankton communities of phytoplankton, crustaceans and rotifers in 28 lakes in the Adirondack Park, USA, during 1994-2012, and examined the spatiotemporal trends in their alpha and beta diversity during recovery from acidification. For all plankton assemblages, Shannon diversity increased towards recent years and high lake pH, and there was an increasing community dissimilarity with pH changes. The spatial mean Bray-Curtis dissimilarities across all lakes decreased over time for phytoplankton and rotifers leading to an increase in spatial homogenization. Such a homogenization cooccurred however with the overall increasing diversity in this region, which contrasts with the previous classic view that homogenization is mainly driven by loss of species and results in biodiversity loss. We further observed lower temporal mean beta diversity in low-pH lakes for crustaceans and rotifers, but not for phytoplankton. Generally, spatial and temporal mean beta diversity of the three taxonomic groups were primarily driven by lake-water ion variables, and rotifers were also constrained by nutrients and climate. Collectively, our results show how and why plankton community compositions vary over space along with acidification recovery, and further highlight the importance of spatiotemporal studies combined with long-term monitoring programs in assessing biodiversity change during the recovery of disturbed ecosystems.
