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.
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.
通讯机构:
[Hong-Yuan Zeng] H;[Ai-Ping Wu] E;Ecology Department, College of Resources and Environment, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Hunan Institute of Microbiology, Changsha 410009, China
摘要:
Abstract: Water level rise is considered an environmental filter for the growth and reproduction of aquatic plants in lakes. Some emergent macrophytes can form floating mats, enabling them to escape from the negative effects of deep water. However, an understanding of which species can be uprooted and form floating mats easily and what factors affect these tendencies remains greatly elusive. We conducted an experiment to determine whether the monodominance of Zizania latifolia in the emergent vegetation community in Lake Erhai was related to its floating mat formation ability and to try to find the reasons for its floating mat formation ability during the continuous increase in water level over the past few decades. Our results showed that both the frequency and biomass proportion of Z. latifolia were greater among the plants on the floating mats. Furthermore, Z. latifolia was more likely to be uprooted than the other three previously dominant emergent species due to its smaller angle between the plant and the horizontal plane, rather than the root:shoot or volume:mass ratios. The dominance of Z. latifolia in the emergent community in Lake Erhai is due to its easier ability to become uprooted, allowing it to outperform other emergent species and become the single dominant emergent species under the environmental filter of deep water. The ability to uproot and form floating mats may be a competitive survival strategy for emergent species under the conditions of continuous significant water level rise. Keywords: aquatic plant; floating mat; emergent macrophyte; uprooting; angle; environmental filter; deep water; survival strategy
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.
作者机构:
[Ke, Yong; Du, Jiali; Wang, Yunyan; Cao, Junjie; Min, Xiaobo; Zhang, Limin; Xu, Hui; Yu, Lin; Luo, Yongjian] Cent South Univ, Sch Met & Environm, Changsha 410083, Peoples R China.;[Ke, Yong; Wang, Yunyan; Min, Xiaobo] Chinese Natl Engn Res Ctr Control & Treatment Heav, Changsha 410083, Peoples R China.;[Ke, Yong; Wang, Yunyan; Min, Xiaobo] Water Pollut Control Technol Key Lab Hunan Prov, Changsha 410004, Peoples R China.;[Yao, Liwei] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Peoples R China.
通讯机构:
[Liwei Yao] C;[Yunyan Wang] W;College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Water Pollution Control Technology Key Laboratory of Hunan Province, Changsha 410004, China<&wdkj&>School of Metallurgy and Environment, Central South University, Changsha 410083, China<&wdkj&>Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
摘要:
Abstract: Sulfide precipitation has been widely applied to remove arsenic from acidic wastewater containing As(III) and As(V), due to its simple process and high efficiency. However, the characteristics and composition of the precipitates are also of importance for its further treatment and disposal. To explore the characteristics of elemental S formed by reduction and the combined form of the generated S and As2S3, the characteristics of precipitates sulfurized from As(III) and As(V) and the effects of temperature, the S(-II) to As ratio (S/As), Cl− concentration (cCl−), and the volume fraction of H2SO4 (φH2SO4(v)) on the sulfurization of As(III) and As(V) were investigated in detail. The results showed that the contents of As and S were 60.37% and 39.73% in precipitate-As(III), while they accounted for 47.46% and 52.64% in precipitate-As(V); both precipitate-As(III) and precipitate-As(V) were mainly composed of amorphous As2S3, while the latter contained elemental S. Temperature and S(-II)/As(III) slightly affected the sulfurization process of As(III), while for As(V), as the temperature increased, the content of As2S3 in precipitate-As(V) increased significantly. Additionally, with the S(-II)/As(V) increasing, the content of A2S3 increased continuously. This study provides a further clarification of the specific composition and structure of the complex precipitates of arsenic sulfide, which will benefit the efficient stabilization of the arsenic sulfide sludge. Keywords: sulfurization; precipitate-As(III); precipitate-As(V); elemental S; As2S3
摘要:
Pesticide residues in market products pose a serious threat to consumers' health. This study aimed to analyze pesticide residues in agricultural products in the Chinese market. According to the data on agricultural products exceeding maximum residue levels (MRLs) obtained by the market supervision administration, 5387 batches of agricultural products (BAPs) in the Chinese market from 2011 to 2020 were extracted. The basic information of the data, time, region, crops and pesticides were discussed. The characteristics and trends of unqualified pesticide residues (UQPRs) in the Chinese market were statistically analyzed. The results showed that the BAPs withUQPRs increased over time, mainly occurring in spring and autumn. Most of the crops with UQPRs were leafy crops, among which Leek and Celery accounted for 28.3% and 16.9% of the total, respectively. Meanwhile, the regions with the most BAPs were Shandong, Henan, and Chongqing. Combining the statistical results and analyzing the reasons, the occurrence of UQPRs can be reduced from three aspects: government, market, and farmers.
关键词:
Surface ion imprinting;support;heavy metal ions;adsorption
摘要:
Surface ion-imprinting technology (SIIT) is a novel and effective alternative to conventional methods of preparing ion-imprinted polymers. SIIT involves the coating of support materials with a polymeric layer that selectively binds with imprinted metal ions, particularly heavy metal ions. Given its specificity, predictability, and stability, SIIT has been quickly adopted in ion detection, separation, enrichment, and sensing. Here, building on the latest advances in this emerging new technology, we carried out a systematic review to summarize the 1) principles and basic components of surface ion-imprinted polymers (SIIPs); 2) preparations, properties, advantages, and disadvantages of three types of SIIP supporting materials, including inorganic (minerals, carbonaceous materials, metal oxides), organic, and composite (organic/organic, organic/inorganic, inorganic/inorganic) supports; 3) current applications of SIIT, and 4) future challenges and opportunities related to SIIT. Finally, perspectives and future research are discussed to address the pressing need for the development of SIIT for heavy metal ion treatment.
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.
关键词:
Lead-acid battery;Low temperature alkaline smelting;FeO-SiO 2-CaO-Na 2 O smelting system;Bath smelting;Lead recovery
摘要:
Recycling lead from waste lead-acid batteries has substantial significance in environmental protection and economic growth. Bearing the merits of easy operation and large capacity, pyrometallurgy methods are mostly used for the regeneration of waste lead-acid battery (LABs). However, these processes are generally operated at the temperature higher than 1300 degrees C. To shorten the energy consumption, a novel pyrometallurgy process which consisted of low temperature alkaline and bath smelting was proposed in this work. The reduction of lead and smelting of slag system are the key factors determine the energy consumption. Thermodynamic calculation suggested that the addition of Na2CO3 can make the reduction of PbSO4 spontaneously at the temperature higher than 288 degrees C (PbSO4 -> PbCO3 -> PbO -> Pb), while direct reduction of PbSO4 necessitated the temperature higher than 1499 degrees C (PbSO4 -> PbO -> Pb). To achieve the efficient reduction of PbSO4, the molar ratios of C/PbSO4 and Na2CO3/PbSO4 should be higher than 0.5 and 1.0, respectively. Meanwhile, a new smelting system (i.e., FeOSiO2-CaO-Na2O) was established in the presence of Na2CO3. Phases with low melting temperatures, such as NaFe2O3, Na2FeSiO4, Na2Ca2Si2O7, Na14Fe6O16 and Na0.5FeO2, were formed. The melting temperature of Fe-SiCa-Na system was lowered to 1050 degrees C at the mass dosage of Na2CO3 at 30%. Recovery of lead under various reduction conditions were systematically evaluated. Under optimum operational conditions, i.e., the dosages of C and Na2CO3 at 10% and m(actual)/m(theory) ratio of 1.3 (all in mass), smelting temperature of 1050 degrees C, and smelting time of 75 min, respectively, the lead recovery efficiency reached >98.0%. Moreover, this method has been successfully applied for the industrial recovery of lead at the scale of 200, 000 tons annually since 2019. Taken together, this method is robust for recovery of lead from the waste LABs and is helpful for building the resource-conserving society.
摘要:
Expose of cadmium (Cd) leads to severe leaf chlorosis and reducing nutrient uptake. It is unclear how plants responded to Cd stress in the roots, and its relation to the leaf chlorosis. Our results showed Cd disturbed the homeostasis of multiple nutrient element at different levels. The most reduced elements were Mn, Fe, with 96 %, 89 % decline in the leaves, that caused leaf chlorosis. The plants actively downregulated the expression of metal transporters to reduce Cd uptake, but consequently reducing Fe and Mn uptake. Moreover, Cd stress promoted the formation of iron plaque and significantly reduced the exchangeable ions on root surface. Importantly, ethylene plays an essential role in regulating iron plaque formation and the existent forms of Cd. Blocking ethylene biosynthesis significantly increased exchangeable Cd on the root surface and decreased the percentage of iron oxides bound Cd, thus leading to increase of Cd in the shoots. Above all, our results revealed plants actively control the expression of metal transporter and the ethylene-dependent iron plaque formation to reduce Cd uptake, but sacrificed iron nutrition. The mechanism of sequester Cd on rhizosphere by ethylene in response to Cd stress may provide guidelines for the mitigation of Cd accumulation in rice via ethylene-dependent rhizosphere regulation.
摘要:
Soil microbes and fauna as key components of belowground food webs play important roles in energy flux and carbon cycling in terrestrial ecosystems. However, it remains unclear whether forestry management regimes alter the energetic structure of soil food webs and thereby reshape the patterns of soil CO2 emissions in planted forest. Here, we tested the effects of legume (Cassia alata) addition, understory removal, understory removal with legume addition and all plants removal on energy fluxes through soil food webs and soil CO2 flux in the wet and dry seasons. We show that soil heterotrophic respiration contributed 36.9-57.8% of total CO2 flux in the soil. In the dry season, C. alata addition increased soil heterotrophic respiration by 24.6% and 57.3%, respectively, when compared with the control and understory removal treatment. Compared with the understory removal treatment, the total energy flux across the whole food web increased with legume addition (i.e., C. alata addition and understory removal with C. alata addition). Legume addition supported a high proportion of energy flux through herbivorous nematodes, whereas understory vegetation removal supported a high proportion of energy flux through microbivorous nematodes. Less energy fluxes were transferred from basal resources to fungivorous mites and collembolans compared with microbivorous and herbivorous nematodes. The total soil CO2 flux was posi-tively correlated with metabolic rates of herbivorous and omnivorous-predatory nematodes, and energy fluxes through multitrophic groups. Taken together, legume addition and understory vegetation removal modify the patterns of soil CO2 emissions via changing nematode metabolic rates and re-shaping the energetic structure of soil food webs.