Preliminary discussion on the ignition mechanism of exploding foil initiators igniting boron potassium nitrate

Exploding foil initiator(EFI)is a kind of advanced device for initiating explosives,but its function is unstable when it comes to directly igniting pyrotechnics.To solve the problem,this research aims to reveal the ignition mechanism of EFIs directly igniting pyrotechnics.An oscilloscope,a photon Doppler velocimetry,and a plasma spectrum measurement system were employed to obtain information of electric characteristics,impact pressure,and plasma temperature.The results of the electric characteristics and the impact pressure were inconsistent with ignition results.The only thing that the ignition success tests had in common was that their plasma all had a relatively long period of high-temperature duration(HTD).It eventually concludes that the ignition mechanism in this research is the microconvection heat transfer rather than the shock initiation,which differs from that of exploding foil initiators detonating explosives.Furthermore,the methods for evaluating the ignition success of semiconductor bridge initiators are not entirely applicable to the tests mentioned in this paper.The HTD is the critical parameter for judging the ignition success,and it is influenced by two factors:the late time discharge and the energy of the electric explosion.The longer time of the late time discharge and the more energy of the electric explosion,the easier it is to expand the HTD,which improves the probability of the ignition success.

Strategies of selective electroreduction of aqueous nitrate to N_(2) in chloride-free system:A critical review

Electroreduction of nitrate has been gaining wide attention in recent years owing to it's beneficial for converting nitrate into benign N_(2) from the perspective of electrocatalytic denitrification or into value-added ammonia from the perspective of electrocatalytic NH_(3) synthesis.By reason of the undesired formation of ammonia is dominant during electroreduction of nitrate-containing wastewater,chloride has been widely used to improve N_(2) selectivity.Nevertheless,selective electroreduction of nitrate to N2 gas in chloride-containing system poses several drawbacks.In this review,we focus on the key strategies for efficiently enhancing N_(2) selectivity of electroreduction of nitrate in chloride-free system,including optimal selection of elements,combining an active metal catalyst with another metal,manipulating the crystalline morphology and facet orientation,constructing core–shell structure catalysts,etc.Before summarizing the strategies,four possible reaction pathways of electro-reduction of nitrate to N_(2) are discussed.Overall,this review attempts to provide practical strategies for enhancing N2 selectivity without the aid of electrochlorination and highlight directions for future research for designing appropriate electrocatalyst for final electrocatalytic denitrifi-cation.

Nitrate reduction capacity of the oral microbiota is impaired in periodontitis:potential implications for systemic nitric oxide availability

The reduction of nitrate to nitrite by the oral microbiota has been proposed to be important for oral health and results in nitric oxide formation that can improve cardiometabolic conditions. Studies of bacterial composition in subgingival plaque suggest that nitrate-reducing bacteria are associated with periodontal health, but the impact of periodontitis on nitrate-reducing capacity(NRC)and, therefore, nitric oxide availability has not been evaluated. The current study aimed to evaluate how periodontitis affects the NRC of the oral microbiota. First, 16S rRNA sequencing data from five different countries were analyzed, revealing that nitratereducing bacteria were significantly lower in subgingival plaque of periodontitis patients compared with healthy individuals(P < 0.05 in all five datasets with n = 20–82 samples per dataset). Secondly, subgingival plaque, saliva, and plasma samples were obtained from 42 periodontitis patients before and after periodontal treatment. The oral NRC was determined in vitro by incubating saliva with 8 mmol/L nitrate(a concentration found in saliva after nitrate-rich vegetable intake) and compared with the NRC of 15healthy individuals. Salivary NRC was found to be diminished in periodontal patients before treatment(P < 0.05) but recovered to healthy levels 90 days post-treatment. Additionally, the subgingival levels of nitrate-reducing bacteria increased after treatment and correlated negatively with periodontitis-associated bacteria(P < 0.01). No significant effect of periodontal treatment on the baseline saliva and plasma nitrate and nitrite levels was found, indicating that differences in the NRC may only be revealed after nitrate intake. Our results suggest that an impaired NRC in periodontitis could limit dietary nitrate-derived nitric oxide levels, and the effect on systemic health should be explored in future studies.

OsNPF3.1,a nitrate,abscisic acid and gibberellin transporter gene,is essential for rice tillering and nitrogen utilization efficiency

Low-affinity nitrate transporter genes have been identified in subfamilies 4-8 of the rice nitrate transporter 1(NRT1)/peptide transporter family(NPF),but the OsNPF3 subfamily responsible for nitrate and phytohormone transport and rice growth and development remains unknown.In this study,we described OsNPF3.1 as an essential nitrate and phytohormone transporter gene for rice tillering and nitrogen utilization efficiency(NUtE).OsNPF3.1 possesses four major haplotypes of its promoter sequence in 517 cultivars,and its expression is positively associated with tiller number.Its expression was higher in the basal part,culm,and leaf blade than in other parts of the plant,and was strongly induced by nitrate,abscisic acid(ABA)and gibberellin 3(GA_3)in the root and shoot of rice.Electrophysiological experiments demonstrated that OsNPF3.1 is a pH-dependent low-affinity nitrate transporter,with rice protoplast uptake assays showing it to be an ABA and GA_3 transporter.OsNPF3.1 overexpression significantly promoted ABA accumulation in the roots and GA accumulation in the basal part of the plant which inhibited axillary bud outgrowth and rice tillering,especially at high nitrate concentrations.The NUtE of OsNPF3.1-overexpressing plants was enhanced under low and medium nitrate concentrations,whereas the NUtE of OsNPF3.1 clustered regularly interspaced short palindromic repeats(CRISPR)plants was increased under high nitrate concentrations.The results indicate that OsNPF3.1 transports nitrate and phytohormones in different rice tissues under different nitrate concentrations.The altered OsNPF3.1 expression improves NUtE in the OsNPF3.1-overexpressing and CRISPR lines at low and high nitrate concentrations,respectively.

Assessment of Nitrates and Nitrites in Borehole Water from the Southern and the Northern Region of Côte d’Ivoire (West Africa)

This study aimed to evaluate the quality of water from village boreholes by measuring physicochemical parameters such as nitrates, nitrites, and total organic carbon (TOC). Forty-five (45) village pumps from the Southern (Basse Côte) and the Northern (Korhogo) region of Cte d’Ivoire (west Africa) were sampled. Physicochemical parameters such as temperature, pH, conductivity at 25˚C, and turbidity were determined in situ, while nitrite and nitrate were analyzed according to ISO 10304-1 (2007) standard and total organic carbon (TOC) by NF EN 1484 (1997) standard. The results showed that the borehole waters of the Basse Côte and Korhogo analyzed are acidic, with an average temperature of 27.51˚C ± 0.16˚C and 29.95˚C ± 0.51˚C respectively for the Basse Côte and Korhogo regions. The borehole waters of the Basse Côtedo not contain nitrites, while those of Korhogo have average nitrite contents of 0.32 mg/l. The average nitrate rate in the waters of the Basse Côte and Korhogo are 12.08 ± 2.11 mg/l and 11.03 ± 3.18 mg/l respectively. The average TOC concentration of the waters of the Basse Côte is 1.28 ± 0.32 mg/l and that of Korhogo is 0.56 ± 0.09 mg/L. The study showed that the borehole waters of the Basse Côte and Korhogo have average temperatures between 27.4˚C and 29.95˚C with a slightly acidic pH value and acceptable salinity. The TOC concentrations obtained at the different sampling points were all below the French standard (2 mg/L) except for certains pumps of the Basse Côte. The water samples from the Basse Côte were devoid of nitrite. On the other hand, those from Korhogo revealed the presence of nitrite. Also, the borehole waters of the regions of the Basse Côte and Korhogo contain relatively high nitrate contents, presumably due to anthropometric activity. Overall, our study on the quality of drinking water showed that the waters analyzed are in compliance with international standards and safe for consumption.

Identifying the Hydrochemical Characteristics,Genetic Mechanisms and Potential Human Health Risks of Fluoride and Nitrate Enriched Groundwater in the Tongzhou District,Beijing,North China

Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas and economic hubs.This study focuses on the high F^(−)and NO_(3)^(−)concentration groundwater in Tongzhou District,Beijing,North China.A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics,elucidate genetic mechanisms and evaluate the potential human health risks.The results of the analysis indicate:Firstly,most of the groundwater samples are characterized by Mg-HCO_(3) and Na-HCO_(3) with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471-2337 mg/L.The NO_(3)^(−)concentration in 38.89%groundwater samples and the F^(−)concentration in 66.67%groundwater samples exceed the permissible limited value.Secondly,F^(−)in groundwater originates predominantly from water-rock interactions and the fluorite dissolution,which is also regulated by cation exchange,competitive adsorption of HCO_(3)−and an alkaline environment.Thirdly,the effect of sewage disposal and agricultural activities have a significant effect on high NO3-concentration,while the high F^(−)concentration is less influenced by anthropogenic activity.The alkaline environment favors nitrification,thus being conducive to the production of NO_(3)^(−).Finally,the health risk assessment is evaluated for different population groups.The results indicate that high NO_(3)^(−)and F^(−)concentration in groundwater would have the largest threat to children’s health.The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.

Comprehensive understanding of the thriving electrocatalytic nitrate/nitrite reduction to ammonia under ambient conditions

Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the conventional Haber–Bosch process that operates under harsh conditions,which consumes large quantities of fossil fuels and releases a large amount of carbon dioxide.As an alternative,electrosynthesis is a prospective method for producing NH_(3)under normal temperature and pressure conditions.Although electrocatalytic nitrogen reduction to ammonia has attracted considerable attentions,the low solubility of N_(2)and high N≡N cracking energy render the achievements of high NH_(3) yield rate and Faradaic efficiency difficult.Nitrate and nitrite(NO_(x)^(-))are common N-containing pollutants.Due to their high solubilities and low dissociation energy of N=O,NO_(x)^(-)−are ideal raw materials for NH_(3) production.Therefore,electrocatalytic NO_(x)^(-)−reduction to NH_(3)(eNO_(x)RR)is a prospective strategy to simultaneously realise environmental protection and NH_(3) synthesis.This review offers a comprehensive understanding of the thriving eNO_(x)RR under ambient conditions.At first,the popular theory and mechanism of eNO_(x)RR and a summary of the measurement system and evaluation criteria are introduced.Thereafter,various strategies for developing NO_(x)−reduction catalysts are systematically presented and discussed.Finally,the challenges and possible prospects of electrocatalytic NO_(x)^(-1) reduction are outlined to facilitate energy-saving and environmentally friendly large-scale synthesis of NH_(3) in the future.

Oxygen‑Coordinated Single Mn Sites for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Electrocatalytic nitrate reduction reaction has attracted increasing attention due to its goal of low carbon emission and environmental protection.Here,we report an efficient NitRR catalyst composed of single Mn sites with atomically dispersed oxygen(O)coordination on bacterial cellulose-converted graphitic carbon(Mn-O-C).Evidence of the atomically dispersed Mn-(O-C_(2))_(4)moieties embedding in the exposed basal plane of carbon surface is confirmed by X-ray absorption spectroscopy.As a result,the as-synthesized Mn-O-C catalyst exhibits superior NitRR activity with an NH_(3)yield rate(RNH_(3))of 1476.9±62.6μg h^(−1)cm^(−2)at−0.7 V(vs.reversible hydrogen electrode,RHE)and a faradaic efficiency(FE)of 89.0±3.8%at−0.5 V(vs.RHE)under ambient conditions.Further,when evaluated with a practical flow cell,Mn-O-C shows a high RNH_(3)of 3706.7±552.0μg h^(−1)cm^(−2)at a current density of 100 mA cm−2,2.5 times of that in the H cell.The in situ FT-IR and Raman spectroscopic studies combined with theoretical calculations indicate that the Mn-(O-C_(2))_(4)sites not only effectively inhibit the competitive hydrogen evolution reaction,but also greatly promote the adsorption and activation of nitrate(NO_(3)^(−)),thus boosting both the FE and selectivity of NH_(3)over Mn-(O-C_(2))_(4)sites.

Advancements in Catalysts for Electrochemical Nitrate Reduction: A Sustainable Approach for Mitigating Nitrate Pollution: A Review

Nitrate pollution is of great importance in both the environmental and health contexts, necessitating the development of efficient mitigation strategies. This review provides a comprehensive analysis of the many catalysts employed in the electrochemical reduction of nitrate to ammonia, and presents a viable environmentally friendly approach to address the issue of nitrate pollution. Hence, the electrochemical transformation of nitrate to ammonia serves the dual purpose of addressing nitrate pollution in water bodies, and is a useful agricultural resource. This review examines a range of catalyst materials such as noble and non-noble metals, metal oxides, carbon-based materials, nitrogen-doped carbon species, metal complexes, and semiconductor photocatalysts. It evaluates catalytic efficiency, selectivity, stability, and overall process optimization. The performance of catalysts is influenced by various factors, including reaction conditions, catalyst structure, loading techniques, and electrode interfaces. Comparative analysis was performed to evaluate the catalytic activity, selectivity, Faradaic efficiency, current density, stability, and durability of the catalysts. This assessment offers significant perspectives on the structural, compositional, and electrochemical characteristics that affect the efficacy of these catalysts, thus informing future investigations and advancements in this domain. In addition to mitigating nitrate pollution, the electrochemical reduction of nitrate to ammonia is in line with sustainable agricultural methods, resource conservation, and the utilization of renewable energy resources. This study explores the factors that affect the catalytic efficiency, provides new opportunities to address nitrate pollution, and promotes the development of sustainable environmental solutions.

Humic Acid Effects on Reducing Corn Leaf Burn Caused by Foliar Spray of Urea-Ammonium Nitrate at Different Humic Acid/Urea-Ammonium Nitrate Ratios

Technologies for reducing corn leaf burn caused by foliar spray of urea-ammonium nitrate (UAN) during the early growing season are limited. A field experiment was carried out to evaluate the effects of humic acid on corn leaf burn caused by foliar spray of undiluted UAN solution on corn canopy at Jackson, TN in 2018. Thirteen treatments of the mixtures of UAN and humic acid were evaluated at V6 of corn with different UAN application rates and different UAN/humic acid ratios. Leaf burn during 1 2, 3, 4, 5, 6, 7, and 14 days after UAN foliar spray significantly differed between with or without humic acid addition. The addition of humic acid to UAN significantly reduced leaf burn at each UAN application rate (15, 25, and 35 gal/acre). The reduction of leaf burn was enhanced as the humic acid/UAN ratio went up from 10% to 30%. Leaf burn due to foliar application of UAN became severer with higher UAN rates. The linear regression of leaf burn 14 days after application with humic acid/UAN ratio was highly significant and negative. However, the linear regression of leaf burn 14 days after application with the UAN application rate was highly significant and positive. In conclusion, adding humic acid to foliar-applied UAN is beneficial for reducing corn leaf burn during the early growing season.

Pollution characteristics of peroxyacetyl nitrate in karst areas in Southwest China

桂林是世界著名的地处喀斯特地区的旅游胜地,其光化学污染问题日益严重,过氧乙酰硝酸酯(PAN)被认为是光化学污染的可靠指标,也是本研究的重点.本研究于2021年10月首次观测了桂林的PAN的浓度为0.087-2.559ppb,同时探讨了PAN典型高值过程的成因.此次污染主要来源于东北方向污染气团的水平和高空输送,同时,高温,强辐射和低湿度等气象条件也促进了本地PAN的形成.本研究同时估算了桂林市的O3背景浓度为20.347ppb.这项研究为城市的光化学污染控制工作提供了理论基础。

Highly soluble organic nitrate additives for practical lithium metal batteries

The stability of lithium metal anodes essentially dictates the lifespan of high-energy-density lithium metal batteries.Lithium nitrate(LiNO_(3))is widely recognized as an effective additive to stabilize lithium metal anodes by forming LiN_(x)O_(y)-containing solid electrolyte interphase(SEI).However,its poor solubility in electrolytes,especially ester electrolytes,hinders its applications in lithium metal batteries.Herein,an organic nitrate,isosorbide nitrate(ISDN),is proposed to replace LiNO_(3).ISDNhas a high solubility of 3.3M in ester electrolytes due to the introduction of organic segments in the molecule.The decomposition of ISDN generates LiN_(x)O_(y)-rich SEI,enabling uniform lithium deposition.The lifespan of lithium metal batteries with ISDN significantly increases from 80 to 155 cycles under demanding conditions.Furthermore,a lithium metal pouch cell of 439Whkg^(−1) delivers 50 cycles.This work opens a new avenue to develop additives by molecular modifications for practical lithium metal batteries.

Identification of Dynamic Active Sites Among Cu Species Derived from MOFs@CuPc for Electrocatalytic Nitrate Reduction Reaction to Ammonia

Direct electrochemical nitrate reduction reaction(NITRR)is a promising strategy to alleviate the unbalanced nitrogen cycle while achieving the electrosynthesis of ammonia.However,the restructuration of the high-activity Cu-based electrocatalysts in the NITRR process has hindered the identification of dynamical active sites and in-depth investigation of the catalytic mechanism.Herein,Cu species(single-atom,clusters,and nanoparticles)with tunable loading supported on N-doped TiO_(2)/C are successfully manufactured with MOFs@CuPc precursors via the pre-anchor and post-pyrolysis strategy.Restructuration behavior among Cu species is co-dependent on the Cu loading and reaction potential,as evidenced by the advanced operando X-ray absorption spectroscopy,and there exists an incompletely reversible transformation of the restructured structure to the initial state.Notably,restructured CuN_(4)&Cu_(4) deliver the high NH_(3) yield of 88.2 mmol h^(−1)g_(cata)^(−1) and FE(~94.3%)at−0.75 V,resulting from the optimal adsorption of NO_(3)^(−) as well as the rapid conversion of^(*)NH_(2)OH to^(*)NH_(2) intermediates originated from the modulation of charge distribution and d-band center for Cu site.This work not only uncovers CuN_(4)&Cu_(4) have the promising NITRR but also identifies the dynamic Cu species active sites that play a critical role in the efficient electrocatalytic reduction in nitrate to ammonia.

Lithium nitrate regulated carbonate electrolytes for practical Li-metal batteries: Mechanisms, principles and strategies

Li-metal batteries(LMBs)regain research prominence owing to the ever-increasing high-energy requirements.Commercially available carbonate electrolytes exhibit unfavourable parasitic reactions with Limetal anode(LMA),leading to the formation of unstable solid electrolyte interphase(SEI)and the breed of Li dendrites/dead Li.Significantly,lithium nitrate(LiNO_(3)),an excellent film-forming additive,proves crucial to construct a robust Li_(3)N/Li_(2)O/Li_(x)NO_(y)-rich SEI after combining with ether-based electrolytes.Thus,the given challenge leads to natural ideas which suggest the incorporation of LiNO_(3) into commercial carbonate for practical LMBs.Regrettably,LiNO_(3) demonstrates limited solubility(~800 ppm)in commercial carbonate electrolytes.Thence,developing stable SEI and dendrite-free LMA with the incorporation of LiNO_(3) into carbonate electrolytes is an efficacious strategy to realize robust LMBs via a scalable and cost-effective route.Therefore,this review unravels the grievances between LMA,LiNO_(3)and carbonate electrolytes,and enables a comprehensive analysis of LMA stabilizing mechanism with LiNO_(3),dissolution principle of LiNO_(3) in carbonate electrolytes,and LiNO_(3) introduction strategies.This review converges attention on a point that the LiNO_(3)-introduction into commercial carbonate electrolytes is an imperious choice to realize practical LMBs with commercial 4 V layered cathode.

Monitoring Water Quality in Ballona Lagoon, Los Angeles, California: Nitrate Level Fluctuation in Low and High Tide Condition

The coastal wetland, Ballona Lagoon in Southern California has experienced degradation and size reduction due to urbanization. This study analyzes nitrate concentrations in the lagoon to identify contamination sources and assess its impact. The study includes determining nitrate levels during high and low tides during wet and dry seasons, establishing concentration gradients, and examining the relationship between salinity and nitrate concentrations. The nitrate concentrations were found to be higher in locations closer to the head of the lagoon, particularly in urbanized areas, suggesting land-based sources during the dry season’s high tide (S2: 2.37 mg/l;S3: 3.85 mg/l;S4: 3.91 mg/l). Findings highlight the importance of managing nitrate contamination near urban areas. Monitoring nitrate levels over time are crucial for sustainability efforts. This research emphasizes the need for long-term monitoring and conservation strategies to mitigate nitrate contamination in Ballona Lagoon.

Continuous Monitoring of Serum Tumor Necrosis Factor-α for Patients with TEMIS Treated by Nitrates Postconditioning during PCI

Objective: To investigate the protective effect of nitrates postconditioning on myocardial ischemia-reperfusion injury and whether it plays a regulatory role in TNF-α in patients with STEMI during PCI. Methods: Patients with STEMI who underwent PCI were selected, except for obvious anemia, head trauma, cerebral hemorrhage, hypotension (systolic blood pressure less than 90 mmHg), and patients with autoimmune diseases, all kinds of acute and chronic infections and malignant tumors. They were randomly divided into PCI standardized treatment group and isosorbide dinitrate postconditioning during PCI group. The concentrations of cTnI and TNF-α in serum were detected by ELISA method in each group before PCI and after 2 hours, 1 day, 4 days and 7 days of PCI. Results: 1) There were no statistically significant differences in sex, age, smoking history, diabetes, hypertension and blood lipid abnormality in two groups. 2) Before operation, the concentration of cTnI in two groups was not statistically significant. The concentration of cTnI in the experimental group was lower than that of the control group after 4 days and 7 days of PCI, and P α in two groups before operation. The concentration of TNF-α in the experimental group was lower than that in the control group after 1 day, 4 days and 7 days of PCI, and P α in two groups was both in 1 day after operation, and the peak level of the experimental group and the level of each time after the operation were lower than that of the control group. Conclusion: Nitrates postconditioning during PCI in patients with STEMI has a protective effect on myocardial ischemia-reperfusion injury. Nitrates postconditioning has an effect to reduce the level of TNF-α of patients with STEMI after PCI treatment, and may have the mechanism of alleviating the inflammatory response after myocardial ischemia and reperfusion.

The nitrate-responsive transcription factor Md NLP7 regulates callus formation by modulating auxin response

Under appropriate culture conditions,plant cells can regenerate new organs or even whole plants.De novo organ regeneration is an excellent biological system,which usually requires additional growth regulators,including auxin and cytokinin.Nitrate is an essential nutrient element for plant vegetative and reproductive development.It has been reported that nitrate is involved in auxin biosynthesis and transport throughout the growth and development of plants.In this study,we demonstrated that the ectopic expression of the MdNLP7 transcription factor in Arabidopsis could regulate the regeneration of root explants.MdNLP7 mainly participated in the regulation of callus formation,starting with pericycle cell division,and mainly affected auxin distribution and accumulation in the regulation process.Moreover,MdNLP7 upregulated the expression of genes related to auxin biosynthesis and transport in the callus formation stage.The results demonstrated that MdNLP7 may play a role in the nitrate-modulated regeneration of root explants.Moreover,the results revealed that nitrate–auxin crosstalk is required for de novo callus initiation and clarified the mechanisms of organogenesis.

Selective synthesis of nitrate from air using a plasma-driven gas-liquid relay reaction system

The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation processes. However, the slow kinetics of nitrogen oxidation and the difficult selective control of oxidation products hinder the development of this process. In this study, a plasma-driven gas-liquid relay reaction system was developed to overcome these limitations. A typical feature of this reaction system is that it can efficiently generate NO_x under plasma exposure;moreover, the specific anions in the absorption solution can be oxidized to strong oxidants capable of relay oxidation of low-valence nitrogen oxides. This feature allows for the deep oxidation of nitrogen, thus enabling the oxidation products of nitrogen to exist in high-valence states in the absorption solution. For experimental verification, we achieved the 100% selective synthesis of nitrate under plasma exposure, with air as the supply gas and a sodium sulfate solution as the absorption solution.

Exogenous addition of nitrate nitrogen regulates the uptake and translocation of lead (Pb) by Iris lacteal Pall. var. chinensis (Fisch.) Koidz.

Since Pb is a non-biodegradable inorganic pollutant and a non-essential metal,its long-term presence in soil poses a great threat to the environment.Iris lactea Pall.var.chinensis(Fisch.)Koidz.,a perennial dense bush herb with high resistance of Pb and wide adaptability,was used in pot experiments to study the effects of exogenous nitrate N(NO_(3)^(–)-N)on the absorption and transportation of Pb and plant growth under different Pb concentrations.Then,the mechanism of NO_(3)^(-)-N affecting Pb and nutrient uptake and transport was explored.The concentration of Pb in the experiment ranged from 0 to 1600 mg/kg,and the added concentration of NO_(3)^(-)-N was 0.0–0.3 g/kg.The results showed that I.lactea was highly tolerant to Pb,and the shoot fraction was more sensitive to varied Pb concentrations in the soil than the root fraction.This protective function became more pronounced under the condition of raised Pb concentration in the soil.When the concentration of Pb in the soil reached 800 mg/kg,the highest Pb content of I.lactea was found under the condition of 0.1 g/kg of NO–3-N addition.When Pb concentration in the soil increased to 1600 mg/kg,the increase in NO_(3)^(-)-N addition promoted Pb uptake by the root.To ensure the well growth of I.lactea and the effect of remediation of Pb-contaminated soil,the recommended concentration of NO–3-N in the soil is 0.1 g/kg.This result provides a theoretical basis for exogenous N regulation of phytoremediation of Pb-contaminated soil.

Removal of Nitrate and Phosphate Ions from the Bafing River by an Adsorbent Obtained from the Shells of Mango Cores

The valorization of agricultural waste in the treatment of our rivers can be an alternative to waste management. This study deals with the use of mango kernel shells in the depollution of the Bafing River (rural commune of Tolo, Mamou prefecture) in the Republic of Guinea. Thus, the different concentrations of ions found in April (low water period) were determined and which are: a reduction of 35.64 mg/l (79.69%);a reduction of 41.53 mg/l (81.24%);and 47.53 mg/l (82.10%) and 3.83 mg/l (75.24%);8.45 mg/l (81.72%);11.67 mg/l (87.94%) at the sampling points P1, P2, and P3 respectively. In October (flood period), the concentrations found are 24.98 mg/l reductions (79.88%);29.83 mg/l reduction (81.41%) and 35.15 mg/l (85.50%) at the same sampling points P1, P2 and P3, respectively. This study can be considered as a water treatment alternative for the village community of the Tolo sub-prefecture (Mamou prefecture).