Nitrogen and phosphorus co-doped activated carbon induces high density Cu^(+)active center for acetylene hydrochlorination

This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)with different content(mCu-xNP/AC)were manufactured and applied in the acetylene hydrochlorination reaction.It was found that the doping of carriers N and P induced the transformation of Cu^(2+)to Cu^(+),and the catalytic activity was markedly improved.Under the optimal reaction temperature of 220℃,the gas hourly space velocity(GHSV)of C_(2)H_(2)was 90 h^(-1)and V_(HCl):V_(C_(2)H_(2))was 1.15.The initial activity of the 5%Cu-30 NP/AC catalyst reached 95.59%.Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon,which increased the ratio of Cu^+/Cu^(2+).The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C_(2)H_(2)decreased slightly,and the chemisorption capacity for HCl increased significantly,which was the reason for the increased activity of the catalyst.The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.

Spatial patterns of leaf nitrogen and phosphorus stoichiometry across southeast to central Tibet

Leaf N and P stoichiometry in terrestrial ecosystems has been widely investigated in recent years owing to the importance of these elements in improving the predicted vegetation responses to global changes.The vertical distribution of leaf N and P stoichiometry has attracted increasing attention because of the dramatic changes in environmental factors at regional scales.However,the characteristics of leaf N and P stoichiometry in the southeast Qinghai–Tibet plateau(SET)are not clear,although this area is sensitive to global change.Here,we analyzed the leaf N and P concentrations in dominant plant species on natural altitudinal gradients on the Duoxiongla(DXL),Sejila(SJL),Mila(ML),and Gangbala(GBL)mountains across the SET all the way to central Tibet.Our results showed that the leaf N concentrations were comparable among the regions,whereas the leaf P concentrations dramatically decreased from SET to central Tibet(CT).The leaf N concentrations were 23.6,21.3,20.8,and 22.4 g kg^(-1),and the leaf P concentrations were 2.40,2.49,1.94,and 1.59 g kg^(-1) on the SJL,DXL,ML and GBL mountains,respectively.The leaf N/P ratios on the DXL,SJL,ML,and GBL mountains were 8.81,10.3,11.2,and 14.2,respectively.Considering the increasing trend of the leaf N/P ratio from southeast Qinghai–Tibet plateau to central Tibet,N limitation might widely exist in well vegetated ecosystems in the Qinghai–Tibet plateau.

Effects of metal lead on growth and mycorrhizae of an invasive plant species (Solidago canadensis L.)

It is less known whether and how soil metal lead （Pb） impacts the invasion of exotic plants. A greenhouse experiment was conducted to estimate the effects of lead on the growth and mycorrhizae of an invasive species （Solidago canadensis L.） in a microcosm system. Each microcosm unit was separated into HOST and TEST compartments by a replaceable mesh screen that allowed arbuscular mycorrhizal （AM） fungal hyphae rather than plant roots to grow into the TEST compartments. Three Pb levels （control, 300, and 600 mg/kg soil） were used in this study to simulate ambient soil and two pollution sites where S. canadensis grows. Mycorrhizal inoculum comprised five indigenous arbuscular mycorrhizal fungal species （ Glomus mosseae, Glomus versiform, Glomus diaphanum, Glomus geosporum, and Glomus etunicatum）. The ^15N isotope tracer was used to quantify the mycorrhizally mediated nitrogen acquisition of plants. The results showed that S. canadensis was highly dependent on mycorrhizae. The Pb additions significantly decreased biomass and arbuscular mycorrhizal colonization （root length colonized, RLC%） but did not affect spore numbers, N （including total N and ^15N） and P uptake. The facilitating efficiency of mycorrhizae on nutrient acquisition was promoted by Pb treatments. The Pb was mostly sequestered in belowground of plant （root and rhizome）. The results suggest that the high efficiency of mycorrhizae on nutrient uptake might give S. canadensis a great advantage over native species in Pb polluted soils.

Fertilization Affects Biomass Production of Suaeda salsa and Soil Organic Carbon Pool in East Coastal Region of China

Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon （SOC） is considered as an essential indicator of soil quality. The objective of this study was to assess the effects of N and P applied to Suaeda salsa on biomass production, SOC concentration, labile organic carbon （LOC） concentration, SOC pool and carbon management index （CMI） as well as the effect of the land use practice on soil quality of coastal tidal lands in east coastal region of China. The study provided relevant references for coastal exploitation, tidal land management and related study in other countries and regions. The field experiment was laid out in a randomized complete block design, consisting of four N-fertilization rates （0 （NO）, 60 （N1）, 120 （N2） and 180 kg ha-1 （N3））, three P-fertilization rates （0 （P0）, 70 （P1） and 105 kg ha-~ （P2）） and bare land without vegetation. N and P applied to S. salsa on coastal tidal lands significantly affected biomass production （above-ground biomass and roots）, bulk density （Pb）, available N and P, SOC, LOC, SOC pool and CMI. Using statistical analysis, significantly interactions in N and P were observed for biomass production and the dominant factor for S. salsa production was N in continuous 2-yr experiments. There were no significant interactions between N and P for SOC concentration, LOC concentration and SOC pool. However, significant interaction was obtained for CMI at the 0-20 cm depth and N played a dominant role in the variation of CMI. There were significant improvements for soil measured attributes and parameters, which suggested that increasing the rates of N and P significantly decreased Pb at the 0-20 cm depth and increased available N and P, SOC, LOC, SOC pool as well as CMI at both the 0-20 and 20-40 cm depth, respectively. By correlation analysis, there were significantly positive correlations between biomass （above- ground biomass and roots） and SOC as well as LOC in 2010 and 2011 across all soil depth, respectively. The treatment with N at 180 kg ha-~ and P at 105 kg ha-1 was superior to the other treatments. The results from the 2-yr continuous experiments indicated that, in short-term, there were a few accumulation of SOC and LOC concentrations by means of N and P application to S. salsa, whereas in the long run, S. salsa with N and P application was recommended for coastal tidal lands because of its great potential of carbon sequestration, improvements of soil nutrition status and promotion of soil quality.

Replanting of broadleaved trees alters internal nutrient cycles of native and exotic pines in subtropical plantations of China

Background:The replanting of broadleaved trees in pure coniferous plantations is widely implemented,as mixed plantations are generally more stable and functional.However,the effect of interspecific interactions between broadleaved and coniferous trees on internal nutrient cycles of conifers remains unclear.Methods:We selected pure coniferous plantations of a native(Pinus massoniana)and an exotic(P.elliottii)pine species and their corresponding mixed plantations with broadleaved trees(Schima superba)in subtropical China,and measured the nitrogen(N)and phosphorus(P)contents in the rhizosphere soils,fine roots,twigs,needles and needle litter of pines.We calculated the root capture,needle resorption and translocation of N and P by pines to determine the mobility of nutrients in trees.Results:Although the N and P in the rhizosphere soils increased due to the replanting of broadleaved trees,the N and P contents in the aboveground tissues of the two pine species did not increase in mixed plantations.Mixed planting had a negative effect on the N and P capture of native pine and a positive effect on that of exotic pine.The N and P resorption efficiencies increased in native pine but were unchanged in exotic pine after the replanting of S.superba.Native pine preferentially employed an aboveground nutrient resorption strategy,whereas exotic pine tended to adopt a belowground nutrient capture strategy after replanting.Translocation of N and P in trees was detected,which reflected the trade-offs between root nutrient capture and needle nutrient resorption.Conclusions:The effect of mixed planting varied between the species of native and exotic pines,and the internal nutrient cycles of both pine species might be dominated by interspecific interaction effects on nutrients rather than soil nutrients.Our study highlights the importance of selecting suitable broadleaved species for replanting in coniferous plantations.

Ecological stoichiometry and biomass response of Agropyron michnoi Roshev.under simulated N deposition in a sandy grassland,China

Sandy grassland in northern China is a fragile ecosystem with poor soil fertility.Exploring how plant species regulate growth and nutrient absorption under the background of nitrogen(N)deposition is crucial for the management of the sandy grassland ecosystem.We carried out a field experiment with six N levels in the Hulunbuir Sandy Land of China from 2014 to 2016 and explored the Agropyron michnoi Roshev.responses of both aboveground and belowground biomasses and carbon(C),N and phosphorus(P)concentrations in the plant tissues and soil.With increasing N addition,both aboveground and belowground biomasses and C,N and P concentrations in the plant tissues increased and exhibited a single-peak curve.C:N and C:P ratios of the plant tissues first decreased but then increased,while the trend for N:P ratio was opposite.The peak values of aboveground biomass,belowground biomass and C concentration in the plant tissues occurred at the level of 20 g N/(m2•a),while those of N and P concentrations in the plant tissues occurred at the level of 15 g N/(m2•a).The maximum growth percentages of aboveground and belowground biomasses were 324.2%and 75.9%,respectively,and the root to shoot ratio(RSR)decreased with the addition of N.N and P concentrations in the plant tissues were ranked in the order of leaves>roots>stems,while C concentration was ranked as roots>leaves>stems.The increase in N concentration in the plant tissues was the largest(from 34%to 162%),followed by the increase in P(from 10%to 33%)and C(from 8%to 24%)concentrations.The aboveground biomass was positively and linearly correlated with leaf C,N and P,and soil C and N concentrations,while the belowground biomass was positively and linearly correlated with leaf N and soil C concentrations.These results showed that the accumulation of N and P in the leaves caused the increase in the aboveground biomass,while the accumulation of leaf N resulted in the increase in the belowground biomass.N deposition can alter the allocation of C,N and P stoichiometry in the plant tissues and has a high potential for increasing plant biomass,which is conducive to the restoration of sandy grassland.

Novel sediment source fingerprinting quantifying erosion-induced total nitrogen and total phosphorus outputs from an intensive agricultural catchment,North China

Intensive farming is a primary cause of increased sediment and associated nitrogen(N)and phosphorus(P)loads in surface water systems.Determining their contributing sources,pathways and loads present major challenges in the high-intensity agricultural catchments.Herein,we quantify the sediment sources and magnitude of sediment total N and total P from different sources using a novel application of compound-specific stable isotope(CSSI)and fallout radionuclides(FRNs)of^(137)cs and^(210)pbex in an intensive agricultural catchment in North China.Sediment sources from surface and sub-surface soils were estimated from FRNs fingerprint and accounted for 62±7%and 38±7%respectively,while surface soil from land uses that originated from hillslope were identified by CssI fingerprint.Using a novel application of FRNs and CSSI sediment fingerprinting techniques,the dominant sediment source was derived from maize farmland(44±0.1%),followed by channel bank(38±7%).The sedimentation rate(13.55±0.30 t ha^(-1)yr^(-1))was quantifed by the^(137)cs cores(0-60 cm)at the outlet of this catchment.The total N and total P in sediment were both mostly derived from maize farmland and least from channel banks.The channel banks are significant sediment sources but contribute little to the input of sediment N and P for eutrophication.It implies that chemically-applied farmlands are the main hotspots for catchment erosion control and pollution prevention.The novel application of FRNs and CSSI techniques cost-effectively quantified sediment N and P loads from different sources with a single visit to the catchment,enabling rapid assessment for optimizing soil conservation strategies and land management practices.

Assessing non-point source pollution in an apple-dominant basin and associated best fertilizer management based on SWAT modeling

Investigating the impact of apple-dominated areas on nitrogen(N)and phosphorus(P)losses at a basin scale was essential for the sustainable development of apple industry in China.This study conducted a survey on fertilizer application and built a Soil and Water Assessment Tool(SWAT)model to quantita-tively analyze the N and P losses in the Qixia apple-dominated area.Additionally,the decreases in N and P losses through adjusting the fertilizer application modes were evaluated.Results showed that average N and P losses in the Wulong River Basin(WRB)were 44.4 and 0.365 kg ha^(-1)in 2011-2017,respectively,and apple orchards accounted for 733%and 51.4%of the total N and P losses in the basin.Under nine fertilizer scheduling scenarios,three fertilizer schedule scenarios,automatic fertilizer application(S-AUTO),"one shot"mode(S1),and regulated fertilizer application(S-BSD),had the lowest N and P losses in apple orchards.The decreases in N loss ranged from 20.6%to 26.1%at the subbasin scale and 14.8%-30.7%at the basin outlet when applying the S-AUTO,S1,and S-BSD fertilizer application modes in Qixia apple orchards and all apple orchards in the WRB.The reductions in P loss varied from 22.0%to 46.1%at the subbasin scale and 14.6%-25.6%at the basin outlet.In orchard-dominated basin,N and P losses can be effectively reduced by optimizing the orchard fertilizer scheduling strategies.

1.82 wt.% Pt/N, P co-doped carbon overwhelms 20 wt.% Pt/C as a high-efficiency electrocatalyst for hydrogen evolution reaction

Cost-effective electrocatalysts for the hydrogen evolution reaction （HER） play a key role in the field of renewable energy. Although tremendous efforts have been devoted to the search of alternative materials, Pt/C is still the most efficient electrocatalyst for the HER. Nevertheless, decreasing the loading of Pt in the designed eletrocatalysts is of significance. However, with low Pt loading, it is challenging to maintain excellent catalytic performance. Herein, a new catalyst （Pt/NPC） was prepared by dispersing Pt nanoparticles （PtNPs） with an average diameter of 1.8 nm over a three-dimensional （3D） carbon network co-doped with N and P. Because of the high electronegativity of the N and P dopants, PtNPs were uniformly dispersed on the carbon network via high electronic affinity between Pt and carbon, affording a Pt/NPC catalyst; Pt/NPC exhibited superior HER activity, attributed to the down-shift of the Pt d-band caused by the donation of charge from N and P to Pt. The results show that Pt/NPC with an ultralow Pt loading of 1.82 wt.% exhibits excellent HER performance, which corresponds to a HER mass activity 20.6-fold greater than that observed for commercial 20% Pt/C at an overpotential of 20 mV vs. RHE.

Nitrogen addition mediates the response of foliar stoichiometry to phosphorus addition: a meta-analysis

Background:Changes in foliar nitrogen(N)and phosphorus(P)stoichiometry play important roles in predicting the efects of global change on ecosystem structure and function.However,there is substantial debate on the efects of P addition on foliar N and P stoichiometry,particularly under diferent levels of N addition.Thus,we conducted a global meta-analysis to investigate how N addition alters the efects of P addition on foliar N and P stoichiometry across different rates and durations of P addition and plant growth types based on more than 1150 observations.Results:We found that P addition without N addition increased foliar N concentrations,whereas P addition with N addition had no efect.The positive efects of P addition on foliar P concentrations were greater without N addition than with N addition.Additionally,the efects of P addition on foliar N,P and N:P ratios varied with the rate and duration of P addition.In particular,short-term or low-dose P addition with and without N addition increased foliar N concentration,and the positive efects of short-term or low-dose P addition on foliar P concentrations were greater without N addition than with N addition.The responses of foliar N and P stoichiometry of evergreen plants to P addition were greater without N addition than with N addition.Moreover,regardless of N addition,soil P availability was more efective than P resorption efciency in predicting the changes in foliar N and P stoichiometry in response to P addition.Conclusions:Our results highlight that increasing N deposition might alter the response of foliar N and P stoichiometry to P addition and demonstrate the important efect of the experimental environment on the results.These results advance our understanding of the response of plant nutrient use efciency to P addition with increasing N deposition.