Changes in Phosphorus Fractions and Nitrogen Forms During Composting of Pig Manure with Rice Straw

The study was conducted to reveal P fractions and N forms changing characters during composting of pig manure with rice straw.During composting,the NH 4 ＋-N concentration decreased and reached at a relatively low value（〈400 mg kg-1） in the final compost,while the NO 3--N concentration increased.Total N losses mainly occurred during thermophilic phase due to the high temperature,the high NH 4 ＋-N concentration and the increase of pH value.Labile inorganic P was dominated in the pig manure and initial compost mixture.During composting,the proportion of labile inorganic P of total extracted P decreased,while the proportion of Fe＋Al-bound P,Ca＋Mg-bound P and residual P increased.The evolutions of the proportion of labile inorganic P,Fe＋Al-bound P and Ca＋Mg-bound P were well correlated with the changes of pH value,organic matter and C/N ratio.Therefore,composting could increase the concentration of N and P and decrease the presence of NH 4 ＋-N and labile P fractions which might cause environmental issues following land application.

Removal efficacy and mechanism of nitrogen and phosphorus by biological aluminum-based P-inactivation agent (BA-PIA)

In this study,aluminum-based P-inactivation agent(Al-PIA)was used as a high-efficiency microbial carrier,and the biological Al-PIA(BA-PIA)was prepared by artificial aeration.Laboratory static experiments were conducted to study the effect of BA-PIA on reducing nitrogen and phosphorus contents in water.Physicochemical characterization and isotope tracing method were applied to analyze the removal mechanism of nitrogen and phosphorus.High-throughput techniques were used to analyze the characteristic bacterial genus in the BA-PIA system.The nitrogen and phosphorus removal experiment was conducted for 30 days,and the removal rates of NH_(4)^(+)-N,TN and TP by BA-PIA were 81.87%,66.08%and 87.97%,respectively.The nitrogen removal pathways of BA-PIA were as follows:the nitrification reaction accounted for 59.0%(of which denitrification reaction accounted for 56.4%),microbial assimilation accounted for 18.1%,and the unreacted part accounted for 22.9%.The characteristic bacteria in the BA-PIA system were Streptomyces,Nocardioides,Saccharopolyspora,Nitrosomonas,and Marinobacter.The loading of microorganisms only changed the surface physical properties of Al-PIA(such as specific surface area,pore volume and pore size),without changing its surface chemical properties.The removal mechanism of nitrogen by BA-PIA is the conversion of NH_(4)^(+)-N into NO_(2)^(−)-N and NO_(3)^(−)-N by nitrifying bacteria,which are then reduced to nitrogen-containing gas by aerobic denitrifying bacteria.The phosphorus removal mechanism is that metal compounds(such as Al)on the surface of BA-PIA fix phosphorus through chemisorption processes,such as ligand exchange.Therefore,BA-PIA overcomes the deficiency of Al-PIA with only phosphorus removal ability,and has better application prospects.

Sex-specifically responsive strategies to phosphorus availability combined with different soil nitrogen forms in dioecious Populus cathayana

Aims Phosphorus(P)availability and efficiency are especially important for plant growth and productivity.However,the sex-specific P acquisition and utilization strategies of dioecious plant species under different N forms are not clear.Methods This study investigated the responsive mechanisms of dioecious Populus cathayana females and males based on P uptake and allocation to soil P supply under N deficiency,nitrate(NO3−)and ammonium(NH4+)supply.Important Findings Females had a greater biomass,root length density(RLD),specific root length(SRL)and shoot P concentration than males under normal P availability with two N supplies.NH4+supply led to higher total root length,RLD and SRL but lower root tip number than NO3−supply under normal P supply.Under P deficiency,males showed a smaller root system but greater photosynthetic P availability and higher leaf P remobilization,exhibiting a better capacity to adaptation to P deficiency than females.Under P deficiency,NO3−supply increased leaf photosynthesis and P use efficiency(PUE)but reduced RLD and SRL in females while males had higher leaf P redistribution and photosynthetic PUE than NH4+supply.Females had a better potentiality to cope with P deficiency under NO3−supply than NH4+supply;the contrary was true for males.These results suggest that females may devote to increase in P uptake and shoot P allocation under normal P availability,especially under NO3−supply,while males adopt more efficient resource use and P remobilization to maximum their tolerance to P deficiency.

瓦埠湖沉积物中氮与磷赋存形态分析

利用连续提取法研究了瓦埠湖沉积物中磷的赋存形态和氮的组成特征。结果显示:瓦埠湖沉积物中总磷含量为293～874 mg/kg,平均为470 mg/kg,总磷主要由无机磷组成;在沉积物的提取磷中铁结合态磷为主要赋存形态;铁磷、钙磷、铝磷的相对百分含量指示出该湖泊的磷源自污染较少的区域。瓦埠湖沉积物中总氮的含量为208～464 mg/kg,平均为265 mg/kg,氮的主要组成为有机氮,有机氮、有机指数等显示该湖泊属于清洁类型,未遭受污染。瓦埠湖流域的社会与自然状况的调查结果、湖泊底泥的有机碳氮比等均表明湖泊营养物质来自面源,各指标含量在空间分布的特点与相关性的差异,说明了物质沉积存在重力分离与水动力作用的过程。

地下水中氮的表现形式及其污染的微生物控制

论述了地下水环境中氮的表现形式及其对地下水污染的途径和特点，提出了利用人工诱变得到的高效除氮菌来进行地下环境除氮的理论和方法．通过模拟实验证明该方法是可行的，同时，对细菌除氮效率、影响因素及其变化规律进行了研究．对方法应用过程中有关问题进行了讨论．

根际促生菌对沉水植物的促生效应及其与沉积物氮磷赋存形态的关系

研究在沉积物高有机质条件下,通过接种根际促生菌(Plant growth-promoting rhizobacteria,PGPR)PC2(Bacillus stratosphericus)、H19(Bacillus subtilis)和L3(Bacillus cereus)的方式探讨其对苦草(Vallisneria natans)植株的促生效应及其与沉积物氮磷赋存形态的关系。结果表明,接种组对苦草生长具有显著促进作用,空白处理种植的苦草生长受到抑制,PGPR对苦草生长促进的综合影响为PC2>H19>L3,PC2处理组株高、根长、地上鲜重和根鲜重比空白分别增加了165.0%、17.4%、378.8%和165.1%。进一步分析不同时期苦草的各种生长指标增量与氮磷赋存形态增量的关系,通过RDA分析及皮尔森相关分析,苦草生长指标增量与沉积物中无机氮(Inorg-N)、亚硝态氮(NO_(2)-N)、硝态氮(NO_(3)-N)、无机磷(Inorg-P)和铁/铝磷(Fe/Al-P)等增量显著负相关,表明PGPR对沉积物中无机态N、P具有一定的控制作用。因此,接种PGPR对解决受污染湖泊沉水植物恢复及内源污染等问题具有一定潜力。