长期定位施肥对土壤的碳氮共济效应情景分析

碳氮共济的概念体现了二者间共同依赖、共同转化、共同协作的关系,将土壤碳和氮均作为改善土壤质量的主动因素,这一概念有别于其它碳氮关系论述时只考虑元素间的被动耦合机制。土壤碳和氮之间存在着相互依存和相互制约的关系,土壤碳、氮在数量上和结构上需要处于什么样的状态才能够实现土壤碳氮的共济关系,土壤碳对氮有多大的承载能力等是值得探讨的问题。文章利用我国长期定位试验中的土壤碳氮数据,分析土壤的碳氮质量分数变化特征、施肥对土壤w（C）/w（N）比的影响、土壤碳对氮素的储存能力、碳氮共济关系及其情景分析,以便为充分挖掘土壤碳氮的生物学潜力、提高土壤生产力、改善环境和实现碳氮的良性循环提供依据。通过检索文献数据库,选取了69篇记载有土壤碳氮数据的有代表性的文章,获得土壤碳氮数据1782项。分析结果表明：土壤碳氮关系可以用yC＝7.66xN＋1.8162（r2＝0.734＊＊, n=737）表达,土壤平均全氮质量分数为1.17 g·kg-1,变化范围在0.08~3.52 g·kg-1之间,土壤平均有机碳质量分数为10.8 g·kg-1,变化范围在0.64~32.08 g·kg-1之间;土壤w（C）/w（N）比集中在7.6~10.7之间,占总样本的80%左右,有机无机配施有利于提高土壤的w（C）/w（N）比,单施化肥,特别是偏施某一种化肥时,将显著降低土壤的w（C）/w（N）比;在土壤氮素储存率为N 20 kg·hm-2·a-1,目标w（C）/w（N）比为9、10、11的情景下,目前已经处于碳饱和的土壤分别占：52.7%、72.1%、87.5%;储存率为N 50 kg·hm-2·a-1的情景下分别占：58.2%、78.2%、91.4%;储存率为N 100 kg·hm-2·a-1的情景下分别占68.7%、87.6%、95.8%。土壤碳氮质量分数变异很大,总体碳氮比稳定在7.66左右,偏施化肥将显著降低土壤的w（C）/w（N）比,较低的土壤w（C）/w（N）比和较高的氮素储     

人工接种堆肥和自然堆肥微生物区系与分子多态性的变化

采用传统培养方法和PCR-DGGE技术研究了人工接种堆肥和自然堆肥微生物群落的演变过程。结果表明:(1)传统培养方法显示,两种堆肥堆制过程中微生物数量均呈“升高—降低—升高—降低”变化趋势,整个堆肥过程中细菌数量占优势。(2)DGGE图谱显示,两种堆肥不同时期存在不同的细菌种群,其条带数量亦呈“升高—降低—升高—降低”变化趋势。堆肥升温期条带丰富但优势条带不明显;堆肥高温期条带数量减少但出现优势条带,表明高温阶段以嗜热菌或耐高温菌为主;堆肥降温期条带数量再次增多;堆肥腐熟期条带数量少且无优势条带,表明腐熟阶段微生物种群数量少且代谢强度趋于平缓。(3)DGGE图谱表明,人工接种菌株成为堆肥高温期优势菌株。人工接种增加了堆肥中微生物总量,提高了堆肥微生物种群多样性,并且促进了堆肥菌群演替,从而缩短堆肥腐熟时间。     

堆肥修复土壤金属污染研究进展

堆肥是有机废弃物资源化的产物,利用堆肥修复土壤的金属污染有着重大意义.堆肥可通过直接与金属产生氧化还原作用、沉淀作用、吸附作用或间接改变土壤理化性质如酸碱度,氧化还原电位等降低土壤金属的生物有效性和移动性,但具体修复效果因土壤、金属、堆肥三者性质的不同而差异甚大.本文对国内外利用堆肥修复土壤金属污染的研究进展进行了综述,指出了理论研究和实际修复中存在的一些问题,并对其发展前景进行了展望.     

新型调理剂CTB-2污泥堆肥的氧气时空变化特征研究

采用新型CTB-2调理剂与城市污泥进行堆肥,研究了堆肥过程中氧气、温度的时空变化特征。结果表明,m（CTB-2调理剂）：m（污泥）=1：2能够有效降低污泥容重,改善堆体结构;堆体能够快速升温至高温期并持续7d以上,最终完成无害化;采用该比例的调理剂能够保证堆体的通风供氧,使堆体各层通风后的氧气体积分数都恢复至19％以上,最低氧气体积分数维持在数17％以上;堆肥过程中堆体的氧气体积分数、耗氧速率和温度都具有明显的层次效应,堆体耗氧速率呈先升高后降低的趋势,堆体通风后的氧气和最低氧气体积分数均随着堆肥的进行而增加。     

发酵基质含水率对牛粪好氧堆肥发酵产热的影响

以牛粪和玉米秸秆为原料进行好氧堆肥试验,采用氧弹量热法测定发酵产热量,研究堆肥原料不同初始含水率(物料初始含水率w分别为41%、50%、55%、65%和75%)对发酵产热的影响,以及堆肥过程中有机质损失与产热的关系。结果表明,在堆肥第3天各处理(除初始含水率75%处理)温度均达55℃以上,堆肥各处理均表现为前3 d有机质降解最快,热值损失最多。物料初始含水率为41%～65%时,发酵产热量与物料初始含水率呈显著正相关。初始含水率65%对堆肥最有利,有机质损失和总热值变化最大,有机质损失29.18%,总产热量为2 236 kJ.kg-1,若所产热量全部用于去除水分,可以使堆肥物料水分完全去除。     

不同C/N值下亚硝酸盐氧化菌和异养菌混合体系的微生物多样性

采用PCR-RFLP技术研究了不同C/N比下亚硝酸盐氧化菌及异养菌混合体系的微牛物多样性,并探讨了微生物菌群结构与其功能(硝化件能)的关系.C/N=0时,混合体系主要由自养菌和寡营养菌(85.1%)组成,包括亚硝酸盐氧化菌(NOB)、拟杆菌门、α-变形菌纲、浮霉菌门和绿色非硫细菌中的一些菌株.C/N=0.44时,混合体系中的自养菌减少,异养菌(主要是γ-变形菌纲的成员)大量出现.C/N=8.82时,γ-变形菌纲的菌株尤其是反硝化菌Pseudomonas sp.占主导(93.8%),与此同时,随着C/N升高,该混合体系的硝化性能也由专一的亚硝酸盐氧化过程转变为同时硝化反硝化过程.微生物菌群结构的转变较好地解释了其硝化性能的改变.本研究揭示了微生物菌群结构与其功能的内在联系,同时表明PCR-RFLP技术与化学分析相结合是研究微生物菌群结构与功能的有力工具.图3表2参13     

等碳量不同有机物料添加对红壤团聚体组分分布及有机碳、氮含量的影响

由于土壤理化性质不同,不同肥力的红壤上适宜的有机物料种类可能存在差异。为精准分类指导不同肥力红壤选择适宜的有机物料种类,选择长期进行花生、油菜轮作的红壤旱地,采集0～20和>20～40 cm深度土壤样品,分别代表高肥力和低肥力土壤,设置不施有机碳(C0)以及施用油菜秸秆碳(OSC)、水稻秸秆碳(RSC)、玉米秸秆碳(MSC)、猪粪碳(PMC)处理,其中各有机物料处理的碳投入量相同,进行连续90 d的避光培养,测定不同处理团聚体组分及有机碳、氮含量,分析有机物料投入C/N比与团聚体组分C/N比的相关关系。结果表明：(1)与C0对照相比,各有机物料处理均显著提高了>2 mm团聚体比例。在高肥力土壤中,OSC、RSC、MSC和PMC处理>2 mm团聚体组分比例分别增加217.89%、283.97%、286.63%和210.63%,低肥力土壤中上述处理的增幅分别为72.25%、84.45%、72.11%和46.47%。(2)有机物料投入后,>2、>0.25～2、≥0.053～0.25和<0.053 mm团聚体组分有机碳含量均显著提升,但不同肥力土壤中各有机物...     

碳氮施加对农田黑土氮素转化和温室气体排放的影响

研究外源碳氮施加对土壤氮素转化和温室气体排放的影响可为土壤养分管理、温室气体减排提供科学依据。以东北农田黑土为对象,采用室内培养试验,在25℃和60%WHC水分条件下研究外源碳(葡萄糖和乙酸)、氮(硫酸铵)施加对土壤净氮转化速率和温室气体排放的影响。结果表明,对照处理土壤净氮矿化速率为0.03 mg·kg^-1·d^-1,单施氮肥抑制了土壤有机氮的矿化,净氮矿化速率降为-0.56 mg·kg^-1·d^-1,表现为对氮素的固定,而净硝化速率和N₂O排放速率分别显著增加至对照处理的33.3倍和4.69倍,但对CO₂排放速率没有显著影响。与单施氮肥处理相比,氮肥配施葡萄糖或乙酸处理显著降低了土壤中铵态氮和硝态氮含量,氮肥配施葡萄糖对铵态氮的影响程度大于氮肥配施乙酸处理。碳氮配施使得净氮矿化速率进一步降低,氮肥配施葡萄糖处理的净氮矿化速率为-5.97 mg·kg^-1·d^-1,显著低于氮肥配施乙酸处理(-5.00 mg·kg     

氧化E氮形成的微生物学分子机制研究进展

1氧化亚氮(N2O)的形成 N2O是继CO 2、CH4之后的第三大温室气体,它能破坏大气中的臭氧层.在过去的20～30年间,N2O以每年0.2%～0.3%的速率增长,并且有进一步增长的趋势[1].地球上人类和其他生物的活动是N2O产生的主要来源,而微生物是其中最重要的生物源.微生物产生N2O的机理主要是通过硝化作用和反硝化作用过程进行的,如图1所示.     

浮游植物细胞程序化死亡研究进展

过去,动物摄食和沉降被认为是浮游植物死亡的原因。后来人们发现病毒感染以及逆境条件下的主动死亡(或程序化死亡),也是引起浮游植物死亡的重要原因。文章介绍了浮游植物存在细胞程序化死亡的实验证据和半胱氨酰天冬氨酸特异蛋白酶(caspase)在浮游植物细胞程序化死亡中可能起的作用及浮游植物基因组中的caspase直系同源物。程序化死亡是细胞自主死亡的过程,具有坏死的形态和生物化学过程。浮游植物具有一套后生动物caspase的直系同源物蛋白。作者构建了东海原甲藻cDNA文库,其中有两组EST分别与两个细胞程序化死亡的关键蛋白同源,它们分别是半胱氨酰天冬氨酸特异蛋白酶和分裂细胞核抗体。因此作者推断东海原甲藻可能存在细胞程序化死亡过程。尽管已从细胞生物学特征角度,获得了真核微藻程序化死亡的证据,并从基因组序列中预测出和大规模表达序列标签中鉴定出细胞程序化死亡相关蛋白的编码基因,但离全面认识单细胞真核浮游藻程序化死亡的分子机制以及其生态学意义相差甚远。     

氮磷等营养盐对尖刺拟菱形藻生长的影响

尖刺拟菱形藻Pseudo-nitzschiapungensHalse是我国沿海常见的赤潮生物。通过对采集和分离于珠江口大亚湾海域的尖刺拟菱形藻藻种,在实验室条件下,研究不同浓度氮、磷等营养盐限制下该藻生长增殖的关系和特征,以及氮磷比(c(N)/c(P))变化等对该藻生长的影响。实验结果表明:尖刺拟菱形藻对氮、磷的依赖性较强,随浓度的变化而变化,属于营养依赖型藻类。实验进一步发现,尖刺拟菱形藻的生长对氮、磷的需求并不是越多越好,而要求有一定的比例范围,得出c(N)/c(P)在10～32范围内有相对较大的生长,而当c(N)/c(P)<5或c(N)/c(P)>100时,尖刺拟菱形藻的生长明显受到抑制。     

Environmental effects and risk control of antibiotic resistance genes in the organic solid waste aerobic composting system: A review

• ARGs were detected in livestock manure, sludge, food waste and fermentation dregs. • The succession of microbial community is an important factor affecting ARGs. • Horizontal transfer mechanism of ARGs during composting should be further studied. Antibiotic resistance genes (ARGs) have been diffusely detected in several kinds of organic solid waste, such as livestock manure, sludge, antibiotic fermentation residues, and food waste, thus attracting great attention. Aerobic composting, which is an effective, harmless treatment method for organic solid waste to promote recycling, has been identified to also aid in ARG reduction. However, the effect of composting in removing ARGs from organic solid waste has recently become controversial. Thus, this article summarizes and reviews the research on ARGs in relation to composting in the past 5 years. ARGs in organic solid waste could spread in different environmental media, including soil and the atmosphere, which could widen environmental risks. However, the conventional composting technology had limited effect on ARGs removal from organic solid waste. Improved composting processes, such as hyperthermophilic temperature composting, could effectively remove ARGs, and the HGT of ARGs and the microbial communities are identified as vital influencing factors. Currently, during the composting process, ARGs were mainly affected by three response pathways, (I) “Microenvironment-ARGs”; (II) “Microenvironment-microorganisms-ARGs”; (III) “Microorganisms-horizontal gene transfer-ARGs”, respectively. Response pathway II had been studied the most which was believed that microbial community was an important factor affecting ARGs. In response pathway III, mainly believed that MGEs played an important role and paid less attention to eARGs. Further research on the role and impact of eARGs in ARGs may be considered in the future. It aims to provide support for further research on environmental risk control of ARGs in organic solid waste.     

Enhancing the efficiency of nitrogen removing bacterial population to a wide range of C:N ratio (1.5:1 to 14:1) for simultaneous C & N removal

• Simultaneous C & N removal in Methammox occurs at wide C:N ratio. • Biological Nitrogen Removal at wide C:N ratio of 1.5:1 to 14:1 is not reported. • Ammonia removal shifted from mixotrophy to heterotrophy at high C:N ratio. • Acetogenic population compensated for ammonia oxidizers at high C:N ratio. • Methanogens increase the plasticity of nitrogen removers at high C:N ratio. High C:N ratio in the wastewater limits biological nitrogen removal (BNR), especially in anammox based technologies. The present study attempts to improve the COD tolerance of the BNR process by associating methanogens with nitrogen removing bacterial (NRB) populations. The new microbial system coined as ‘Methammox’, was investigated for simultaneous removal of COD (C) and ammonia (N) at C:N ratio 1.5:1 to 14:1. The ammonia removal rate (11.5 mg N/g VSS/d) and the COD removal rates (70.6 mg O/g VSS/d) of Methammox was close to that of the NRB (11.1 mg N/g VSS/d) and the methanogenic populations (77.9 mg O/g VSS/d), respectively. The activities established that these two populations existed simultaneously and independently in ‘Methammox’. Further studies in biofilm reactor fetched a balanced COD and ammonia removal (55%–60%) at a low C:N ratio (≤2:1) and high C:N ratio (≥9:1). The population abundance of methanogens was reasonably constant, but the nitrogen removal shifted from mixotrophy to heterotrophy as the C:N ratio shifted from low (C:N≤2:1) to high (C:N≥9:1). The reduced autotrophic NRB (ammonia- and nitrite-oxidizing bacteria and Anammox) population at a high C:N ratio was compensated by the fermentative group that could carry out denitrification heterotrophically. The functional plasticity of the Methammox system to adjust to a broad C:N ratio opens new frontiers in biological nitrogen removal of high COD containing wastewaters.     

Preliminary techno-economic analysis of three typical decentralized composting technologies treating rural kitchen waste: a case study in China

● Decentralized composting (DC) is a profitable KW treating technology. ● SAC and BEC were economically attractive in rural area, while HDC was unprofitable. ● KW handling subsidy plays a vital role in making DC profitable. ● SAC and BEC have great potential in promoting rural KW treatment. This study was designed to evaluate whether the decentralized rural kitchen waste (KW) composting technologies used in China can be widely applied. To this end, we completed a techno-economic analysis of three typical types of KW compositing, namely solar-assisted (SAC), bio-enhanced (BEC), and heat-dewatering composting (HDC). These evaluations revealed that all three technologies produce composting products that meet China’s organic fertilizer standard and that both SAC and BEC are economically self-sustaining and generate net profits (18824.94 and 17791.52 US$/a) and positive net present values (32133.11 and 25035.93 US$). Subsequent sensitivity analysis demonstrated that the KW-handling subsidy plays a critical role in making decentralized composting economically attractive. Based on these analyses, we believe that reducing the coverage area of SAC, reducing the operating cost of BEC and HDC, upgrading composting products, and strengthening secondary pollution control would aid in supporting the technological improvement of these processes. Moreover, providing appropriate subsidies and promulgating specific standards and policies for KW fertilizer are key strategies for decentralized rural KW composting management.     

The performance of nitrate-reducing Fe(II) oxidation processes under variable initial Fe/N ratios: The fate of nitrogen and iron species

•Bacterially-mediated coupled N and Fe processes examined in incubation experiments. •NO₃⁻ reduction was considerably inhibited as initial Fe/N ratio increased. •The maximum production of N₂ occurred at an initial Fe/N molar ratio of 6. •Fe minerals produced at Fe/N ratios of 1–2 were mainly easily reducible oxides. The Fe/N ratio is an important control on nitrate-reducing Fe(II) oxidation processes that occur both in the aquatic environment and in wastewater treatment systems. The response of nitrate reduction, Fe oxidation, and mineral production to different initial Fe/N molar ratios in the presence of Paracoccus denitrificans was investigated in 132 h incubation experiments. A decrease in the nitrate reduction rate at 12 h occurred as the Fe/N ratio increased. Accumulated nitrite concentration at Fe/N ratios of 2–10 peaked at 12–84 h, and then decreased continuously to less than 0.1 mmol/L at the end of incubation. N₂O emission was promoted by high Fe/N ratios. Maximum production of N₂ occurred at a Fe/N ratio of 6, in parallel with the highest mole proportion of N₂ resulting from the reduction of nitrate (81.2%). XRD analysis and sequential extraction demonstrated that the main Fe minerals obtained from Fe(II) oxidation were easily reducible oxides such as ferrihydrite (at Fe/N ratios of 1–2), and easily reducible oxides and reducible oxides (at Fe/N ratios of 3–10). The results suggest that Fe/N ratio potentially plays a critical role in regulating N₂, N₂O emissions and Fe mineral formation in nitrate-reducing Fe(II) oxidation processes.     

Characterization and variation of dissolved organic matter in composting: a critical review

● Effect of composting approaches on dissolved organic matter (DOM). ● Effect of composting conditions on the properties of DOM. ● Character indexes of DOM varied in composting. ● The size, hydrophobicity, humification, and electron transfer capacity increased. ● The hydrophilicity, protein-like materials, and aliphatic components reduced. As the most motive organic fraction in composting, dissolved organic matter (DOM) can contribute to the transfer and dispersal of pollutants and facilitate the global carbon cycle in aquatic ecosystems. However, it is still unclear how composting approaches and conditions influence the properties of compost-derived DOM. Further details on the shift of DOM character indexes are required. In this study, the change in properties of compost-derived DOM at different composting approaches and the effect of composting conditions on the DOM characteristics are summarized. Thereafter, the change in DOM character indexes’ in composting was comprehensively reviewed. Along with composting, the elements and spectral properties (chromophoric DOM (CDOM) and fluorescent DOM (FDOM)) were altered, size and hydrophobicity increased, and aromatic-C and electron transfer capacity were promoted. Finally, some prospects to improve this study were put forward. This paper should facilitate the people who have an interest in tracing the fate of DOM in composting.     

三江平原退化湿地和农田土壤养分的比较研究

三江平原农业开垦导致地表水位和土壤水分下降,原生湿地退化为沼泽化草甸和典型草甸,或者直接转化为水田和旱田.退化湿地与农田土壤养分的对比研究结果表明,4种样地类型0-30 cm土层土壤有机质含量为水田＞沼泽化草甸＞旱田＞典型草甸,全氮含量差异与有机质含量差异相一致,速效磷含量为水田＞旱田＞沼泽化草甸＞典型草甸.这说明在湿地退化为典型草甸的过程中土壤养分严重下降,水分状况是影响湿地土壤养分下降的关键因素;但是农田土壤养分仍然保持较高水平,主要是由于耕作、施肥等非水分因素的影响.由此可见,水分条件和人为干扰共同决定了退化湿地和农田土壤养分状况.