控释氮肥对洞庭湖区双季稻田表面水氮素动态及其径流损失的影响

用渗漏池模拟洞庭湖区2种主要稻田土壤(河沙泥和紫潮泥),研究了施用尿素(CF)和控释氮肥(CRNF)对双季稻田表面水pH、电导率(EC)、全氮（TN）、铵态氮（NH₄⁺-N）和硝态氮（NO₃^--N）浓度变化规律及TN径流损失的影响.结果表明,双季稻田施用尿素后,表面水TN、NH₄⁺-N浓度分别在第1、3天达到高峰,然后迅速下降;NO₃^--N浓度普遍很低;早稻表面水pH在施用尿素后15 d内(晚稻3 d)逐渐升高;EC与NH₄⁺动态变化一致.与尿素相比,施用CRNF能显著降低双季稻田表面水pH、EC、TN和NH₄⁺-N浓度,70% N控释氮肥的控制效果最显著;但后期NO₃^--N浓度略有升高.径流监测结果表明,洞庭湖区种植双季稻期间施用尿素的TN径流损失为7.70 kg·hm^-2,占施氮量的2.57%;施肥后20 d内发生的径流事件对双季稻田TN径流损失的贡献极为显著;与施用尿素相比,施用控释氮肥显著降低了施肥后10 d内发生的第1次径流液中的TN浓度,施用CRNF和70%N CRNF的氮素径流损失分别降低24.5%和27.2%.     

长江三角洲地区雨水中NH4+-N/NO3--N和δ15NH4+值的变化

2003年6月至2005年7月,利用自行设计的雨水收集器对位于长江三角洲地区的常熟、南京和杭州3个观测点进行了全年性雨水观测,分析了雨水中NH₄⁺-N/NO₃^--N和铵态氮自然丰度(δ¹⁵NH₄⁺)值的变化.结果表明：研究区3个观测点雨水中NH₄⁺-N/NO₃^--N和δ¹⁵NH₄⁺值均呈相似的季节性变化规律,两者的规律性变化在以田间农事耕作为主的常熟观测点尤其明显,而位于市区的南京观测点和位于城乡结合部的杭州观测点的规律性次之;雨水中NH₄⁺-N/NO₃^--N的峰值出现在6月下旬到8月上旬,然后逐渐下降,冬季降到最低;雨水中δ¹⁵NH₄⁺值在6月下旬到8月中旬为负值,在8月下旬到11月中下旬为正值,12月至翌年3月又变为负值,5至6月中旬又转变为正值.雨水中NH₄⁺-N/NO₃^--N和δ¹⁵NH₄⁺值的季节变化与不同作物生育期间氮肥的施用、当地气候的季节性变化以及其他NH3释放源的NH3挥发有关（人和动物排泄物、氮污染水体及有机氮源中的氨挥发）,其对大气湿沉降中NH₄⁺的来源、形态组成及陆地不同NH₃排放源的强度具有明显的指示意义.     

草坪系统对城市降雨初期径流氮污染控制作用

为了控制城市旅游区降雨径流污染,在武汉动物园鹿苑区构建草坪系统,研究了草坪系统对城市降雨初期径流氮污染的控制与持留作用。结果表明：草坪系统使预处理后降雨径流中的总氮（TN）、溶解态总氮（DN）和铵态氮（NH₄⁺-N）浓度分别降低16.0％、13.9％和75.6％;草坪系统对氮素的持留率为NH₄⁺-N>90%、TN、DN>65％、硝态氮 (NO₃^--N)>5％;水力负荷显著影响TN出水浓度和处理效率,进水浓度相近、水力负荷从3.3 cm·d^-1升高到8.3 cm·d^-1,TN去除率由28.0%降低至19.8%;草坪宽度影响污染物出水浓度,NH₄⁺-N浓度随着草坪宽度增加而下降,而NO₃^--N浓度变化趋势与之相反,DN在流程10 m处出现最低值。草坪系统在净化降雨初期径流的同时利用了营养盐和水资源,降低了草坪维护的水肥投入。     

元素硫和双氰胺对蔬菜地土壤硝态氮淋失的影响

采用温室盆栽淋洗试验,以NH₄HCO₃为氮肥源,研究了元素硫(S₀)和双氰胺（DCD）对种葱和不种作物土壤NO₃^--N淋失量和NO₃^--N、NH₄⁺-N浓度的影响.结果表明,在12周试验期间,与对照相比,S₀+DCD和S₀处理NO₃^--N淋失量分别低83%～86%和83%;NH₄⁺-N淋失量分别高16.8～21.0 mg·盆^-1和20.4～25.0 mg·盆^-1;而同期无机氮（NO₃^--N、NH₄⁺-N）淋失量则低60%.试验结束后,,S₀+DCD和S₀处理土壤无机氮含量分别比对照高79.9%～85.4%和74.9%～82.6%,以NH₄⁺-N为主.S₀+DCD处理无机氮淋失量比S₀和DCD处理分别低4.6%～14.4%和15.4%～30.1%;试验结束后土壤无机氮分别高6.1%和16.8～36.0%.在Na₂S₂O₃+DCD、Na₂S₂O₃和DCD处理中也发现类似结果.可见S₀施入土壤具有与DCD同样的氨稳定和硝化抑制作用.S₀与DCD配合施用可使DCD的硝化抑制性增强,其作用机理是S₀氧化中间体S₂O₃^2-、S₄O₆^2-,具有抑制硝化和DCD降解作用,延缓DCD硝化抑制效果.S0与DCD配合施用可用于延缓太湖流域蔬菜地土壤NH₄⁺-N向NO₃^--N转化,减少氮向水体迁移风险.     

红豆草与土壤氮含量对大气二氧化碳浓度升高的响应

在封闭的植物培养箱中,通过盆栽实验,研究了红豆草和土壤氮含量对CO₂浓度增加的响应.结果表明,与正常CO₂浓度(355～370 μmol·mol^-1)相比,CO₂浓度升高(700 μmol·mol^-1),植物生物量增加25.1%(P＜0.01),但植物体氮浓度降低25.3%(P＜0.001),植物全氮没有显著的变化.经3个月盆栽实验后,与原始土壤相比,两种CO₂浓度处理土壤全N、NO₃^--N和NH₄⁺-N都有所降低,而土壤微生物氮则显著增加,这可能与植物生长有关.不同CO₂浓度处理土壤NH₄⁺-N浓度基本一致,但在高CO₂浓度下,土壤NO₃^--N浓度显著降低,而微生物生物氮显著增加.对整个土壤-植物系统而言,盆栽实验后,整个系统全氮有少量增加,但变化不显著,特别是在高CO₂浓度条件下,土壤-植物系统全氮最大,这可能与培养材料红豆草为豆科植物,而且在高CO₂浓度下生物量增加,导致氮的固定量增加有关.     

A comparison of nitrate transport in four different rice (Oryza sativa L.) cultivars

As rice can use both nitrate (NO₃^-) and ammonium (NH₄⁺), we have tested the hypothesis that the shift in the pattern of cultivars grown in Jiangsu Province reflects the ability of the plants to exploit NO₃^- as a nitrogen (N) source. Four rice cultivars were grown in solution culture for comparison of their growth on NO₃^- and NH₄⁺ nitrogen sources. All four types of rice, Xian You 63 (XY63), Yang Dao 6 (YD), Nong Keng 57 (NK) and Si You 917 (SY917), grew well and produced similar amounts of shoot biomass with 1 mmol/L NH₄⁺ as the only N source. However, the roots of NK were significantly smaller in comparison with the other cultivars. When supplied with 1 mmol/L NO₃^-, YD produced the greatest biomass; while NK achieved the lowest growth among the four cultivars. Electrophysiological measurements on root rhizodermal cells showed that the NO₃^--elicited changes in membrane potential (ΔE_m) of these four rice cultivars were significantly different when exposed to low external NO₃^- (<1 mmol/L); while they were very similar at high external NO₃^- (10 mmol/L). The root cell membrane potentials of YD and XY63 were more responsive to low external NO₃^- than those of NK and SY917. The ΔE_m values for YD and XY63 rhizodermal cells were almost the same at both 0.1 mmol/L and 1 mmol/L NO₃^-; while for the NK and SY917 the values became larger as the external NO₃^- increased. For YD cultivar, ΔE_m was measured over a range of NO₃^- concentrations and a Michaelis-Menten fit to the data gave a K_m value of 0.17 mmol/L. Net NO₃^- uptake depletion kinetics were also compared and for some cultivars (YD and XY63) a single-phase uptake system with first order kinetics best fitted the data; while other cultivars (ND and SY917) showed a better fit to two uptake systems. These uptake systems had two affinity ranges: one had a similar K_m in all the cultivars (0.2 mmol/L); the other much higher affinity system (0.03 mmol/L) was only present in NK and SY917. The expression pattern of twelve different NO₃^- transporter genes was tested using specific primers, but only OsNRT1.1 and OsNRT2.1 expression could be detected showing significant differences between the four rice cultivars. The results from both the physiological and molecular experiments do provide some support for the hypothesis that the more popular rice cultivars grown in Jiangsu Province may be better at using NO₃^- as an N source.     

利用水生植物原位修复污染水体

在实验围隔系统中,夏季利用凤眼莲、冬季利用耐寒型沉水植物伊乐藻等恢复水生生态系统,研究水生植物对水体氮、磷营养盐、透明度等理化性质的影响.结果表明：水生植物处理围区营养盐水平均显著低于围区对照和大湖水体.最初15 d,凤眼莲生长速度快,覆盖面积从100 m²增加到470 m²;44 d后,覆盖面积达到65％,处理围区的水质最佳,总氮(TN)、铵态氮(NH₄⁺ -N)、亚硝态氮(NO₂^- -N)、高锰酸钾盐指数(COD_Mn)和叶绿素a浓度最低,透明度达到1.7～1.8 m(水底).10月份后,处理围区水体总磷(TP)维持在0.1 mg·L^-1左右.处理围区透明度提高后,伊乐藻逐渐成为优势种(覆盖面积达到总水域的1/3),在净化水质、维持水质理化性质稳定和提高透明度方面作用显著.表明水生植被恢复可以有效降低水体营养盐,控制浮游植物增长,是改善富营养湖泊水质的重要措施.     

畜禽粪便堆肥的理化腐熟指标及其红外光谱

选择新鲜的牛粪、猪粪和鸡粪为堆肥原料,通过室内模拟直接堆肥试验,研究堆肥过程理化参数变化、种子发芽指数以及腐熟物红外光谱特征.结果表明: 堆肥过程温度变化明显,牛粪出现一次堆肥高温阶段,鸡粪和猪粪各两次,堆肥温度超过50 ℃以上时间均大于10 d,温度可以最直观地表征堆肥的腐熟程度.堆肥过程中pH值变化幅度较大,其中猪粪的pH值从6.63上升至7.74,鸡粪从7.73上升至8.66,牛粪则先从7.86上升至8.36再下降至7.52;有机碳含量逐渐降低,牛粪、猪粪和鸡粪分别下降23.3%、28.2%和31.7%;堆肥过程中,牛粪、猪粪和鸡粪的铵态氮含量分别下降87.8%、73.6%和79.7%,硝态氮含量分别增加至堆肥前的56.81、6.49和4.85倍,铵态氮/硝态氮均下降至2以下.温度、pH值、有机碳含量和铵态氮/硝态氮能较好地反映3种粪便高温堆肥的腐熟程度,且与种子发芽率相关性较高(P≤0.05).红外光谱分析表明,在堆肥过程中,牛粪和猪粪的脂肪族、多糖类物质减少,芳香结构化增强,腐殖化程度增加;鸡粪则相反.在建立理化指标体系的同时,应兼顾物质结构的稳定性.     

模拟氮沉降下南方针叶林红壤的养分淋溶和酸化

以中国科学院红壤生态实验站林草生态试验区针叶林红壤为研究对象,在恒温(20 ℃)条件下,通过大土柱（直径10 cm、高60 cm）,8个月间隙性淋溶试验模拟研究了不同氮输入量（0、7.8、26和52 mg N/月/柱）对针叶林红壤NO₃^-、NH₄⁺、H⁺和土壤盐基离子(Ca²⁺、Mg²⁺、K⁺、Na⁺⁾淋溶以及土壤酸化的影响.结果表明,土壤交换态盐基总量、Ca²⁺和Mg²⁺淋溶量随氮输入量的增加而增加,土壤交换态Na⁺和K⁺则无明显影响.4种N输入处理的土壤交换态盐基总量净淋溶（淋溶出的盐基与淋洗液累计输入的盐基之差）分别占土壤交换性盐基总量的13.9%、18.6%、31.8% 和57.9％,土壤交换态Ca²⁺净淋溶分别占土壤交换性Ca²⁺总量的19.6%、25.8%、45.3%和84.8%,土壤交换态Mg²⁺净淋溶分别占土壤交换性Mg²⁺总量的4.4%、6.1%、10.9%和17.1%.随氮输入量增加,表层土壤pH值逐渐下降,4种N输入处理的表层土壤pH（KCl）分别为3.85、3.84、3.80和3.75;随氮输入量增加,淋溶液中无机氮、NO₃^-和H⁺逐渐增加.氮沉降可促进针叶林红壤的有机氮矿化,加速养分淋失和土壤酸化.     

氮肥施用量对设施番茄氮素利用及土壤NO3--N累积的影响

在宁夏引黄灌区滴灌条件下，以温棚番茄为研究对象，采用田间试验与室内分析的方法，研究不同施氮量对番茄产量、氮素利用率及土壤NO₃^--N残留的影响，并对土壤-番茄体系的氮平衡进行了表观评估。试验结果表明：2004年秋冬茬番茄，施用氮肥显著增加了当茬番茄果实、植株产量 （增产幅度19.9%～29.6%）及地上部总吸氮量（204～232.6 kg/hm²）。2005年冬春茬番茄，与空白处理产量相比（106 kg/hm²）只有N200处理的果实增产达显著水平（120 kg/hm²）。两季番茄的氮肥利用率都随氮肥施用量的增加而明显降低（3.3%～10.9%）。2004年秋冬茬番茄收获后，表层0~30 cm的NO₃^--N大量累积（200～650 kg/hm²），其累积量随施氮量增加呈增加的趋势，经过2005年冬春茬番茄种植后，上茬0~30 cm土层NO₃^--N向下有淋失的趋势，淋失层次主要在90 cm以上的土体（250~380 kg/hm²）。综合考虑番茄果实产量、氮肥利用率及土壤NO₃^--N残留等因素，秋冬茬番茄推荐氮肥用量在100~200 kg/hm²和适量的磷钾肥配施为当茬氮肥优化管理处理。而冬春茬番茄氮肥推荐在200~400kg/ hm² 范围可以满足当茬番茄对氮肥的需求。     

葡萄籽对猪粪秸秆高温堆肥中微生物群落与碳氮含量的影响

以猪粪与秸秆(鲜质量10.5∶1)为基础,在自制的强制通风静态堆肥反应箱中进行堆肥化试验,研究添加8%葡萄籽对猪粪秸秆高温堆肥中微生物群落演替和碳氮转化的影响.在堆肥化的30 d里,分7次采集不同时期的堆肥样品,测定堆肥中微生物区系、微生物生理群的数量及堆肥碳氮含量.结果表明：添加葡萄籽使堆肥中细菌数量略高、放线菌数量显著增加、真菌数量明显降低,细菌/放线菌下降;氨化细菌和反硝化细菌数量降低;而硝化细菌、固氮菌和纤维素分解菌数量增多;铵态氮和有机碳含量下降,而硝态氮含量明显提高.堆肥中硝态氮含量与放线菌数量呈极显著正相关关系.添加葡萄籽使堆体升温快且高温期稳定,堆肥含水率波动较小,从而使堆肥高温期放线菌和亚硝化细菌的波动较小,数量较高,有利于堆肥中硝态氮含量的增加.     

不同管理方式下橡胶林土壤氮动态特征

对西双版纳割胶、未割胶条件下橡胶林种植带土壤及其保护带土壤氮素动态变化特征进行了研究,并比较了不同保护带种植方式(距瓣豆绿肥覆盖与野生杂草覆盖)对土壤氮素动态的影响。结果表明,橡胶林种植带土壤全氮、碱解氮和硝态氮含量低于保护带。橡胶林土壤全氮、碱解氮、铵态氮、硝态氮均呈现明显的动态变化,种植距瓣豆绿肥覆盖与野生杂草生长覆盖的橡胶林土壤氮变化趋势一致。土壤全氮随时间逐渐下降,碱解氮含量先升后降,铵态氮和硝态氮含量变化幅度较大。橡胶林土壤全氮和碱解氮含量呈现表层(0～20cm)>中层(20～40cm)>底层(40～60cm)的趋势,且未割胶处理全氮和碱解氮含量>割胶处理,而保护带为距瓣豆绿肥覆盖的割胶橡胶林>杂草生长覆盖的橡胶林。距瓣豆绿肥覆盖的保护带土壤硝态氮含量高于杂草生长覆盖。碱解氮与铵态氮含量呈显著的负相关、与硝态氮呈显著正相关。割胶橡胶林土壤氮养分含量最低。橡胶林土壤种植豆科距瓣豆绿肥能够改善土壤氮素肥力。     

Aerobic composting of chips from clear-cut trees with various co-materials

Swollen chips made from trees felled during clear-cutting were composted with various organic and inorganic materials in an aerobic composting reactor for 5 months and then piled for 5 months. The organic materials included chicken feces, urea, nitrogenous lime (calcium cyanamide, manure), and material rapidly composted from food garbage in 24-h bacterial fermentation, while the inorganic materials were coal ash and volcanic ash. In this paper, we first attempt to estimate the quality and degree of maturity of each compost from its chemical properties. Furthermore, we try to calculate the maturity of the fermented wood chip composts from their mixture ratio of the initial materials by multiple linear regression analysis. We measured changes in the C/N ratio, nitrate nitrogen (NO3-N) content, percentage of humic acid in the alkali soluble fraction (PQ), cation exchange capacity, pH, and EC during the composting period. The degrees of maturity of the composts were estimated via a plant growth test using Chinese cabbage. We found that the CN ratio, NO3-N concentration, and PQ were suitable for estimating the degree of maturity of wood chip composts. For maturity, the CN ratio should be less than 14, the PQ more than 66.2, and the NO3-N concentration more than 853 mgkg-1. We devised an equation to estimate the degree of maturity after 10 months by a multiple linear regression analysis from the mixing ratio of wood chips and the co-composted materials. From the multiple linear regression analysis, the above three indices of compost maturity could be estimated from the mixing ratio of the initial materials. This equation should enable us to determine the degree of compost maturity after 10 months based on the initial mixing ratio.     

Patterns and quantities of NH(3), N(2)O and CH(4) emissions during swine manure composting without forced aeration--effect of compost pile scale

To evaluate the NH(3), N(2)O, and CH(4) emissions from composting of livestock waste without forced aeration in turned piles, and to investigate the possible relationship between the scale of the compost pile and gas emission rates, we conducted swine manure composting experiments in parallel on small- and large-scale compost piles. Continuous measurements of gas emissions during composting were carried out using a chamber system, and detailed gas emission patterns were obtained. The total amount of each gas emission was computed from the amount of ventilation and gas concentration. NH(3) emission was observed in the early period of composting when the material was at a high temperature. Sharp peaks in CH(4) emission occurred immediately after swine manure was piled up, although a high emissions level continued after the first turning only in the large-scale pile. N(2)O emissions started around the middle stage of the composting period when NH(3) emissions and the temperature of the compost material began to decline. The emission rates of each gas in the small and large piles were 112.8 and 127.4 g NH(3)-N/kg T-N, 37.2 and 46.5 g N(2)O-N/kg T-N, and 1.0 and 1.9 g CH(4)/kg OM, respectively. It was found that changing the piling scale of the compost material was a major factor in gas emission rates.     

环境因素对东平湖沉积物细菌群落结构的影响

【目的】探讨环境因素对东平湖沉积物细菌群落结构的影响。【方法】应用T-RFLP(Terminal RestrictionFragment Length Polymorphism)技术分析和比较了6个不同位置的东平湖沉积物在丰水期和枯水期的细菌多样性,并结合不同样品环境因子的差异,采用主成分分析(PCA)和典型对应分析(CCA),探讨了环境因子对细菌多样性的影响。【结果】不同沉积物样品的T-RFLP图谱具有较高的相似性。除2号样品外,所有枯水期样品的细菌群落具有较高的丰富度、多样性、均匀度和较低的优势度。CCA结果表明,558bp T-RF的丰度与总磷、总氮、总有机碳、铵态氮和硝态氮含量呈负相关而与碳氮比和水深呈正相关;64.5、164、509和543bp T-RFs的丰度与总氮、总有机碳、铵态氮、硝态氮、碳氮比和水深呈正相关;而其它14种主要的T-RFs在不同样品间分布较为稳定受环境因子影响不大。90、136.5、138和488bp等T-RFs可能代表了东平湖沉积物中占优势地位的土著菌群。通过Phylogenetic Assignment Tool在线分析结果推测,东平湖沉积物中的优势菌群可能属于Firmicutes和Proteobacteria门。【结论】环境因素对东平湖沉积物的细菌多样性产生显著影响,但对其土著菌群的影响不大。     

Allantoin-N concentration changes and analysis of the influencing factors on its changes during different manure composting

Allantoin is one of important nitrogenous compounds in manure. In this study, the simulation experiment of aerobic composting was adopted to explore concentration changes, degradation and relevant influencing factors of allantoin-N during six manure composting. The result showed that the allantoin-N concentration was markedly different among different manures. The various livestock and poultry excreted 1.92-11.14gkg(-1) allantoin-N which accounted for 9.98-32.27% of the total excreted nitrogen. The changing trend of the allantoin-N concentration firstly increased (for 0-14 days), then decreased (for 14-70 days) during different manure composting, and the allantoin-N concentration after composting was lower than the initial allantoin-N concentration in all manure composting. During allantoin degradation for 14-70 days of composting, the half-life of allantoin-N was 57.76 days in broiler manure, 46.21 days in layer-hen manure, 27.73 days in hog manure, 25.67 days in sow manure, 38.51 days in young pig manure and 15.75 days in dairy manure, and the sequence in the half-life was chicken manure>pig manure>dairy manure. Allantoin degradation conformed to first-order kinetics. Through the correlation analysis, hippuric acid, hydrolyzable nitrogen, amino acid-nitrogen, HUN fraction, NO(3)(-)-N and total hydrolyzable nitrogen could be closely related to allantoin-N transforming during composting. Humification could be the main influencing factor for reducing allantoin-N concentration during composting.     

氮素形态对树木养分吸收和生长的影响

由于NH₄⁺-N和NO₃^--N形态的差异,二者对树木养分吸收和生长发育的影响不同,树木常表现出对NH₄⁺-N和NO₃^--N的选择性吸收,树种对NH₄⁺-N和NO₃^--N吸收的偏好特性可能与生长地的土壤pH有关,来自于酸性土壤的树种通常具有喜NHON的特性,而来自于中性或碱性土壤的树种常表现出喜NO₃^--N的趋势,由于NH₄⁺-N和NO3^--N所带电荷的差异,通常NH₄⁺-N有利于阴离子的吸收,而NO3^--N则促进阳离子的吸收,在有些情况下,NH₄⁺-N会抑制NO₃^--N的吸收,但抑制的机制目前还不清楚,树木吸收NH₄⁺-N时,引起根际pH下降,相反吸收NO₃^--N时根际pH升高,根际pH变化可以改变土壤养分的有效性,并影响树木对养分的吸收利用,树木对NH₄⁺-N和NO₃^--N的生长反应不同,有些喜NH₄⁺-N的针叶树在供应NH₄⁺-N时生长较好,多数植物在同时供应NH₄⁺-N和NO₃^--N时生长量最大,有些树种在同时供应NH₄⁺-N和NO₃^--N时也表现出最高的生长,但对于树木类似的研究还少,这一现象对于树木是否具有普遍性还需要大量试验证明。     

连续可调式沉水植物网床对河道水质的修复

在太湖贡湖水源保护区陆域的一条长约200 m的污染河道内构建了一系列连续可调式沉水植物网床,形成了以菊花草、苦草、伊乐藻、轮叶黑藻和菹草等沉水植物构成的水生植物群落;跟踪监测了总氮(TN)、铵态氮(NH4 +-N)、亚硝态氮(NO2--N)、硝态氮(NO3--N)、总磷(TP)和磷酸盐(PO43--P)等水质指标,分析沉水植物网床引导沉水植被恢复对污染河道的水质修复效果.结果表明:沉水植被网床构建后,水体透明度显著升高,由修复前的0.5m提高到1.7 ～1.8 m;在沉水植被网床构建后的第5天和第20天,TN和TP的削减率分别为35.6％、66.3％和29.4％、63.2％;5个月后,修复河道水体内NH4+-N、NO2--N、NO3--N、TN、PO43--p和TP的浓度比对照组显著降低,削减率分别达到92.4％、76.8％、72.7％、73.9％、90.5％和92.0％.由连续可调式沉水植被网床引导恢复的水生植物群落可用于河道,特别是陆域浅水污染水体的生态修复.     

水、肥添加对内蒙古典型草原土壤碳、氮、磷及pH的影响

采用野外田间实验和室内分析相结合的方法,研究了水分、氮肥和磷肥添加对内蒙古典型草原土壤碳、氮、磷含量及pH的影响。结果表明:土壤有机碳和全氮含量对水、肥添加无显著响应;水分添加降低了土壤铵态氮(31.1%,P<0.01)和硝态氮(7.9%,P<0.001)含量,而添加氮肥显著增加了土壤铵态氮和硝态氮的含量(P<0.001);添加磷肥显著增加了土壤全磷和速效磷含量,分别为不施磷肥的1.7和5.9倍(P<0.001);水分添加提高了土壤pH值,氮、磷肥的添加均不同程度地降低了土壤pH值(P<0.001)。表明:水分以及氮肥、磷肥的添加对内蒙古典型草原土壤的性质具有明显的调节作用,这将为退化草地的管理提供科学参考。     

退化设施蔬菜地修复过程中土壤可溶性有机碳与无机氮动态

土壤强还原处理(reductive soil disinfestation,RSD)可以有效修复退化设施蔬菜地土壤,但实施过程中亦会存在可溶性有机碳(DOC)与无机氮(NO3--N和NH4+-N)的淋溶风险。本研究选用水稻秸秆及其制备的生物质炭(biochar,BC)作为修复材料,采用BC、RSD以及RSD+BC三种方法修复退化蔬菜地土壤,探究修复过程中土壤基本性质、DOC与无机氮的动态变化。结果表明,与对照土壤相比,BC处理显著提高了土壤pH、EC和DOC含量(P<0.05),但对土壤NO3--N和NH4+-N无显著影响。对于RSD和RSD+BC处理,土壤NO3--N含量在1~3 d内快速下降,之后维持在较低水平;土壤DOC含量呈先上升后下降趋势,在整个培养时段均显著高于对照处理(P<0.05)。方差分析表明,BC与RSD处理对土壤DOC、全碳(TC)、全氮(TN)和C/N存在交互作用。可见,RSD和RSD+BC处理能有效去除NO3--N,但DOC含量大幅度增加,存在淋溶风险。