唐岛湾网箱养殖区沉积物-水界面溶解无机氮的扩散通量

2004-08～2005-05分4个航次对唐岛湾网箱养殖区的10个站的沉积物间隙水和上覆水中的溶解无机氮营养盐（NH⁺₄-Ｎ、NO^-₃-Ｎ、NO^-₂-Ｎ）进行了现场调查, 并使用Fick第一定理对该海区沉积物-水界面溶解无机氮的扩散通量进行了估算.结果表明,网箱养殖区的上覆水和沉积物间隙水中溶解无机氮均以NO^-₃-Ｎ为主,分别占溶解无机氮总量的73.34%和61.45%;上覆水中溶解无机氮（DIN）和NO^-₃-Ｎ含量的季节变化趋势一致,在2004-10达到峰值,NH⁺₄-Ｎ的季节变化稍有不同;间隙水中溶解无机氮（DIN）和NO^-₃-Ｎ、NH⁺₄-Ｎ的变化趋势一致,表现为从5月份到8月份含量逐渐增加,到10月份达到最大,然后到次年2月份又减少;上覆水和间隙水中NO^-₂-Ｎ的含量随养殖进程表现为一个逐步积累的过程.NH⁺₄-Ｎ、NO^-₃-Ｎ和NO^-₂-Ｎ在沉积物-海水界面上的扩散通量分别为5.46、-5.04、8.71 μmol/（m²·d）,NO^-₂-Ｎ的扩散释放对唐岛湾网箱养殖区的水环境质量影响较大.     

阿哈水库枯水期入库河流可溶性氮、磷含量分布特征

以贵阳市阿哈水库五条入库河流为研究对象,研究了阿哈水库枯水期入库河流水体可溶性氮、磷含量分布特征,可溶性氮组分比例及沿程变化规律。结果表明：五条入库河流水体可溶性氮、磷含量差异较大,可溶性总氮（DTN）、可溶性总磷（DTP）平均含量分别为1.71~9.74 mg/L和0.03~0.52 mg/L。蔡冲河、烂泥沟河、金钟河受人类活动影响较大,水体DTN、DTP含量较高。不同河流水体可溶性氮组分比例差异显著,受人类活动影响小的游鱼河、白岩河,其水体可溶性氮以可溶性有机氮（DON）为主,DON占DTN的比例高达94%。受人类活动影响大的蔡冲河、烂泥沟河、金钟河则相反,以可溶性无机氮（DIN）为主。不同河流氮、磷含量自上到下游沿程波动较大,人为源造成的氮、磷污染远高于自然源。金钟河的DTN、DTP年输入量分别为97.03 t、46.64 t,对阿哈水库的DTN、DTP输入贡献最大,分别达到45%和66%。     

不同氨氮填加量下沉水植物对沉积物DOM荧光特性的影响

采用三维荧光光谱技术,模拟研究了不同氨氮添加量(0,100,200和400 mg/kg)下沉水植物对湖泊沉积物DOM(溶解性有机质)荧光特性的影响.结果表明:不同氨氮添加量下,沉水植物的存在明显增强沉积物DOM荧光强度,其中对类蛋白质和类氨基酸组分荧光强度影响较大(荧光强度分别增大了20%～77%和27%～56%);而对类腐殖酸和类富里酸组分影响相对较小(荧光强度分别增大了5%～25%和21%～29%). 添加氨氮可增强沉水植物对沉积物DOM荧光强度影响的程度,当添加量为100 mg/kg时,沉水植物生长最旺盛,沉积物DOM中类蛋白质和类氨基酸组分荧光强度增幅最大(分别约77%和56%);即外源氨氮通过增加沉积物蛋白质和氨基酸含量增强了沉积物有机氮的生物有效性;而在其他添加量下,DOM各荧光组分强度增幅不大,即适当添加外源氨氮,可通过促进沉水植物生长增加沉积物中蛋白质和氨基酸等含量,从而提高沉积物有机氮的生物有效性.      

太湖溶解有机质光谱和氮磷污染的区域分布差异特征

对太湖水体溶解有机质三维荧光光谱、紫外吸收系数、溶解性有机碳(DOC)、总氮和总磷的分布特征进行了研究,定量估算了溶解有机质的来源. 研究发现:太湖水体溶解有机质的各物理化学参数以及氮磷质量浓度的区域分布特征明显. 水体三维荧光光谱显示有2个特征的类蛋白荧光峰,但不同湖区水样荧光峰位置以及强度并不完全一致. ρ(DOC)和荧光强度〔Fn(355)〕与吸收系数(α)有显著的相关性,但其相关关系也存在明显的区域特征. 根据有机质光谱学和理化指标的分布特点、梯度变化规律及地理特征要素,将太湖分为4个区域(Ⅰ,Ⅱ,Ⅲ和Ⅳ区),讨论了各区域的特征和变化规律. 利用有机质来源与荧光光谱指数的定量关系,估算了溶解有机质的来源贡献率,结果显示,北部湖区城市污水、陆源和生物活动对DOM的来源均有影响,其他湖区DOM以生物作用为主,陆源贡献率均不超过25%.      

Natural organic matter quantification in the waters of a semiarid freshwater wetland (Tablas de Daimiel, Spain)

Dissolved organic matter (DOM) concentrations have been measured in the waters of a semiarid freshwater wetland, the Tablas de Daimiel, Spain, when the system-characterised by variable hydroperiodicity conditions, was completely flooded (February 2011). Fluxes of DOM from the wetland soils to the overlying waters were measured by using a passive diffusion sampler (peeper). Not only dissolved organic carbon (DOC) concentrations were measured but refractory organic matter (ROM, usually known as humic substances) was also quantified using a novel voltammetric method. Fluorescence spectra were recorded to help in selecting the appropriate standard for ROM quantification, test the homogeneity of DOM in the waters and get an indication of their source. The results obtained show a 7-fold increase in measured ROM concentrations from the Gigu¨ela River to the outlet, which points to a net exportation of ROM from the wetland and to the existence of an internal source of ROM in the system, probably diffusion from the wetland soils. This hypothesis is confirmed by the flux of ROM from the soils to the water column measured with the peeper and by the common fluorescence characteristics of column and interstitial waters. The smaller increase in DOC concentrations along the wetland, in spite of the higher DOC fluxes from soils, suggests that there is significant turnover of organic carbon (OC) in the water column. The system acts as a major carbon sink but, when flooded, exports OC as DOM.     

巢湖溶解性有机物时空分布规律及其影响因素

为研究巢湖溶解性有机物(dissolved organic matter,DOM)的时空分布规律及其影响因素,于2013年4月至2014年4月每月在巢湖3个不同湖区17个点位采集表层水样,测定了水体溶解性有机碳(dissolved organic carbon,DOC)和溶解性有机氮(dissolved organic nitrogen,DON)浓度.结果表明,东部、中部和西部这3个湖区DON浓度具有显著差异(P0.01,n=13),这可能与西湖区入湖河流的外源输入以及DON的可利用性有关.水华期间,水体总氮总磷比、总溶解性氮磷比以及溶解性无机氮(dissolved inorganic nitrogen,DIN)与溶解性活性磷(soluble reactive phosphorus,SRP)比值迅速降低,其中西湖区DIN/SRP在2013年8月降至5±7,表明水体出现氮限制.此外,DON浓度迅速降低,西部湖区叶绿素浓度与DON显著负相关(r=-0.265,P0.05,n=91),表明在氮限制条件下,DON具有一定生物可利用性.DOC浓度不存在显著空间差异,水温是控制这3个湖区DOC浓度变化的重要因素.东部和中部湖区DOC浓度还受叶绿素和硝态氮浓度的影响.此外,巢湖DOC/DON变幅较大,由于含氮化合物更易降解,因此DON是影响碳氮比值的主导因子,是表征DOM可利用性的重要组分.     

Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light

Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter(DOM) was investigated in this study. Solar light significantly decreased the UV_(254) absorbance and fluorescence(FLU) intensity of reclaimed water.However, its effect on the dissolved organic carbon(DOC) value of reclaimed water was very limited. The decrease in the UV_(254) absorbance intensity and FLU excitation–emission matrix regional integration volume(FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV_(254) absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV_(254) absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV_(254) and FLU intensity were independent of light intensity. The peaks of the UV_(254) absorbance and FLU intensity with an apparent molecular weight(AMW) of 100 Da to 2000 Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change.     

蔬菜类废物两相厌氧消化水解酸化相颗粒降解规律

研究蔬菜类废物两相厌氧消化过程中水解酸化液物化性质随水解时间的变化情况,结合总有机碳(TOC)、溶解性有机碳(DOC)、颗粒粒径和溶解性有机物(DOM)分子量的分析,探讨了蔬菜类废物水解酸化过程中TOC溶出和颗粒降解之间的关系,分析了水解酸化相颗粒物降解规律.实验结果表明,蔬菜类废物水解过程可以分成两个阶段:易水解的颗粒物在前5d迅速水解,TOC浓度迅速升高,在第5d达到最大值4920mg/L,水解产生颗粒态物质的二次平均直径从第1d的58.38μm降至第5d的4.64μm,有机物快速溶出,DOC/TOC比值在第4d达到最大值85%,该水解过程可用Contois模型模拟;第5d后,难水解颗粒物质的缓慢水解起主导作用,颗粒态物质的二次平均直径从4.64μm开始逐渐增大,并稳定在8.97~10.68μm范围内,TOC和DOC溶出率逐渐降低,且DOC溶出率小于TOC溶出率.大分子溶解性有机物的降解也主要集中在水解过程的前5d,水解第1d产生的大分子DOM(1.6×109~1.9×109Da)到第5d已经全部降解成分子量在5×104~4×106Da的DOM;第5d过后,DOM的分子量分布情况并未发生较大变化.表明蔬菜类废物两相厌氧消化工艺过程中水解时间可缩短为5d.     

钦州湾内湾茅尾海营养状况分析与评价研究

根据2011年-2012年茅尾海水质监测调查资料分析其营养特征,结果显示:茅尾海总体处于中度富营养状态,时空差异较为明显,以夏季最为严重,从湾顶河口往南部湾口减轻.有机污染等级为轻至中度,空间分布与富营养状况相似.水体盐度以湾顶河口区域向中南部呈梯度递增,与富营养化指数(EI)、有机污染指数(AI)、化学需氧量(COD)、亚硝酸盐(NH2-N)、硝酸盐(NO3-N)、铵盐(NH4-N)、溶解态无机氮(DIN)呈显著负相关,表明湾顶钦江、茅岭江的入海污染是茅尾海富营养和有机污染的主要物质来源,其径流输入与外湾潮流运动综合作用对茅尾海营养分布特征具有控制作用.茅尾海丰、枯水期氮磷比分别为60、18,丰、平水期均以磷营养限制为主,茅岭江是该海湾溶解态无机磷(DIP)的主要贡献者.DIP与盐度、EI、AI相关性不显著,对富营养和有机污染程度的贡献相比COD、DIN较为有限.     

填埋垃圾浸提液与地下水污染物组成差异及成因

为揭示垃圾渗滤液污染地下水特征,采用常规分析、三维荧光光谱和多元统计分析,研究了某简易填埋场垃圾浸提液与地下水中无机盐、有机物及重金属的分布特征及成因.结果表明,填埋场垃圾异质性强,浸提液中NH+4-N浓度高,而Cl-、SO2-4、溶解性有机物(DOM)、重金属含量低,强还原氛围导致硝化过程受阻,NO-3-N、NO-2-N含量低,浸提液中Cu主要结合在DOM上,而Ba、Cd、Cr、Fe、Mn、Ni、Zn及As主要结合在疏水性有机物上.除填埋场所在点地下水外,其余点地下水污染物来源相似,其中的DOM以微生物来源为主;与垃圾浸提液中污染物分布特征相反,地下水中NH+4-N含量低而Cl-、SO2-4、DOM、NO-3-N、NO-2-N含量高,Cu、Ba、Cd、Fe、Mn及Ni的分布与DOM有关,主要结合在荧光有机物上.研究结果显示,基于地下水中污染物组成差异,采用聚类分析方法可识别出地下水受渗滤液污染点.     

Environmental fate and behavior of silver nanoparticles in natural estuarine systems

Silver nanoparticles (AgNPs) are widely used in many consumer products, whereas their environmental behaviors in natural aquatic systems remain unknown, especially in natural brackish media. Therefore, it is urgent to investigate the environmental fate of AgNPs in natural brackish waters. Here, we investigated the stability of citrate-coated AgNPs in natural brackish water collected from 6 different sites with distinct salinities in the Xinglinwan Reservoir, located in Xiamen City, southeast China. The obtained results showed that AgNP colloids remained stable in low-salinity waters, which was mainly determined by the effects of dissolved organic matter (DOM) promoting the stability of the nanoparticles. However, the environmental fate of AgNPs in high-salinity waters was dominated by the salinity or ionic strength, especially the free ion concentrations of Cl^?, SO₄^2?, or S^2?, resulting in rapid sedimentation and dissolution. In addition, both DOM and salinity contributed to the environmental behavior of AgNPs in moderate-salinity waters, ultimately resulting in either colloidal stability or sedimentation. Overall, these results may reveal that AgNPs remain relatively stable for a long period in low-salinity natural waters, and that the stability might gradually decrease as AgNPs are transferred from freshwaters through brackish waters and eventually end up in seawater along the bay. Our findings also further indicate that the toxicity and potential risks of AgNPs may present more serious threats to the environment and organisms in natural freshwaters than in natural estuarine systems or seawater.     

Assessing the utility of dissolved organic matter photoreactivity as a predictor of in situ methylmercury concentration

Methylmercury(MeHg) bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter(DOM) and other photoreactive ligands can convert MeHg into less toxic forms of mercury through photodemethylation. In this study, spectral changes and photoreactivity of DOM were measured to assess the potential to control photoreactions and predict in situ MeHg concentration. Water samples collected from a series of lakes in southwestern Nova Scotia in June, August, and September were exposed to controlled ultraviolet-A(UV-A) radiation for up to 24 hr. Dissolved organic matter photoreactivity, measured as the loss of absorbance at 350 nm at constant UV-A irradiation, was positively dependent on the initial DOM concentration in lake waters(r~2=0.94). This relationship was consistent over time with both DOM concentration and photoreactivity increasing from summer into fall across lakes. Lake in situ MeHg concentration was positively correlated with DOM concentration and likely catchment transport in June(r = 0.77) but not the other sampling months. Despite a consistent seasonal variation in both DOM and Fe, and their respective correlations with MeHg, no discernable seasonal trend in MeHg was observed. However, a 3-year dataset from the 6 study lakes revealed a positive correlation between DOM concentration and both Fe(r = 0.91) and MeHg concentrations(r = 0.51) suggesting a more dominant landscape mobility control on MeHg.The DOM-MeHg relationships observed in these lakes highlights the need to examine DOM photoreactivity controls on MeHg transport and availability in natural waters particularly given future climate perturbations.     

淹水条件下三峡库区典型消落带土壤释放DOM的光谱特征:荧光光谱

作为水体DOM的重要来源,消落带土壤淹水释放过程十分重要.本文以三峡库区典型消落带土壤为例,通过模拟正常淹水和厌氧淹水的两种条件,利用荧光光谱,着重定性地分析并讨论了土壤向上覆水体释放DOM的动态特征.结果表明,消落带4个区域土壤淹水后产生的DOM荧光特性,呈现出和可见-紫外光谱相似特征,对上覆水体DOM荧光特征有重要贡献.淹水初期的快速释放及后期去除机制,是水体DOM荧光组分的动态"源-汇"平衡的关键;其中类腐殖峰(A和C)受无机矿物相的吸附-释放影响明显,而类蛋白峰(B和T)受微生物影响较为明显.另外,所有土壤淹水释放后水体DOM均呈现出"内源+外源"的复合特征.除忠县石宝寨(SB)外,整个淹水周期,其余区域土壤在厌氧和正常淹水条件下,水体DOM荧光特征的差异性不明显,这可能和土壤自身组成(例如无机矿物组成和有机组分)的复杂程度有关.结合可见-紫外光谱,两种技术相互补充,证明了土壤释放("源")和去除("汇")机制是控制DOM动态变化的重要因素;而淹水初期的较强芳香性和腐殖化程度,以及较强的陆源特征,无疑有利于进一步解释污染物在淹水过程中的环境行为,为进一步了解DOM的环境角色提供数据基础和实验支撑.     

Prediction of DOM removal of low specific UV absorbance surface waters using HPSEC combined with peak fitting

High performance size exclusion chromatography (HPSEC) is used in water quality research primarily to determine the molecular weight distribution of the dissolved organic matter (DOM), but by applying peak fitting to the chromatogram, this technique can also be used as a tool to model and predict DOM removal. Six low specific UV absorbance (SUVA) source waters were treated using coagulation with alum and both the source and treated water samples were analysed using HPSEC. By comparing the molecular weight profiles of the source and treated waters, it was established that several DOM components were not effectively removed by alum coagulation even after high dosage alum treatment. A peak-fitting technique was applied based on the concept of linking the character (molecular weight profile) of the recalcitrant organics in the treated water with those of the source water. This was then applied to predict DOM treatability by determining the areas of the peaks which were assigned to removable organics from the source water molecular weight profile after peak fitting, and this technique quantified the removable and non-removable organics. The prediction was compared with the actual dissolved organic carbon (DOC) removal determined from jar testing and showed good agreement, with variance between 2% and 10%. This confirmed that this prediction approach, which was originally developed for high SUVA waters, can also be applied successfully to predict DOC removal in low SUVA waters.     

Characterization of dissolved organic matter as N-nitrosamine precursors based on hydrophobicity, molecular weight and fluorescence

It is very important to identify the dominant precursors for N-nitrosamine formation from bulk organic matter, to enhance the understanding of N-nitrosamine formation pathways in water treatment plants and allow the development of practical treatment technologies. In this study, dissolved organic matter (DOM) from two source waters was fractionated with XAD resins and ultra- filtration membranes. The N-nitrosamine formation potential (FP) (ng of N-nitrosamines formed per mg of dissolved organic carbon (DOC)) from raw water and each fraction were measured and correlated with the fluorescence excitation-emission matrix (EEM), molecular weight (MW) and other assays. The results showed that the hydrophilic fraction had N-nitrosamine FP 1.3 to 3.5 times higher than the hydrophobic fraction from both source waters. The DOM fraction with low MW was the dominant fraction in these two source waters and contributed more precursors for N-nitrosamine formation than the larger MW fraction. The EEM spectra indicated there were notable amounts of soluble microbial products (SMPs) and aromatic proteins in the two studied rivers, which probably originated from wastewater discharge. The SMPs tended to be more closely correlated with N-nitrosodimethylamine formation potential than the other DOM components. Higher N-nitrosamine FP were also related to fractions with lower DOC/DON ratios and lower SUVA 254 values.     

九龙江流域地表水中硝酸盐来源辨析

从九龙江流域遴选出2个典型小流域--仙都和五川小流域作为研究区,于2005年春季运用15N同位素示踪法对其地表水中硝酸盐来源进行研究.结果表明,仙都小流域地表水中溶解态总氮、硝氮和氨氮的浓度范围(以N计,下同)分别为1.47～5.31 mg/L、0.83～4.05mg/L和0.21～0.36mg/L,硝酸盐的δ15N值(以样品相对于标准大气N2的15N和14N比值的千分偏差表示)范围在2.5460-7.92%之间;五川小流域地表水中溶解态总氮、硝氮和氨氮的浓度范围分别为1.14～5.56mg/L、0.96～1.46mg/L和0.12～1.28mg/L,硝酸盐的δ15N值范围在-0.19‰～5.89‰之间.对照不同来源的硝酸盐δ15N特征值,结合研究区的农作物种植和施肥状况,得出如下结论:仙都小流域地表水中硝酸盐主要来自无机化肥与土壤有机氮,有机肥有一定的贡献;五川小流域地表水中硝酸盐的来源以无机化肥与土壤有机氮为主,有机肥的贡献很小;2个小流域地表水中硝酸盐的来源随时空变化而有差异,与当地农作物种类及农田时令密切相关.     

有机物料还田对稻田土壤DOM碳源代谢能力的影响

以成都平原典型稻麦轮作长期定位施肥试验土壤为研究对象,设置常规施肥(T1)、猪粪替代50%氮肥(T2)和猪粪替代50%氮肥+秸秆全量还田(T3)这3种处理,采用Biolog-ECO方法,研究长期有机物料还田下土壤和土壤可溶性有机质(DOM)的碳源代谢能力.结果表明,T3处理较T1和T2处理显著增加了土壤的碳源代谢能力,平均颜色变化率(AWCD)分别增长16%和48%;同时T3处理提高了土壤DOM的碳源代谢能力,其AWCD值为0.43.从微生物碳代谢功能多样性指数来看,土壤和土壤DOM中微生物的碳代谢功能多样性指数均以T3处理最高,其中土壤DOM中微生物的Shannon、 Simpson和McIntosh指数分别为2.73、 0.91和3.75.主成分分析和富集分析结果显示,不同施肥处理下土壤和土壤DOM的主要利用碳源类型存在差异,对于DOM而言,T1和T2处理的DOM主要利用碳源仅为糖类,而T3处理增加了对氨基酸类、羧酸类、聚合物类和胺类的利用.土壤pH和质地的改变是引起土壤DOM碳源代谢能力差异的主要因素.综上,猪粪配合秸秆施用显著增加了土壤和土壤DOM的微生物群落多样性和碳源代谢能...     

太湖东北部沉积物可溶性氮、磷的季节性变化

通过快速释放实验,研究了太湖东北部营养水平不同的梅梁湾、贡湖湾和胥口湾3个湖区表层沉积物中可溶性氮、磷的季节性变化.结果表明,沉积物总磷(TP)与其释放的可溶性总磷(DTP)在春、夏两季显著相关并且以可溶性有机磷(DOP)为主;春、夏两季DOP与可溶性无机磷(DIP)的形态间转化较秋、冬两季更为活跃.藻型湖区沉积物的总氮(TN)多为夏季减少,而清洁型湖区则为夏季大幅增加;沉积物释放的NH₄⁺-N以夏、冬两季居多,夏季达到最大值;沉积物释放的NO₃^--N夏季大幅度增加,冬季较少.清洁型湖区夏季沉积物的TN及其释放的NH₄⁺-N、NO₃^--N显著高于藻型湖区.     

农业常用有机物料中水溶性有机物的理化性质特征

以水稻土水溶性有机物(DOM)为对照,采用物理化学和光谱学实验研究了农业上常用有机物料:猪粪、绿肥和污泥DOM的理化性质差异.结果表明,水稻土、污泥、猪粪和绿肥DOM含量分别为122, 23793, 12904, 380560mgC/kg.若施用等量有机物料,带入土壤的DOM量最多的应是绿肥.不同有机物料DOM中大分子组分含量高低顺序为:水稻土(51.08%)>猪粪(41.25%)>污泥(23.33%)>绿肥(7.36%);而极性组分含量的顺序则相反,水稻土(10.71%)猪粪DOM(1.12)>污泥DOM(1.11)>绿肥DOM(0.98),紫外图谱也证实了这一点.     

木醋液酸化生物炭与氮素配施对盐渍土壤活性氮及氨挥发的影响

以盐渍土壤为研究对象,通过吸附试验和室内土壤培养试验,分析生物炭及木醋液酸化生物炭与尿素配施后对盐渍土壤活性氮、脲酶活性和氨挥发的影响,为提高盐渍土壤氮素有效性提供理论和技术支撑.吸附试验表明,木醋液酸化生物炭提高了对铵态氮的吸附量,与生物炭相比,提高了2.28%～18.18%.土壤培养试验表明,与单施尿素处理相比,生物炭和木醋液酸化生物炭与尿素配施处理使土壤硝态氮、铵态氮分别减少了0.72%和25.26%、 1.11%和16.93%;提高了土壤可溶性有机氮和可溶性全氮含量.木醋液酸化生物炭与尿素配施提高了脲酶活性,而生物炭与尿素配施处理则降低了土壤脲酶活性.木醋液酸化生物炭与尿素配施处理氨挥发累积量在不同培养时期均低于单施尿素处理及生物炭与尿素配施处理,且能降低土壤的pH,而未改性的生物炭则提高了土壤pH.因此,在盐渍土区,采用木醋液对生物炭进行酸化后再与氮肥配合施用,不仅有效降低了土壤pH,提高土壤脲酶活性以及可溶性有机氮含量,还可以适当降低土壤铵态氮和硝态氮含量,减少氨挥发,有利于减少土壤无机氮素的损失和提高盐渍土壤氮素有效性.