汤浦水库沉积物碳、氮、磷的分布与评价

[目的]研究汤浦水库沉积物中氮、磷及有机碳等污染物现状,为水质安全保障提供依据。[方法]在库区采集沉积物柱状样品,分析其中碳、氮、磷的含量,并采用有机指数法对沉积物污染现状进行评价。[结果]沉积物中有机碳平均含量12.23g/kg,总氮平均含量1.22g/kg,总磷平均含量为0.49g/kg;氮、磷及有机碳等污染物主要集中于沉积物表层0—20cm范围内。随沉积物厚度的增加,各类污染物含量下降,40cm以下的沉积物中污染物含量变化不大;有机指数评价结果显示,水库沉积物有机指数为0.13,等级为Ⅱ级,较清洁。[结论]汤浦水库沉积物受到的污染较小,但沉积物中含氮物质略多,应该引起重视。     

Carbon balance in the soils of abandoned lands in Moscow region

A quantitative assessment of the carbon balance was performed in gray forest soils of the former agricultural lands abandoned in different time periods in the southern part of Moscow oblast. It was based on the field measurements of the total and heterotrophic soil respiration and the productivity of biocenoses. Geobotanical investigations demonstrated that the transformation of the species composition of herbs from weeds to predominantly meadow plants occurred in five–ten years after the soil was no more used for farming. The amount of carbon assimilated in the NPP changed from 97 g C/m² year in the recently abandoned field to 1103 g C/m² year in the 10-year-old fallow, and the total annual loss of carbon from the soil in the form of CO₂ varied from 347 to 845 g C/m² year. In five years, the former arable lands were transformed into meadow ecosystems that functioned as a stable sink of carbon in the phytomass and the soil organic matter.     

碳氮添加对雨养农田土壤全氮、有机碳及其组分的影响

为探明碳氮添加4年后,土壤全氮、有机碳及其组分(可溶性有机碳、微生物量碳、轻组和重组有机碳)的变化特征,依托布设于甘肃省定西市安定区李家堡镇的不同碳源配施氮素田间定位试验,涉及秸秆、生物质炭、氮素3个因素,秸秆设置为不施、施用秸秆2水平;生物质炭为不施和施用生物质炭2个水平;氮素设置为不施氮、施纯氮50 kg/hm^2、施纯氮100 kg/hm^2 3个水平,共9个处理。结果表明:不同处理下土壤全氮、有机碳及其组分的含量均随土层的加深而降低。添加生物质炭对土壤全氮、有机碳及其组分均具有不同程度的提升效应。添加秸秆对土壤全氮、有机碳和可溶性有机碳、微生物量碳、轻组有机碳均具有显著提升效应,仅在0-5 cm土层对重组有机碳有显著提高。添加氮素可显著提升土壤全氮、有机碳和可溶性有机碳、微生物量碳、轻组有机碳含量。较其他处理,添加生物质炭对土壤全氮、有机碳和重组有机碳的提升效应最高,添加秸秆对可溶性有机碳、微生物量碳、轻组有机碳的提升效果最优。从提升土壤质量的角度出发,推荐秸秆配施氮素模式,该模式下土壤碳素有效性高、易于被微生物利用,有利于作物生长。从提高土壤固碳角度考虑,推荐生物质炭配施氮素模式,该模式有利于碳的封存。     

渭河陕西段河道沉积物中碳氮磷来源分析及污染评价

基于渭河陕西段及其支流河道16个采样点中沉积物的总氮(TN)、总磷(TP)和总有机碳(TOC)含量,运用C/N和N/P比值法研究沉积物中营养元素的可能来源,并采用有机污染指数法评价沉积物污染状况。结果表明,沉积物中TN含量为0.069~3.839g/kg,66.1%的样品含量低于平均值0.639g/kg;TP含量为0.453~1.841g/kg,62.7%的样品含量低于平均值0.713g/kg;TOC含量为0.772~25.221g/kg,62.3%的样品含量低于平均值5.609g/kg。渭河陕西段沉积物中有机质主要受内源影响,以藻类和浮游动植物为主;沉积物中磷的来源主要为外源输入。2014—2016年所有采样点的N/P值均小于Redfield比,这可能与沉积物中碳氮磷的生物地球化学过程有关。2016年11月,在局部河道如林家村、卧龙寺桥、常兴桥、兴平、草滩、清姜河入渭处可能受到外源有机质的影响。2015年内有机指数与有机氮指数变化一致,即汛前<汛中<汛后。在2014—2016年,渭河陕西段沉积物中有机氮污染和有机污染整体上得到有效控制,但在局部河道如咸阳铁桥、草滩、黑河入渭和灞河入渭处等距离城市较近区域存在污染反弹可能,需引起注意。     

Carbon Mineralization and Water-Extractable Organic Carbon and Nitrogen as Predictors of Soil Health and Nitrogen Mineralization Potential

ABSTRACT

The United States Department of Agriculture Natural Resources Conservation Service (NRCS) launched a national “Soil health initiative” in 2012; as a part of that effort, a soil health index (SHI) has been developed. The SHI is calculated using results of three soil tests: 24-h carbon mineralization following rewetting of air-dried soil (C_min, by the “Solvita” proprietary method) and water-extractable organic carbon (C) and nitrogen (N). These tests are being promoted both as the inputs into the SHI calculation and as predictors of soil N mineralization potential. Soil was collected from 35 California fields in annual crop rotations; 20 fields were under certified organic management and the other 15 under conventional management, to provide a range of soil properties and management effects. Carbon mineralization was determined by the Solvita method, and by a comparison method utilizing head space carbon dioxide (CO₂) monitoring by infrared gas analyzer (IRGA); additionally, two soil wetting protocols were compared, capillary wetting (the Solvita method) and wetting to 50% water-filled pore space (WFPS). Both water-extractable C (WEOC) and N (WEON) were determined using NRCS-recommended protocols. Net N mineralization (N_min) was also determined after a 28-day aerobic incubation at 25°C. Solvita C_min was highly correlated with the IRGA method using capillary wetting (R² = 0.81). However, capillary soil wetting resulted in high gravimetric water content that significantly suppressed C_min compared to the 50% WFPS method. N_min was correlated with Solvita C_min (r = 0.54) and with WEOC and WEON (r = 0.62 for each comparison); combining these three measurements into the SHI slightly improved the correlation with N_min. The organically managed soils scored higher than the conventional soils on the SHI, with a minority of organic soils and the majority of conventional soils scoring below the NRCS target threshold. SHI and soil organic matter were correlated, suggesting an inherent bias that would complicate the application of a national SHI standard.     

汉江上游水体氮素污染特征

2011年对汉江上游干流进行了6次采样,分析了水体氮素的污染特征。结果表明,汉江上游水体NH₃-N,NO₃-N和NO₂-N的年平均值分别为:1.037,1.751和0.044 mg/L。氮素时间分布曲线表现为:NH₃-N浓度的周年变化趋势为双峰型,呈现:丰水期 >枯水期 >平水期的规律。NO₃-N,NO₂-N浓度的周年变化趋势为单峰型曲线,NO₃-N呈现:丰水期 >枯水期 >平水期的规律,NO₂-N丰水期最高,枯水期和平水期相差不大。汉江上游水体氮素空间分布表现为:NH₃-N,NO₃-N浓度自源头向下游呈现出"低值-升高-降低"的趋势。NH₃-N污染主要来自农村生活污水和畜禽养殖排放物,NO₃-N污染主要来自水土流失。     

改良剂对旱地红壤微生物量碳、氮及可溶性有机碳、氮的影响

基于室内模拟培养试验,研究改良剂(生物质炭、过氧化钙)对旱地红壤微生物量碳、氮及可溶性有机碳、氮的影响。试验设置4个处理,即CK、Ca(过氧化钙,1.72g/kg)、C(生物质炭,21.46g/kg)、C+Ca。结果表明:各处理土壤微生物量碳、氮以及可溶性有机碳具有相同的变化趋势,即前期(3d内)都增加较快,在第3天达到最大值,随试验进行有所下降,配施效果优于单施。各处理可溶性有机氮在21d内缓慢增加;第21天时,C+Ca、Ca、C相比CK分别显著增加了62.1%,55.5%,40.9%;35d以后,配施(C+Ca)与单施过氧化钙(Ca)的效果显著优于单施生物质炭(C)和对照(CK)。120d培养期内,配施(C+Ca)处理能够明显提高微生物量碳、氮以及可溶性有机碳、氮的平均含量;微生物量碳的平均含量大小顺序为C+CaCCKCa,微生物量氮的平均含量C+Ca处理显著高于其他处理;可溶性有机碳的平均含量大小顺序为C+CaCaCCK,可溶性有机氮的平均含量C+Ca、Ca处理显著高于CK、C处理。微生物量碳、氮以及可溶性有机碳之间互为极显著正相关(P0.01),而微生物量碳与可溶性有机氮之间呈极显著负相关。因此,生物质炭和过氧化钙能有效提高旱地红壤微生物量碳、氮及可溶性有机碳、氮,且生物质炭与过氧化钙配合施用更有助于土壤改良。     

春季解冻过程对2种温带森林土壤微生物量碳氮和可溶性有机碳氮的影响

为了研究春季土壤冻融过程对碳氮周转的影响,以长白山地区2种森林土壤为研究对象,利用原位培养连续取样法,测定和分析了土壤微生物量碳(MC)、氮(MN)和可溶性有机碳(DOC)、氮(DON)在春季解冻期间的含量动态变化。结果表明:土壤解冻过程中,2种林型土壤微生物量碳、氮的时间变化动态不同,且土壤微生物量碳、氮表现出明显的垂直空间异质性,0—10cm土层土壤微生物量氮显著高于10—20cm土层。除个别时期外,0—10cm土层土壤微生物量碳亦显著高于10—20cm土层土壤。解冻过程中,2种林型0—10cm土层土壤DOC含量时间变化动态基本一致,而红松阔叶林10—20cm土层土壤最大DOC释放量早于次生白桦林。2种林型DOC释放过程集中于解冻中后期。解冻期2种林型土壤DON时间变化动态表现一致,最大土壤DON释放量出现在解冻中后期。解冻期2种林型土壤DON存在明显的垂直空间分布特征,0—10cm土层土壤DON含量显著高于10—20cm土层。     

长期秸秆还田与施氮后土壤活性碳、氮的变化

通过长期定位试验,研究了秸秆还田和施氮后小麦生育期内土壤微生物量碳、氮(MBC、MBN)及可溶性有机碳(DOC)的变化,以期为关中麦玉轮作区土壤肥力的提升以及农业的可持续发展提供科学依据。采用裂区设计,主处理为玉米秸秆全量还田(S+N)和秸秆不还田(N),副处理为3个不同施氮水平(0,168,252kg/hm~2)共6个处理。结果表明:土壤MBC从小麦分蘖期至越冬期降低,此后至拔节期升高且达到峰值,拔节期至成熟期降低。各处理土壤DOC从分蘖期至拔节期增加,拔节期达到峰值,此后至成熟期降低;而土壤MBN的动态变化在整个生育期呈现降低的趋势。秸秆还田处理的土壤MBC和DOC显著高于秸秆不还田处理,平均分别提高6.7%和9.3%;秸秆还田后土壤MBN均高于秸秆不还田处理,且在越冬期、拔节期和成熟期达显著水平;各处理的土壤MBC和MBN随着施氮量的增加而显著降低,还田处理的土壤DOC随施氮量的增加而显著增加,平均增加11.8%;而秸秆不还田各处理中土壤DOC含量表现出先增高后降低的趋势。可见,秸秆还田有提高土壤活性有机碳氮的作用,而过量施用氮肥对活性碳氮的提高有抑制作用。因此,关中平原麦玉轮作区实行秸秆还田配合施用适量氮肥是提高土壤肥力水平、实现农业可持续发展的有效措施。     

The Pollution Load by Nitrogen and Phosphorus in the Cetina River

The objective of the investigations of the Cetina River, located in southern Croatia, was to record specific characteristics and properties of the Cetina waters at nine stations. In addition to measurements undertaken in the Cetina River, the water quality of its most significant springs and tributaries, such as Kosinac, ?ilovka, Studenci and Mala Ruda, Velika Ruda and Grab, has also been measured. The water quality in the Cetina watershed has been evaluated in the following storage reservoirs: Peru?a, Bu?ko Blato and Pran?evi?i. The nitrogen compounds and phosphorus concentrations have been estimated at all these sampling sites over a 3-year period (2005–2008). Concentration levels at the Cetina-Vinali? sampling site for total N (from August 2005 to December 2008) ranged from 0 to 1.759 mg/L, for NH₃–N from 0 to 0.374 mg/L, for NO₃–N from 0.063 to 0.916 mg/L and for PO₄–P from 0 to 0.099 mg/L. The results prove that the Cetina-Vinali? sampling site is not polluted by nitrogen and phosphorus compounds. The river section from Trilj to the Pran?evi?i dam, where the water is used for the water supply of Omi?, Makarska and Dalmatian islands, has been polluted by wastewater because the majority of agricultural area, roads, industry and settlements are located upstream of it. The highest concentration for total N of 1.128 mg/L and of 1,527 total coliforms in 100 mL, expressed as a mean value for a 3-year period of investigations, was found at the sampling site Trilj. The results of concentration changes at the ?ikotina La?a and Cetina Radmanove Mlinice sampling sites show no regularities. The highest concentration for total N of 0.941 mg/L was measured at the Cetina Radmanove Mlinice during 2007. The highest concentration for NO₃–N of 0.916 mg/L was measured at the same sampling site. According to the investigations of the water quality of the Cetina springs and tributaries, the bacteriological most polluted river spring is Kosinac, and the bacteriological most polluted river tributary is Grab. With reference to the water quality in the Cetina storage reservoirs, it may be concluded that the lowest quality standard has been found within the Pran?evi?i storage reservoir regarding nitrogen compounds and phosphorus concentration levels.     

Absorption Kinetics of Nitrogen Oxides using Sodium Chlorite Solutions in Twin Spray Columns

NO _X is a major pollutant that causes acid deposition and photochemical smog. A large amount of NO _X is emitted from combustion sources such as power plants. As some articles have indicated, NO _X removal with NaClO₂ solution in an absorption column is an effective control approach. In this approach, first insoluble NO is oxidized into water-soluble NO₂ under acidic conditions, then NO₂ is removed in alkaline NaClO₂ solutions. The results indicate that the reaction rate constant is 9.1×10⁴ (L)^4.4/cm⁶/s/mol^2.4 in the first absorption column with acidic conditions, and the reaction orders with respect to NO and NaClO₂ are 1.4 and 2, respectively. In the second absorption column with alkaline conditions, the reaction rate constant is 3.2×10⁷ (L)^5.2/cm⁶/s/mol^3.2 and the reaction orders with respect to NO and NaClO₂ are 1.6 and 2.5, respectively. The activation energies in the first and second absorption column are 71.8 and 139.6 kJ/mol, respectively.     

Near-Infrared-Spectroscopy for Determination of Carbon and Nitrogen in Indian Soils

The present study aims to evaluate the potential of near-infrared reflectance (NIR) spectroscopy to determine the carbon and nitrogen content in soils and also to assess the effectiveness of NIR spectroscopy to predict carbon and nitrogen content in freshly collected soil samples. Soil samples (n = 179) were collected from different locations in India. Soil carbon and nitrogen contents were successfully predicted (R² = 0.90 for carbon and R² = 0.85 for nitrogen) by NIR spectroscopy. The root mean square error (RMSE) and ratio performance deviation (RPD) for the validation of predicted equations for carbon and nitrogen were 0.83 and 2.83 and 0.01 and 6.98, respectively. The efficacy of NIR spectroscopy on the prediction of carbon and nitrogen content in Indian soils is highly reliable. Water content in soil samples could affect the NIR absorbance spectra and in turn affect the quantification of carbon and nitrogen.     

密云土门流域出口氮磷污染分析

为了满足水污染控制规划和流域水资源保护的需要,在土门西沟出口对径流量、径流水质进行同步监测,结合以前的监测资料,对径流量与污染负荷之间的关系进行分析.结果显示:流域内水质氮磷含量超标,特别是氮远远高于Ⅴ类水.总磷在Ⅲ类水标准以内,流域的非点源氮磷源已成为流域主要污染物;径流量和污染负荷有很好的相关性,其中总磷与地表径流量相关性最高,总氮与地表径流量相关性比较差,氨氮是氮源污染的主要形态,而且氨氮容易挥发和转化;这与当地居民使用氮肥和二铵有关;总氮与氨氮的相关关系较好,和硝态氮相关系数较小;控制污染物的排放和减小暴雨径流是有效治理非点源污染措施.     

不同氮水平下有机碳对蕹菜碳氮代谢及生长的影响

碳是植物必需的首要营养元素,但在植物营养、平衡施肥等理论和技术层面上长期被忽略,碳营养已成为影响作物高产优质的短板。本研究分别在三个氮水平下,研究了外源喷施两种不含氮的有机碳对蕹菜鲜重、干重、分枝数、碳氮代谢及营养品质指标的影响。结果表明,在不同氮水平下喷施有机碳有促进蕹菜生长的作用,效果因不同的氮水平及有机碳源而异。中氮(100 mg kg~(-1))水平下,以丙三醇的效果最好,其鲜重、干重、全碳含量及全氮含量与CK相比均有显著提高,增幅分别为12.88%、15.48%、7.05%和8.33%,且铁(Fe)含量与CK相比也显著提高,增幅高达16.2%,亚硝酸盐及钾(K)含量显著降低。高氮(120 mg kg~(-1))水平下,以α-酮戊二酸的效果最好,其鲜重、干重、全碳及全氮与CK相比均差异显著,增幅分别为17.97%、20.91%、7.97%和9.56%,蕹菜中的锌(Zn)与CK相比也显著提高,增幅高达16.18%,亚硝酸盐及K含量显著降低。在试验的三种氮水平下,有机碳处理可使蕹菜叶片中水溶性碳占全碳的百分比(WC/TC)及水溶性氮占全氮的百分比(WN/TN)下降,表明外源有机碳可促进蕹菜碳氮的合成代谢,从而促进生长,改善品质。研究结果提供了一条通过施肥补碳调控碳氮平衡实现蔬菜高产优质的新途径。     

昆明盆地浅层地下水氮的分布及污染机理

通过对研究区内多年水质监测资料的分析,查明了昆明盆地浅层地下水中三氮的含量及其分布规律,在此基础上,从地下水污染源、区内的地质环境条件以及地下水开采等方面探讨了地下水中三氮的迁移、转化及其污染机理.最后,指出三氮污染已成为昆明盆地浅层地下水污染的普遍问题,地下水三氮入湖通量在一定程度上对滇池的富营养化发展起了作用.     

长寿湖表层沉积物中氮的赋存形态及污染评价

为揭示长寿湖表层沉积物中营养盐的赋存特征,于2009年4月采集了该湖15个样点的表层沉积物,利用化学提取法测定并分析了表层沉积物中氮的赋存形态和污染程度。结果表明:（1）长寿湖表层沉积物中总氮（TN）的含量为1240.0～5110.0 mg/kg,其组成部分为有机氮（ON）、无机氮（IN）中以氨态氮（NH₄⁺—N）为主。（2）各形态氮的变异系数均为0.1～1.0,属于中等强度变异。（3）水流作用对长寿湖表层沉积物中氮的分布和迁移起到重要作用,养殖活动对其影响并不显著;水位高低对氮的分布也有一定影响。（4）相关性分析表明,总氮（TN）的含量和空间分布几乎完全受到有机氮（ON）控制,无机氮（IN）的变化主要受到氨态氮（NH₄⁺—N）的影响。（5）长寿湖表层沉积物的污染较为严重,应加强治理。     

我国集约化农业中氮污染问题及防治对策

概述了我国部分地区因过量施用化肥氮而导致对地面水、地下水及蔬菜造成硝酸盐污染的现状 ;提出了制定《农田施肥污染防治管理规定》等防止农业生态环境氮污染的对策意见     

Effects of Chronic Nitrogen Amendments on Production of Dissolved Organic Carbon and Nitrogen in Forest Soils

Chronic N deposition has been hypothesized to affect DOC production in forest soils due to the carbon demand exerted by microbial immobilization of inorganic N. We tested this hypothesis in field experiments at the Harvard Forest, Petersham, Massachusetts, USA. During four years of sampling soil solution collected beneath the forest floor in zero-tension lysimeters, we observed little change in DOC concentrations (10-30% increase, not statistically significant) associated with elevated N inputs, but did observe significant increases in DON concentrations. Both DOC and DON varied seasonally with highest concentrations in summer and autumn. Mean DON concentrations increased 200-300 % with the highest rate of inorganic N fertilization, and concentrations of DON were highest in samples with high inorganic N concentrations. We conclude that the organic chemistry of soil solution undergoes qualitative changes as a result of long-term N amendment at this site, with small changes in DOC, large increases in DON, and a decline in the C:N ratio of dissolved organic matter.     

Vegetation Type Affects the Relationship Between Soil Carbon to Nitrogen Ratio and Nitrogen Leaching

Nitrate leaching occurs when the soil's nitrogen immobilisation and plant uptake capacity has been saturated. Several widely-used models of nitrogen saturation incorporate a breakthrough function in which N begins to be leached at C/N values below an upper threshold, and is completely leached at C/N values below a lower threshold. In a survey of deciduous and coniferous woodland, acid grassland and heathland sites for which both C/N and nitrate flux measurements were available, deciduous woodland and acid grassland typically had lower C/N ratios, and began leaching nitrate at a lower C/N ratio, than coniferous woodland and heathland. Least-square fits of nitrate breakthrough functions gave upper thresholds (no nitrate leaching) of 27 mol C mol^?1 N for deciduous woodland and acid grassland and 50 mol C mol^?1 N for coniferous woodland and heathland. Upper thresholds were similar, at 24 and 51 mol C mol^?1 N, respectively, for total inorganic N (NH₄ + NO₃) leaching flux as a proportion of total inorganic N influx. In conifer plantations, stand maturity had a large effect, suggesting that a breakthrough function is unsuitable for modelling systems that are in disequilibrium. However, there was sufficient evidence to suggest that using different breakthrough C/N thresholds for different groups of vegetation would improve predictions of N saturation and leaching at both plot and catchment scales. The difference may be related to the reactivity of soil carbon; soils with a large proportion of recalcitrant carbon are likely to begin leaching nitrate at a higher C/N value than soils with more labile carbon.