桓台县高产农田土壤硝态氮淋失动态研究

试验研究高产农田生态系统条件下N肥施用量和秸秆还田对土体硝态氮（NO3^--N）的时空分布动态结果表明，NO3^- -N含量在空间上随土壤深度而降低，这一相关关系可用Y=aX^b函数表达。小麦-玉米2季秸秆还田同单季小麦秸秆还田对NO3^- -N的动态影响较小，但相同施N量下未进行玉米秸秆还田0-40cm土层土壤中NO3^- -N含量偏高，土体NO3^- -N有淋失较强的趋势。土体NO3^- -N含量年度内波动大小与施N量密切相关，0-40cm土层土壤内NO3^- -N含量起伏最大，60cm土层以下相对稳定。各土层内NO3^- -N含量与施N量相关密切，这一相关关系影响到2m土层深度。土体中NO3^- -N含量周年内出现2次峰值和1次低谷，峰值出现在玉米和小麦收获后，低谷发生在小麦苗期-开花期土体养分大量吸收时期。9月下旬2m土层土壤NO3^- -N含量可高达10mg/kg，而且有淋失出2m土体的趋势。     

北方褐土区土壤硝态氮运移动态及合理施肥调控

通过设计不同纯氮（N）施入水平（分别为0、150、300、600、900和1200 kg/hm^2共6个处理）,重点研究了北方褐土区夏玉米大田土壤硝态氮（NO3^--N）运移动态,并讨论了夏玉米N肥的经济环保施用量及其相关机制。试验结果表明,土壤-作物系统内土壤NO3^--N垂直方向上的运移有向上、向下两个方向。不同生育时期土壤NO3^--N运移特征不同,拔节期以前,0-40 cm土层随N肥用量的增加,土壤NO3^--N含量快速增加,40 cm以下深度土壤NO3^--N含量变化不明显,随植株的生长和根系的壮大,0-100 cm土层内的NO3^--N整体运移活跃。土壤有自动调节NO3^--N含量的功能,各土层NO3^--N含量均存在一个最低点,其中耕层为3.1 mg/kg附近;玉米旺盛生长期各土层内土壤NO3^--N饱和值在20.33 mg/kg附近,施肥量过多,NO3^--N向下运移,造成资源浪费和对土壤环境质量的威胁。北方褐土区夏玉米最高纯N施用量应控制在600 kg/hm^2以内,300 kg/hm^2（纯N）是最为环保、经济的施肥量。     

秸秆覆盖方式和施氮量对河套灌区夏玉米氮利用及产量影响

为探究夏玉米氮素转运利用规律、产量及土壤NO3－-N含量分布对秸秆覆盖方式和施氮量的响应,在河套灌区开展2a不同秸秆覆盖方式（秸秆表覆B处理、秸秆深埋S处理）和不同施氮水平（不施氮N0、低氮N1、中氮N2、高氮N3）的田间试验,以传统耕作模式为对照（CK处理）。结果表明：在0～100 cm土层,各处理NO3－-N含量随施氮量增加而增大,成熟期B和CK处理随土层加深呈先减后增趋势,而S处理呈先增后减趋势;B处理提高0～20 cm土层NO3－-N含量,而S处理提高20～40 cm土层NO3－-N含量（P<0.05）;秸秆覆盖可减少0～100 cm土层NO3－-N累积损失量,且显著提高氮肥利用率及夏玉米氮素转运量对籽粒产量的贡献率,SN2处理效果较佳。相比CK处理,成熟期的SN2处理2 a平均NO3－-N累积损失量降低39.6%,氮肥利用率较提高28.5%,夏玉米氮素转运量对籽粒产量的贡献率提高32.1%,增产9.3%。综合分析,秸秆深埋配施中氮效果较佳,可实现河套灌区夏玉米提效增产的目标,并减少深层土壤NO3－-N累积损失量,为优化河套灌区夏玉米耕作施氮模式和缓解农业面源污染提供参考。     

长期种植苜蓿对土壤氮素营养的作用

13年长期施肥和轮作试验结果表明，连续种植苜蓿对N肥、P肥、有机肥的配合施用（NPM）较单施P肥对提高土壤硝态氮（NO3^-N)含量水平有较好效果；而无论施肥与否，种植苜蓿对土壤深层NO3^-均造成不同程度的亏缺。苜蓿（NPM）连作较小麦（NPM）连作土壤NO3^--N利用率高；种植苜蓿对土壤铵态氮（NH4^ -N)分布影响与NO3^--N不同，深层土壤CK、NPM配施处理CK、NPM配施处理NH4^ -N含理明显高于施P和裸地处理，不同作物种植系统中以苜蓿连作土壤剖面中NH4^ -N含量最高。与其他轮作相比，苜蓿连作在提高土壤剖面供N能力方面有较好作用。     

太湖地区稻麦轮作农田氮素淋洗特点

通过排水采集器模拟试验研究了太湖地区不同施肥水平下农田N素淋洗特点。结果表明,N的渗漏损失以硝态氮（NO3^--N）为主,并发生在麦季,铵态氮（NH4^ -N)淋洗量则很少,NO3^--N的量占渗漏液总N量的43%-72%,浓度为20-110mg/kg;渗漏水中N的含量与土壤N的淋洗量随施肥量的增加而增加,麦季土壤中NO3^--N肥量的3.7%-12.2%;与纯化肥处理比较,化肥 猪粪处理增加了农田N的淋失,化肥 秸秆处理减少了土壤中N的淋失,与麦田渗漏水相比较,稻田渗漏水除水稻生长早期的部分样品外,NO3^--N和NH4^ -N含量均很低,分别在1mg/kg和0.5mg/kg以下。     

控释复合肥田间养分释放特征及对土壤硝态氮和铵态氮累积的影响

通过水中溶出率法和田间玉米根下土埋法,研究聚合物包膜控释复合肥的养分释放特征及其对土壤中NO3^--N和NH4^＋-N累积的影响。结果表明,浸提温度越低,控释复合肥的养分释放速率越慢,CRF1和CRF2在15℃的释放期分别是25℃的1.5,1.67倍,5℃的释放期皆为25℃的2倍;夏季CRF3田间养分释放速率稍慢于水中溶出速率,从第7天到第84天二者累积养分释放率平均变幅为3.12%;春季CRF4田间养分释放明显慢于水中溶出速率,最大变幅达31.8%;与CCF处理相比,施用控释复合肥能够显著提高玉米生长期耕层的NH4^＋-N含量和0-20 cm土层的NO3^--N含量,显著减少20-40 cm土层的NO3^--N的累积,且CRF3-H处理与CCF处理比较,在第14天和第84天时20-40 cm土层的NO3--N含量仍然表现为差异显著。因此,应根据不同地域的气候条件和作物需求,选用养分释放特征适宜的控释肥料,达到增效、节肥、安全、环保的目的。     

长期定位施肥对无石灰性潮土0～100 cm土层NO-3-N动态变化的影响

在无石灰性潮土26年的定位试验进行过程中，在12个不同处理CK、N1、N2、M1、M1N1、M1N2、M2、M2N1、M2N2、NP2K、N2P和N2K中，于2003研究了长期定位施肥对非石灰性潮土0-100cm土层NO3^--N动态变化的影响，结果表明，长期单施有机肥及其配施无机氮肥，氮磷钾或氮磷以适当比例配施，可减少土体中NO3^--N的积累。单施氮肥以及氮钾配施的土壤剖面中NO3^--N积累增加，对土壤环境和地下水构成潜在污染。降水、灌溉、氮肥用量及作物吸收利用是影响土壤NO3^--N淋洗、积累的主要因素。     

有机组分对N素在砂壤土中淋溶运移的影响

采用室内土柱模拟的试验方法,研究了风化煤和腐化秸秆两种不同的有机组分对N素在砂壤土中淋溶运移的影响。结果表明:肥料N可以淋溶到100 cm以下,淋失率在5.58%～8.73%之间,其中NH4+-N占46%～65%,NO3--N占35%～54%,0-30,30-60,60-100 cm土层的N累积淋出量比值为4∶1∶20。施N肥使N累积淋出量增加了165.75%,风化煤、腐化秸秆的添加可以使0-30 cm土层N累积淋出量比NPK处理分别增加187.07%和45.09%,而总N累积淋出量分别降低17.78%和24.17%。可见风化煤和腐化秸秆的添加对肥料N在土壤耕层中的保持及抑制向下层淋溶方面具有积极作用。     

尿素在潮土中淋溶和转化特征研究

采用不同灌溉水量和施N量,研究了尿素在潮土中的淋溶和转化特征。结果表明,在小麦返青期结合灌溉施尿素后,NH4 -N在40cm以上土层中积累,不会产生深层淋溶。而土层中NO3--N含量有较大变化,相同灌溉水量下,施N量越大,NO3--N向下层淋溶越深;相同施N量下,灌溉水量越大,NO3--N也有淋溶越深的趋势。在麦季,即使在超过当地的施N量(N180kg/hm2)和灌溉水量(750m3/hm2)条件下,收获时所有处理的NO3--N主要积累在130cm以上的土层中,NO3--N淋溶深度不超过130cm,不会产生对地下水的污染。     

不同灌水和施氮对黄土性土壤中NO3^——N迁移和淋失的影响

通过室内土柱渗透试验,研究了不同灌水和施氮对黄土性土壤中NO3^--N迁移和淋失的影响。结果表明：土壤含水量随灌水量增大而增大,大灌水定额时,在近饱和土壤水分条件下,氮素淋失严重;在小灌水定额条件下,0-35 cm土层含水量显著减小,NO3^--N未发生淋失;施氮量一定时,土壤剖面NO3^--N含量随灌水量增大而减小,随土层深度增加呈显著增加趋势;土壤剖面NO3^--N含量随施氮水平的增加有递增趋势、与土壤含水量成消长关系。土壤NO3^--N累积量与施氮量、土层深度、渗透时间成正比,与灌水量成反比,符合多元非线性模型。因此,为减小NO3--N淋溶损失,从经济和环境效益方面考虑,黄土性土壤适宜灌水量应小于121 mm,次施氮量不宜高于2.40 mg/cm^2。     

中国华北地区近40年物候春季变化

根据华北地区7个观测站物候资料,分析了华北地区1963-1996年及北京1963-2005年物候春季的变化特征及其与气温的关系。结果表明:华北地区的物候春季有明显提早来临的趋势,而造成这一变化的主要因素是本地区近40 a来冬春季气温的明显上升。其中1963-1996年间华北地区1-3月及4月的平均气温分别上升了2.3℃与1.7℃,物候春季起止日期分别提前了9d和4d,因而使得春季长度也延长了5d;北京1963-2003年间1-3月及4月的平均气温分别上升了3.5℃与2.6℃,物候春季的起止日期分别提前了11d和10d,但春季长度没有明显变化。     

Sediment denitrification in waterways in a rice-paddy-dominated watershed in eastern China

Purpose

Rice-paddy-dominated watersheds in eastern China are intensively cultivated, and lands with two crops receive as much as 550–600 kg?ha^–1?year^–1 of nitrogen (N), mainly through the addition of N-based fertilizers. However, stream N concentrations have been found to be relatively low. Waterways in the watersheds are assumed to be effective “sinks” for N, minimizing its downstream movement. We directly measured net sediment denitrification rates in three types of waterways (ponds, streams/rivers, and a reservoir) and determined the key factors that control net sediment denitrification. Such information is essential for evaluating the impact of the agricultural N cycle on the quality of surface water.

Materials and methods

The pond–stream–reservoir continuum was sampled every 2 months at nine sites in an agricultural watershed between November 2010 and December 2011. Net sediment N₂ fluxes/net sediment denitrification rates were determined by membrane inlet mass spectrometry and the N₂/Ar technique. A suite of parameters known to influence denitrification were also measured.

Results and discussion

Net denitrification rates ranged between 28.2?±?18.2 and 674.3?±?314.5 μmol N₂–N?m^–2?h^–1 for the streams, 23.7?±?23.9 and 121.2?±?38.7 μmol N₂–N?m^–2?h^–1 for the ponds, and 41.8?±?17.7 and 239.3?±?49.8 μmol N₂–N?m^–2?h^–1 for the reservoir. The mean net denitrification rate of the stream sites (173.2?±?248.4 μmol N₂–N?m^–2?h^–1) was significantly higher (p?<?0.001) than that of the pond sites (48.3?±?44.5 μmol N₂–N?m^–2?h^–1), and the three types of waterways all had significantly higher (p?<?0.01) mean net denitrification rates in summer than in other seasons. Linear regression and linear mixed effect model analysis showed that nitrate (NO₃ ^?–N) concentration in surface water was the primary controlling factor for net sediment denitrification, followed by water temperature. Using monitoring data on NO₃ ^?–N concentrations and temperature of the surface water of waterways and an established linear mixed effect model, total N removed through net sediment denitrification in the pond–stream–reservoir continuum was estimated at 46.8?±?24.0 t?year^–1 from July 2007 to June 2009, which was comparable with earlier estimates based on the mass balance method (34.3?±?12.7 t?year^–1), and accounted for 83.4 % of the total aquatic N. However, the total aquatic N was only 4.4 % of the total N input to the watershed, and thus most of the surplus N in the watershed was likely to be either denitrified or stored in soil.

Conclusions

High doses of N in a rice-paddy-dominated watershed did not lead to high stream N concentrations due to limited input of N into waterways and the high efficiency of waterways in removing N through denitrification.     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

Trends in soil science in Switzerland

Phytoremediation is an emerging technology based on the use of green plants to remove, contain, inactivate or destroy harmful environmental pollutants. Recent developments in Europe and the USA show that the approach is somewhat different on both sides of the Atlantic. In Europe, phytoremediation has more basically been research driven and, based on the outcomes, applications have been envisaged. By contrast, the approach in the USA is more application and experience driven. In spite of a growing track record of commercial success, more demonstration projects are needed to prove that phytoremediation is effective in order to rigorously measure its underlying economics, and to expand its applications. More fundamental research is also required to better understand the complex interactions between pollutants, soil, plant roots and micro-organisms at the rhizosphere level, to increase the bioavailability of pollutants, to fully exploit the metabolic diversity of plants and, thus, to successfully implement this new green technology.     

沈阳市城市表土中微生物区系变化的初步研究

在沈阳市远郊-近郊-市区等不同城市化水平区内选取林地、草地和路边土几种不同利用方式下的表层土壤,对土壤中的微生物状况进行了初步分析。结果表明,随着城市化水平的提高,土壤中微生物的数量表现为明显的减少趋势。其中变化较大的是细菌,而真菌和放线菌的变化不明显。     

Patterns in trace elements in lichens

Water, Air, & Soil Pollution - Epiphytic lichens were sampled in a Dutch national monitoring survey, which was carried out twice within 5 yr. The samples were analyzed by neutron activation...     

Trace metals in precipitation in Sweden

Trace metals (Cd, Cu, Fe, Mn, Pb, and Zn) concentrations in atmospheric precipitation have been routinely monitored in Sweden since the autumn of 1983. Concentrations are highest in southern Sweden and decrease northward. It is postulated that the long range transport of anthropogenic pollutants from the rest of Europe is the major source of Cd, Pb, and Zn in precipitation. Evidence for this hypothesis is that enrichment factors indicate anthropogenic origin, and Swedish atmospheric emissions of Zn and Cd are 2 to 3 times smaller than deposition fluxes. Also, Cd, Pb, and Zn concentrations are correlated in both space and time and are also well correlated with exSO₄ ⁺, a substance known to be of anthropogenic origin transported long distances.     

Variation in ozone concentration in relation to local climate in south-west Sweden

Ozone (O₃) concentration and air temperature/relative humidity were monitored using diffusive samplers (weekly, 3 m above ground) and Tinytag loggers (10 min sampling, 1 m above ground, self-ventilating radiation shields), respectively, in the forested landscape of south-west Sweden, 40 km north-east of Gothenburg. Two forest sites were included, one at a hilltop (175 m a.s.l.), and one in a nearby (～1 km) valley (110 m a.s.l.). In addition, a valley site (～3 km from the forest sites, 60 m a.s.l.) in an agricultural landscape was included, where ozone was measured using both a UV-based monitor and diffusive sampling. At the agricultural site measurements of temperature and relative humidity were made using a radiation shield with forced ventilation and with Tinytags, as on the forest sites, in addition to observations of wind speed and the vertical temperature gradient. Furthermore, comparison with O₃ concentrations at urban and coastal sites in the region was made. The temperature dependent, systematic error of using a self-ventilating radiation shield was estimated and corrected for. It was found that the elevated forested site experienced higher O₃ concentrations and lower evening cooling rates in calm situations as compared to the forest site in the valley and in particular as compared to the agricultural site. This can be explained by a stronger coupling with the planetary boundary layer at the elevated site and more pronounced night-inversions at the valley sites. The difference in weekly O₃ concentration between the two forested sites was correlated with the difference in average minimum night-time temperature. The coastal site had the highest ozone concentrations, related largely, but not fully, to higher night-time O₃ concentrations. The urban site showed a depression in O₃ concentration associated with the combination of large NO emissions and slow air mixing during the morning traffic rush hours.     

不同种植模式下菜地土壤腐殖质组分特性的动态变化

通过在南京普朗克有机农场开展的9年长期定位监测,研究了有机(露地和大棚)和常规种植模式下蔬菜地耕层土壤有机碳和土壤腐殖质组分特性的动态变化。结果表明,有机露地、有机大棚和常规露地种植土壤有机碳含量分别从11.41、9.29、9.00 g k g-1提高至15.35、20.90、10.00 g kg-1;胡敏酸碳(CHA)分别从1.79、1.23、1.14 g kg-1提高至2.11、3.11、1.31 g kg-1;富里酸碳(CFA)分别从2.19、1.88、1.73 g kg-1提高至2.44、2.68、1.91 g kg-1。两种有机种植模式的土壤有机碳及腐殖质组分含量增加达到显著水平,而常规种植模式下的变化不显著。两种有机种植模式下表征土壤腐殖质品质的胡/富比(CHA/CFA)、胡敏酸占总腐殖物质的比例(PQ值)均高于常规种植模式,土壤富里酸的E4/E6值、色调系数(ΔlogK)值随着种植时间增加的幅度较常规种植模式更大,土壤胡敏酸芳化度呈现先降低后增高的趋势,但在常规种植下变化不明显。说明土壤在长期有机种植模式下不仅更有利于土壤有机碳的积累,而且能促进土壤腐殖化进程。