滇池流域不同利用方式红壤渗滤液的磷素形态变化

利用土柱模拟实验方法对滇池流域不同土地利用方式红壤渗滤的磷素含量及形态特征进行研究,每隔1周进行灌水处理,并在当天采集分析水样,共4次处理。结果表明:(1)TP含量为0.09~0.90mg/L,MRP含量为0.01~0.71mg/L,DOP含量为0.03~0.28mg/L,PP含量为0.01~0.52mg/L。同种利用方式红壤渗滤液各形态磷含量呈TDPPPMRPDOP。不同利用方式红壤渗滤液的TP、TDP和PP含量存在大棚露地草地的规律;MRP和DOP含量存在大棚露地和草地的规律。(2)土壤渗滤液磷素形态变化方面,草地土壤表现为MRP含量先增后减,TP、TDP和PP含量持续增加;大棚土壤表现为TP和PP含量先增后减,TDP、MRP和DOP含量持续增加;露地土壤表现为TP、TDP、MRP和PP含量先增后减。(3)土壤渗滤液中TP含量高于V类地表水(湖库)标准,草地、大棚和露地分别高出230%,305%和245%,各形态磷中以TDP所占比重最大,均值达60%~70%,从土壤磷素流失途径看侧渗和下渗方式大于地表径流。     

我国4种土壤磷素淋溶流失特征

磷素是水体富营养化的主要限制因子,地表水磷的污染负荷主要来源于农业面源污染。采集黑土、潮土、红壤和水稻土4种土壤,采用土柱模拟的试验方法,研究磷素在4种土壤剖面中空间分布特征,以及土壤渗漏液中TP、TDP的含量、动态变化以及流失量特征。结果表明:(1)不同类型土壤全磷和有效磷含量差异性显著,由高到低依次为水稻土潮土黑土红壤;黑土、红壤和水稻土土壤全磷和有效磷含量都表现出,随土壤深度的增加,不断降低;而潮土剖面呈上下层高,中间低的分布格局。(2)4种土壤渗漏液中占主导的磷形态不一致,潮土以MRP占主导,黑土和水稻土以DOP为主,而红壤则以PP为主。土壤磷素动态变化方面,潮土表现为TP含量先减后增再减,TDP含量先增后减;黑土表现为TP含量先增后减,TDP含量持续下降;红壤和水稻土TP和TDP含量变化不显著。(3)相关分析表明,4种土壤中Olsen-P与渗漏液中TP呈指数关系,具有极显著相关性。(4)4种土壤TP、TDP下渗流失量都以潮土最高,其次是黑土和水稻土,红壤流失量最小,磷素流失以TDP为主。     

不同土地利用方式下红壤磷素径流流失特征

土壤磷素流失已成为地表水富营养化的重要威胁,红壤在我国分布范围广、分布面积大,研究红壤磷素累积与流失特征可为红壤区农业面源污染控制、防止区域地表水污染提供科学依据。选取红壤区牧草地、休闲地、玉米地、菜地、大棚5种常见土地利用方式,采用人工模拟降雨方法,研究了红壤区不同土地利用方式下磷素累积状况、形态组成和随地表径流的迁移特征及其环境阈值。结果表明:(1)供试土壤Olsen-P含量的范围为6.81～178.17 mg/kg,土壤溶解态活性磷(CaCl_2-P)含量的范围为0.29～8.26 mg/kg,藻类可利用总磷(NaOH)的变化范围为30.34～369.81 mg/kg,不同利用方式红壤中均存在一定程度的磷素累积;(2)不同利用方式红壤的磷吸持指数PSI范围为31.95～47.05,均值大小表现为牧草地玉米地菜地休闲地大棚;(3)红壤地表径流中TP的浓度范围为0.245～2.073 mg/L,TDP浓度范围为0.023～0.308 mg/L,PP浓度范围为0.223～1.826 mg/L,不同场次降雨地表径流中TP和PP平均浓度和流失量大小与土壤表层Olsen-P含量分布规律一致,TDP平均浓度表现为大棚菜地旱地玉米牧草地休闲地,而TDP流失量却表现为大棚菜地牧草地休闲地旱地玉米;径流输出以PP为主,占TP的比例为82.46%～90.15%;(4)土壤Olsen-P与NaOH-P和CaCl_2-P存在极显著正相关,随着Olsen-P含量的增加,NaOH-P和CaCl_2-P提高,且Olsen-P与NaOH-P之间存在一个明显的"突变点",确定36.17 mg/kg为红壤磷素流失的环境阈值,同时还指出,径流TP浓度或流失量与土壤NaOH-P含量呈显著正相关。     

滇池宝象河流域土壤磷的累积及吸附特征研究

磷是导致湖泊水体富营养化的主要污染物质。本文对滇池宝象河流域稀疏林地、坡耕地、平地耕地及大棚土壤的0～5cm、5～10cm、10～20cm层土壤全磷、有效磷、磷固定量及磷吸持指数(PSI)等指标进行了测定或计算,并就磷的累积与分布特征、吸附特征等进行了评价。结果表明:流域表层土壤的全磷、Olsen-P和水溶性磷均有明显的累积,尤以大棚土壤磷的累积效应最为明显(平均值分别为1·67gkg-1、75·9mgkg-1和27·7mgkg-1),且Olsen-P和水溶性磷的含量在耕层各层次上表现为从上往下依次降低的趋势。吸附特征方面,表层土壤的磷固定量在68·4～351·2mgkg-1之间,不同土地利用类型不同土壤层次间的土壤磷固定量无显著差异;而土壤的PSI值以上游稀疏林地和坡耕地土壤中的显著较高,根据PSI值低于30的比例,推测出中上游平地耕地和下游大棚区土壤磷素存在着较大的潜在流失风险。     

长期施肥对塿土磷素状况的影响

利用塿土12年长期肥料定位试验,研究了不同施肥方式对耕层土壤全磷(TP)、有机磷(OP)与有效磷（Olsen-P）的影响。结果表明,施用化学磷肥提高了耕层土壤TP、Olsen-P含量,但并未提高OP含量;对照与磷钾处理的OP含量有降低趋势。当基于含氮量施有机肥时,土壤TP和Olsen-P含量大幅度提高,也提高了OP含量,但OP/TP比率在降低到一定程度后维持在一个较为稳定的水平;即使施用有机肥的处理,磷素也主要以无机形态累积。土壤Olsen-P与TP或两者的增加量都呈显著的线性相关,塿土TP每提高100 mg/kg,Olsen-P增加量约为20.8 mg/kg,且单位土壤全磷增加带来的Olsen-P增加有随施肥时间降低的趋势。在土壤Olsen-P含量达到一定水平时应考虑减少磷肥用量。基于有机肥中磷素含量来推荐有机肥施用或延长其施用的时间间隔,将有助于减少由于有机肥施用带来的磷素大量快速累积。     

滇池流域原位模拟降雨条件下不同土壤质地磷素流失差异研究

在滇池流域的设施大棚和露地两种土地利用类型上,选择粉砂质壤土、粘壤土、砂质粘土、壤质粘土等4种典型土壤质地,应用原位模拟人工降雨设备,对地表径流和渗漏的流失过程以及水中的总磷(TP)、水溶性总磷(DTP)和溶解性正磷酸盐(DRP)的浓度、流失量变化特征进行了研究,模拟降雨量为80 mm,雨强采用40 mm/h以模拟渗漏流失过程和120 mm/h以模拟径流流失过程。结果表明:在不同土壤质地下,壤质粘土在两种流失方式下都极易发生养分流失,而砂质土的径流量和渗漏量较高,养分流失风险增加;壤质粘土的TP流失浓度和流失量高,而砂质土的DTP、DRP流失浓度和流失量高;在两种不同流失方式下,径流比渗漏初始产流时间早,产流历时短;而且径流是磷素流失的主要途径,砂质壤土、粘壤土、壤质粘土(露地)径流水中的TP、DTP、DRP流失浓度和流失量要高于渗漏,但砂质粘土和壤质粘土(大棚)的渗漏流失量较高。在不同土地利用方式下,露地比大棚更易发生径流流失,且土壤磷素流失多以泥砂结合态的PP为主要流失形态,而砂质粘土和壤质粘土(大棚)以水溶性总磷(DTP)为磷素流失的主要流失形态;在本研究区域内,土壤速效磷含量已经高达272.38 mg/kg,远远超过了作物适宜生长的土壤速效磷含量,也超过了土壤磷素淋溶的临界值,因此,滇池流域土壤磷素向下淋溶的趋势对地下水的富营养化造成了巨大威胁。     

牛粪中磷释放运移特征

采用取样分析和室内土柱模拟的方法,研究牛粪中磷在水、0.5mol/LNaHCO3和土体中的释放运移特点。研究结果表明,牛粪经H2O和NaHCO3分别提取后,H2O提取液中总磷(Pt)占全磷(TP)质量分数的31.54%,NaHCO3提取液中Pt占TP质量分数的64.74%;不同牛粪施用量处理土柱淋溶液中水溶性总磷(TDP)、水溶性无机磷(DRP)和水溶性有机磷(DOP)质量浓度均随着淋溶次数的增加呈先上升后降低的趋势;同一淋溶次数,随着牛粪施用量的增加,淋溶液中TDP、DRP和DOP质量浓度增加;在前6次淋溶液中,同一处理、同一次淋溶液中DOP质量浓度明显高于DRP质量浓度。土壤大量施用牛粪(30t/hm2以上),增加0-30cm土体中土壤全磷(TP)和0-60cm土体中土壤速效磷(Olsen-P)的质量分数。     

风浪扰动引起湖泊底泥磷释放的模拟实验研究

为研究湖泊沉积物在不同风浪扰动情况下对水体中各形态磷的变化的影响,进行了室内模拟风浪扰动实验。结果表明,水体中总磷(TP)的含量随着扰动频率的增加而升高。在水体其他各形态磷中,溶解性总磷(DTP)、溶解性有机磷(DOP)的含量在模拟风速大于10~12 m/s时保持稳定,并呈下降趋势。溶解性活性磷(SRP)的含量在模拟风速大于8~10 m/s时保持稳定,并随着扰动频率的增加略下降。颗粒磷(PP)的含量随着扰动频率的增加而增加。PP为上覆水中主要形态的磷,占上覆水磷总量的54.55%~67.09%,SRP仅占上覆水磷总量的1.94%~3.19%,PP占TP的百分比随着模拟风速的升高逐渐升高,而DTP,SRP和DOP占TP的百分比随着模拟风速的升高逐渐降低。水体中颗粒物分形维数随着扰动频率的升高呈现先增大后降低的趋势。在模拟风速5~7 m/s时水体中各形态磷的含量出现激增。实验结果表明随着风浪扰动的加强能引起浅水湖泊中颗粒态和溶解态磷的浓度的迅速提高,但是由于水中颗粒物的絮凝作用的加强,悬浮颗粒物对磷的吸附能力也相应提高,因此高频风浪扰动后水体溶解性磷浓度的增幅并不明显,而仅是对浮游生物生长贡献不大的PP增幅明显。     

长期不施肥条件下几种典型土壤全磷和Olsen-P的变化

研究了11个不同气候条件、不同耕作制度、典型土壤类型长期定位试验不施肥处理土壤全磷和Olsen-P变化及其影响因素。结果表明,在长期不施肥条件下耕作,土壤Olsen-P含量下降比全磷的明显;在试验进行5年左右,土壤全磷含量都有所降低,以后各点表现不尽相同,新疆灰漠土、长沙水稻土和郑州潮土全磷含量随时间延长呈显著直线下降,其它试验点全磷的变化不明显;作物携出磷与土壤全磷下降之间,无论绝对含量或相对含量都不成比例。土壤Olsen磷下降率比全磷高几倍。Olsen-P下降趋势与起始土壤Olsen磷含量有关:起始土壤Olsen-P磷大于20 mg/kg时,25年内一直呈现明显下降趋势,降低40.5 mg/kg,特别是前5年下降更快,降低30 mg/kg;起始土壤Olsen-P为10～20 mg/kg时,下降趋势比前者缓慢,15年内一直呈明显下降趋势,下降19 mg/kg, 前5年下降15 mg/kg,15年后几乎不变;起始土壤Olsen-P小于10 mg/kg时,25年内无明显变化。Olsen-P下降量与起始Olsen-P占全磷的比例成显著直线关系。     

洛桑试验站Broadbalk长期小麦试验地排水中磷组分研究

Total P (TP), total participate P (PP), total dissolved P (TDP), molybdate reactive P (MRP) and dissolved organic P (DOP) were determined in waters from pipe-drains (at 65-cm depth) from the Broadbalk Experiment at Rothamsted Research, UK. Average TP and PP exceeded 1 mg L^-1 in about half of the 12 plots receiving superphosphate for the 5 measurements taken between December 2000 and April 2001. Ranging between 33.8% and 87.3% of TP, PP was the largest P fraction in drainage waters, with DOP, ranging from 0.5% to 26.2% of TP, being the smallest fraction. Mean proportions of PP, MRP and DOP in TP in drainage waters were 63.4%, 32.5% and 4.1%, respectively. These findings support previous findings that P losses from soil to drainage waters were much larger than previously thought, and could therefore make a significant contribution to eutrophication.     

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.     

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。     

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.