黄河粗泥沙集中来源区洪水泥沙阶段变化研究

黄河粗泥沙集中来源区为治理黄河泥沙的核心区域。根据建站至2016年黄河中游粗泥沙集中来源区皇甫川、窟野河、孤山川、秃尾河、佳芦河、大理河和延河等支流次暴雨洪水泥沙资料,以支流为分析单元,通过Pettitt检定法把各支流划分为早期、中期和近期三个时段,按照暴雨洪水和暴雨泥沙的关系分析了区内各支流的变化特征。结果表明:各支流中期和近期时段不完全一致,这主要是与支流下垫面治理有关;按照支流入选标准在研究区内各支流中共选取486场洪水参与计算,对建立的暴雨洪水和暴雨泥沙关系进行分析得出,与早期下垫面相比,中期和近期所表现出来的减洪减沙比例不尽相同,总体上次洪径流量中期减少1/3、近期减少3/4,次洪输沙量中期减少2/5、近期减少9成以上,减沙比例大于减洪比例。     

黄土高原粗泥沙集中来源区水沙变化特征及趋势性分析

黄土高原粗泥沙集中来源区为治理黄河泥沙的重点核心地区.根据1960-1999年黄土高原粗泥沙集中来源区皇甫川、孤山川I、窟野河,秃尾河和佳芦河径流及输沙资料,以流域为单元,分析了区内各流域径流量、输沙量的年内、年际变化特征及变化趋势.结果表明,区内径流量及输沙量的年际、年内变化较大.在季节上,除秃尾河径流量集中期为6月份外,其余4条流域径流量的集中期均为8月份;5条流域输沙量的集中期均为8月份.各流域径流量、输沙量的突变时间均在20世纪70年代,说明各流域水沙量呈现减少的趋势,尤以20世纪90年代减少最明显.人类活动和气候变化是影响该区内各流域水沙变化的主要因素.     

黄河中游严重水土流失区侵蚀物粒径钻探分析

通过对黄河中游严重水土流失区侵蚀物粒径钻探分析,发现在钻探范围内存在两个明显的粗泥沙产区,即皇甫川—佳芦河区间和大理河上游一带。产沙粒径变化总趋势是由西南向东北逐渐变粗,并以窟野河到皇甫川成倒“U”形区域内泥沙粒径最粗;无定河下游部分区域泥沙粒径较粗,但平均粒径和粗泥沙比例均小于上述两区。这一研究成果为进一步确定粗泥沙集中来源区奠定了基础。     

浅谈黄河中游多沙粗沙区重点支流的生态环境建设

“两川两河”(皇甫川、孤山川、窟野河、秃尾河)流域水土流失治理是黄河中游多沙粗沙区生态环境建设的重中之重。加强这一地区的生态环境建设,对减少入黄泥沙,改善当地生态环境,实施西部大开发战略具有十分重要的意义和必要性。在对该区自然特征及土壤侵蚀特征分析的基础上,初步提出了生态环境建设的基本思路、防治目标及措施布局     

黄土高原四条流域生态农业措施动态监测方法研究

以黄河流域严重水土流失区的窟野河、秃尾河、孤山川、清水川四条黄河一级支流为研究对象，划分宏观尺度、中观尺度、微观尺度的监测区域，利用“3S”技术，进行了不同尺度监测方法的探讨，研究结果可为黄河流域水土保持生态农业措施的监测提供技术支持。     

黄河中游粗泥沙集中来源区重点支流深化研究

在黄河中游粗泥沙集中来源区界定研究的基础上,基于数字高程模型、卫星影像、电子地图及有关研究成果,在地理信息系统软件支持下,分析研究了窟野河、皇甫川、清水川等9条支流的特性。经过分析认为,支流内上中下游、左右岸差异较大,从支流上游向下游坡度增大,治理措施密度减小,土壤抗蚀性增大;区域内以自然侵蚀为主,侵蚀类型总体表现以水蚀为主,有部分区域为水蚀和风蚀复合侵蚀,侵蚀等级从南向北递增,治理难度相应增大。     

黄土高原多沙粗沙区泥沙集中度变化特征及驱动因素

[目的]揭示黄土高原多沙粗沙区的泥沙和泥沙集中度的变化规律,阐明泥沙集中度的影响因素,进而为流域水土流失治理和生态保护提供一定的科学依据。[方法]基于1956—2010年皇甫川、孤山川、秃尾河、窟野河和无定河流域的输沙量数据,利用Mann-Kendall趋势检验法、Pettitt突变点检验法、Morlet小波分析方法分析了黄土高原多沙粗沙区泥沙集中度的时空变化特征,通过Pearson相关系数探究了泥沙集中度与生态建设措施的相关性。[结果](1) 1956—2010年,黄土高原多沙粗沙区的输沙量呈现显著减少的趋势,但是皇甫川、孤山川、无定河流域的泥沙集中度呈现显著增加的趋势。(2)孤山川与无定河流域的泥沙集中度具有显著的(p<0.05)突变点,分别为1990年与1986年。(3)研究区泥沙集中度主周期介于15～55 a。(4)径流集中度对于研究区泥沙集中度有显著的影响。除此之外,生态建设措施面积与泥沙集中度有显著的正相关关系,其中梯田、造林和种草对于研究区的泥沙集中度的影响程度最大。[结论]黄土高原多沙粗沙区的输沙量逐渐减少且越来越集中,泥沙集中度受到降雨径流和生态建设措施等因素影...     

黄土高原丘陵沟壑区淤地坝的淤地拦沙效益分析

根据皇甫川、窟野河、佳芦河、秃尾河、大理河5条支流内黄丘区小流域淤地坝的调查资料，分析了淤地坝单坝的淤积速度、拦沙指标和拦沙效益，以及与其影响因素之间的关系。研究结果表明，黄土高原丘陵沟壑区淤地坝的淤地拦沙效益与淤地坝的规格、流域的侵蚀产沙特征有着密切的关系。淤地坝的平均淤积库容在0.9～2.4万m³之间，平均淤地面积在0.14～0.45 hm²之间，与坝高、坝控面积、侵蚀产沙模数和泥沙粒径成正比；拦沙指标变化在500～760万t/km²之     

黄河中游粗沙的来源主要是风沙

黄河泥沙主要来自河口镇至龙门区间。这一区间的窟野河、皇甫川、无定河、秃尾河等多沙支流,上游风沙区面积大,风积沙粒径大于0.05mm的粗沙含量在90％以上。风沙通过风力吹扬和水力冲刷搬运进入河道,形成枯水期和少水年河道淤积,汛期和丰水年河道冲刷,使黄河“水大沙大”的特点十分突出。作者根据调查和实测资料分析认为,这一地区的粗沙主要来源是风沙,风沙主要来自毛乌素沙漠和库布齐沙漠,而过去认为粗沙来自流域内的黄土和下游基岩是片面的,在黄河治理开发中,除全面加强黄河中游地区水土流失治理外,对治理风沙、防止土地沙化应增加紧迫感,并提出了一些相应的防治措施。     

河道冲淤调整对窟野河产沙量影响初步分析

实测资料表明窟野河流域神木—温家川区间输沙模数异常偏大,通过对该区间泥沙冲淤调整特点的分析和洪水期河道冲刷增加沙量的计算,阐明了河道冲淤调整对窟野河产沙量的影响,并提出了水土保持综合治理建议,以期为预测黄河来沙量及流域水土保持提供支持。     

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.     

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...     

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。     

Changes in proteolytic bacteria in paddy soils in response to organic management

Proteolytic bacterial communities, which mineralize organic nitrogen, play a key role in agricultural systems. In this study, alkaline metalloprotease (apr) gene fragments from proteolytic bacteria were investigated in bulk and rhizosphere paddy soil from four fields under organic management (for 2, 3, 5, and 9 years), and from one field under conventional management (for 2 years). We analyzed the abundance and structure of the proteolytic bacterial communities using real-time quantitative PCR and denaturing gradient gel electrophoresis. Our results showed that the abundance of proteolytic bacteria ranged from 1.57?×?10⁸ to 8.02?×?10⁸?copies/g of soil. In addition, the abundance of the proteolytic bacteria in the paddy soils under organic management was significantly higher than those in the paddy soil under conventional management. Moreover, the gene copy numbers in the rhizosphere soils were significantly higher than those in the bulk soils. The abundance of proteolytic bacteria tended to increase with the duration of organic management, with the highest abundance being found in the soil that had been under organic management for 5 years. However, the proteolytic bacteria communities in the paddy soils were not significantly affected by management practices. Phylogeny analysis showed that all gel bands obtained represented genes from Pseudomonas. Additionally, correlation analysis and canonical correspondence analysis showed that C/N, C, and N were important factors that influenced the abundance and community structure of the proteolytic bacteria. These results suggest that proteolytic bacteria are indicators in organic management systems, depolymerize organic N and hence maintain soil sustainability.

Abbreviations: CM: conventional management; OM: organic management; DGGE: denaturing gradient gel electrophoresis; qPCR: real-time quantitative PCR detecting system; COFCC: China organic food certification center; CCA: canonical correspondence analysis