珠三角城市群水土保持生态建设体系探讨

本文选取珠三角城市群为研究区,探讨分析了城市水土保持生态建设需求,明确了包括生态都市、清洁小流域及水土保持生态工程建设等城市水土保持生态建设内容,并以此构建珠三角城市群水土保持生态建设体系,进而防治区域水土流失;通过水土保持生态建设体系探讨,提高了区域水土保持工作对经济社会发展的支撑、保障能力,也为城市化建设过程产生的水土流失防治提供技术支撑。     

风电场建设项目水土流失特点及防治对策

江苏省沿海平原沙土区地表沙土松软,土壤扰动后,在强降水的情况下极易产生流失。随着开发建设项目的日益增加,导致沿海地区的河道淤塞,灌排困难,农田日益减少,生态平衡遭到破坏。本文以华能启东风电场工程为例,在分析沿海平原沙土区水土流失成因和特点的基础上,针对工程建设产生的水土流失和存在的水土流失隐患,提出了相应的水土保持防护措施,并在此基础上对以水力侵蚀为主的平原沙土区域的水土保持工程的措施设计和水土保持设施的建设进行了探讨。在水土保持工程措施落实和水土保持设施实施后,项目范围内的水土流失得到了有效防治,为开发建设项目中类似工程的水土流失防治提供了典型的经验。     

濂溪区水土保持区划与防治布局研究

水土保持区划可为区域水土保持规划与宏观管理、水土保持生态文明建设提供重要的参考。在《江西省水土保持区划及防治布局研究》确立的原则与方法的基础上,根据全国、全省和九江市水土保持区划划分方法,分析濂溪区各乡镇地形地貌、水土流失特点、水土流失防治及经济社会发展等的区域差异,将全区划分为城市人居环境维护区、平原农田防护水质维护区、丘陵保土生态维护区3个五级区,同时基于水土保持功能,提出了各分区的详细水土流失防治布局,为濂溪区及其他区域的水土保持规划与宏观决策,加快推进各地生态文明建设提供重要的参考和借鉴。     

辽宁省水土保持规划方略与总体布局研究

水土保持是生态文明建设的重要组成部分,水土保持规划是依法防治水土流失的重要依据和战略部署。为满足生态文明建设的迫切需求,以辽宁省为研究对象,依据区域自然、社会经济及水土流失状况,分析确定了全省水土流失防治方略,在辽宁省水土保持区划的基础上,依据各总体格局区的区域特征、水土流失特点及水土保持需求,研究提出了水土流失防治的总体布局,为全省水土流失防治体系的构建奠定了基础,为地方水土保持工作的开展指明了方向。     

呼和浩特市水土流失重点防治区划分及分区研究

水土流失重点预防区和重点治理区划分是水土保持规划中水土保持措施合理布局的重要依据。在国家和自治区水土流失重点预防区和重点治理区划分的基础上,根据全市地形地貌特征、植被类型及分布、水土流失现状及分布特点、现有水土流失治理成效及水土流失防治工作实际需要,并充分考虑原水土流失重点防治区“三区”划分成果及划分区内相似性和区间差异性,按照以乡镇为基本划分单元、集中连片面积达到一定规模、定量指标与定性分析相结合的要求,进行了呼和浩特市水土流失重点预防区和重点治理区划分。合理划定水土流失重点预防区和治理区,为落实地方政府水土保持目标责任制和考核奖惩制度,为全市水土流失防治明确了重点工作区域,确定了分区防治方略,为规范生产建设项目水土保持管理工作提供了重要技术支撑。     

黑龙江山区风电场工程水土流失特点及防治措施

结合风电场工程水土保持方案编制和验收技术评估工作实践,对黑龙江省山区风电场水土流失特点、防治分区、措施布设进行了分析、探讨。风电场工程建设周期短、扰动强度差异显著、植被破坏点多面广、植被恢复难度大,具有点线面侵蚀并存、风蚀与水蚀共存的水土流失特点;运输道路区是产生水土流失的主要区域,是防治和监测的重点部位。将水土流失防治分区划分为风电机组区、运输道路区、输电线路区、升压站区、施工生产生活区,并有针对性地布设了水土保持措施。     

全国水土保持区划概述

全国水土保持区划是全国水土保持规划的基础和前提,是我国水土保持工作因地制宜、分区防治的体系保障,对水土保持科学决策具有重要意义。水土保持区划是根据自然和社会条件,水土流失类型、强度和危害,以及水土流失治理的区域相似性和区域差异性进行的水土保持区域划分,主要是明确各区的生产发展方向(或土地利用方向)和水土流失防治措施。依据三级分区体系,选定海拔、大于10℃积温、年均降水量、水土流失成因及强度等指标组成各级分区指标体系,将全国共划分为8个一级区、41个二级区、117个三级区(含港、澳、台地区)。简要介绍了全国水土保持区划成果并提出了区划应用的相关建议。     

修水县水土保持区划及其防治布局研究

在《江西省水土保持区划及防治布局研究》确立的原则与方法基础上,根据全国、全省和九江市水土保持区划,分析修水县各乡镇水土流失特点、水土流失防治以及经济社会发展等的区域差异,将全县划分为低山丘陵土壤保持区、中低山地生态维护区、城镇人居环境维护区等3个五级区,同时基于水土保持功能提出了3个五级区的防治布局,为修水县水土保持规划与宏观决策,加快推进修水县以及其它区域的水土保持生态文明建设提供了重要借鉴与指导。     

全国水土保持规划任务与总体布局

全国水土保持规划是预防和治理水土流失的总体战略部署。根据规划拟定的全国水土保持总体任务,今后一段时期我国水土保持工作的重点是抓好预防、治理、监管,协调推进,形成合力。规划总体布局以全国水土保持区划为基础,结合各区实际和在国家主体功能区划中的区域定位,根据水土保持需求,按照国家生态保护和建设的总体要求,以水土流失防治"六带六片"战略格局为指导,拟定了一级区水土流失防治方略和二级区区域布局,这对我国实施分区防治战略、优化水土保持格局具有重要意义。     

皖西大别山区水土流失特征及其综合防治研究

皖西大别山区是我国典型的集山区、库区、多省交界区、水土流失严重区、贫困区于一体的革命老区,由于自然条件和历史原因,严重的水土流失给当地经济社会和生态环境产生了很大危害。提出了要抓住近年来国家高度重视革命老区和集中连片贫困地区的扶持开发工作的机遇,编制高水准的皖西大别山区水土保持综合防治规划,调整土地利用结构,整合资金,加快大别山区水土流失治理力度,促进区域可持续发展。同时,要依法防治人为水土流失的发生和发展,积极开展水土流失规律和水土保持防治技术研究,提高水土保持科技水平。     

pH对磷钾铝石形成的影响

Effects of column temperature and flow rate on separation of organic acids were studied by determining nine low-molecular-weight organic acids on reversed-phase C18 column using high performace liquid chromatography(HPLC) with a wavelength of UV(ultraviolet)214 nm and a mobile phase of 18 mmol L^-1 KH2PO4 buffer solution (pH2.1).The thermal stabiltiy of organic acids was determined by comparing the recoveries of organic acids in different temperature treatments.The relationships between column temperature,flow rate or solvent pH and retention time were analyzed.At low solvent pH,separatioin efficiency of organic acids was increased by raising the flow rate of the solvent because of lowering the retention time or organic acids.High column temperature was unfavorable for the separation of organic acids.The separating effect can be enhanced through reducing column temperature in organic acid determination due to increasing retention time.High thermal stability of organic acids with low concentrations was observed at temperature of 40℃-45℃,Sensitivity and separation effect of organic acid determination by HPLC were clearly improved by a combination of raising flow rate and lowering column temperature at low solvent pH.     

Emission of carbon dioxide and dynamics of inorganic N in a gradient of alkaline saline soils of the former lake Texcoco

A plan was developed to apply biosolid to soil of the former lake Texcoco to fertilize the pioneer vegetation. Because, no information exists about how differences in electrolytic conductivity (EC) might affect mineralization of biosolid and dynamics of C and N in soil, 20 soil samples forming a gradient in EC ranging from 22 to 150 dS m⁻¹ were characterized, amended with 500 mg biosolid C kg⁻¹ dry soil and incubated aerobically at 22 ± 2 °C while production of CO₂, concentrations of ammonium (NH₄⁺), nitrite (NO₂⁻), and nitrate (NO₃⁻), and NH₃ volatilization were monitored at 22 ± 2 °C for 70 days. Soil characteristics showed large variations with maximum values often >10-times larger than minimum values. The production of CO₂ in the unamended soil ranged from 25 to 159 mg CO₂-C kg⁻¹ day⁻¹ and NH₃ volatilization from 0 to 189 μg NH₃-N kg⁻¹ day⁻¹_. Application of biosolid increased production of CO₂ significantly 1.4-fold and volatilization of NH₃ 11.5-fold. The EC explained most of the variation in production of CO₂, while particle size distribution explained most of the variation in volatilization of NH₃. The concentration of NH₄⁺ in the biosolid-amended soil decreased sharply in the first 14 days, with the EC explaining most of the variation found, and remained constant thereafter with a small increase at day 70. Significant increases in the concentration of NO₃⁻ were generally found in soil with EC < 64 dS m⁻¹. The EC explained most of the variation in production of CO₂, and dynamics of NH₄⁺ and NO₃⁻ while clay positively and sand content negatively affected NH₃ volatilization. It was found that increases in EC inhibited C and N mineralization in soil of the former lake Texcoco.     

华北土石山区天然植被种间联结和生态位研究

 在华北土石山区潮关西沟流域天然森林植被调查的基础上,对森林植被群落种间联结和生态位进行研究。结果表明:种间正联结关系非常显著的有柞栎和蒙椴、柞栎和迎红杜鹃、蒙椴和山杨、蒙椴和白蜡、山杨和白蜡、春榆和北京丁香、春榆和大花溲疏、臭椿和山杏、臭檀和栾树、臭檀和大花溲疏、锐齿鼠李和孩儿拳头、小叶鼠李和酸枣。另外,依据种间联结关系,划分了4个生态种组。分析了主要乔灌木的生态位宽度,乔木树种蒙椴、柞栎、春榆和灌木树种荆条、小叶朴和酸枣的生态位宽度均较大。比较了不同种对的生态位重叠指数,乔木不同种对中,山杏和北京丁香、柞栎和白蜡、蒙椴和春榆具有较大的生态位重叠,灌木不同种对组合中,荆条和酸枣、绣线菊和迎红杜鹃、荆条和小叶朴、蚂蚱腿子和迎红杜鹃的生态位重叠较大。     

Mechanisms of persistence of low numbers of bacteria preyed upon by protozoa

Tetrahymena pyriformis cultures were maintained when transferred serially in solutions containing 10⁵ to 10⁷Klebsiella pneumoniae cells.ml^?1, bacterial numbers that were observed to persist in the presence of protozoa. The number of cells of one strain of K. pneumoniae surviving predation in solution was essentially the same in the absence of an alternative prey as in the presence of a second K. pneumoniae strain. Toxins deleterious to protozoa did not appear as the animal consumed the bacteria. T. pyriformis reduced the abundance of Escherichia coli from about 10⁸ to 10⁶.ml^?1. but the latter number persisted for 15 days; however, in solutions containing chloramphenicol, the abundance of E. coli fell to 590 cells. ml^?1 in 15 days. In solutions containing the antibiotic, T. pyriformis reduced the Rhizobium sp. population from more than 10⁶ to less than 10³ cells in 10 days and K. pneumoniae from more than 10⁸.ml^?1 to zero in 18 days. An appreciable decline in abundance of these bacteria did not occur in the antibiotic-amended liquid free of protozoa. T. pyriformis did not greatly reduce Rhizobium sp. numbers when both were added to irradiated soil, but the predator caused the bacterial population to decline from 4 × 10⁸ to fewer than 10⁵.g^?1 in 16 days in chloramphenicol-treated soil. Colpoda sp. inoculated with Rhizobium sp. into soil sterilized by autoclaving only reduced the prey abundance from 10⁹ to 10⁸.g^?1, but the protozoan caused the bacterial population to fall to about 100.g^?1 in 15 days in the presence of the antibiotic. The population of Rhizobium sp. added to nonsterile soil dropped from in excess of 10⁸ to 6 × 10⁶.g^?1 in 29 days. but it declined to 550. g^?1 in the same period when chloramphenicol was also introduced. It is concluded that the ability of these bacteria to maintain themselves in solution and in soil is governed by their capacity to reproduce and replace the cells consumed by predation.     

Hydrochemistry of Waters of Volcanic Rocks: The Case of The Volcanosedimentary Rocks of Thrace, Greece

This work is referred to the characterization of the environmental hydrochemistry in the broader Sapes area – Thrace region, on the basis of physico-chemical properties of surface and groundwaters occurring in the volcanosedimentary formations of this area, where gold mining activities are planned to operate. Volcanic rocks are considerably altered where they are in contact with hydrothermal solutions. Aquifers are formed within these formations. Surface and ground waters are strongly metalliferous and their hydrochemical facies present similar but complex water types. Certain characteristic chemical types are the following: Ca-Mg-HCO₃-SO₄, Ca-Mg-SO₄-HCO₃. Ca-SO₄, Ca-Mg-SO₄. Ca-Na-Cl-HCO₃, Na-Cl. A small majority of the water samples present the following order of anion dominance HCO₃ ^? > SO₄ ^2? > Cl^?. Calcium is the dominant cation. Bicarbonates and sulfate ions are the dominant anions. The order of dominance for the heavy metals in surface and ground waters is as follows: Fe > Mn > Zn > Ni > Cu. The saturation index of waters regarding minerals is low. Computer simulation indicates that calcite and dolomite are common minerals in all water samples which are saturated in respect to quartz and argillaceous-siliceous minerals. The most pronounced property of waters is their acidic character. The high metal concentrations are related to water with low pH. Sulfide minerals control the low pH values of waters which is an important control factor for the evolution of the water chemical composition. The abundance of sulfates is attributed to the dissolution of the minerals pyrite (FeS₂) and alunite (KAl₃(SO₄)₂(OH)₆. The water–mineral interactions are responsible for the chemical composition of waters. Water quality problems can be successfully handled by the use factor analysis. 17 chemical parameters can be substituted by five factors which successfully represent the hydrochemical processes as well as their geographic distribution. Volcanic rocks in the study area have the potential to produce acid drainage.     

Evidence of Long-Range Transport of Pollutants from the Size-Fractionated Ionic Composition of Aerosols in the Jeju Island of Korea

The ionic composition of total suspended particulate (TSP) and fine (PM_2.5) fractions was investigated from an 1,100 site in the middle of Mt. Halla in Jeju Island, Korea from March to November 2006. The sum concentrations of cation and anion species in TSP fraction were 205 ± 170 and 183 ± 164 neq m^?3, respectively, while those for PM_2.5 as 118 ± 129 and 88.5 ± 89.3 neq m^?3, respectively. In TSP, the concentration of the major ions changed in the order of SO₄ ^2? > NH₄ ⁺ > Ca²⁺ > Na⁺ > NO₃ ^? > Mg²⁺ > K⁺ > Cl^?, while its PM_2.5 counterpart as NH₄ ⁺ > SO₄ ^2? > Ca²⁺ > NO₃ ^? > Na⁺ > Mg²⁺ > K⁺ > Cl^?. Inspection of the temporal variabilities of ionic components indicated that most ions peaked in spring or fall months. The back trajectory analysis showed that the atmospheric composition of the major ionic species was affected fairly sensitively by long-range transport from China under the favorable meteorological conditions. In contrast, the lowest ionic concentration levels were seen most abundantly, when air masses passed from South Sea. Hence, the analysis of ionic concentration data suggests that their distributions are controlled by the combined effects of various source processes including the most prominent Chinese origin and the meteorological condition favorable for such transport.     

Effect of reducing conditions on P sorption of soils

Abstract

The phosphate sorption (P _sor) capacity of soils increased when the soils were reduced (Willet and Higgins, Aust. J. Soil Res., 16, 319–326, 1978). The present study aimed at the elucidation of this mechanism using Na₂S₂O₄ and 5 different soils. The P _sor of the 5 soils increased with the addition of a small amount of Na₂S₂O₄. Fe(II) was released from the soils with the addition of the same small amount of Na₂S₂O₄. Furthermore, when the amount of FeCl₂ corresponding to the amount of Fe(II) released along with the small amount of Na₂S₂O₄ was added, the P _sor of the soil increased. However, the P _sor of the lowland soils, of which the hydrous Fe oxide content was lower than the others, decreased when the amount of Na₂S₂O₄ addition was increased up to 150–200 g kg^?1. Based on these results, the following process is inferred for the increase in the P _sor of the soils when they are reduced. Hydrous Fe oxide in soil takes the form of very fine, high-density particles and reacts with P mainly on their surface. When a small amount of Na₂S₂O₄ is added, the hydrous Fe oxide is partially reduced, dissolved and finally re-precipitates with P by oxidation with O₂ from the air during the experiment.     

Determination of surface charge density of soils

Abstract

A simple and precise method for determination of surface charge density of soils is described. It involves saturating the negative and positive exchange sites with NH⁺ ₄ and NO^‐ ₃ ions, respectively, removing the excess solution by centrifugation, and determining the ions on the exchange sites by a steam distillation method. Results showed that the concentration and type of saturating ions and the extractant used significantly affected the surface negative charge densities. The average value of surface negative charge densities of 10 surface soils from Iowa, Chile, and Costa Rica by the proposed method agreed closely with that obtained by the original method proposed by Schofield in 1949 (14.6 vs. 13.7 cmol(‐) kg^‐1 soil). The advantages of the proposed method are no need for the laborious extraction steps and simplicity of the steam distillation method for determination of NH⁺ ₄ and NO^‐ ₃ in soil samples.     

Evaluation of nitrogen fixation by different strains of theAzolla-Anabaena symbiosis in the presence of a high level of ammonium

Summary The proportion of N derived from N₂ fixation for 99 strains ofAzolla spp. (comprising all known species) in the presence of ammonium (40 mg/1) was assessed using a¹⁵N-dilution technique. The percentage of N derived from air varied from 29.5% to 79.9%. Although the N concentration ofAzolla spp. was not correlated with fertilizer N, it correlated fairly well with N₂ fixation. Regression analysis suggests that the N yield ofAzolla spp. is more dependent on N₂ fixation than on ammonium assimilation. The high correlation between N yield and isotopically determined, fixed N₂ indicates that the N yield could be used as a parameter in the selection ofAzolla spp. strains that are capable of maintaining high N₂ fixation in the presence of a high level of ammonium.     

Mechanisms of fixation and release of ammonium in paddy soils after flooding II. Effect of transformation of nitrogen forms on ammonium fixation

An incubation experiment under aseptic and septic conditions using ¹⁵N-labelled NH₄⁺-N and NO₃^–-N, was carried out to study the effect of N transformations after flooding on NH₄⁺ fixation in a paddy soil from China. After flooding ammonification was favoured, providing NH₄⁺ for fixation by clay minerals. NH₄⁺ fixation was more pronounced under low redox potential (E_h) conditions. Close correlations existed between exchangeable NH₄⁺, E_h, and non-exchangeable NH₄⁺. Therefore, two major conditions for NH₄⁺ fixation induced by flooding in paddy soil were found, namely flooding promoted net production of NH₄⁺ due to the deamination of organic N and, in addition, decreased the E_h of the soil. A lower E_h was caused by reduction and dissolution of Fe oxide coating on the clay minerals' surfaces, eliminating the obstacles for NH₄⁺ diffusing into or out of the interlayers of clay minerals. A higher concentration of exchangeable NH₄⁺ from deamination of organic N would drive NH₄⁺ diffusing from the soil solution into the interlayers of clay minerals. ¹⁵N-labelled NO₃^– incorporated into the flooded soil was not reduced to NH₃. The addition of NO₃^– retarded the decrease in the soil E_h and, therefore, NH₄⁺ fixation.