针对耕地土壤Cd、Pb污染问题,选取3种提取剂(提取剂 Ⅰ:1.0 mol/L NaOH;提取剂 Ⅱ:0.1 mol/L NaOH+0.1 mol/L Na4P2O7;提取剂Ⅲ:0.1 mol/L KOH+0.1 mol/L K4P2O7)分别从5种物料中(风化褐煤、污泥、鸡粪、泥炭土、牛粪)中提取腐殖质(HS)淋洗去除土壤中的Cd、Pb.结果表明,不同提取剂及物料中提取出的HS性质差异大,其中风化褐煤提取的HS总有机碳(TOC)含量最高;不同HS淋洗对土壤pH的影响总体不大;用提取剂Ⅱ 从风化褐煤中提取的HS(HMⅡ)对Cd的淋洗去除率最高(45.09％),用提取剂Ⅲ从风化褐煤中提取的HS(HMⅢ)对Pb的淋洗去除率最高(30.01％).从Cd、Pb淋洗去除效率、淋洗后土壤结构变化以及耕地使用功能上综合考虑,HMⅢ更适合做土壤重金属污染修复淋洗剂.

为调查陆良县菜地土壤重金属的污染状况与来源,采集陆良县蔬菜种植基地表层土壤样品(0～20 cm)分析Cd、Pb、Cr、Cu、Zn和As的含量,采用地累积指数法和内梅罗综合指数法对菜地土壤重金属污染程度及生态风险进行评价,通过多元统计分析方法揭示菜地土壤重金属污染的主要来源.结果表明,菜地土壤中Cd平均值高于《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618—2018)中的风险筛选值,其余5种重金属平均值均低于风险筛选值;地累积指数评价结果表明,露地菜地未污染,设施菜地Cu、As处于轻度污染水平;内梅罗综合指数法评价结果显示,菜地土壤整体处于轻度污染和中度污染水平,露地菜地受污染点位占33.33％,而设施菜地受污染点位占50.00％;多元统计结果显示,露地菜地中的重金属主要来源于肥料施用与交通污染,设施菜地中重金属主要来源于肥料施用、成土母质以及农药使用.

腐殖质(HS)是土壤有机质的重要组分,广泛应用于土壤改良.通过文献调研,在综述HS对土壤重金属的作用及其机制基础上,分析了HS在植物修复重金属污染土壤领域的应用潜力.已有研究表明:(1)大分子胡敏素(HM)和胡敏酸(HA)可钝化重金属离子,降低重金属对植物的毒害作用,小分子富里酸(FA)则可促进重金属从植物地下部向地上部迁移;(2)除受土壤理化性质影响外,HS与重金属离子的结合主要受HS的pH、溶液离子强度、分子量大小和活性官能团数量等条件影响;(3)叶面喷施HS可以抑制重金属向植物体内运输,保护光合系统不受重金属危害;土壤添加低浓度HS可以促进重金属转运,高浓度HS则会对植物产生负面效应;(4)根据HS与重金属作用下的生态毒理学效应、土柱淋溶效果和植物生长发育评估结果,认为HS不会产生次生环境风险.因此,HS可以作为重金属污染土壤植物修复的环境友好型促进剂,扩大重金属污染土壤植物修复的应用范围.

土壤有机碳是陆地碳库的重要组成部分.土壤有机碳的流失不仅造成了土地生产力的降低,而且在一定程度上也加剧了全球变暖的趋势.土壤中有机碳的流失在水土流失及其治理研究中受到越来越多的关注.植被覆盖作为影响水土流失的重要因子,在土壤有机碳的流失中起着至关重要的作用.文章从斑块、坡面、小流域等3个空间尺度分析和总结了植被覆盖对土壤有机碳流失的影响方式及程度.植被的斑块特征(覆盖度、类型、根系分布等)可以抑制径流冲刷以减轻降雨对土壤颗粒的侵蚀作用,因控制有机碳赖以附着的物理载体而有效防止了土壤中有机碳的流失;坡度、坡位、坡向等坡面特征通过影响植被的生长与分布格局,进而影响土壤中有机碳的流失;小流域尺度下植被对土壤有机碳流失的影响表现为景观格局对土壤有机碳分布和流域水文过程的控制特征.在对前人研究成果全面梳理的基础上,作者提出了不同尺度植被覆盖下土壤中有机碳流失研究存在的问题,并对本研究方向未来的发展趋势进行了初步分析.

本文研究了NaCl、Na2SO4、Na3PO43种背景电解质对牛粪生物质炭中腐殖酸吸附和解吸的影响.结果表明:在这3种背景电解质作用下,牛粪生物质炭对腐殖酸的吸附量和吸附率随着加入液腐殖酸浓度的增加而增加,但是增加速度逐渐变缓.3种背景电解质相比,NaCl中牛粪生物质炭对腐殖酸的吸附量和吸附率均为最高,吸附量范围为0.13～6.10 mg/g,吸附率范围为25.40％ ～87.14％.随着加入液腐殖酸浓度的增加,吸附态腐殖酸的解吸量逐渐增加,解吸率逐渐减小.3种背景电解质相比,Na2SO4中牛粪生物质炭吸附的腐殖酸的解吸量最高,解吸量范围为0.15～0.78 mg/g.加入液腐殖酸浓度为140 mg/L,3种背景电解质中牛粪生物质炭吸附的腐殖酸的解吸量均达到最大值,解吸量的大小顺序为Na2SO4>Na3PO4>NaCl.Na3PO4对腐殖酸的解吸率影响最大,解吸率范围为17.24％ ～90.55％,NaCl对腐殖酸的解吸率影响最小,解吸率范围为8.22％ ～53.54％.用Langmuir拟合3种背景电解质中腐殖酸的等温吸附曲线和等温解吸曲线,其相关系数都达到显著水平.研究结果揭示了不同背景电解质对牛粪生物质炭吸附和解吸腐殖酸的影响,可为土壤保土保肥提供理论参考.

[目的]研究龙川江流域6种不同植被类型对紫色土腐殖质(胡敏酸、富里酸、胡敏素)和土壤养分(总磷、速效磷、总氮、碱解氮)剖面分布特征的影响,为该地区保持土壤肥力提供科学依据.[方法]采用锯齿形布点法,采集紫色土表层至30 cm深度的3个土层紫色土样品,用3次4分法分离多余样品,并测定相应指标.[结果]总磷、速效磷、总氮、碱解氮的含量和腐殖质、胡敏素、胡敏酸、富里酸碳量随土壤深度的增加而减小,枯枝落叶层显著高于其他层(地下0-10,10-20,20-30 cm),不同植被类型土壤无显著差异.果园土壤腐殖质及其组成显著高于桉树林覆盖土壤,表现为果园＞落叶阔叶林＞暖温性针叶林＞针阔混交林＞灌丛＞桉树林.土壤腐殖质各组分之间均存在极显著正相关关系,腐殖质组成与土壤有机质、总磷、速效磷、总氮、碱解氮均存在显著正相关关系.[结论]果园和落叶阔叶林下土壤腐殖质及其组分显著高于其他植被类型土壤,腐殖质组分含量与土壤理化性质之间呈极显著正相关.

以牛粪为原料,在不同炭化温度下(200、300、400、500、600、700℃)采用热裂解法制备生物炭,借助扫描电子显微镜、元素分析仪、比表面积分析仪,结合Boehm滴定法、碘吸附及亚甲蓝吸附等,对所制得的牛粪生物炭的形貌特征、元素组成、比表面积、孔径、表面官能团和吸附性能等进行分析.结果表明:随着炭化温度升高,产率和挥发分含量降低,灰分和固定碳含量升高,pH值增加,制得生物炭的形貌特征更有规则且孔隙更加紧密.适当的升高炭化温度有利于孔隙的形成及微孔数量的增多,比表面积和孔容逐渐变大,而孔径逐渐减小.随炭化温度升高,牛粪生物炭的C含量增加,而H、O含量减小,N含量先增加后减小,H/C、(O+N)/C和O/C均下降,说明制得生物炭的芳香性和结构稳定性增强,但极性和亲水性减弱.表面官能团中羧基含量随炭化温度升高先增加后降低,羰基含量持续增加,而内酯基、酚羟基含量、酸总量和表面含氧官能团总量逐渐降低.碘吸附值和亚甲基蓝吸附值随炭化温度升高先增加后减小,在600℃下吸附值最大.

为了减少紫色土腐植酸的流失,提高龙川江流域紫色土肥力,采用土柱室内模拟方法,通过模拟降雨淋溶,研究了不同生物炭处理下(CK、1％、3％、5％和10％)对紫色土淋溶液pH值、 电导率、 体积以及胡敏酸和富里酸的影响.结果表明:在29 d试验过程中,淋溶液的pH值和电导率随着生物炭比例增加而增加;与CK相比,在1％、3％、5％和10％的生物炭处理条件下紫色土水分损失分别减少了6.33％、10.13％、16.46％和25.32％;胡敏酸浓度和累积淋失量随着生物炭比例增加而减小;除了1％和3％之外,富里酸浓度和累积淋失量也随着生物炭比例增加而减小;生物炭比例为10％的处理条件下对紫色土淋溶液中胡敏酸和富里酸浓度及累积淋失量最小,胡敏酸浓度和累积淋失量分别为1.46 mg/L、0.12 mg,富里酸浓度和累积淋失量分别为149.64 mg/L、29.60 mg,该处理有利于更大程度吸附胡敏酸和富里酸,减少其流失.

长时期的土地利用变化研究有利于提高对土地利用和土地覆被变化动态过程的认识.基于1982年和2016年龙川江流域遥感影像及地理信息软件,将该流域土地利用类型主要分成9类,即暖温性针叶林、常绿阔叶林、人工林、暖温性石灰岩灌丛、干热河谷稀树灌木草丛、水田、旱地、水域和居民区.基于Arcmap10.1软件的分类统计功能,从土地利用类型的面积变化、时空动态变化、动态度变化以及面积转移矩阵四个方面对研究区土地利用变化进行了分析.结果表明:研究区土地利用类型主要以暖温性针叶林、常绿阔叶林、暖温性石灰岩灌丛、干热河谷稀树灌木草丛为主.1982～2016年,暖温性针叶林、暖温性石灰岩灌丛以及旱地面积呈下降趋势,面积减少最多的是暖温性针叶林;常绿阔叶林、人工林、干热河谷稀树灌木草丛、水田、水域和居民区面积呈增加趋势,但是水域面积增加不多.动态度最大的是人工林,其变化幅度也是最大,面积大幅增加;干热河谷稀树灌木草丛和水域的动态度最小,其增幅也不大.研究成果对该流域水土保持工作的开展具有一定参考价值.

通过探讨牛粪生物炭对紫色土吸附-解吸腐殖酸的影响,以减少紫色土腐殖酸的流失、提高腐殖酸利用率,为提高龙川江流域紫色土肥力提供理论依据.采用土培实验,用Langmuir和Freundlich模型、Lagergren准一级和Lagergren准二级动力学方程,研究了不同添加比例牛粪生物炭(BC、CK、1％、3％、5％)对腐殖酸的吸附与解吸的影响.采用扫描电镜、BET等方法分析牛粪生物炭的表面结构以及比表面积,来探讨牛粪生物炭对紫色土吸附和解吸HA的影响机理.结果表明,牛粪生物炭对紫色土等温吸附HA过程符合Langmuir模型,动力学模型符合Lagergren准二级动力学方程;各处理对紫色土等温吸附-解吸HA过程有明显的影响,CK对HA的吸附量和吸附率最低,解吸率最高;5％对HA的吸附量、吸附率和解吸量最高.同时,各处理对紫色土吸附-解吸HA动力学也有明显的影响,在前12 h,吸附速率逐渐增加,随后吸附逐渐达到平衡,吸附过程以化学吸附为主.各处理方法相比,5％更有利于吸附HA,防止HA流失.

[Objective] The effects of land use on humus (humic acid,fulvic acid and humin) and four kinds of important soil enzymes in different yellow soil horizon under soil erosion condition were studied in order to provide some scientific basis for maintaining soil fertility.[Methods] Soil samples were collected in different soil horizon (0-10 cm,10-20 cm and 20-30 cm) at each sample point by zigzag method.Then,soil samples of each layer were mixed evenly in situ and removing of redundant sample was performed by quartering in three times and the corresponding indicators were determined.[Results] (1) Scrub woodland and garden plot had better effect in maintaining soil fertility.However,cultivated land was extremely susceptible to erosion.Soil fertility was directly related with the content of humin of yellow soil.(2) Soil erosion may also affect humic acid content through the loss of water and nitrogen.Fulvic acid of soil in forest land,garden plot and cultivated land lost more easily.However,the grassland had only impact on maintain soil surface fertility.(3) Tillage had significantly adverse effect for activity of urease,alkaline phosphatase and catalase.Meanwhile,soil erosion also evidently affects soil enzymes through the change of soil pH value.(4) Correlation analysis showed that the content of humus component had close contact with the activities of the four kinds of soil enzymes and influenced each other.[Conclusion] The land use types of yellow soil have significantly different effects on humus and soil enzyme activity under erosion.

根据云南省第二次土壤普查资料,采用土壤类型法估算了云南省主要土壤类型的有机碳(SOC)密度和储量,并对云南省土壤有机碳密度的空间分布差异和影响土壤有机碳储量的主要因子进行了分析.结果表明,云南省0-20 cm土层平均SOC密度为59.77 t/hm2,SOC储量为2.30×109 t;0-100 cm土层平均SOC密度为159.95 t/hm2,SOC储量为6.15×109 t,占全国储量的7.28％,占全球陆地生态系统SOC储量的0.41％;其中SOC储量占前4位的土壤类型为红壤、黄棕壤、赤红壤、棕壤,不同深度下4者之和约占云南省总储量的60％.在土壤有机碳密度空间分布上,SOC密度分布最高的区域为云南省西北部和东北部地区,其次是西部的横断山脉和东部的云南高原地区,而以紫色土为主的中北部地区SOC密度则最低.由于降雨量、温度、海拔和土地利用类型的共同影响,导致了区域内的SOC密度分布不均,其中降雨量、温度和海拔等自然因素是影响SOC密度分布的主要因子.

An experiment was conducted to analyze change of land use by means of the 1990 and 2001 remote sensed images as data sources in Yangbijiang river basin.Results showed that the area of woodland and residential-industrial quarter increased 2 791.71 and 1 290.55 hm2 respectively,while the area of grassland reduced 4 014.18 hm2.The speed of the LUCC was relatively high and the overall dynamic land use rate was 0.77 %.The index of the LUCC did not change too much 215.037 in 1990 and 215.567 in 2001.The LUCC was still in developing status.2 148.45 hm2 farmland still should be converted to woodland or grassland.

The soil erosion is serious in our country.This paper specializes the harmfulness of soil erosion and summarizes the reasons of soil erosion.And the methods of measuring soil erosion rate are discussed.The last part of the paper put forward the preventing methods of soil erosion.

Analyzing the condition of soil erosion dynamic changes was conducted in Yangbijiang River basin by means of RS and GIS.The results show that soil erosion has been alleviated with erosion area dropping from 275 867.24 hm2 to 247 282.09 hm2,total erosion modulus decreasing from 1 830.37 t/(km2·a) to 1 729.04 t/(km2·a)and total erosion amount reducing from 7 967 560.11 t to 7 526 463.32 t.The amount of mild erosion and moderate erosion respectively accounts for 75.46% and 75.46% of the total amount in 1990 and 2001.The mild erosion,moderate erosion and grassland erosion control is the core of the handing operation.

A case study of the Heihui River,Panglong River and Longchuan River valleys was carried out to explore relationship between sediment discharge and land use in longitudinal river valleys in Yunnan.Results show that implementation of the "Grain for Green" policy,increased the area of forest lands and decreased the area of croplands and grasslands,thus,significantly reduced sediment discharge from the rivers.Whereas reclamation of forest lands into farmland or grassland or of grasslands into farmlands resulted in significant rise in sediment discharge.In the ten years following 1990,in the Hehui River and Panglong River basins the land use became more reasonable and as a result the annual sediment discharge appeared to be on the decline,while in the Longchuan River basin,the land use turned reversely,and so did the annual sediment discharge.The variation of sediment discharge in the three basins accorded with the general trend of the change in climate.Change in land use is the main cause of the variation of sediment discharge.Sediment discharge in the three river valleys follow the same general law for mountain rivers in responding to changes in land use.The response is much strong in mountainous areas than in flat areas.

Yangbijiang River basin is taken as a case study.Remote sensing technology is used in the land use classification and the maps of the region in two periods of land use are obtained.The results show that this method of land use classification,especially in the southwest mountainous region,has a promising prospect.

The landscape pattern characteristics of land use and cover change(LUCC) of Longchuan River basin was analyzed by using ASTER image as a data source and combining GIS with landscape ecology under the support of remote sensing and GIS technology.The results showed that the vegetation coverage rate of Longchuan River basin was relatively high and the area of forest land,shrub land and grass land accounted for 86.27% of the total investigated area,and because the various landscape type with a small area was scattered,the landscape connectivity degree was poor,which hindered the normal material and energy flow of the entire ecosystem.Therefore,the ecological environment of Longchuan River basin should be improved further.

Land use changes the pattern and extent of soil erosion directly,and it has outstanding erosion-environmental effect.This study,taking three drainage areas as an example,probes into the effect of land use on soil erosion in the Longitudinal Range-Gorge Region in west Yunnan.The results show that an internal and mutual transformation of land-use types cause striking changes in soil erosion extent.The transition of cultivated land to woodland and grassland medicates erosion intensity,and the one from forestland to cultivated land and grassland aggravates erosion.In addition,land-use practices,including mainly human activities,have impacts on the content of suspended sediment.In the places with an increase of forest area and a decrease of soil erosion,suspended sediment concentration is reduced.A contrary result is seen in poorly forested and highly eroded areas.

The MLP-ANN model was applied to research the response for the climate changes to the transportation of Sediment in Longchuanjiang River.The results showing:(1)The temperature,rainfall,intensity of storm and the water discharge have a directly relationship with the Sediment whereas the frequency of storm,evaporation and the humidity have no response explicitly;(2)Without delay effect appears to the transportation of Sediment model while considering the water discharge,otherwise,A month delay effect appears;(3)The response for the climate changes to the transportation of Sediment in Longchuanjiang River has a obvious deviation since1990,it shows that the other factors should disturb this response mechanism strongly except the climate.