酸沉降下加速土壤酸化的影响因素

酸沉降对土壤和水域的酸化影响是土壤环境化学研究前沿的热点问题之一。酸沉降的化学组成对酸性土壤的进一步酸化起着催化剂的作用。在酸雨影响下，SO4^2-,NO3^-，有机阴离子是加速土壤酸化和盐基淋溶损失的主要阴离子，外源H^ 的进入会加速铝离子水解。自然因素与人为因素导致土壤酸化的实际酸化速率差异表明：HCO3^－，RCOO^－在土壤剖面中的淋失状况可反映自然土壤的酸化速率，而SO4^2－和N3^- 溶产生的质子负荷揭示土壤受人为因素影响的酸化速率。通过计算酸沉降的主要化学成分进入土壤前后的质子负荷平衡，与酸中和容量（ANC）相结合，反映酸沉降加速土壤酸化的进程。     

土壤酸化成因及其对农田土壤-微生物-作物系统影响的研究进展

自然土壤酸化是一个缓慢的过程,但是农田土壤因频繁的人类活动加速了这一过程,从而给农田土壤-微生物-作物系统带来一系列的负面影响。论文从大气酸沉降、施肥和管理方式、种植作物以及作物移除四个方面介绍了农田土壤酸化的主要原因;重点阐述了土壤酸化对农田土壤肥力、土壤盐基离子以及土壤酸缓冲体系的影响。总结了酸性农田土壤对土壤细菌群落结构、功能性微生物（如氨氧化古菌和氨氧化细菌等）群落结构以及土传病害的影响;分析了土壤酸化对作物的毒害作用,如造成农作物减产、迫使作物根系受到铝毒害等;从外源添加物减缓土壤酸化角度,论述了可持续利用酸性土壤的策略,提出了土壤酸化后的改良措施,展望了土壤酸化需进一步探究的课题。     

土壤对酸雨的耐性

<正> 日本的酸性物质沉降量与欧洲、北美大体相同,但因酸性物质所造成的森林衰退却与欧美之间有很大差别。产生这种差别的原因之一是由于土壤的性质不同。土壤对酸性沉降物的耐性,是由土壤对酸的中和能力与土壤中铝的溶出能力所决定的。因为铝即使在低浓度下也会对植物产生强烈的毒害。例如,火山灰土虽然可有效地吸附酸性物质,但也非常容易将铝离子溶出。因此,火山灰土对酸雨的耐性并不大。     

酸沉降与我国南方森林土壤的酸化

通过模拟酸沉降土壤连续浸泡试验，研究了我国南方5种森林土壤的酸化过程，并讨论了影响土壤酸化的几个因素。结果表明，土壤对酸沉降H^ 的中和能力，对酸沉降阴离子（SO4^2-和NO3^-）的吸附，土壤阳离子（Ca^2 ,Mg^2 )等盐基离子以及Al^3 )的风化，土壤pH和BS的变化，都在土壤酸化过程中有着重要作用。同时，酸沉降的酸度（pH值）是决定土壤酸化的主要因素，而酸沉降中高含量的盐基离子可能缓解土壤的酸化过程。结合土壤本身物理化学基本特性可以得知，福建土壤对酸沉降引起的酸化最为敏感；江西、湖南土壤次之；重庆土壤的酸化敏感性较弱；而贵州土壤对酸沉降不太敏感。     

模拟酸雨对酸性土壤铝溶出及其形态转化的影响

通过采样、酸雨模拟试验和样品分析，研究了我国南方酸沉降区主要土壤类型在模拟酸雨影响下，土壤中铝离子释放及铝形态转化的特点。结果表明，酸雨淋洗造成土壤中铝离子释放；酸雨pH值越低，则铝离子释放量越大。酸雨淋洗还造成土壤中铝形态发生变化；酸雨pH值越低，则土壤中羟基态铝和腐殖质铝含量越低，交换态铝含量越高，从而导致土壤中的铝对植物和生态系统的危害性也越大。     

酸沉降对土壤微生物活性的影响

酸沉降可以影响陆地的环境,并能导致化学的和生物学的变化。这种化学变化包括由于基本营养离子被淋溶而导致土壤生产力降低,以及重金属和铝的增溶作用,造成对地下水和地表水的环境的有害影响。生物学变化包括土壤中微生物生长和活性的降低,     

我国南方红壤酸化和铝毒现状及防治

南方红壤区是我国农业生产的重要基地,然而,红壤酸化和铝毒导致该区耕地生产力和质量下降.本文整理分析了近5年南方红壤酸化的相关报道和广东主要酸雨区森林土壤的调查结果,发现,红壤酸化面积加大,并且酸化程度和铝毒害日趋严重.本文还详尽阐述了导致南方红壤酸化加快和铝毒加重的主要因素,如酸沉降加剧、化肥不合理使用以及农业集约化生产和单一化种植.在此基础上,指出控制酸沉降、合理的施肥方式和作物栽培方式,是防治红壤酸化的主要措施.     

森林生态景观土壤酸化及修复技术研究

2010年在鼎湖山自然保护区,通过野外原位模拟酸雨控制实验和施用石灰、污水污泥和联合施用石灰＋污水污泥3种土壤酸化改良剂,研究了保护区内三种森林土壤在受到酸沉降影响后,土壤pH值和交换性Al3＋、H＋浓度的动态变化以及投加修复剂后混交林土壤酸度的变化情况。结果表明：三种森林土壤酸化严重（pH〈4.5）,pH值随处理酸度降低而下降;土壤交换性酸（H＋、Al3＋）含量随处理酸度降低而增加。酸沉降中H＋的输入,导致土壤铝被活化。三种改良剂的施用均可以缓解土壤酸化,降低土壤交换性酸（H＋、Al3＋）含量,从而降低植被铝中毒风险。三种修复技术中,联合施用石灰＋污水污泥修复技术效果最好。     

酸沉降影响下广东陆地生态系统表层土壤特征

研究并比较了广东省鼎湖山、鹤山、白云山陆地生态系统表层土壤特征。结果表明，3个采样点表层土壤酸化都较严重、pH值低相对于较低的p H值，三个采样点土壤的有效阳离子交换量（CECE）介于59．63－124．06mmol.kg^-1，盐基饱和度（BS）介于10．6％－30．3％，表明表层土壤仍具有一定的酸缓冲能力3个采样点表层土壤同时处于阳离子缓冲范围和铝缓冲范围内，活性铝较高，考虑酸沉降对森林生态系统的影响时应重点考虑铝毒的影响。     

可变电荷土壤中特殊化学现象及其微观机制的研究进展

综述了近年来可变电荷土壤化学研究的进展,着重总结了可变电荷土壤中的盐吸附、铁铝氧化物对土壤自然酸化的抑制作用和离子强度对离子专性吸附的影响等特殊化学现象及其微观机制的研究进展。用颗粒表面扩散层重叠导致有效电荷数量减小的原理解释了盐吸附现象和铁铝氧化物对土壤自然酸化的抑制作用。阐明了可变电荷土壤和矿物中介质离子强度影响离子专性吸附的机制,用四层吸附模型解释了离子专性吸附随离子强度增大而增加的现象,并根据胶体zeta电位随离子强度改变而变化的趋势进一步证明了离子强度增大使胶体专性吸附面上静电电位的绝对值减小,是离子专性吸附随离子强度增大而增加的主要原因。带电颗粒表面双电层结构和双电层相互作用的深入研究,有助于阐明可变电荷土壤中一些特殊化学现象的微观机理,从而进一步完善土壤化学理论。     

Assessing the potential for forest effects due to soil acidification in Maryland

Calculations with the PROFILE model indicates that present acid deposition will lead to soil solution BC/Al molar ratios in the forest soils of Maryland far below the limits used for calculation of critical loads in Europe. Weathering rates and molar soil solution BC/Al ratios were calculated using measured mineralogy and texture. It has been assumed that the laboratory experiments on tree seedling response to soil solution Al concentration is applicable to field conditions as applied in the PROFILE model and that the observed connection between growth and needle loss for Sweden is also valid for North America. The assumptions were utilized to estimate the potential for forest damage due to soil acidification in Maryland. The results for Maryland was used to speculate over the possibilities for adverse effects due to soil acidity in Northeastern United States. A preliminary comparison with Maryland and European results, suggests that the threat of soil acidification to forest health in the Northeastern United States may have been underestimated.     

沿海地区海盐沉降对酸性土壤的影响

The characteristics of sea.salt deposition and its impact on acid soils in maritime regions are reviewed. It is pointed out that studies involving the impact of sea.salt deposition on acid soils have been concentrated on short-term effects on soil and water acidification. A deep consideration of long-term effects on soil acidification in maritime regions is still needed.     

Atmospheric deposition in maritime environments and its impact on terrestrial ecosystems

Seasalts are the dominant chemical constituents of precipitation in maritime regions. Dry deposition of these salts is also an important process and consequently, canopy interception by forest ecosystems greatly augments wet deposition. The separation of seasalt from non-seasalt sulphur is usually accomplished by reference to the concentration ratio of other major component ions of seawater, such as sodium-, chloride-, or magnesium-to sulphate. Biogenic sulphur, from the oceans or from terrestrial ecosystems is sometimes of importance in maritime regions. Seasalts, which dominate atmospheric deposition in maritime regions can induce short-term acidification in surface waters as a result of ion-exchange reactions following storm events. The results of one large storm in western Ireland in 1991 and the recovery process in a peat soil were clearly discernible in soil water analysis. The seasalt impact on acid mineral soils can be seen in the exchangeable sodium levels and the degree of base saturation of these soils.     

基于CNKI数据库的土壤酸化文献计量分析

为探索近年来国内土壤酸化研究的热点与发展趋势,以CNKI数据库为基础,采用统计与聚类等分析方法,借助CiteSpace信息可视化软件及文献计量学知识,统计并绘制有关国内土壤酸化研究文献的机构、关键词、文献被引频次等信息图表,挖掘土壤酸化研究的整体发展趋势、高产机构、高频关键词等信息。研究发现我国土壤酸化研究的主题从森林土壤逐渐转移至农田土壤,酸沉降及土壤化学在土壤酸化研究中一直属于重点关注对象。研究机构主要集中在高校和科研院所,同时高频关键词显示国内土壤酸化研究主要集中在酸沉降、施肥管理、土壤结构、作物生长、酸化成因及改良、连作障碍及土壤污染等方面。该研究有助于全面了解国内土壤酸化研究现状及进展,为农田土壤酸化改良方面的研究及应用提供重要参考。     

Acidic deposition and its effects on the forests of Nordic Europe

Air pollution effects on the forest of Nordic Europe are analyzed with respect to the situation before and after 1980. No adverse effects were reported up to 1980. Inventories of forest vitality in terms of needle loss or crown density as well as tree growth have been made in parts of Norway and the whole of Sweden. For Norway spruce, needle loss was found to increase with tree age and climatic stress with increasing latitude and altitude. However, decreased crown density was also reported for SW Sweden. Needle loss is a non-specific signal not reacting to air pollution alone. Direct effects of gases such as SO₂ are not likely to occur, but high episodic levels of O₃ have been measured at a level possibly leading to chronic injuries. Increasing soil acidity is reported from forests in SW Sweden and also from an alpine locality in southern Norway. A differentiation of biological and deposition-dependent acidification has been attempted. A soil acidification of up to 1 pH unit has occurred in both humus and mineral soil layers. An increased release of A1 and heavy metals combined with an increased loss of basic cations is now occurring. Soil acidification probably also results in less available amounts of phosphorus and is suggested to interact with N as limiting forest growth.     

Some Approaches to the Research of Forest Soils Affected by Acidification in the Czech Republic

Soil acidification in mountainous regions of the Czech Republic presents a serious problem. This paper summarizes several projects dealing with this problem exploiting different methods and having different objectives: 1) Long-term soil and forest development in the Krkonoše Mountains. 2) Soil and forest development along an elevation transect in the Šumava Mountains. 3) Long-term effects of liming. 4) Comparison of soil acidification between three mountainous regions, with emphasis on labile Al content. 5) Spatial distribution and factors of soil acidification and Al release in the Jizera Mountains. The results of these projects showed that acidification in forest soils in the mountainous areas is caused by a combination of different factors, especially by the type of vegetation, atmospheric deposition, parent rock, altitude, and others. A slight improvement of soil properties is apparent after the decrease of immissions in the 1990's.     

Tiefengradienten der Bodenversauerung

Depth gradients of soil acidification In dystric Cambisols, developed from diabas and clay schist/greywacke in the Sösemulde (Harz), the depth gradient of the acid/base status has been assessed by measuring pH and the composition of exchangeable cations. After the soil in the root zone has acidified to within the aluminum buffer range, a marked acidification front is formed below the rooting zone. Strong acids (protons, Mn, Al ions) are buffered completely above the acidification front. Long-term measurements of the input and output of acids and bases in nine forest ecosystems in NW-Germany show that the acid input due to acid deposition into soil horizons in the Al- or Al/Fe- buffer range appears almost quantitatively as output in the seepage water from these horizons. The kind of acid responsible for the soil acidification can be identified by the anion composition of the seepage water. The deep reaching acidification is traced back to acid deposition.     

Effects of gaseous pollutants on forests in Eastern North America

The purpose of this paper is to summarize the current state of knowledge concerning direct forest damage caused by atmospheric gaseous pollutants. The major gaseous pollutants affecting forest growth are O₃, SO₂, and HF. Ozone is the most prevalent phytotoxic air pollutant on a regional scale in eastern North America. It has been demonstrated to cause foliar injury and growth effects on trees in both laboratory and field studies. Both SO₂ and HF have been found to cause damage to forests primarily in the vicinity of strong point sources. Case histories of forest damage are reported in the paper which describe foliar and radial growth effects, with associated volume losses. Threshold levels of the gaseous pollutants causing effects on forest growth are provided.     

Deposition of acidifying compounds in Sweden

The Swedish Environmental Research Institute (IVL) has monitored deposition of acidifying compounds in Sweden. The monitoring programmes were initiated by various air quality protection associations, and regional forest and environmental authorities. The purpose is to quantify sulphur (S) and nitrogen (N) deposition to forests, and to illustrate possible acidification of the soil. Actual deposition of S and N is compared with critical loads. Deposition is investigated by precipitation studies in open field areas and by throughfall studies in forest stands. Soilwater chemistry is examined in the forest stands and used as indication of soil conditions. For most of the study sites, data on needle loss, forest growth, and soil chemistry are available from the National Board of Forestry. All available data are combined in a computer database for evaluation. Evaluation of data during 1985–94 shows that regional deposition monitoring illustrates the size and distributional pattern of S and seasalts. Monitoring data can identify certain regions receiving heavy loads of N, which can be found mainly in southern Sweden. Soilwater analyses indicates that large areas in Sweden have heavily acidified forest soils, low pH-values, low levels of calcium (Ca²⁺), magnesium (Mg²⁺), and potassium (K⁺), and raised levels of inorganic aluminium (iAl). Forest sites in the coastal regions of southern and south-western Sweden also showed raised inorganic N levels in soilwater. The relationship between deposition load and effects on soil chemistry is recognised by a correlation between S deposition and iAl levels in soilwater. Another correlation was found between N deposition (throughfall) and N levels in soilwater.     

Using the long‐term experiments at rothamsted to address current agricultural and environmental issues

In the Broadbalk Experiment at Rothamsted winter wheat has been grown in monoculture since 1843; wheat in rotation and additional treatments have been introduced during the course of the experiment. Since 1968, when new crop varieties and fungicides were introduced, yields have averaged over 6 t ha^‐1with either inorganic fertilizers or farmyard manure. With high‐yielding varieties of winter wheat on Boardbalk, or spring barley on the Hoosfield experiment, maximum yields are currently achieved with a combination of inorganic and organic inputs. The long‐term experiments have provided much information on the losses of nitrate and phosphate to water from different treatments and also on the impact of recent decreases of sulphur deposition on soil S dynamics and crop composition. Archived samples of soils and crops from the Park Grass Experiment (continuous cut pasture) and experiments in which arable land has reverted to forest have provided information on soil acidification. This has resulted mainly from acid deposition, previously SO₂ but now dominated by oxides of nitrogen. Acidification has caused the mobilization of toxic metals including Al, Mn and Zn and their increased uptake in herbage. Archived samples have also made it possible to study the deposition and accumulation of metals and organic pollutants in soils and crops and the changes in soil organic carbon and nitrogen content resulting from different management practices. Such data has been used to construct models of soil C and N dynamics. The on‐going sites provide experimental material for biological studies including fertilizer and management impacts on nitrous oxide fluxes and for testing hypotheses on soil biodiversity and quality.