本溪山区森林枯落物对水质的影响

以本溪山区主要水源涵养林红松、落叶松、蒙古栎、水曲柳、核桃楸纯林为研究对象,运用定位观测法,对5种类型林分的林外雨与枯落物渗透雨(枯透雨)的水质进行了研究,以及利用5种类型林分之间枯落物渗透水的水质对比,测定林外降雨及各林分枯落物渗透水的pH值、硝酸盐(以N计)、氨氮(以N计)、硫酸盐(以SO_4~(2-)计)、全氮(TN)、全磷(TP)、氟离子(F~-)、氯离子(Cl~-)、钙(Ca~(2+))、钠(Na~+)、镁(Mg~(2+))、钾(K~+)等12种指标,结果表明:大量化学元素和离子通过枯落物后均显著增加,其中变幅最大的K~+,浓度为4.19mg·L~(-1),是林外雨20倍。林外雨各指标浓度依次为SO_4~(2-)TNCa~(2+)Cl~-Na~+NH_3-NNO_3~-NMg~(2+)K~+F~-TP;枯透雨各指标浓度依次为SO_4~(2-)Ca~(2+)TNNO_3~-NCl~-K~+Mg~(2+)NH_3-NTPF~-Na~+。枯透雨中SO_4~(2-)浓度最高,为12.59mg L~(-1);TP浓度最小,为0.25mg L~(-1)。5种纯林在调查期间林外雨和枯透雨的pH趋于中性,而在经过枯枝落叶层的淋溶后,有明显的酸化现象,pH范围在5.1~6.6。     

杉木枯落物燃烧释放污染物特征及PM2.5成分分析

【目的】探究杉木人工林枯落物在不同燃烧状态时的气态及颗粒态污染物排放特征,并提取、测定细颗粒物(PM 2.5 )污染物的化学成分,揭示林火及林地清理等对杉木枯落物分解、养分循环和大气环境的影响。【方法】分别以杉木人工林枯落物中的叶、枝、皮、干4种主要组分为研究对象,运用自主设计的生物质模拟燃烧系统,采用室内模拟燃烧试验,分析阴燃和明燃2种不同燃烧状态不同枯落物组分释放的气态污染物和PM 2.5 特征及差异。采用德国Elementar元素分析仪,测定PM 2.5 中的碳质成分;采用超声提取-离子色谱和ICP/MS技术,测定PM 2.5 中的水溶性离子和水溶性无机元素。【结果】基于杉木枯落物燃烧时的实时测定,CO 2、CO、NO x 、C x H y 、PM 2.5 的排放因子(EF,单位质量燃料在燃烧后产生的污染物质量)变化范围在阴燃条件下分别是1 001.4~1 364.5、202.3~358.8、0.53~3.09、23.17~53.07、5.11~38.37 g ·kg -1 ,而明燃时分别为1 092.4~1 520.7、115.1~242.6、0.16~1.96、1.21~41.50、2.58~21.07 g ·kg -1 。此外,提取测定PM 2.5 成分的结果表明,颗粒物主要由碳质组分、水溶性离子及少量水溶性无机元素等组成。其中碳质组分含量最大,占50%以上,有机碳(OC)和元素碳(EC)平均质量分数分别为43.29%和12.91%;PM 2.5 中测定出6种阳离子(Li +、Na +、NH + 4、K +、Mg 2+、Ca 2+)和5种阴离子(F -、Cl -、NO 2 -、SO 4 2-、NO - 3),总水溶性离子占10%~33%,阴燃以Cl -、K +、Ca 2+、SO 4 2-为主要组分,明燃以K +、Cl -、SO 4 2-、Na +为主;PM 2.5 中提取测定出16种无机元素,分别为K、Ca、Na、Mg、P、Zn、Al、Cu、As、Ba、Cr、Fe、Mn、Cd、Li、Pb,含量极少,仅占PM 2.5 的0.04%~0.58%,其中K、Ca、Na、Mg、P、Zn为主要元素成分,占总无机元素的96.8%~98.8%。【结论】在不同燃烧状态下,杉木枯落物释放各污染物的排放因子存在显著差异,除CO 2外的其他污染物排放因子在阴燃时显著高于明燃;在同一燃烧状态时,杉木枯落物不同组分的CO、CO 2、NO x 、C x H y 和PM 2.5 等污染物的排放因子也存在显著差异。杉木枯落物燃烧排放的PM 2.5 主要由碳质组分、水溶性离子及少量无机元素等成分组成,阴燃时的各成分排放因子整体表现为高于明燃时。     

宜昌市城区典型灰霾日PM2．5污染特征研究

对2013年白龙岗站点自动监测数据和手工采集的 PM 2．5中水溶性阴离子进行了分析,结果表明：宜昌市城区灰霾发生频率较高,PM2．5为首要污染物,冬季灰霾天数和PM2．5月均值最高,夏季最低;在典型灰霾日,PM2．5、PM10、SO2和NO2具有相同的变化趋势,在污染物排放总量不改变的情况下,短暂降雨难以从本质上改变灰霾状态;NO3-和SO2-4是PM2．5中的主要水溶性离子,其灰霾日的质量浓度高于非灰霾日,工业区高于商业区;灰霾日NO3-/SO2-4的比值大于非灰霾日,机动车尾气对灰霾的形成影响较大。     

滨海地区土壤化学因子对杨树生长影响的研究

本文采用相对变率关联分析法,对滨海地区杨树的树高、直径、单株木材积和材积生长量与主要的土壤化学因子:HCO_3~-,Cl~-,SO_4~(2-),Ca~(2+),Mg~(2+),Na~++K~+,阴离子总量、全盐量及pH值,进行了关联分析。结果表明,影响滨海地区杨树生长的主要土壤化学因子是土壤pH值,其次为HCO_3~-离子,再次为Ca~(2+)离子,从而为改良滨海土壤及提高造林质量,提供了理论依据。     

滇中安宁“3.29”重大森林火灾火烧迹地的可燃物特征初步分析

在滇中安宁“3·29”重大森林火灾火烧迹地选择无人为干扰的灌木林设置样地,并与未过火的灌木林进行比较,通过外业调查和实验室测定,研究了可燃物的种类、高度、绝对含水量、载量等特征。结果表明,火烧迹地死可燃物的高度为5．7m,与未过火的活灌木高度5．4m差不多,活灌木平均高度达1．5m;火烧迹地活灌木、死可燃物、CWD的热值及点着温度与未过火样地的差异均不明显;火烧迹地CWD的灰分含量仅为未过火的25．87％;火烧迹地总的可燃物载量为9．07kg/m^2,明显超过了未过火样地7．82kg／m^2。     

脱硫石膏改良龟裂碱土对枸杞根际土壤理化性质及根系生长的影响

In this study, the rhizosphere soil properties of Takyr Solonetzs ameliorated with FGDG, and its effect on root growth of Lycium barbarum were studied. The results indicated that with increasing applications of FGDG, the contents of Na⁺, K⁺, Mg²⁺, Cl^-, and HCO₃^- in rhizosphere soil decreased gradually with the ratio of 51.9%, 16.7%, 42.7%, 44.7% and 28.2%, respectively, while the contents of Ca²⁺ and SO₄^2- showed an increasing trend and increased by 96.9% and 80.4% compared with those of the CK. As the content of exchangeable Na⁺ decreased with the increasing application of FGDG, the exchangeable sodium percentage (ESP) and soil pH values decreased from 32.2% and 10.5 to 18.1% and 7.82, respectively and thus the soil physical properties improved. However, the lowest total salt content (2.91 g·kg^-1) was found in T2 (2.5 t/(667m²)), and similarly, the highest values of taproot length (44.78 cm), root surface area(179.97 cm²) and root dry weight (17.53 g) were also found in T2, which suggested that applications of FGDG were not always positively correlated with soil reclamation, and excessive amount of FGDG would inhibit root’s growth. Overall, application of FGDG is effective in ameliorating Takyr Solonetzs, but high amount of FGDG would result in excess salts against root growth and subsequently influence production.     

闽东北海涂土壤理化性状分析

根据闽东北沿海滩涂土壤剖面化验数据，比较分析了该地区海涂土壤的理化性状及相关性，并分析了总盐量与８种主要离子的相关性，结果表明，有机质与全氮、全磷、阳离子代换量存在显著相关性，土壤总盐量与Ｃｌ－、ＳＯ２－４、ＨＣＯ－３、Ｃａ２＋、Ｍｇ２＋、Ｋ＋、Ｎａ＋存在显著的相关性。     

Microbial properties and litter and soil nutrients after two prescribed fires in developing savannas in an upland Missouri Ozark Forest

On some landscapes periodic fire may be necessary to develop and maintain oak-dominated savannas. We studied the effects of two annual prescribed burns to determine their effect on microbial activity and soil and litter nutrients 1 year after the last burn. Surface litter and soil from the upper 0–5 cm soil layer in three developing savannas (oak-hickory, Quercus-Carya), oak-hickory-pine (Quercus-Carya-Pinus), and pine (Pinus) were collected one year after the second of two annual prescribed burns. Surface litter was analyzed for nutrients and soil was analyzed for phospholipid fatty acids (PLFAs) and nutrients. Surface litter chemistry differed across the three savannas for potassium (K) and boron (B), being significantly (P < 0.05) higher for unburned forest than for burned forest. Among savannas, only sulfur (S) was higher for the pine savanna and B for the oak-hickory savanna, both were higher for unburned forest than for burned forest. For soil, calcium (Ca) and B differed across savannas, being higher for burned forest than for unburned forest. Among savannas, soil pH, Ca, and B concentrations were higher in soil from burned forest than from unburned forest. Total PLFA differed among savannas, but was not affected by burning treatments. However, the amounts of biomarkers for Gram-positive and Gram-negative bacteria were higher while the amount of biomarker for fungal PLFA was lower for burned forest than for unburned forest. Our results indicate that the two annual prescribed burns moderately affected PLFA microbial community structure and litter and soil nutrient concentrations. However, the long-term effects of fire on these study sites are not known and merit further study.     

Herbaceous species diversity in relation to fire severity in Zagros oak forests,Iran

Zagros forests are mainly covered byQuercus brantii L. coppices and oak sprout clumps occupy the forest area like patches. We investigated post-fire herbaceous diversity in the first growing season after fire. For this purpose neighboring burned and unburned areas were selected with the same plant species and ecological conditions. The data were collected from areas subjected to different fire severities. Overall 6 treatments were considered with respect to fire severity and the mi-crosites of inside and outside of oak sprout clumps including： unburned inside and outside of sprout clumps （Ni and No）, inside of sprout clumps that burned with high fire severity （H）, inside of sprout clumps that burned with moderate fire severity （M）, outside of sprout clumps that burned with low fire severity （OH and OM）. Different herbaceous com-position was observed in the unburned inside and outside of oak sprout clumps. The species diversity and richness were increased in treatments burned with low and moderate fire severity. However, in treatment burned with high fire severity （H）, herbaceous cover was reduced, even-ness was increased, and richness and diversity were not significantly changed. We concluded that besides the microsites conditions in forest, fire severity is an inseparable part of the ecological effect of fire on her-baceous composition.     

Mineral Nutrition in Sierra Nevada Mixed Conifer: Wildfire Effects,Species Distinctions,and Temporal Variation

An investigation of wildfire effects on mineral nutrition of Jeffrey pine (Pinus jeffreyi Grev. & Balf.) along with species comparisons of the nutrition of unburned specimens of this pine to those of unburned California white fir (Abies concolor var. lowiana [Gord.] Lemm.) were conducted in an eastern Sierran mixed conifer stand. Foliar Fe and Mn concentrations were frequently higher and Al was consistently so in burned than in the unburned pine as assessed in six sampling periods distributed over more than two postfire growing seasons while base cation/metallic element molar ratios consisting of Ca/Al, K/Al, K/Mn, Ca/Fe, Mg/Fe, K/Fe, and Ca/Zn were often lower in the former. Foliar N, P, Fe, Zn, and Cu were frequently higher in unburned pine than unburned fir while the reverse proved true concerning K, Ca, Mn, B, and Al; and likewise several molar ratios involving Al and Mn were higher in the former while several involving Fe, Zn, and Cu were higher in the latter. At midstudy, mineral soil in the burned stand portion had lower K but higher S, Mn, and Zn than that in the unburned portion, and the former had several molar ratios that were lower as well.     

林火对土壤氮含量的扰动作用

通过对大兴安岭地区新林林业局 2 0a内不同年份间隔的 11块火烧迹地土壤进行调查取样和室内实验分析 ,发现火烧后不同年限、不同强度的火烧迹地 ,土壤全氮与有效氮含量变化情况如下 :低强度火烧后 9d ,土壤全氮和有效氮含量均比未烧前低 ,这与中、高强度火烧后的情况正好相反。火烧后 4a内 ,土壤氮的含量基本都比未烧林地有所下降 (中强度火烧迹地土壤有效氮含量除外 )。以后有逐年增加的趋势。火烧迹地降第一场雨后 ,低强度火烧迹地土壤全氮比降雨前减少 ,有效氮增加 ;中强度火烧迹地土壤全氮和有效氮均比降雨前增加 ;高强度火烧迹地土壤全氮和有效氮均比降雨前有所下降。连年火烧迹地土壤全氮减少 ,有效氮增加     

Association of wildfire with tree health and numbers of pine bark beetles, reproduction weevils and their associates in Florida

Wildfires burned over 200,000 ha of forest lands in Florida from April to July 1998. This unique disturbance event provided a valuable opportunity to study the interactions of summer wildfires with the activity of pine feeding insects and their associates in the southeastern United States. We compared tree mortality with abundance of bark and ambrosia beetles, reproduction weevils and wood borers relative to fire severity. Over 27% of residual live trees in stands that experienced high fire severity died between October 1998 and May 1999. An additional 2–3% of trees that initially survived the fire died during the second year compared to <1% mortality in unburned stands. One year after the fire, more than 75% of the trees surviving in high fire severity stands had roots infected with one or more species of Leptographium and/or Graphium spp. and nearly 60% of the sampled roots were infected. No such fungi were recovered from roots of trees in unburned stands. Significantly, more root weevils, Hylobius pales and Pachylobius picovorus, were captured in unbaited pitfalls in the moderate and high fire severity stands than in the controls. Mean trap catches of Ips grandicollis, Dendroctonus terebrans and Hylastes salebrosus, three common bark beetles that feed on phloem tissue of pines, were lower in Lindgren traps in the fire-damaged areas than in the control stands. In contrast, catches of the ambrosia beetles, Xyleborus spp. and Monarthrum mali, were higher in burned stands than in control stands. The generalist predator, Temnochila virescens (Coleoptera: Trogositidae), showed a strong positive relationship between abundance and fire severity, while the flat bark beetle, Silvanus sp. (Coleoptera: Sylvanidae), exhibited the reverse trend. Our results show that most tree mortality occurred within 1 year of the fire. Ips or Dendroctonus bark beetle populations did not build up in dead and weakened trees and attack healthy trees in nearby areas. The prevalence of Leptographium spp. in roots may be a symptom of, or result in, weakened trees that may affect the trees’ susceptibility to bark beetles in the future.     

Prescribed fires as ecological surrogates for wildfires: A stream and riparian perspective

Forest managers use prescribed fire to reduce wildfire risk and to provide resource benefits, yet little information is available on whether prescribed fires can function as ecological surrogates for wildfire in fire-prone landscapes. Information on impacts and benefits of this management tool on stream and riparian ecosystems is particularly lacking. We used a beyond-BACI (Before, After, Control, Impact) design to investigate the effects of a prescribed fire on a stream ecosystem and compared these findings to similar data collected after wildfire. For 3 years after prescribed fire treatment, we found no detectable changes in periphyton, macroinvertebrates, amphibians, fish, and riparian and stream habitats compared to data collected over the same time period in four unburned reference streams. Based on changes in fuels, plant and litter cover, and tree scorching, this prescribed fire was typical of those being implemented in ponderosa pine forests throughout the western U.S. However, we found that the extent and severity of riparian vegetation burned was substantially lower after prescribed fire compared to nearby wildfires. The early-season prescribed fire did not mimic the riparian or in-stream ecological effects observed following a nearby wildfire, even in catchments with burn extents similar to the prescribed fire. Little information exists on the effects of long-term fire exclusion from riparian forests, but a “prescribed fire regime” of repeatedly burning upland forests while excluding fire in adjacent riparian forests may eliminate an important natural disturbance from riparian and stream habitats.     

Eight years of seasonal burning and herbicidal brush control influence sapling longleaf pine growth,understory vegetation,and the outcome of an ensuing wildfire

To study how fire or herbicide use influences longleaf pine (Pinus palustris Mill.) overstory and understory vegetation, five treatments were initiated in a 5–6-year-old longleaf pine stand: check, biennial arborescent plant control by directed herbicide application, and biennial burning in March, May, or July. The herbicide or prescribed fire treatments were applied in 1999, 2001, 2003, and 2005. All prescribed fires were intense and averaged 700 kJ/s/m of fire front across all 12 burns. Using pretreatment variables as covariates, longleaf pine survival and volume per hectare were significantly less on the three prescribed fire treatments than on checks. Least-square means in 2006 for survival were 70, 65, 64, 58, and 56% and volume per hectare was 129, 125, 65, 84, and 80 m³/ha on the check, herbicide, March-, May-, and July-burn treatments, respectively. A wildfire in March 2007 disproportionately killed pine trees on the study plots. In October 2007, pine volume per hectare was 85, 111, 68, 98, and 93 m³/ha and survival was 32, 41, 53, 57, and 55% on the check, herbicide, March-, May-, and July-burn treatments, respectively, after dropping trees that died through January 2009 from the database. Understory plant cover was also affected by treatment and the ensuing wildfire. In September 2006, herbaceous plant cover averaged 4% on the two unburned treatments and 42% on the three prescribed fire treatments. Seven months after the wildfire, herbaceous plant cover averaged 42% on the two previously unburned treatments and 50% on the three prescribed fire treatments. Before the wildfire, understory tree cover was significantly greater on checks (15%) than on the other four treatments (1.3%), but understory tree cover was similar across all five treatments 7 months after the wildfire averaging 1.1%. The greater apparent intensity of the wildfire on the previously unburned treatments most likely resulted from a greater accumulation of fuels on the check and herbicide plots that also collectively had a higher caloric content than fuels on the biennially prescribed burned plots. These results showed the destructive force of wildfire to overstory trees in unburned longleaf pine stands while also demonstrating the rejuvenating effects of wildfire within herbaceous plant communities. They caution for careful reintroduction of prescribed fire even if fire was excluded for less than a decade.     

Long term effects of fire on ectomycorrhizas and soil properties in Nothofagus pumilio forests in Argentina

The forests of Nothofagus pumilio have historically been affected by forest fires. The effects of fire on certain above and belowground, biotic and abiotic components of these ecosystems have been previously documented, albeit belowground components have received much less attention. It has been suggested that the effects observed in the short-term after a fire usually differ from the longer-term effects. The long-term effects of fire (i.e. >5 years after burning) on belowground components in Nothofagus forests are currently unknown. In the present study we evaluated the long-term effect of fire on ectomycorrhiza (ECM) colonization and morphotype composition in N. pumilio roots, as well as soil chemical properties in temperate forests in Patagonia. Sampling was conducted in three mature monospecific forests. In each, nearby burned and unburned sites were selected. The time since the occurrence of fires differed between areas (i.e. 6-10 years). Within each site, 3 transects of 40 m were established randomly along which 5 samples of roots and soil were collected in spring and autumn. The main results were: (1) in comparison with the unburned site, ECM colonization was lower in the burned site in the area with the shorter time length since fire occurrence and no effects in the other two areas were observed; (2) richness and diversity were not significantly affected by fire but there was a significant effect of season for both parameters, being higher in spring; (3) ECM dominance was significantly higher in the unburned than in the burned site in Tronador, while in Challhuaco the opposite was observed, mainly in autumn; (4) in general carbon, nitrogen and phosphorous decreased while pH increased in the burned sites; (5) ECM colonization positively correlated with NH⁴⁺ and phosphorus and negatively with pH but was not significantly correlated with organic matter or any other soil variable. Altogether the results suggest that effects of fire on ectomycorrhiza and soil properties in N. pumilio forests are probably related to the time elapsed since fire occurrence combined with site characteristics. In addition, the direct and indirect effects of fire in these forest systems may persist for more than 10 years.     

南水北调中线水源林水质年际变化及趋势——以秦岭火地塘天然林为例

在南水北调中线水源地天然林分布区--秦岭南坡中山地带,选择火地塘林区2个小流域及2个支沟集水区,对8年间径流水化学成分年际变化及其影响因素进行分析.结果表明:火地塘林区径流pH值年际变化总体上呈降低趋势,NO-3、NH 4、Ca、Mg及Cd 浓度呈上升趋势,主要与当地汽车尾气排放等交通污染有关;Pb浓度上升为土壤吸附Pb解吸或含Pb矿物的溶解所致;K、PO3-4、Na、Mn及Zn浓度呈降低趋势缘于森林植被的逐渐恢复. 据此对南水北调中线水源地天然林水质发展趋势进行初步预测,结果表明:中线水源地天然林径流pH值将呈降低趋势,NO-3、NH 4、Ca及Mg浓度会上升,但均不会对水质造成较大的不利影响;K、PO3-4、Na、Mn、Zn浓度亦将呈降低趋势,其中PO3-4浓度降低有利于缓解丹江口水库水质富营养化的威胁;Cd、Pb浓度可能上升,应引起重视.     

Genotypic Variation in Nutrient Selectivity in Populus under NaCl Stress

We used a salt-resistant poplar genotype Populus euphratica and two salt-sensitive genotypes, Populus 'popularis 35-44' (P. popularis) and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) to examine genotypic differences in nutrient selectivity under NaCl stress. One-year-old seedlings of P. euphratica and one-year-old hardwood cuttings of P. popularis were used in a short-term study (24 hours), while in a long-term study, up to 4 weeks, two-year-old seedlings of P. euphratica and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) were compared. In the short-term study, K+ concentration in the xylem sap ([K+]xylem) of P. euphratica significantly increased after salt stress was initiated, and maintained 1-2 fold higher than control levels during the period of salt stress (24 hours). Xylem Ca2+ and Mg2+ concentrations ([Ca2+]xylem, [Mg2+]xylem) in P. euphratica resembled the pattern of K+ despite a lesser magnitude in elevation. However, [K+]xylem, [Ca2+]xylem and [Mg2+]xylem in P.     

Distribution of saproxylic beetles in a recently burnt landscape of the northern boreal forest of Québec

This study evaluated the importance of burned habitat characteristics as well as the likely dispersal from specific habitats in the distribution of saproxylic beetles the same year as a fire occurred, in burned black spruce stands (Picea mariana [Mill] B.S.P.) in the northern boreal forest of Québec. The distribution of early post-fire saproxylic species was mainly driven by burned habitat attributes at the plot scale (0.04 ha), especially fire severity, suggesting that the effect of environment attributes can act at a relatively fine scale. Some xylophagous and most predaceous species were more abundant in severely burned stands whereas fire severity had the opposite effect on several common mycophagous species. The amount of newly fire-killed trees that could be used as breeding substrates in the burned stands had only a weak positive influence on these functional groups. The great majority of early saproxylic species were weakly associated with the distance from unburned forests or other recently burned patches that could act as potential “source habitats”. Indeed, these variables were of lesser importance than the attributes of the burned habitat. Woody debris that were already present in plots before the fire, potentially serving as local of source-populations for early colonizers, had virtually no influence on the local abundance of species. Many saproxylic species, including some true pyrophilous, clearly showed higher abundance as distance from unburned stands increased. This unexpected relation may reflect that dispersal of insects toward the burnt landscape very shortly after fire could be driven by the higher amount of volatiles released by severely burned forests, which are more likely as distance from unburned forest increased.     

黔中山地2种喀斯特森林对降雨量分配和降雨中离子浓度的影响

黔中山地2种喀斯特森林的林冠截留总量均值为76.36mm、灌草层截留总量均值为435.75mm、净地表径流总量均值为11.06mm、90cm壤中流量均值为10.76mm、蒸发及其它量均值为509.75mm,其相对值为7.32%、41.76%、1.06%、1.03%、48.84%,与其它森林类型对降雨量的影响模式明显不同。不同喀斯特森林类型对随降雨流动的Ca^2＋,Mg^2＋,K^＋,Na^＋,Cl^-,NO3^-,NH4^＋,SO4^2-有稀释或积聚作用,主要受森林树种组成和结构以及土壤类型的影响,这为利用喀斯特森林改善水质、净化空气提供了依据。除马尾松树干径流中所测离子浓度均有积聚作用外,杨树、枫香、樟和冬青对部分离子有积聚作用、对另一部分离子有稀释作用,因树种而异。相对于林外降雨,林内降雨中离子浓度增大的有Ca^2＋、Mg^2＋、K^＋、NH4^＋、SO4^2-、NO3^-、降低的有Na^＋,地表径流中所测离子浓度均增大,相应集水区溪流中离子浓度增大的有Ca^2＋、Mg^2＋、Na^＋、NO3^-、降低的有K^＋、NH4^＋、SO4^2-。黑色石灰土和黄色石灰土对90cm壤中流的离子浓度有不同效应,二者均具有集聚作用的是Ca^2＋、Mg^2＋、SO4^2-、稀释作用的是NO3^-。Cl^-在喀斯特森林降雨中的规律性较差。     

秦岭林区径流水化学对雨水酸化的响应

在秦岭南坡天然林分布地带选择火地塘典型林区,测定区内雨季降雨和流域出口径流水样pH值及水化学成分,探讨秦岭林区径流水化学对雨水酸化的响应.结果表明:长期雨水酸化可导致林区径流pH值降低,Ca2+和Mg2+浓度降低,K+和Na+浓度变化与雨水酸化关系不大;径流Zn,Pb和Cd浓度对雨水酸化响应不明显,酸化雨水未导致森林土壤富集的重金属释放.