Chemistry of atmospheric precipitation at the Western Arabian Gulf Coast

Rainwater and atmospheric bulk deposition samples were collected at a station on the rooftop of the Research Institute of King Fahd University of Petroleum and Minerals in Dhahran. Continuous sampling was carried out manually throughout the rainy season between December 1987 and February 1988, and for one rainfall event in March 1987. A total number of 13 samples were collected and investigated for pH and dissolved ionic composition using inductivity coupled plasma emission spectrometry (ICP) and ion chromatography (IC). The range and volume-weighted average pH were 5.1–7.2 and 5.48, respectively. Significant negative linear correlations were observed between the precipitation pH and rain depth, and between pH and the summation of dissolved {(Ca²⁺ + Mg²⁺)−(SO₄²⁻ + NO₃⁻ + NO₂⁻)} (in μeqℓ⁻¹). The ionic summation also correlated negatively with rain depth. The ionic abundance in rainwater (in μeqℓ⁻¹) expressed in concentration order showed the general trend SO₄²⁻ > HCO₃⁻¹ = Cl⁻ = NO₃⁻ > NO₂⁻ for anions and Ca²⁺ > Na⁺ > Mg²⁺ > NH₄⁺ > K⁺ > H⁺ > Sr²⁺ for cations. Good mass balance between cations and anions was observed. Total NO₃⁻ contribute equally to precipitation acidity as SO₄²⁻ and Ca²⁺ plus Mg²⁺ in alkaline suspended particulates from natural sources are the major ions which buffer the acidity of precipitation. The NH₄⁺ ion which is also present plays an insignificant role in the acid/base equilibrium of rainwater.     

Origin of soluble chemical species in bulk precipitation collected in Tokyo,Japan: Statistical evaluation of source materials

An iterative least-squares method with a receptor model was applied to the analytical data of the precipitation samples collected at 23 points in the suburban area of Tokyo, and the number and composition of the source materials were determined. Thirty-nine monthly bulk precipitation samples were collected in the spring and summer of 1987 from the hilly and mountainous area of Tokyo and analyzed for Na⁺, K⁺, NH₄⁺, Mg²⁺, Ca²⁺, F⁻, Cl⁻, Br⁻, NO₃⁻ and SO₄²⁻ by atomic absorption spectrometry and ion chromatography. The pH of the samples was also measured. A multivariate ion balance approach (Tsurumi, 1982, Anal. Chim. Acta138, 177–182) showed that the solutes in the precipitation were derived from just three major sources; sea salt, acid substance (a mixture of 53% HNO₃, 39% H₂SO₄ and 8% HCl in equivalent) and CaSO₄. The contributions of each source to the precipitation were calculated for every sampling site. Variations of the contributions with the distance from the coast were also discussed.     

Factor analysis of trends in Texas acidic deposition

Precipitation chemistry data collected between 1980 and 1987 for 11 NADP/NTN sites in Texas have been analyzed using factor analysis and a trend analysis of monthly averages. Factor analysis identified four major factors which differed significantly from site to site: (1) a Gulf factor of Na⁺, Cl^-, and Mg²⁺; (a) a soil factor of Ca²⁺, K⁺, Na⁺, and Mg²⁺; (3) an acid factor of H⁺, NO₋³, and SO₄⁴⁻; and (4) an aged aerosol factor of NO₃⁻, SO₄²⁻, and NH₄⁺. At Longview, the acid and Gulf factors accounted for 18 and 46%, respectively, of the variation of the data. A trend analysis was performed on the logarithm of the monthly averages at the Longview and Victoria sites, the two sites with the largest and most complete data. Results suggest that hydrogen ions have been increasing at both sites, while calcium ions have been decreasing.     

Spatial variability of urban precipitation chemistry and deposition: Statistical associations between constituents and potential removal processes of precursor species

The precipitation chemistry of Greater Manchester, a Metropolitan County in the northwest of England, has been examined for small scale spatial variability using a network of 18 bulk precipitation collectors. Significant spatial variability was found for concentrations of non-marine SO₄²⁻, NO₃⁻, NH₄⁺, Ca²⁺ and H⁺ ions. The statistical associations between the data were investigated using correlation, partial correlation and principal components analyses. It was found that zero-order correlation coefficients were inadequate for the interpretation of the data and that the computation of first, and higher order partial correlation coefficients was necessary in order to explain the interrelationships between the data and their spatial variability. The statistical associations between the data suggest relationships between Ca²⁺ and non-marine SO₄²⁻, and NO₃⁺ in precipitation which are discussed in terms of their possible precursor species. Potential source effects were examined in conjunction with atmospheric removal processes. The dry deposition of SO₄ particles, rather than the dry deposition of SO₂, may explain the spatial variability of non-marine SO₄²⁻. The erosion of CaSO₄ formed from the reaction of SO₂ with CaCO₃ on urban surfaces with subsequent resuspension is thought to be the basis of the relationship between Ca²⁺ and non-marine SO₄²⁻ concentrations in precipitation. The wet and dry deposition of CaCO₃ particles from local sources may be partially responsible for the spatial variability of H⁺, and dry deposition and scavenging of NH₃, in conjunction with the predominant wind direction may explain the spatial variability of NO₃⁻ and NH₄⁺ ions. Ammonia is thought to originate from sources both outside the study area and within it.     

Rainwater composition in Athens,Greece

Wet precipitation-only samplers were used to collect wet deposition at two sites in the Athens basin, Greece for the period March 1986–February 1987.Concentrations of major cations (H⁺, NH⁺₄, Na⁺, K⁺, Ca²⁺ and Mg²⁺) and major anions (Cl⁻, NO⁻₃ and SO²⁻₄) were determined for the first time in rainwater samples in Greece. Bicarbonate concentrations were calculated. The relative importance of natural and anthropogenic sources were estimated by a chemical balance. The majority of rain collected has a neutral or alkaline character. Acidity was due to the presence of H₂SO₄ and HNO₃. The statistical analysis of the correlation between the concentration of chemical species confirm the influence of natural and anthropogenic sources. In all samples, SO²⁻₄ concentrations exceed NO⁻₃ concentrations despite the dominance of low S oil burning in the region. The wet flux of S was calculatd to be 0.34 gm⁻²a⁻¹.     

Urban precipitation chemistry: A review and synthesis

Urban sampling sites have been specifically excluded from recent large networks for measuring chemical composition of precipitation. Because information on precipitation composition in urban areas is needed for a variety of current applications, it is useful to summarize present knowledge. Most of the available information is based on samples of bulk precipitation, collected by continuously open collectors. This method is now widely acknowledged to be of limited value because of its poor sampling characteristics for dry deposition. For many ions, particularly those residing on large airborne particles, urban bulk sampling yielded considerably higher concentrations than found in samples collected in ‘wet-only’ samplers. Spatial variability of ionic concentrations in urban areas is expressed in terms of the sample standard deviation of site precipitation-weighted means, as a percentage of the overall urban mean. Median values of the most major ions were near 30%; half of the available measurements were between 20 and 47%. Differences between urban and nearby rural concentrations of ions in precipitation were often reported. Those ions with some tendency to occur in higher concentrations in cities included Na⁺, Mg²⁺, Ca²⁺, NO₃⁻, SO₄²⁻ and Cl⁻. These differences should be viewed with caution, however, because they were usually based on one or two, possibly unrepresentative, rural sampling sites. Seasonal variations of urban [H⁺] were different in Europe and the U.S. Highest concentrations occurred in winter in Europe, but in summer in the U.S. There is a pressing need for additional urban precipitation chemistry monitoring and research.     

A comparison of urban and suburban precipitation chemistry

Precipitation samples at an urban Chicago site and a nearby suburban site were compared in order to examine the influence of emissions within a large urban area on local precipitation chemistry. Precipitation samples were collected from June 1981 to May 1982, initially for events and subsequently weekly, and precipitation-weighted concentrations (PWCs) of the major chemical constituents were calculated from concurrent urban-suburban pairs of samples, stratified according to the estimated mixed-layer wind quadrant. Overall, PWCs at the urban site were higher than those at the suburban site for Ca²⁺, Mg²⁺, NH₄⁺, NO₃⁻ and Cl⁻; approximately equal for Na⁺ and SO₄²⁻; and lower for H⁺. For precipitation in southwesterly flow, in which the suburban site was upwind of the urban site and most urban emissions, PWCs of all species except Na⁺ were higher at the urban site. For the few precipitation cases in northeasterly flow, however, differences between sites did not have a pattern consistent with a reversal in the upwind-downwind relationship.     

Chemical composition of rain in Thessaloniki,Greece, in relation to meteorological conditions

Wet precipitation was collected in Thessaloniki, Greece, during the period March 1989–December 1990 by using an automatic wet-only precipitation sampler.Rainwater samples were analysed for major cations (H⁺, NH₄⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺) and anions (Cl⁻, NO₃⁻, SO₄²⁻), in addition to acidity and conductivity measurements. The majority of rain had a neutral or alkaline character as a result of neutralization, primarily caused by calcareous soil dust and secondarily by atmospheric ammonia. In all rain, SO₄²⁻ concentration exceeded NO₃⁻ concentration. The contribution of maritime sources to the total SO₄²⁻ concentration was very low (<2%).The chemical composition of precipitation was analysed in conjunction with meteorological variables (season of the year, precipitation type, airflow patterns) to evaluate temporal variations and chemical source influence. Rain caused by weak, localized flows showed the highest acidity and the minimum influence of neutralization processes.     

Chemical characterization of acid precipitation in Albany,New York

Chemical composition of precipitation in Albany, NY from July 1986 to December 1988 has been studied. Mean volume-weighted concentrations (μeq^ℓ−1) were: acidity, 104.0; alkalinity, −63.7; SO₄²⁻, 52.8; NO₃⁻, 29.8; Cl⁻, 5.6; F⁻, 0.50; NH₄⁺, 19.3; Ca²⁺, 6.5; Mg²⁺, 2.8; Na⁺, 3.5; and K⁺, 1.4. Mean pH was 4.2 . Seasonal patterns were pronounced for most species. Concentrations of H⁺, SO₄²⁻, NO₃⁻, NH₄⁺ and Ca²⁺ peaked in the summer and spring. Deposition was related to rainfall amount by a power law relationship in which the exponent of the equation was ∮.6. Wet SO₄²⁻ deposition was 2.35 keq ha⁻¹ over a 30-month period. The SO₄²⁻ and NO₃⁻ deposition rates observed at Albany indicate that transport from midwestern sources have a major influence at this site. On the average, free H⁺ ion concentrations determined from pH measurements accounted for 51% of the measured total acidity. There were unknown species, most likely organic acids, that could contribute to the acidity. Correlation and regression analyses indicated that major anions, SO₄²⁻ and NO₃⁻, were closely associated with H⁺ and NH₄⁺ ions. Factor analysis revealed four common factors which are related to fossil-fuel combustion, sea spray, cement factory and biomass burning.     

A paired comparison of two precipitation chemistry sites in East-Central Mississipi

A paired comparison was performed on 2 years of precipitation chemistry data from Meridian and Newton, MS. The Meridian site is in violation of several National Atmospheric Deposition Program siting criteria, whereas the Newton site, 35 km west, is mostly in compliance. The two sites are compared through the use of volume-weighted means, deposition, logarithmic distributions, boxplots, paired t-tests, the nonparametric Wilcoxon test, and a form of linear regression analysis that accounts for cases in which both populations are subject to error. Results indicate Meridian has higher concentrations of all measured ions except NH₄⁺. Elevated NH₄⁺ concentrations at Newton are most likely due to the location of the site in a cattle pasture. Significant differences (95% confidence level) were found for Cl⁻, Na⁺, K⁺, Ca²⁺ and Mg²⁺. SO₄²⁻ was found to be borderline significant.     

缙云山常绿阔叶林湿沉降过程中不同空间层次水质变化特征

为全面调查森林生态系统各层次降水水质状况以及对降水中各离子的截留特征,于2013年9月至2014年8月对重庆市缙云山常绿阔叶林大气降雨、林内降雨、地表枯透水、土壤渗滤液进行了持续1a的水质效应研究.结果表明,缙云山大气降雨偏酸性(pH=4.75);土壤层和林冠层均能调升降雨的pH值,其中土壤层对pH值的调升幅度最大,其次为森林林冠层.森林林冠层对NO_3~-、Na~+有一定的吸附净化作用,降雨能够淋溶森林林冠层的NH_4~+、SO_4~(2-)、PO_4~(3-)、Mg~(2+)、Ca~(2+)和K~+.另外,枯枝落叶的降解导致构成植物组织的有机物降解为无机物,进而促使各离子质量浓度在地表枯透水中增加.森林土壤中的官能团以及胶体能够吸附并中和渗滤液中的NO_3~-、SO_4~(2-)、NH_4~+、PO_4~(3-)、K~+和Mg~(2+),同时长期处于酸性条件下的土壤层也释放出部分Na~+、PO_4~(3-)和Ca~(2+).该森林生态系统对大气降水中各离子具有较强的截留作用,但各层次对降水中的各离子表现出的截留特征不尽相同,其中以林冠层的截留作用最强.     

Elements in the precipitation of S. Paulo City (Brazil)

Rainwater samples in S. Paulo city were collected on an event basis from October 1983 to October 1985 covering two dry and two rainy periods. Bulk samples only were obtained. At the same site and period, fine, coarse and inhalable particles were also collected. Na⁺, Ca²⁺, K⁺, Mg²⁺, NO₃⁻, SO₄²⁻ and NH₄⁺ contents were determined in rainwater samples, while Na, Ca, K, Cl and S concentrations were measured in aerosol samples. Rainwater is slightly acid (mean pH = 5.0), and contains high concentrations of Ca²⁺, NO₃⁻, SO₄²⁻ and NH₄⁺. Dry and wet fluxes and washout ratios were determined for some elements. Results obtained suggest that the atmospheric composition in this city is strongly influenced by anthropogenic sources.     

中国西南酸雨区降水化学特征研究进展

西南酸雨区为我国主要酸雨沉降区,且是全球三大喀斯特集中分布区之一.本文将该区9个地点的降雨资料进行了总结、整理和分析,数据包括pH值和主离子成分(Cl~-、SO_4~(2-)、NO_3~-、Ca~(2+)、NH_4~+、Mg~(2+)、K~+、Na~+).该地区降雨中的主要阴离子为SO_4~(2-)和NO_3~-,主要阳离子为Ca~(2+)和NH_4~+.与我国其它地区相比,其酸性离子、碱性离子和总离子浓度均普遍高于东南地区、而低于我国北方地区.西南酸雨区主要以pH值为4.5~5.6的弱酸性降雨为主,占总降雨频次的58%左右.根据酸、碱性离子的相关性、中和因子等分析结果,该区雨水中的酸性物质可能受到了碱性离子的中和作用,其中起主要中和作用的离子为Ca~(2+)和NH_4~+.将该区雨水pH值和酸、碱性离子浓度与我国其它地区进行对比研究发现,西南酸雨区降雨受到的中和作用要强于东南地区,但弱于北方地区的降雨.通过对西南酸雨区降雨中主要离子来源的分析和估算,降雨中的酸性离子SO_4~(2-)和NO_3~-主要来自于人为污染;99.7%的Ca~(2+)和84.0%的Mg~(2+)为陆源贡献,这可能与西南地区碳酸盐岩广泛分布有关.     

中亚热带常绿阔叶林湿沉降过程中盐基离子变化特征

基于野外实验和室内实验相结合的方法,于2012年9月至2013年8月对四面山常绿阔叶林大气降水、穿透水、地表枯透水、土壤渗滤液进行了持续一年的森林不同层次盐基离子季节动态变化特征的研究.结果表明,四面山大气降水全年pH平均值为4.90,最大值为5.14,大气降水明显偏酸性;土壤层和林冠层能使降雨的p H值有所升高,其中土壤层对p H值的调升幅度最大,其次为森林冠层;森林冠层只对Na~+有一定的截留作用,降雨能够淋溶森林冠层的Ca~(2+)、Mg~(2+)、K~+;研究结果也表明,枯枝落叶的降解是导致各盐基离子质量浓度在枯透水中增加的主要原因;枯透水下渗的过程淋溶了森林土壤中的Ca~(2+)、Mg~(2+)、Na~+.四面山大气降水经过森林生态系统后Ca~(~(2+))、Mg~(2+)、Na~+、K~+的总截留率分别为33.82%、-7.06%、74.36%、42.87%,森林生态系统对Ca~(2+)、Na~+、K~+表现出了截留作用,其中对Na~+截留率最大.     

不同植被类型及土壤对径流水化学特征的影响

在不同植被类型覆盖条件下,对降雨形成地表径流和地下径流的化学成分变化及其与土壤剖面性质的关系进行分析,结果表明:地表径流和地下径流的化学特征与雨水基本相同,阳离子主要以Ca²⁺为主,离子排序为Ca²⁺>K⁺>Na⁺>Mg²⁺>NH₄⁺,阴离子以SO₄^2-为主,SO₄^2->NO₃^->Cl^-.降雨形成地表径流和地下径流后,各成分浓度发生了明显的变化,水体中主要的阴阳离子如Ca²⁺、Mg²⁺、K⁺、Na⁺、SO₄^2-、Cl^-等浓度增加,与雨水相比为内贮型化学成分,地下径流中Ca²⁺、Mg²⁺、SO₄^2-和Cl^-增加的幅度显著高于地表径流.相关分析结果显示,地下径流pH受到土壤pH的强烈影响,受土壤胶体吸附的影响,水体中Ca²⁺、Mg²⁺、K⁺、Na⁺等阳离子与土壤交换性阳离子之间一般呈负相关的关系,由于阴离子容易随水流失,水体中SO₄^2-、NO₃^-和Cl^-与土壤相关离子之间普遍呈正相关关系.     

Atmospheric dry deposition on pines in the Eastern Brook Lake Watershed,Sierra Nevada,California

Atmospheric dry deposition to branches of Pinus contorta and P. albicaulis was measured during summer 1987 in a sub-alpine zone at Eastern Brook Lake Watershed (EBLW), eastern Sierra Nevada, California. Results are presented as deposition fluxes of NO₃⁻, SO₄²⁻, PO₄³⁻, Cl⁻, F⁻, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺, Zn²⁺, Fe³⁺, Mn²⁺, Pb²⁺ and H⁺, and compared with other locations in California and elsewhere. Deposition fluxes of anions and cations to the pine branches were low, several times lower than the values determined near the Emerald Lake Watershed (ELW), another sub-alpine location in the western Sierra Nevada. The sums of deposition fluxes of the measured cations and anions to pine surfaces were similar, in contrast to the ELW location where the sums of cation fluxes were much higher than the sums of anion fluxes. A strong positive correlation between depositions of NO₃⁻ and NH₄⁺, as well as SO₄²⁻ and Ca²⁺, suggested that large portions of these ions might have originated from particulate NH₄NO₃ and CaSO₄ deposited on pine surfaces. An estimated total N dry deposition (surface deposition of NO₃⁻ and NH₄⁺ and internal uptake of NO₂ and HNO₃) to the forested area of the EBLW was 29.54 eq ha⁻¹ yr⁻ (about 414 g H ha⁻¹ yr⁻¹).     

Cloud chemistry measurements and estimates of acidic deposition on an above cloudbase coniferous forest

The wet, dry and cloud water deposition of acidic substances on the forest canopy are considered as major mechanisms for pollutant induced forest decline at high elevations. Direct cloud capture plays a predominant role of intercepting acidic substances in above cloud-base forests. We conducted a field study at Mt. Mitchell, North Carolina (35°44′05″N, 82°17′15″W; 2038 m MSL)—the highest peak in the eastern U.S.—during May–September 1986 and 1987 in order to analyze the chemistry of clouds in which the red spruce and Fraser fir stands stay immersed. It was found that Mt. Mitchell was exposed to cloud episodes 71% of summer days, the cloud immersion time being 28% for 1986 (a record drought summer in southeastern U.S.) and 41% for 1987. Sulfate, NO₃⁻, NH₄⁺ and H⁺ ions were found to be the major constituents of the cloud water, which was collected atop a 16.5 m tall meteorological tower situated among 6–7 m tall Fraser fir trees. The initiation of precipitation in clouds invariably diluted the cloud water acidity. The cloud water pH during short episodes (8 h duration or less), which resulted from the orographic lifting mechanisms, was substantially lower than that during long episodes, which were associated with meso-scale and synoptic-scale disturbances. Sulfate accounted for 65% acidity in cloud water, on the average, and contributed 2–3 times more than the NO₃⁻. Inferential micrometeorological models were used to determine deposition of SO₄²⁻ and NO₃⁻ on the forest canopy and the hydrological input due to direct cloud capture mechanism. The cloud water deposition ranged between 32 and 55 cm a⁻¹ in contrast to the bulk precipitation which was about 130 cm a⁻¹ as measured by an on-site NADP (National Atmospheric Deposition Program) collector. For S compounds, wet, dry and cloud water deposition accounted for 19%, 11% and 70%, respectively for 1986, and 16%, 8% and 76%, respectively for 1987. For N compounds, dry deposition contributed 35% and 23% for 1986 and 1987, respectively, whereas, cloud water deposition contributed 50% and 65% for 1986 and 1987, respectively. Our estimates are compared with the reported literature values for the other sites.     

Aspects of wet,acidifying deposition in Arnhem: Source regions,correlations and trends (1984–1991)

A time series of wet deposition in Arnhem, the Netherlands, was analysed for the period 1984–1991. Precipitation was collected with four samplers on a daily basis. A comparative study by the Dutch National Precipitation Network showed significant biases for the observations of the National Network station due to longer exposure to dry deposition. Simultaneous operation of wet-only and bulk collectors demonstrated a concentration bias of about 10% for daily bulk sampling.Using a cluster analysis of backward trajectories, clear distinctions could be made between precipitation from continental and maritime origin. Event-to-event variations in deposition seemed to be determined largely by meteorological influences. As major anthropogenic source regions, the U.K., France, Belgium and the Netherlands itself were identified. The contribution of Dutch sources to wet acid deposition in Arnhem was estimated at 30–40%.Trends and seasonal variations were analysed with an advanced time-series model based on Kalman filtering. Similar seasonal variations were found for SO₄²⁻ and NH₄⁺. Also, seasonal variations in the concentrations of H⁺ and NO₃⁻ corresponded. Significant long-term changes in deposition and concentration were found for SO₄²⁻ (about −3% yr⁻¹) and H⁺ (about −9% yr⁻¹) only. The analysed trends were decreasing, but decreases were larger in the years 1984–1986 than in the following years. The relative decrease in the wet deposition of SO₄²⁻ was substantially smaller than decrease in dry-deposited SO₂ and SO₄²⁻.     

Aerosol characteristics of Arctic haze sampled during AGASP-II

As part of the second Arctic Gas and Aerosol Sampling Program (AGASP-II), Arctic aerosol samples were collected by the NOAA WP-3D aircraft in spring 1986. The samples were analyzed in bulk and individual-particle form, using ion chromatography (IC) and electron microscopy (EM), respectively. Information on the chemical composition of the aerosol as determined by various techniques is presented, as well as morphology, concentration, and size distribution data obtained from individual particle analyses. For most flights, a stratospheric sample and a haze profile samople were collected. Haze samples exhibited greater particle concentrations than stratospheric samples, the highest concentrations in haze reaching ∼10³ cm⁻³ (non-volatile particles > 0.05 μm diam). Sulfur was consistently observed to be a major element in both large and small particles in haze samples. Crustal elements such as Si, Al, K, Ca and Fe were often present in significant concentrations together with S. Particles that did not emit X-rays, possibly organic or sooty C, were observed in significant concentrations in both tropospheric and stratospheric samples. Chemical spot tests confirmed that SO₄²⁻ was the major S-containing species and that NO₃⁻ was not nearly as prevalent as SO₄²⁻ in the Arctic aerosol particles. The mass concentrations of major anions (Cl⁻, SO₄²⁻ and NO₃⁻) and cations (Na⁺, K⁺, NH₄⁺, Ca²⁺ and Mg²⁺) in the bulk aerosols were determined using IC. The ratios between ion concentrations, e.g. Ca²⁺/Na⁺, SO₄²⁻/Na⁺ and Cl⁻/Na⁺, may serve as indicators of aerosol origins and mixing status of various air masses. Aerosols collected on six flights demonstrated variability of particle characteristics in relation to sources and transport of Arctic haze.     

崇左响水地区岩溶地下水主要离子特征及控制因素

以崇左响水地区为研究区域,于2016年丰水期、枯水期、平水期在研究区内采集210个地下水样品并测定,分析岩溶地下水的主要离子化学特征和季节变化,运用多元统计分析法研究地下水主要离子的控制因素.结果表明,研究区岩溶地下水为弱碱性淡水,优势离子均为Ca~(2+)、HCO_3~-为主,分别占全部阳离子和阴离子的75%、70%以上,K~+、Na~+、Cl~-和NO_3~-平均质量浓度表现为丰水期平水期枯水期,Ca~(2+)、Mg~(2+)、HCO_3~-、SO_4~(2-)、p H值、TDS、TZ+和TZ-未出现明显的季节性变化.受碳酸盐岩地层的控制,地下水化学类型以HCO_3~-Ca型为主,丰水期和平水期少部分水点为HCO_3·Cl-Ca和HCO_3·SO_4-Ca型水,平水期出现Cl·NO_3-Ca型水,枯水期可见HCO_3~-Ca·Mg型水,反映出少部分水点受地层中白云岩和铁质泥岩溶解、人类源NO_3~-和Cl~-的影响.地下水中Ca~(2+)、HCO_3~-主要来源于碳酸盐岩灰岩的溶解,Na~+、Cl~-、K~+、NO_3~-来源于大气输入与人为活动的贡献,Mg~(2+)、SO_4~(2-)来源于地层中白云岩、铁质泥岩溶解.地下水化学成分主要受水岩相互作用的控制,碳酸盐岩含水层中的地下水主要受碳酸盐岩溶解因子控制,村庄和人口密集区的地下水主要受大气输入与人为活动因子控制.