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1.
Fogwater, fog drip and rainwater chemistry were examined at a tropical seasonal rain forest in Xishuangbanna, southwest China between November 2001 and October 2002. During the period of observation, 204 days with the occurrence of radiation fog were observed and the total duration of fog was 1949 h, of which 1618 h occurred in the dry season (November to April), accounting for 37.0% of the time during the season. The mean pH of fogwater, fog drip and rainwater were 6.78, 7.30, and 6.13, respectively. The ion with the highest concentration for fog- and rainwater was HCO3 ?, which amounted to 85.2 and 37.3 μeq l?1, followed by Ca2+, Mg2+ and NH4 +. Concentrations of NO3 ?, HCO3 ?, NH4 +, Ca2+, and K+ in fogwater samples collected in the dry season were significantly greater when compared to those collected in the rainy season. It was found that the ionic concentrations in fog drip were higher than those in fogwater, except for NH4 + and H+, which was attributed to the washout of the soil- and ash-oriented ions deposited on the leaves and the alkaline ionic emissions by the leaves, since biomass burns are very common in the region and nearby road was widening.  相似文献   

2.
Chemical composition of fog and rain water was studied during a 47-day experimental period. The differences between the fog and rain water were found to be significantly for most analyzed ions. H+, NH4 +, NO3 ?, and SO4 2? made up 85% of the total median ion concentration in fog and 84% in rain water. The total mean equivalent concentration was 15 times higher in the fog than in the rain water. The fog water samples were classified according to their air mass history. The analysis of the 120 h backward trajectory led to the identification of three advection regimes. Significant differences of ion concentrations between the respective classes were found. Air masses of class I travelled exclusively over the Pacific Ocean, class II were carried over the Philippines, and class III were advected from mainland China. The turbulent fog water deposition was determined by the means of the eddy covariance method. The total (turbulent plus gravitational) fog water fluxes ranged between +31.7 mg m?2 s?1 and ?56.6 mg m?2 s?1. Fog water droplets with mean diameters between 15 μm and 25 μm contributed most to the liquid water flux. The sample based nutrient input was calculated on the basis of the occult and wet deposition, and the concentrations of the simultaneously collected fog and rainwater samples, respectively. The nutrient input through wet deposition was about 13 times higher than through occult deposition.  相似文献   

3.
Fog water and precipitation were collected and analyzed to study fog and precipitation chemistry. The research was carried out through one year from April 1997 to March 1998 at Mt. Rokko in Kobe. Higher fog occurrence and larger volume of fog water were observed in summer, corresponding to the trend of seasonal variation in precipitation amount. The annual mean pH value of fog water (3.80) was lower by ca. one pH unit than that of precipitation (4.74). The concentration of chemical species in fog water was ca. 7 times that in precipitation. The highest anion and cation concentrations were SO4 2? and NH4 + in fog water and Cl? and Na+ in precipitation, although the Cl?/Na+ equivalent ratio in both fog water and precipitation was almost the same value as that in sea water. It is considered that in the longest fog event, NH4 + and nss-SO4 2? in fog water mainly scavenged as (NH4)2SO4, mainly derived from (NH4)2SO4 (aerosol) in the atmosphere, NH3 was scavenged at the growing stage, and SO2 was also scavenged after the mature stage. NO3 ? in this fog event was mainly absorbed as HNO3.  相似文献   

4.
Several fog episodes occurred in California’s San Joaquin Valley during winter 2000/2001. Measurements revealed the fogs to generally be less than 50 m deep, but to contain high liquid water contents (frequently exceeding 200 mg/m3) and large droplets. The composition of the fog water was dominated by ammonium (median concentration?=?608 μN), nitrate (304 μN), and organic carbon (6.9 ppmC), with significant contributions also from nitrite (18 μN) and sulfate (56 μN). Principal organic species included formate (median concentration?=?32 μN), acetate (31 μN), and formaldehyde (21 μM). High concentrations of ammonia resulted in high fog pH values, ranging between 5.8 and 8.0 at the core measurement site. At this high pH aqueous phase oxidation of dissolved sulfur dioxide and reaction of S(IV) with formaldehyde to form hydroxymethanesulfonate are both important processes. The fogs are also effective at scavenging and removal of airborne particulate matter. Deposition velocities for key solutes in the fog are typically of the order of 1–2 cm/s, much higher than deposition velocities of precursor accumulation mode aerosol particles. Variations were observed in deposition velocities for individual constituents in the order NO2 ??>?fogwater?>?NH4 +?>?TOC ～ SO4 2??>?NO3 ?. Nitrite, observed to be enriched in large fog drops, had a deposition velocity higher than the average fogwater deposition velocity, due to the increase in drop settling velocity with size. Species enriched in small fog drops (NH4 +, TOC, SO4 2?, and NO3 ?) all had deposition velocities smaller than observed for fogwater. Typical boundary layer removal rates for major fog solute species were estimated to be approximately 0.5–1 μg m?3 h?1, indicating the important role regional fogs can play in reducing airborne pollutant concentrations.  相似文献   

5.
Ambient particle and gas concentrations, wet deposition and dry deposition were measured in Warren, MI between December 18, 1983 and April 6, 1984. Dry deposition was measured to various surfaces in a cutoff bucket, including a snow surface, a snow/water surface during melting and a deionized water surface. Dry deposition velocities were calculated for various species from the ratio of the dry flux to the ambient concentrations. The dry deposition velocities measured to a snow surface were 0.082 cm s?1 SO2 2.0 for HNO3, 0.083 for NH4 +, 2.0 for Ca++ and 4.3 for Cl?. The values were not significantly different for a snow/water surface during melting compared to a snow surface. However, higher values of 0.69 cm s?1 for SO2, 6.2 for HNO3, 0.33 for NH4 +, and 4.2 for Ca++ were found to a deionized water surface in the spring. These higher values could be due to the higher air temperature, the pH of the liquid or to increased atmospheric mixing during this period.  相似文献   

6.
The purpose of the present study is to analyse the chemical composition of bulk and wet atmospheric deposition samples in the Guaíba Hydrographic Basin (GHB), in south Brazil. Samples of bulk and wet deposition were analysed during a 1-year's period (January to December 2002) at three different stations, i.e., 8° Distrito and CEASA stations in the city of Porto Alegre, and Charqueadas station, in Charqueadas city. Conductivity, pH, Cl?, NO3 ?, F?, SO4 2 ?, Na+, K+, Mg2 +, NH4 + and Ca2 + were determined. The pH presented an average value between 4.75 and 7.45. Enrichment factor was characterised based on groups of acid (pH < 5.65) and alkaline (pH > 5.65) samples. For most of the studied ions, EF in bulk deposition was higher in alkaline samples, while in wet deposition there was little difference between acid and alkaline samples. The Multivariate Analysis technique, i.e. the Canonical Correlation Analysis (CCA), determined relationships between the two different data set (chemical and meteorological), identified the source (anthropogenic or natural) of the studied variables.  相似文献   

7.
Fog/cloud and rain water were collected at the mountainside of Hachimantai range in northern Japan and rain water was also collected at Akita City in order to investigate the air pollutant scavenging mechanism. The concentrations of various ions in these samples were analyzed, and the fog drop size and the wind direction were measured at each fog event. The fog at Hachimantai range had a very high total ion concentration, and was considerably acidified by non sea salt (nss-) SO4 2? and NO3 ?, compared with the rain at Akita and all sites in Hachimantai range. Using the oblique rotational factor analysis, three factors were extracted as the air pollutants; A: (NH4)2SO4+H2SO4, B: sea salts+HNO3+H2SO4, C: NH4NO3+OH?. These salts are well-known as the cloud condensation nuclei (CCN). Combining the factor analysis with the 72h back trajectory at 850hPa level, the contribution of Factor A was closely connected to the long-range transportation of anthropogenic or natural aerosol in air masses of continental origin.  相似文献   

8.
Rain event samples have been collected in Haifa, Israel, for nine hydrological years 1981 to 1990. Precipitation amount, pH, SO4 =, NO3 ?, Cl?, NH4 +, Na+, K+, Ca++, Mg++ and alkalinity of rainwater samples were recorded. The sampling and analysis program was based on WMO recommendations for background networks. The sampling was performed manually, and the analysis was based on wet chemistry for ions and atomic absorptions for metals. Data of 187 rain samples showed that the average pH was 5.3±1.1∶ 26% of the rain events were below pH of 5.6 and 23% above pH of 7.0. Some simple chemical mass-balance considerations indicate that natural sources, sea salt and soil carbonates are the main contributors to rain chemistry. However, the presence of low pH events observed over the years suggests that the impact of anthropogenic emissions may overwhelm the buffering capacity of the alkaline aerosol.  相似文献   

9.
The fluxes of N–NO 3 ? , N–NH 4 + , S–SO 4 2? , Na+, K+, Ca2+ and Mg2+ from bulk precipitation to throughfall, stemflow and soil water surface flows were studied during 1999–2003 in planted Norway spruce forest stands of different ages (11, 24, 91 and 116 years in 1999). Also, runoff from the corresponding Potok Dupniański Catchment in the Silesian Beskid Mts was studied. N deposition was above the critical load for coniferous trees. The interception increased with stand age as well as leaf area index and so did the leaching from the canopy of almost all the analysed elements, but especially S–SO 4 2? , H+ and K+. The nutrient fluxes varied with age of the spruce stands. Throughfall showed a high amount of S and of the strong acids (S–SO 4 2? and N–NO 3 ? ) deposited to the soil, especially in older spruce age classes. Decomposition of organic matter caused a rise in water acidity and an increase in the concentrations of all the analysed ions; the leaching of minerals, however, was low (under 1%). The horizontal soil water flow showed an increase in the amount of water and amount of ions and contributed to a further decrease of pH at the soil depth of 20 cm. Element concentrations and their amounts increased with water penetrating vertically and horizontally on the slopes. Considerable amounts of ions, especially S and alkaline cations, were carried beyond the reach of the root system and then left the catchment. In the long term, these mineral losses will adversely affect health and growth of the spruce stands, and the increased acidity with stand age will presumably have negative effects on the runoff water ecosystem.  相似文献   

10.
Chemical and Statistical Analysis of Precipitation in Singapore   总被引：1，自引：0，他引：1  
The results of chemical analyses of precipitation samples collected in Singapore between August 1997 and July 1998 are presented. Major inorganic and organic ions were determined in 169 rain samples collected using an automated wet-only sampler. The daily sample pH values ranged from 3.49 to 6.54 with a volume-weighted mean of 4.50, and about 88% of the samples had pH values less than 5.0 Nss-SO4 2? accounted for about 53 % of the sum of anions in rain, whereas chloride, nitrate, formate, and acetate accounted for the remainder. Rain chemistry data were analyzed using principal component analysis to find possible sources of the measured chemical species. Three components that accounted for 83.5% of the total variance were extracted: sea-spray (Na+, Cl? and and Mg2+) and soil particles (Ca2+ and K+), acid factor (nss-SO4 2?, NO3 ?, NH4 +, and H+), and biomass burning (HCOO? and CH3COOO?).  相似文献   

11.
The cation content of droplets collected from Phaseolus vulgaris (pinto bean) leaf surfaces during misting was more strongly influenced by mist pH (2.5, 4.0, or deionized water) than by source of acidity (HCI or H2SO4 + HNO3). Concentrations of Ca2+, Mg2+, and K+ were highest in droplets from leaves treated with the pH 2.5 mists, but there were often no differences between the pH 4.0 and deionized water treatments. Cation content and pH of droplets from leaves treated with pH 2.5 mists increased across the three days of treatment, while those from leaves treated with less acidic mists decreased or did not change across the days of treatment. Source of acidity often affected foliar concentrations of Mg2+, K+, and Na+, but in inconsistent directions, and foliar concentrations of Mg2+ and K+ were unaffected by mist pH. Foliar Ca 2+ concentrations were often highest in leaves treated with pH 2.5 mists, in contrast to expectation, perhaps because of effects of acidic mist on foliar carbohydrate status. Despite the large efflux of cations from leaves treated with pH 2.5 mists, foliar cation concentrations in nonmisted foliage were sometimes lower than in misted foliage (Ca2+), but were higher in other cases (Na+) or indistinguishable in still others (K?). While exposure of plants to highly acidic mists appeared to cause accelerated efflux of foliar cations, effects on foliar chemistry are probably dependent on soil nutrient status and on other aspects of plant vigor.  相似文献   

12.
Laboratory experiments were conducted to evaluate the impact of various concentrations (2.5, 5, 10, 25, and 50%) of fertilizer factory effluent on certain physico-chemical properties of soil, and germination, growth, photosynthetic pigments, and dry matter productions of corn (Zea mays L.) and rice (Oryza sativa L.). The effluent was highly alkaline and contained high amounts of N+, Ca2+, Na+, Cl?, CO in3 su? , HCO in3 su? and suspended and dissolved solids. Its BOD value was also high. The effluent treatment to soil resulted in a significant increase in the water soluble salts, electrical conductivity, cation exchange capacity, pH, N, Ca, Na, and Cl content of the soil for effluent concentrations of 10% and above. The effluent in the lower concentrations of 2.5 and 5 % enhanced the growth and development of corn and rice. Higher concentrations of effluent (10% and above), however, inhibited the percentage of seed germination and caused deleterious effects on the dry matter production, yield (quantitative and qualitative) and the photosynthetic pigments of both test crops.  相似文献   

13.
Precipitation chemistry and atmospheric element-deposition in an agroecosystem at the North-Sea Coast of Schleswig-Holstein The objective of this study was to examine the chemistry of bulk precipitation and atmospheric element inputs in an arable soil near the North Sea coast of Schleswig-Holstein, North Germany. Bulk precipitation was collected at weekly intervals from November 1989 to October 1991. Precipitation amount, pH, electrical conductivity, and concentrations of Na+, K+, NH4+, Mg2+, Ca2+, Cl?, NO3?, and SO42? were recorded. The average volume-weighted pH was 5.5 and the average EC was 92 μS cm?1. Sodium and Cl? were with 64% and 76% the dominant ions (equivalent concentration) in bulk precipitation indicating the influence of the North Sea. The contribution of marine alkalinity to neutralization reactions of bulk precipitation was negligible (1%). The neutralizing substances NH3 (63%) and Carbonate (36%) were more important. Deposition rates were in 1990 and 1991 97.0 and 51.7 kg Na+ ha?1, 6.2 and 4.0 kg K+ ha?1, 15.0 and 8.4 kg Mg2+ ha?1, 13.2 and 10.4 kg Ca2+ ha?1, 12.3 and 9.5 kg NH4+-N ha?1, 8.0 and 5.9 kg NO3?-N ha?1, 168 and 83.1 kg Cl? ha?1 and 19.1 and 12.7 kg SO42?-S ha?1. In 1990 both more westerly winds and stronger wind-forces occurred than in 1991 and resulted in higher inputs of marine origin. Calculated on Cl? basis 93% of Na+, 55% of K+, 74% of Mg2+, 24% of Ca2+, and 36% of SO42? were of marine origin. Atmospheric input of marine origin supplied 39–72% of Mg and 21–37% of S requirement for crop production. The North Sea is an important source providing significant amounts of these elements to agricultural crops.  相似文献   

14.
The aim of this trial was to study the spatio-temporal variability in solution nutrient concentration under intensive greenhouse tomato production, to determine the number of suction-cups needed to obtain a representative sample and the influence by the position in the greenhouses. Twenty sampling points were selected within the greenhouse with one suction-cup per sampling point. One soil solution were sampled per point at weekly intervals to analyze for pH, electrical conductivity, chloride, nitrate, phosphate, sulfate, sodium, potassium, calcium, and magnesium (EC, Cl?, NO3?, H2PO4?, SO42—, Na+, K+, Ca2+, and Mg2+) concentrations. The pH, Cl?, H2PO4?, and SO42? concentrations showed no spatio-temporal variation but EC, NO3?, and K+ showed temporal variation. The spatial variability in EC, K+, Na+, Mg2+, and Ca2+ can be influenced by microclimate and topography. The numbers of suction cups required for a representative sample ranged from 1 to 10 depending on nutrient.  相似文献   

15.
Fifty-three bulk deposition samples were collected at the campus of the University of Brunei Darussalam between April and November 1994 using a funnel-in bottle sampler. The pH and conductivity were determined immediately after collection on aliquots of the sample. Samples were refrigerated at 5 °C for subsequent chemical analysis. Analyses for Cl?, NO3 ? and SO4 2? were carried out by means of ion chromatography, while Na+, K+, Ca2+ and Mg2+ were determined by atomic spectroscopy. The recorded pH values were in the range of 4.35 to 6.59. Seventy-seven percent of the samples had pH values below 5.6, demonstrating the occurrence of acidic deposition. The range, mean and standard deviation of measured concentrations are reported. There was very little difference between measurements in filtered and unfiltered samples. Correlation coefficients between pairs of parameters are reported and discussed.  相似文献   

16.
In a laboratory study, KCI- a neutral salt - equivalent to 300kg K/ha and 272 kg CI/ha was applied to the surface of undisturbed columns of a forest soil (Terra Fusca Rendzina) under steady state unsaturated flow conditions (1.0 cm/day). The effluent of the five soil columns was collected daily, and pH, cation- and anion concentrations were measured. Most of the applied K ions were retained in the top 10cm of the soil and moved in decreasing amounts further down the column. Among the cations studied Ca++, Mg++, and Na+ were lost from the system, K+, NH4, Fe+++, Mn++, H+, and Al+++ were retained. Nitrate and sulfate concentrations in the leachates showed a temporary decrease when CI passed through the columns. This decrease was accompanied with a decrease in pH. CI?, NO3?, and SO4? exhibited leaching losses. Besides these anions, HCO3? played an important role.  相似文献   

17.
The Nandong Underground River System (NURS) is located in Southeast Yunnan Province, China. Groundwater in NURS plays a critical role in socio-economical development of the region. However, with the rapid increase of population in recent years, groundwater quality has degraded greatly. In this study, the analysis of 36 groundwater samples collected from springs in both rain and dry seasons shows significant spatial disparities and slight seasonal variations of major element concentrations in the groundwater. In addition, results from factor analysis indicate that NO 3 ? , Cl?, SO 4 2? , Na+, K+, and EC in the groundwater are mainly from the sources related to human activities while Ca2+, Mg2+, HCO 3 ? , and pH are primarily controlled by water–rock interactions in karst system with Ca2+ and HCO 3 ? somewhat from anthropogenic inputs. With the increased anthropogenic contaminations, the groundwater chemistry changes widely from Ca-HCO3 or Ca (Mg)-HCO3 type to Ca-Cl (+NO3) or Ca (Mg)-Cl (+NO3), and Ca-Cl (+NO3+SO4) or Ca (Mg)-Cl (+NO3+SO4) type. Concentrations of NO 3 ? , Cl?, SO 4 2? , Na+, and K+ generally show an indistinct grouping with respect to land use types, with very high concentrations observed in the groundwater from residential and agricultural areas. This suggests that those ions are mainly derived from sewage effluents and fertilizers. No specific land use control on the Mg2+ ion distribution is observed, suggesting Mg2+ is originated from natural dissolution of carbonate rocks. The distribution of Ca2+ and HCO 3 ? does not show any distinct land use control either, except for the samples from residential zones, suggesting the Ca2+ and HCO 3 - mainly come from both natural dissolution of carbonate rocks and sewage effluents.  相似文献   

18.
The study aimed to determine the influence of catchment characteristics and flood type on the relationship between streamflow and a number of chemical characteristics of streamwater. These were specific electrical conductivity (SC), pH, the concentrations of main ions (Ca2+, Mg2+, Na+, K+, HCO 3 ? , SO 4 2? , and Cl?), and nutrients (NH 4 + , NO 2 ? , NO 3 ? , and PO 4 3? ). These relationships were studied in three small catchments with different geological structure and land use. Several flood types were distinguished based on the factors that initiate flooding and specific conditions during events. Geological factors led to a lower SC and main ion concentrations at a given specific runoff in catchments built of resistant sandstone versus those built of less resistant sediments. A lower concentration of nutrients was detected in the semi-natural woodland catchment versus agricultural and mixed-use catchments, which are strongly impacted by human activity. The strongest correlation between streamflow and the chemical characteristics of water was found in the woodland catchment. Different types of floods were characterized by different ion concentrations. In the woodland catchment, higher SC and higher concentrations of most main ions were noted during storm-induced floods than during floods induced by prolonged rainfall. The opposite was true for the agricultural and mixed-use catchments. During snowmelt floods, SC, NO 3 ? , and most main ion concentrations were higher when the soil was unfrozen in the agricultural and mixed-use catchments versus when the soil was frozen. In the case of the remaining nutrients, lower concentrations of NH 4 + were detected during rain-induced floods than during snowmelt floods. The opposite was true of PO 4 3? .  相似文献   

19.
A water quality survey has been performed on selected lakes and streams in southwest China. The purpose of the study was to measure the concentrations of acidic deposition and surface water chemistry in a region of severe air pollution, forest decline, and relatively sensitive geology to acidic deposition. We show that, although there are some high elevation lakes of low acid neutralizing capacity (ANC<150μeq L?1, acidification of lakes has not occurred in southwest China due to production of base cations in soil and dry deposition of dust that serves to neutralize acidic deposition. Water chemistry is buffered by high base cation concentrations (Ca2+, Mg2+, Na+, and K+ greater than 300μeq L?1, and pH values are always greater than 6.5.  相似文献   

20.
The changes in ionic contents were studied in acidic precipitation samples collected for precipitation events in Taipei, which is near the sea. The storage cases under investigation include filtration, refrigeration, and light. Thus the experimental design leads all precipitation samples collected in the same rain event stored under different conditions. They were then analyzed six times successively within two months to provide the information containing potential ionic composition change. The measured constituents are H+, K+, Na+, Ca2+, Mg2+, NH4 +, NO3 ?, SO4 2?, and Cl?. The comparison of measured ionic concentrations corresponding to different storage methods yield no significant difference. The increases of NO3 ? and decreases of NH4 + with time were observed to be of similar magnitude, while the variation of pH values is significant. The presented study indicated the important role played by sample storage in determining the ionic composition of precipitation samples.  相似文献   

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