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PubMed2003

[The influence of simulated acid rain on acidity and K+ leaching regulation of different soil layers].

The influence of simulated acid rain on acidity and K+ release of different soil layers of red soil from Jiangxi was investigated in the lab when surface soil was mixed with KCl. The results indicated that pH of leaching solution first decreased, then increased in the different soil layers, but pH at the beginning moment of leaching existed prominent differences and pH of leachate of pH 2.5 acid rain in A and AB layers again decreased during subsequent stage. There was a peak value of EC of leachate appearing at the beginning stage, it showed that nutrient ions in soil rapidly moved downwards into lower depth of profile. K+ concentration of effluent solution was related to acidity of acid rain and the pH2.5 value of acid rain accelerated K+ transportation downwards along profile. K+ release of A soil layer was divided into two moments which one was the rapid rate of K+ release process at the moment of beginning and then into the middle rate of release process. As to pH 4.5 value of acid rain, it also existed rapid and slow rate processes.

Acid Rain↗
PubMed2004

[Radiation characteristics in a tropical seasonal rain forest canopy gap].

Based on the observations in the radiation with different wavelengths in tropical seasonal rain forest canopy gap, interior of forest, and meteorological station in different seasons, the radiation characteristics of canopy gap were discussed. The results showed that the value of different wavelength radiation had the phenomenon of "suddenly emergent" at the center and north edge of canopy gap. Moreover, each radiation value reached the maximum rapidly, and then decreased quickly around the noon. The daily gross radiation of different wavelengths within the canopy gap was bigger than that in the interior of forest, but smaller than that at meteorological station. Compared to the north edge, the daily gross radiation in the center of the gap was bigger in dry-hot season, rain season and later rain season, but smaller in fog-cool season, which was influenced by dense fog, solar angle and azimuth. The total daily gross solar radiation at the center was the maximum when the solar angle was the biggest in rain season, higher in later rain season and dry-hot season, and was the minimum in fog-cool season. The ratios of infrared and visible light radiation to total solar radiation varied with the seasons at the center and north edge of the canopy gap, which fully indicated the environmental heterogeneity within the canopy gap. Compared with meteorological station and interior of forest, the ratios of infrared radiation to total solar radiation in the gap were bigger than those of meteorological station, but smaller than those of interior of forest, which were just contrary to the ratios of visible light to total solar radiation. In addition, the seasonal variation of the ratios of visible light to total solar radiation was higher than that of the ratios of infrared radiation to total solar radiation within the gap. Generally, canopy gap could increase infrared radiation and decrease visible light radiation in tropical seasonal rainforest.

Environment↗
PubMed1996

Acid rain in Laos and Thailand.

Acid rain has an impact on forestry and human health. Forest degradation was noticed in the early 90's in Laos, a country without polluting industries nor intense automobile traffic. Therefore, in 1993-1994, we collected rain in one location in Thailand (Bangkok) and 4 in Laos (Luang Prabang, Vientiane, Savannaketh, Pakse); measured pH in each sample and resistivity in 2 locations. We obtained sequential meteorological satellite pictures showing the far motion of clouds, their location and course, and ultimately rain over Indochina. We conclude that acid rain forms over Thailand and falls in Laos (Vientiane, Pakse). We also measured peak flows in large groups of children, adults both non-smokers and chronic heavy smokers, in all five locations. Except for a small number of individual variations, we could not correlate the presence of acid rain and deterioration of pulmonary function in these subjects. However, we recommend active measures to curb pollution both in Thailand and Laos.

Acid Rain↗
PubMed1997

Antioxidant responses to simulated acid rain and heavy metal deposition in birch seedlings.

This study measured the responses of different anti-oxidants in 2-year-old birch (Betula pendula Roth) seedlings subjected to simulated acid rain (pH 4.0) and heavy metals (Cu/Ni), applied alone or in combination for 2 months. The applied concentrations of pollutants did not significantly affect seedling biomass or total glutathione levels. Acid rain alone increased superoxide dismutase (SOD) activity both in leaves and roots, while heavy metals alone inhibited SOD activity in roots. Both acid rain and heavy metals applied singly increased ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) activities in leaves but decreased activities in roots. In contrast, acid rain and heavy metal treatments increased glutathione reductase (GR) activity in roots but not in leaves. Spraying birch seedlings with a mixture of acid rain and heavy metals increased SOD, APX and GPX activities in leaves and GR activity in roots. However, the effects of mixed pollutants on enzyme activities usually were less than the summed effects of individual pollutants. Enzyme responses also depended on where pollutants were applied: spraying pollutants onto the shoots initiated higher responses in SOD, APX and GPX than did application to the soil surface, while the opposite was true for GR.

Journal Article↗
PubMed2000

Valuation of consumption and sale of forest goods from a Central American rain forest

Researchers recognize that society needs accurate and comprehensive estimates of the economic value of rain forests to assess conservation and management options. Valuation of forests can help us to decide whether to implement policies that reconcile the value different groups attach to forests. Here we have measured the value of the rain forest to local populations by monitoring the foods, construction and craft materials, and medicines consumed or sold from the forest by 32 Indian households in two villages in Honduras over 2.5 years. We have directly measured the detailed, comprehensive consumption patterns of rain forest products by an indigenous population and the value of that consumption in local markets. The combined value of consumption and sale of forest goods ranged from US$17.79 to US$23.72 per hectare per year, at the lower end of previous estimates (between US$49 and US$1,089 (mean US$347) per hectare per year). Although outsiders value the rain forest for its high-use and non-use values, local people receive a small share of the total value. Unless rural people are paid for the non-local values of rain forests, they may be easily persuaded to deforest.

Journal Article↗
PubMed2005

Biomass burning in the Amazon-fertilizer for the mountaineous rain forest in Ecuador.

BACKGROUND: Biomass burning is a source of carbon, sulfur and nitrogen compounds which, along with their photochemically generated reaction products, can be transported over very long distances, even traversing oceans. Chemical analyses of rain and fogwater samples collected in the mountaineous rain forest of south Ecuador show frequent episodes of high sulfate and nitrate concentration, from which annual deposition rates are derived comparable to those found in polluted central Europe. As significant anthropogenic sources are lacking at the research site it is suspected that biomass burning upwind in the Amazon basin is the major source of the enhanced sulfate and nitrate imput. METHODS: Regular rain and fogwater sampling along an altitude profile between 1800 and 3185 m has been carried out in the Podocarpus National Park close to the Rio SanFrancisco (3 degrees 58'S, 79 degrees 5'W) in southern Ecuador. pH values, electrical conductivity and chemical ion composition were measured at the TUM-WZW using standard methods. RESULTS AND DISCUSSION: Results reported cover over one year from March 2002 until May 2003. Annual deposition rates of sulfate were calculated ranging between 4 and 13 kg S/ha year, almost as high as in polluted central Europe. Nitrogen deposition via ammonia (1.5-4.4 kg N/ha year) and nitrate (0.5-0.8 kg N/ha year) was found to be lower but still much higher than to be expected in such pristine natural forest environment. By means of back trajectory analyses it can be shown that most of the enhanced sulfur and nitrogen deposition is most likely due to forest fires far upwind of the ecuadorian sampling site, showing a seasonal variation, with sources predominantly found in the East/North East during January-March (Colombia, Venezuala, Northern Brazil) and East/SouthEast during July-September (Peru, Brazil). CONCLUSION: Our results show that biomass burning in the Amazon basin is the predominant source of sulfur and nitrogen compounds that fertilize the mountaineous rain forest in south Ecuador. RECOMMENDATION AND OUTLOOK: The mountaineous rain forest in south Ecuador has developed on poor and acid soils, with low nutrient availability. The additional ferilization resulting from anthropogenic biomass burning constitutes a significant disturbance of this ecosystem, its functioning and biodiversity. Thus it is planned to employ isotope analyses for quantifying the pathways. of nitrate and sulfate deposition in these natural forests.

Air Movements↗
PubMed2005

Explosive radiation of Malpighiales supports a mid-cretaceous origin of modern tropical rain forests.

Fossil data have been interpreted as indicating that Late Cretaceous tropical forests were open and dry adapted and that modern closed-canopy rain forest did not originate until after the Cretaceous-Tertiary (K/T) boundary. However, some mid-Cretaceous leaf floras have been interpreted as rain forest. Molecular divergence-time estimates within the clade Malpighiales, which constitute a large percentage of species in the shaded, shrub, and small tree layer in tropical rain forests worldwide, provide new tests of these hypotheses. We estimate that all 28 major lineages (i.e., traditionally recognized families) within this clade originated in tropical rain forest well before the Tertiary, mostly during the Albian and Cenomanian (112-94 Ma). Their rapid rise in the mid-Cretaceous may have resulted from the origin of adaptations to survive and reproduce under a closed forest canopy. This pattern may also be paralleled by other similarly diverse lineages and supports fossil indications that closed-canopy tropical rain forests existed well before the K/T boundary. This case illustrates that dated phylogenies can provide an important new source of evidence bearing on the timing of major environmental changes, which may be especially useful when fossil evidence is limited or controversial.

Biological Evolution↗
PubMed2002

Rain: relaxations in the sky.

We demonstrate how, from the point of view of energy flow through an open system, rain is analogous to many other relaxational processes in nature such as earthquakes. By identifying rain events as the basic entities of the phenomenon, we show that the number density of rain events per year is inversely proportional to the released water column raised to the power of 1.4. This is the rain equivalent of the Gutenberg-Richter law for earthquakes. The event durations and the waiting times between events are also characterized by scaling regions, where no typical time scale exists. The Hurst exponent of the rain intensity signal H=0.76>0.5. It is valid in the temporal range from minutes up to the full duration of the signal of half a year. All of our findings are consistent with the concept of self-organized criticality, which refers to the tendency of slowly driven nonequilibrium systems towards a state of scale-free behavior.

Journal Article↗
PubMed2000

[Seed rain and seed bank of constructive species in evergreen broadleaved forest at Chongqing Simian Mountain].

The study shows that the early and late seed rains of constructive tree species in evergreen broadleaved forest at Chongqing Simian Mountain had no activity. The bigger the seeds of the species and the earlier or later the seeds of the species matured, the higher the proportion of the seed rain damaged by animals. The quantitative variation of seed rain, active seed rain and seed bank did not take place at the same time. At early time, the number of seed banks of Castanopsis fargesii, Lithocarpus glabra, Quercus myrsinrefolia, Castanopsis plasyacantha, Cinamomum subavenium which own more active seed rain increased by geomitric series. The seed banks of Castanopsis orthacantha and Schima argentea were small, only survived a short time, and did not sprout next year. The quantitative dynamics of seed banks and their increasing or decreasing rates were decided by the proportion damaged by animals, dying speed of seeds and their resistance to pathogens and adverse circumstances, and the state of seed germination.

Biological Specimen Banks↗
PubMedDate not supplied

Acid rain: what we know, what we did, what we will do.

This paper reviews the involvement of the Canadian province of Ontario in the acid rain issue. Ontario is a major producer of acid gas emissions and suffers significant environmental consequences because of acid rain. The province's substantial contribution to the scientific understanding of acid rain is summarized with emphasis on the extent and origins of the deposition it receives, the impact on the aquatic environment, and the impact on the terrestrial environment. This paper discusses the history of the government's success at reducing acid gas emissions through the 1970's when legislators set out to enhance local or "ambient" air quality, the first legislation to require SO2 reductions from companies already in compliance with ambient air quality legislation, and the current Countdown Acid Rain program which reduces SO2 emission limits by 67%. The process used to establish the tough new limits while reasonably anticipating the development of SO2 control technologies is detailed along with the specific requirements of the major emitters controlled by the regulations. Projections confirm that while the Countdown reductions will bring about significant reductions in deposition, adequate environmental protection in Canada cannot be achieved without some comparable U.S. acid gas abatement effort.

Acid Rain↗
PubMed1975

Influence of humidity and rain on uptake and metabolism of 14C-azinphos-methyl in bean plants.

In several experiments the influence of relative humidity and rain on uptake and metabolism of carbonyl-14C-azinphos-methyl was examined in bean plants under the following environmental conditions: Growth room with 35/80%, 65/85% and 95/95% (day/night) relative humidity and open field with and without rain. Increasing relative humidity had an enhancing effect on the rate of uptake and metabolism. A higher portion of water-soluble compounds was found in the bean tissue, although the azinphos-methyl itself is relatively non-polar. Low relative humidity and possible dry periods in summer will reduce the uptake and will leave the azinphos-methyl relatively persistent on the leaf surface. Rain or spray irrigation easily removed azinphos-methyl from the leaves. The rate of this removal seemed to depend on the intensity and time of rainfall after application. However, repeated wettings by rain may simultaneously stimulate uptake and metabolism of azinphos-methyl by the leaves.

Azinphosmethyl↗
PubMed2006

Chemical characteristics of rain water at an urban site of south western Turkey.

In this study, chemical composition of the rain water in Mugla was investigated from February to April 2002. Rain water samples were obtained from Mugla, a small city in south western Turkey. The Yatagan Power Plant is located 30 km northwest of Mugla city. The values of pH and the concentrations of major ions (Ca2+, Na+, K+, SO4(2-), NO3-, NH4+) in the rainwater samples were analyzed. The pH varied from 4.5 to 7.7 with an average of 6.9 which was in alkaline range considering 5.6 as the neutral pH of cloud water with atmospheric CO2 equilibrium. In the total 30 rain events, only two events were observed in acidic range (< 5.6) which occurred after continuous rains. The equivalent concentration of components followed the order: Ca2+ > SO4(2-) > NH4 + > NO3- > Na+ > K+ > H+. The volume-weighted mean (VWM) of the measured ionic sum is 371.62 microeq/l. The ratio of between sum cations and sum anions (Sigma cations /Sigma anions) is 1.52 microeq/l. The alkaline components (Ca2+, Na+, K+) contribute 52%, NH4 + 8%, whereas, the contribution from the acidic components is relatively small (40%). The low concentrations of H+ found in rainwater samples from Mugla suggest that an important portion of H2SO4 and HNO3 have been neutralized by alkaline particles in the atmosphere. The dust-rich local and surrounding limestone environment might have caused the high concentration of Ca2+ in Mugla area. The relatively high concentration of NH4+ observed at Mugla is suspected to be due to surrounding agricultural. The results obtained in this study are compared with those other studies conducted at various places in the world.

Agriculture↗
PubMed1985

Effects of simulated acid rain and (+/-)-2-(2,4-dichlorophenoxy) propanoic acid on selected crops.

The effect of foliar-applicated (+/-)-2-(2,4-dichlorophenoxy)propanoic acid (2,4-DP) under simultaneous influence of simulated acid rain at pH levels of 3.3, 4.3, and 5.6 was examined for young plants of white mustard, rape, cress, lettuce, radish, carrot, oat, and barley grown in climate chambers. After 1-2 weeks with daily showers plants received a single foliar application of 2,4-DP in aqueous solution (500 microliter; 0.25-50.0 mg X liter-1). After a post-treatment period of 2-3 weeks with daily showers the plants were sampled. 2,4-DP at 5 mg X liter-1 or higher concentrations caused various symptoms for the dicotyledons. Monocotyledons and carrot remained unaffected. The application of acid rain at pH 3.3 produced morphological changes, increased the symptoms from 2,4-DP, and reduced the dry weight and the leaf to stem ratio. Cress exposed only to acid rain showed necrotic spots and chlorosis at pH 3.3. By decreasing pH taller plants with smaller leaves were observed. The combined effect of acid rain and 2,4-DP was additive rather than synergistic.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2006

Partial neutralization of rain by seaspray: the case of Recôncavo, Bahia-Brazil.

In the Recôncavo of Bahia (located between 12 degrees 33' and 13 degrees 10'S and 38 degrees 00'and 39 degrees 00'W), there are significant discharges of SO(2) and NO(x) due to local, industrial and urban activities. The incoming air masses from the Atlantic Ocean are enriched with seaspray, which neutralizes part of the rain acidity. The extent of seaspray neutralization of rain acidity was quantified in four sites of the region, each with different loads of seaspray. Rain samples were obtained daily at the same time, integrating the precipitation of the previous 24h, using wet-only collectors and analyzed for pH by potentiometry and for sodium by flame photometry. The amount of rain acidity in Recôncavo neutralized by seaspray ranged from <1% up to 88% and depended on the site. On average, neutralization ranged from 5% to 18%.

Acid Rain↗
PubMed2005

Fog drip and its relation to groundwater in the tropical seasonal rain forest of Xishuangbanna, Southwest China: a preliminary study.

Rain, fog drip, shallow soil water and groundwater were collected for two years (2002-2003) for stable isotopic analysis, at a tropical seasonal rain forest site in Xshuangbanna, Southwest China. The fog drip water ranged from -30 to +27 per thousand in deltaD and -6.2 to +1.9 per thousand in delta(18)O, conforms to the equation deltaD=7.64delta(18)O+14.32, and was thought to contain water that has been evaporated and recycled terrestrial meteoric water. The rain was isotopically more depleted, and ranged from -94 to -45 per thousand in deltaD, and -13.2 to -6.8 per thousand in delta(18)O. The shallow soil water had a composition usually between those of the rain and fog drip, and was assumed to be a mixture of the two waters. However, the soil water collected in dry season appeared to contain more fog drip water than that collected in rainy season. The groundwater in both seasons had an isotopic composition similar to rainwater, suggesting that fog drip water does not play a significant role as a source of recharge for the groundwater. This groundwater was thought to be recharged solely by rainwater.

China↗
PubMed2001

High-performance ion-exclusion/cation-exchange chromatography of anions and cations in acid rain waters on a weakly acidic cation-exchange resin.

A new method for the simultaneous determination of anions (sulfate, nitrate, and chloride) and cations (sodium, ammonium, potassium, magnesium, and calcium) in acid rain waters was investigated using high-performance ion-exclusion/cation-exchange chromatography with conductimetric detection on a separation column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the hydrogen-form and an eluent comprising 1.5 mM sulfosalicylic acid-6 mM 18-crown-6 at pH 2.6, operated at 1.5 ml/min. Effective separation and highly sensitive conductimetric detection for the anions and the cations was achieved in about 14 min. Since the ionic balance (equivalents of anions/equivalents of cations) of acid rain waters of different pH (4.40-4.67) ranged from 0.97 to 0.94, evaluation of the water quality of acid rain was possible. This method was successfully applied to the simultaneous determination of the anions and the cations in acid rain transported from mainland China and North Korea to central Japan monitored by a meteorological satellite data analyzer.

Acid Rain↗
PubMed2000

Occurrence of pesticides in rain and air in urban and agricultural areas of Mississippi, April-September 1995.

In April 1995, the US Geological Survey began a study to determine the occurrence and temporal distribution of 49 pesticides and pesticide metabolites in air and rain samples from an urban and an agricultural sampling site in Mississippi. The study was a joint effort between the National Water-Quality Assessment and the Toxic Substances Programs and was part of a larger study examining the occurrence and temporal distribution of pesticides in air and rain in the Mississippi River basin. Concurrent high-volume air and wet-only deposition samples were collected weekly. The air samplers consisted of a glass-fiber filter to collect particles and tandem polyurethane foam plugs to collect gas-phase pesticides. Every rain and air sample collected from the urban and agricultural sites had detectable levels of multiple pesticides. The magnitude of the total concentration was 5-10 times higher at the agricultural site as compared to the urban site. The pesticide with the highest concentration in rain at both sites was methyl parathion. The pesticide with the highest concentration in the air samples from the agricultural site was also methyl parathion, but from the urban site the highest concentration was diazinon followed closely by chlorpyrifos. More than two decades since p,p'-DDT was banned from use in the United States, p,p'-DDE, a metabolite of p,p'-DDT, was detected in every air sample collected from the agricultural site and in more than half of the air samples from the urban site.

Agriculture↗
PubMed2006

Foliar temperature tolerance of temperate and tropical evergreen rain forest trees of Australia.

Australian rain forests extend from tropical climates in the north to temperate climates in the south, providing an opportunity to investigate physiological responses to temperature of both temperate and tropical species within the same forest type. Eight, rain forest canopy tree species were selected to cover the 33 degrees latitudinal range of rain forests in eastern Australia. Temperature tolerance was measured in 6-year-old plants grown in a common environment, by exposing leaves to a series of high temperatures during late summer and a series of freezing temperatures during midwinter. Damage was evaluated based on chlorophyll fluorescence measurements made 2 h after exposure and by visual assessment of leaf damage made a week after exposure. Leaves of the tropical species were more heat tolerant and less frost tolerant than leaves of the temperate species, which is consistent with their climate distributions. In contrast, the temperature tolerance of the photosynthetic apparatus was unrelated to climate in a species' native habitat. However, the tropical species underwent significant photoinhibition during winter. All species maintained the integrity of the photosynthetic apparatus and avoided tissue damage over a similar span of temperatures (about 60 degrees C), reflecting the similar annual temperature ranges in Australia's temperate and tropical rain forests. Chlorophyll fluorescence measurements and visual assessment of leaf damage provided different estimates of the absolute and relative temperature tolerances of the species, thus emphasizing the importance of a direct assessment of tissue damage for determining a species' temperature tolerance.

Australia↗