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PubMed2002

On the relationship between acid rain and cloud type.

Spanish European Monitoring and Evaluation Programme (EMEP) stations were selected to relate acid rain episodes with the meteorological structure that caused the rainfall during a 5-year period. A principal component analysis (PCA) was used to determine the origin of major ions (SO4(2-), NO3-, Cl-, Ca2+, K+, Mg2+, and Na+) in the rainwater. In addition, the meteorological origin of the rain was identified. Previous works suggested a relationship between acid rain and storm convective clouds. However, statistical analyses of pH values show that only the short-lived convective phenomena may cause acid rain in Spain. In fact, rain generated by fronts and that related to long-lived convective systems is neutral or even slightly basic. Results suggest that the acid rain might be related to the meteorological time scale instead of to the cloud type.

Acid Rain↗
PubMed1996

Wet-cold exposure and hypothermia: thermal and metabolic responses to prolonged exercise in rain.

Simulated conditions of hiking in rain, wind, and cold, without protective rainwear, were used to investigate wet-cold hypothermia in 18 male subjects. Thermal, metabolic, and motor responses were monitored during an attempted 5-h walk (5.1 km/h) at 5 degrees C, with continuous exposure to rain (7.4 cm/h) and wind (8.0 km/h) over the final 4 h. The majority of subjects (11) could not complete the protocol because of intolerance of wet-cold conditions during the last 2 h. Therefore, data from 5 subjects who completed the protocol in rain and control conditions were used to describe the general pattern of response. During the 1st h of walking, core temperature rose 1 degree C to 38.1 degrees C. The subsequent 2 h of rain caused substantial cold stress, indicated by a 40% increase in heat production due to shivering and significant loss of strength and manual dexterity. However, core temperature only decreased to 37.1 degrees C, merely eliminating the initial exercise hyperthermia. Over the last 2 h of rain, core temperature remained relatively stable at 36.8 degrees C, decreasing slightly to 36.4 degrees C by 5 h. Two other subjects developed significant hypothermia (35 degrees C). One demonstrated fatigue of shivering after 2.5 h of rain, confirming the exhaustion hypothesis of wet-cold hypothermia. The older cooled rapidly when he failed to maintain the walking pace. We conclude that if a person can tolerate the intense discomfort of prolonged wet-cold exposure, he or she has the potential to resist significant core hypothermia for at least 4 h of walking under the conditions of this experiment. Exceptions to this generalization occur, making exposure of < 4 h a hypothermia risk for some individuals. Exposures > 4 h would involve increasing probability of rapid decline into hypothermia, associated with exhaustion of shivering and exercise heat production.

Adult↗
PubMed2003

Effects of simulated acid rain on the pollen germination and pollen tube growth of apple (Malus sylvestris Miller cv. Golden).

The pollens of apple flowers have been treated with simulated acid rain solutions in range of pHs 2.9 to 5.0 in order to determine the threshold proportion values that lead the observed symptoms of detriments of acid rain. Compared to controls (pH 6.5), pollen germination decreased by 41.75% at pH 3.3 and pollen tube elongation decreased by 24.3% at pH 3.4. Acid rain threshold proportion value was around pH 3.3 and 3.4 for apple pollen germination and pollen tube elongation, respectively. Furthermore, pollen tube elongation was determined to be more sensitive to acid rain than pollen germination. The pH values below 3.1 resulted in complete destruction of pollen tubes. Pollen germination entirely stopped at around pH 3.0. Finally, it has been shown that the acid rain has a blocking effect on pollen germination and pollen tube elongation in apple. The conclusion is that not only pH value but also the quantity of acid rain is important factor in germination. The results were found statistically significant through the LSD test at levels of p < 0.05 and p < 0.01.

Acid Rain↗
PubMed2002

Application of an automatic sampling and measurement system to a mountainous stream investigation during rain events.

An automatic sampling and measurement system was developed to take water samples efficiently during rain events. The system consisted of an automatic sampler, a rain gauge and a data logger as well as sensors for pH, electrical conductivity (EC), and both water and air temperature. The system was tested in a stream in a forested watershed (5.8 km2) located in the middle of Hyogo prefecture, Japan. The sampling program has been improved gradually. For several rain events of 30 to 157 mm, most water samples were in agreement with the hydrograph from the beginning of each rainfall until the rain had stopped and the water level had begun to fall. The fluctuations in water quality in the samples taken by the automatic sampler during those rain events showed patterns similar to those of water samples taken by hand. There were also no problems with the water level or the EC sensor during the investigation periods, but the pH values were lower than those in the laboratory. The results showed that the system is suitable for taking water samples from mountainous streams during rain events.

Altitude↗
PubMed2005

[Effects of simulated acid rain and its acidified soil on soluble sugar and nitrogen contents of wheat seedlings].

The study showed that the cation release of simulated rain caused soil acidification and base ions release. With the decrease of simulated acid rain pH from 5.6 to 2.5, the acid rain-leached soil pH decreased from 6.06 to 3.41, and its total amount of exchange base ions decreased from 56.5 to 41.1 mmol x kg(-1). Spraying simulated acid rain on the shoots of wheat seedlings planted on such acidified soils caused a rapid decrease in the soluble sugar and nitrogen contents of wheat seedlings, and reduced some of their physiological activities. The effect of spraying simulated acid rain on the soluble sugar, nitrogen, and chlorophyll contents and photosynthetic rate of wheat stems and leaves was larger than that of acidified soil, while the effect of the latter on the soluble sugar and nitrogen contents and the physiological activity of NR and GOGAT in root system of wheat seedlings was larger than that of the former. The intensive acid rain of pH < or = 3.0 and the corresponding acidified soil had an obvious harm to the growth and physiological activity of wheat seedlings.

Acid Rain↗
PubMed2005

Effects of simulated acid rain on fertility of litchi.

The regulatory role of calcium in fertility of pollen and pistil under simulated acid rain was investigated. The germination percentage of pollen treated with acid rain of pH 4.5 was 9.42% lower than that of control, and that of pH 3.5, pH 2.5 and pH 1.5 were 22.47%, 45.49% and 71.62%, respectively. Simultaneously, the injury character of pollen was obviously observed when flowers were treated with acid rain of pH 3.5. The difference in fruit setting rate between the female flower treated with acid rain of pH 4.0 and the control was significant at p < 0.05. Ca(NO3)2 of 0.2-0.4 mmol/L could promote pollen germination under the stress of acid rain. The beneficial function was reduced when calcium concentration surpassed 0.8 mmol/L. Spraying 2 mmol/L Ca(NO3)2 reduced the injury of acid rain to pistil and increased fruit-setting rate significantly. The physiological importance of calcium during pollen germination and pistil development was also discussed.

Acid Rain↗
PubMed1997

Effects of birds on the intensity of ant rain: a terrestrial form of invertebrate drift

Large numbers of wood ants, Formica aquiloniacrawl up trees to gather food (arthropods and honeydew), and most return to the ground the same way. A small but noticeable percentage, however, returns to the ground by falling. This continuous rain of free-falling ants, from trees to the ground, is analogous to the drift of invertebrates in freshwater streams, and provides ecologists with an easily replicated terrestrial system for studying the phenomenon of drift. In a field experiment in this system, when birds came to forage, the total numbers and percentages of ants entering the rain increased dramatically. Initial background levels of ant rain (before birds came to forage) ranged from 0 to 11.9% (X=4.0%). When birds came to forage in certain trees, the percentage of ants entering the rain in those trees ranged from 2.9 to 28.4% (X=9.1%). In trees not visited by birds, ant rain decreased slightly during the same period to a mean of 3.7%. As the total time birds spent foraging in a tree increased, ant rain there also increased.

Journal Article↗
PubMed1996

Effects of simulated acid rain and ozone on foliar chemistry of field-grown Pinus ponderosa seedlings and mature trees.

We investigated the additive and interactive effects of simulated acid rain and elevated ozone on C and N contents, and the C:N ratio of one-year-old and current-year foliage of field-grown mature trees and their half-sib seedlings of a stress tolerant genotype of ponderosa pine. Acid rain levels (pH 5.1 and 3.0) were applied weekly to foliage only (no soil acidification or N addition), from January to April, 1992. Plants were exposed to two ozone levels (ambient and twice-ambient) during the day from September 1991 to November 1992. The sequential application of acid rain and elevated ozone mimicked the natural conditions. Twice-ambient ozone significantly decreased foliar N content (by 12-14%) and increased the C:N ratio of both one-year-old and current-year foliage of seedlings. Although similar ozone effects were also observed on one-year-old foliage of mature trees, the only statistically significant effect was an increased C:N ratio when twice-ambient ozone combined with pH 3.0 rain (acid rain by ozone interaction). Enhancing the effect of twice-ambient ozone in increasing the C:N ratio of one-year-old foliage of mature trees in June was the only significant effect of acid rain.

Journal Article↗
PubMed2004

Identification and characterization of rain, a novel Ras-interacting protein with a unique subcellular localization.

The Ras small GTPase functions as a signaling node and is activated by extracellular stimuli. Upon activation, Ras interacts with a spectrum of functionally diverse downstream effectors and stimulates multiple cytoplasmic signaling cascades that regulate cellular proliferation, differentiation, and apoptosis. In addition to the association of Ras with the plasma membrane, recent studies have established an association of Ras with Golgi membranes. Whereas the effectors of signal transduction by activated, plasma membrane-localized Ras are well characterized, very little is known about the effectors used by Golgi-localized Ras. In this study, we report the identification of a novel Ras-interacting protein, Rain, that may serve as an effector for endomembrane-associated Ras. Rain does not share significant sequence similarity with any known mammalian proteins, but contains a Ras-associating domain that is found in RalGDS, AF-6, and other characterized Ras effectors. Rain interacts with Ras in a GTP-dependent manner in vitro and in vivo, requires an intact Ras core effector-binding domain for this interaction, and thus fits the definition of a Ras effector. Unlike other Ras effectors, however, Rain is localized to perinuclear, juxta-Golgi vesicles in intact cells and is recruited to the Golgi by activated Ras. Finally, we found that Rain cooperates with activated Raf and causes synergistic transformation of NIH3T3 cells. Taken together, these observations support a role for Rain as a novel protein that can serve as an effector of endomembrane-localized Ras.

Amino Acid Sequence↗
PubMed2005

"A 30% chance of rain tomorrow": how does the public understand probabilistic weather forecasts?

The weather forecast says that there is a "30% chance of rain," and we think we understand what it means. This quantitative statement is assumed to be unambiguous and to convey more information than does a qualitative statement like "It might rain tomorrow." Because the forecast is expressed as a single-event probability, however, it does not specify the class of events it refers to. Therefore, even numerical probabilities can be interpreted by members of the public in multiple, mutually contradictory ways. To find out whether the same statement about rain probability evokes various interpretations, we randomly surveyed pedestrians in five metropolises located in countries that have had different degrees of exposure to probabilistic forecasts--Amsterdam, Athens, Berlin, Milan, and New York. They were asked what a "30% chance of rain tomorrow" means both in a multiple-choice and a free-response format. Only in New York did a majority of them supply the standard meteorological interpretation, namely, that when the weather conditions are like today, in 3 out of 10 cases there will be (at least a trace of) rain the next day. In each of the European cities, this alternative was judged as the least appropriate. The preferred interpretation in Europe was that it will rain tomorrow "30% of the time," followed by "in 30% of the area." To improve risk communication with the public, experts need to specify the reference class, that is, the class of events to which a single-event probability refers.

Journal Article↗
PubMed2000

Chemistry of rain water in Riyadh, Saudi Arabia.

Twenty-three rain water samples were collected from 15 sampling locations in Riyadh during four rain events in 1994 and analyzed for pH, conductivity, TDS, alkalinity, Cl, NO(3), F, SO(4), Na, Mg, Ca, and 12 trace metals. The pH ranged between 6.83 and 8.21. The major cation and anion were Ca and SO(4), contributing with 30.5% and 20. 8%, respectively, to TDS. Moderate variation in major ions concentration was found to occur between different sites. The concentrations of different metals varied considerably from one sampling location to another. The dominant trace metal ions in the rain water samples were Zn, Pb, and Al. Samples collected from a site near a cement factory in Riyadh showed maximum concentrations of most of the major ions and metals. The concentrations of various ions in the first rain event were comparatively higher than the concentrations of these ions in the later rain events.

Electrochemistry↗
PubMed2004

Impacts of a heavy storm of rain upon dissolved and particulate organic C, N and P in the main river of a vegetation-rich basin area in Japan.

The impacts of a heavy storm of rain upon the dissolved and particulate organic matter (OM), nitrogen (N) and phosphorus (P) in the main river of the vegetation-rich Nagara River basin were investigated using water samples collected along the river line during a critical typhoon-induced heavy rain storm event. Besides, based on a high performance size-exclusion chromatography (HPSEC) system, the variance of dissolved OM (DOM) in its molecular weight (MW) characteristics was also assessed. From the MW standpoint, DOM components merged into the river along the river line resembled those present in its headwater. The MW range changed only slightly from 1010 to 5900 at the upstream (US), to 1130-5900 and 1200-5900 Da at the midstream (MS) and downstream (DS), respectively, while the corresponding weight-averaged MW (M(w)) decreased from 3669 to 3330 and 2962 Da. The heavy storm of rain enhanced the content of DOM; however, apart from a small larger-MW fraction (about 5900-6800 Da), the newly emerged DOM constituents exhibited an MW range similar to those existed before the storm. Due also to the storm of rain, total P and N (TP and TN) changed markedly in the ranges of 6.6-11.9, 8.3-40.6 and 48.4-231.3 microg/l for TP, and 145.4-296.0, 502.2-1168.7 and 1342.7-1927.3 microg/l for TN at the US, MS and DS, respectively. The larger values of TP and TN generally appeared for samples at elevated river water levels. The enhanced presence of P was found largely attributed to its particulate form; while, for N, the contribution from its dissolved form was significant. The newly emerged suspended particles via the storm-water contained lower content of OM, N and P, and a general decreasing trend of the particulate OM, N and P along the river line was also confirmed. The C/N ratio in the dissolved form varied in 0.7-6.7 and decreased downstream, while, that in the particulate form 2.3-17.3. Suspended particles that emerged in the river water during the storm exhibited larger C/N values. N/P in both dissolved and particulate forms varied in the ranges of 2.2-17.1 and 12.9-444.9, respectively, and a general trend of either increasing or decreasing in relation to the storm of rain was not revealed.

Agriculture↗
PubMed2001

Application of a LRT model to acid rain control in China.

For further control of acid rain and SO2 pollution in China, acid rain control zones and sulfur dioxide pollution control zones were designated where acid rain or serious SO2 pollution occurs or may occur. In this study, sulfur deposition in east China was computed through a policy-oriented, two-dimensional Eulerian model for long-range transport and deposition of SO2 and SO4(2-). The model predictions were in accordance with the wet deposition monitored. Results show that concentrations of SO2 and SO4(2-) are higher in north China than those in the south, and high deposition of sulfur occurs in most areas of North China, in the lower reaches of the Changjiang (Yangtze) River and around Chongqing and Guiyang in southwest China. Total emission of SO2 from the modeling region (from 19 degrees N to 42 degrees N, and from 104 degrees E to 124 degrees E) was about 20 million tons in 1995. The model predicts that 48% of this deposits within the region as dry deposition, 38% deposits as wet deposition, and only about 14% was transported out of the region. The modeling results of sulfur deposition were directly applied in designating acid rain control zones in China, and the emission-deposition relationship derived was also used to formulate middle- and long-range planning programs for regional acid rain control in China.

Acid Rain↗
PubMed1977

Sources of sulphur in rain collected below a wheat canopy.

Vegetation plays an important role in the cycle of sulphur between the atmosphere and the soil. We have measured the quantity of sulphur in rain collected below a maturing wheat canopy. This sulphur has three sources: first, the atmosphere, from which falling rain gains SO2 and sulphate; second, leaf surfaces, from which rain washes sulphur which was previously deposited by turbulent transfer ('dry deposition'), and third, leaf tissue, from which rain leaches sulphur. We have now deduced from field and laboratory measurements that leaching supplied nearly 90% of the sulphur gained by rain as it fell through the wheat canopy. Only a small fraction of sulphur which had been dry-deposited on the surface of leaves could be washed off.

Gases↗
PubMed2000

Millennial-scale dynamics of southern Amazonian rain forests.

Amazonian rain forest-savanna boundaries are highly sensitive to climatic change and may also play an important role in rain forest speciation. However, their dynamics over millennial time scales are poorly understood. Here, we present late Quaternary pollen records from the southern margin of Amazonia, which show that the humid evergreen rain forests of eastern Bolivia have been expanding southward over the past 3000 years and that their present-day limit represents the southernmost extent of Amazonian rain forest over at least the past 50,000 years. This rain forest expansion is attributed to increased seasonal latitudinal migration of the Intertropical Convergence Zone, which can in turn be explained by Milankovitch astronomic forcing.

Bolivia↗
PubMedDate not supplied

Leaching from organic matter-rich soils by rain of different qualities: I. Concentrations.

Soil monoliths from an area exposed to acid precipitation and from an unpolluted area were used in a lysimeter experiment to study effects of different rain qualities on the chemical composition of the leachate from shallow soils rich in organic matter. The vegetation was either dominated by moorgrass [Molinia caerulea (L.) Moench] or heather [Calluna vulgaris (L.) Hull]. The lysimeters received either "acid rain" (pH 4.3) or "normal rain" (pH 5.3). High concentrations of dissolved organic carbon (DOC) were characteristic of the leachate. The different "rain" qualities had no significant influence on the DOC concentration. More DOC was, however, leached from lysimeters with heather vegetation. Roughly 50% of the aluminum (Al) was in complex with organic material and the Al charge was calculated to be between +1.4 and +2.0. Sulfate (SO4(2-)) was the only component that was significantly influenced by the treatment, as more was leached from lysimeters receiving "acid rain." Sulfate was poorly correlated with pH, suggesting that reduced SO4(2-) input would not necessarily lead to reduced acidity. Differences in the pH of the leachate due to the treatments were less than 0.15 pH units. Nitrate (NO3-) was only leached in very low concentrations and of little consequence for the leachate acidity. Some observations do, however, suggest that NO3- may contribute to acidification in episodes with high precipitation. High concentrations of Cl- in the leachate and a significant positive correlation between Cl-, H+, and base cations indicate that sea salt episodes may be important for soil acidification and acidity of the leachate.

Acid Rain↗
PubMed2002

[Regulation function of calcium on photosynthesis of Dimocarpus longana Lour. cv. wulongling under simulated acid rain stress].

Studies on the regulation function of calcium on photosynthesis of Dimocarpus longana under simulated acid rain stress showed that the photoreduction activity of chloroplasts was activated when the concentration of calcium ion in reaction medium ranged from 0 to 5 mmol.L-1, and peaked at the 3.5 mmol.L-1, which was 41.90% higher than that of control. Conversely, the activity of chloroplasts reduced 26.06% in the reaction medium with a concentration of 2 mmol.L-1 EGTA, as compared with the control. Both Mn2+ and Mg2+ could inhibit photoreduction activity. The photophosphorylation activity increased when the concentration of calcium ion in reaction medium ranged from 0 to 6 mmol.L-1, and peaked at the 4.5 mmol.L-1, while superoxidase dismutase (SOD) activity rose from 0 to 6 mmol.L-1 and peaked at 6 mmol.L-1. Calcium ion with the concentration of both 10 mmol.L-1 and 15 mmol.L-1 could increase the content of chlorophyll(Chl), stabilize the membrane structure of leaf discs, and reduce the membrane permeability under simulated acid rain with pH value of 3.0. The effect in 15 mmol.L-1 were better than in 10 mmol.L-1. However, the injury of acid rain to leaves was strengthened when the concentration of calcium was higher than 20 mmol.L-1. Net photosynthesis rate (Pn) rose when leaves sprayed with 15 mmol.L-1 Ca(NO3)2 before treatment of acid rain stress of pH 2.5. All of the results represented the excellent protection function of calcium on D. longana leaves under simulated acid rain.

Acid Rain↗
PubMed2002

[Effects of simulated acid rain on chloroplast activity in Dimorcarpus longana Lour. cv. wulongling leaves].

A decreased content of chlorophyll (Chl) and carotenoid (Car) was found in the Dimorcarpus longana Lour. cv. wulongling leaves when treated with < pH 3.5 acid rain. The decline of Chl content was caused by the reduction of Chla, while Chlb was less sensitive to the acid rain, which resulted in a decrease of Chla/Chlb ratio. The content of Car and the ratio of Chla to Chlb reduced with the duration of stress time. The injury of acid rain to photosynthetic pigments was intensified by illumination. The activities of photoreduction, photophosphorylation and H(+)-ATPase activity decreased with the reduction of pH value under the simulated acid rain. Therefore, the injury of electron transport chain and the uncoupling of photophosphorylation might lead to the ineffective absorption, transportation and transformation of light energy. In our study, the process of photophosphorylation was more sensitive to acid rain than that of photoreduction.

Acid Rain↗