Chemical changes in simulated raindrops following contact with leaves of four boreal forest species

Simulated raindrops of pH 5.6 or 3.2 were sprayed on four boreal forest plant species in situ, and raindrops were subsequently collected from their leaves for chemical analysis. The purpose was to understand better the changes involved in foliar neutralisation of acidic raindrops. The species used were Cornus canadensis, Aralia nudicaulis, Maianthemum canadense, and Acer spicatum. Samples were analysed for Ca2+, Mg2+, Na+, K+, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], Cl−, and F−, as well as pH. Changes in leaf raindrop ion concentrations were greater when sprayed with the pH 3.2 than with the pH 5.6 rain. Both increases and decreases in ion concentration were found, indicating leaching and (or) dissolution of particulates on the leaf or retention by the canopy, respectively. Rapid changes in ion concentrations suggest surface deposits play an important role in leaf raindrop neutralisation. Increases in [Ca2+] and [Mg2+] in raindrops with greater neutralisation are evidence that cation exchange may also be occurring (r2 = 0.170 and 0.321, respectively, at pH 3.2; p < 0.01). There were significant negative correlations between changes in [H+] and changes in[Formula: see text], [Formula: see text], and [Formula: see text] (r2 = 0.562, 0.525, and 0.297, respectively, at pH 3.2;p < 0.01). Most of the other ions measured also showed significant correlations with changes in [H+], but generally the correlation could account for only a small percentage of the observed results (low r2). Dry deposition was also measured.

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The neutralisation of acid rain by the leaves of four boreal forest species

Canadian Journal of Botany ◽

10.1139/b88-256 ◽

1988 ◽

Vol 66 (9) ◽

pp. 1877-1882 ◽

Cited By ~ 5

Author(s):

B. A. Gaber ◽

T. C. Hutchinson

Keyword(s):

Boreal Forest ◽

Acid Rain ◽

Cell Walls ◽

Leaf Surface ◽

Weather Conditions ◽

Cornus Canadensis ◽

Exchange Processes ◽

Rapid Changes ◽

Maianthemum Canadense ◽

Rate Of Evaporation

A field study was carried out in the boreal forest of Ontario to measure the neutralisation response of the leaves of Cornus canadensis, Aralia nudicaulis, Maianthemum canadense, and Acer spicatum to simulated acid rain. Plots of each species were sprayed with pH 5.6, 3.8, or 3.2 rain, and the pH of the raindrops on the leaves and on Parafilm (control) was measured with a microelectrode at 15-min intervals until the leaves dried. Species differed in their ability to neutralise the rain, with C. canadensis consistently neutralising acidic raindrops the most. The neutralisation response varied greatly between pH treatments, with greatest neutralisation occurring at the most acidic pH treatment. Raindrop neutralisation primarily took place within the first few minutes following the spray. For this reason, the dissolution of basic particulates on the leaf surface was probably responsible for the rapid changes in raindrop pH, while slower changes may reflect cation exchange processes with the cell walls. Weather conditions determined the rate of evaporation of the raindrops, and this affected their acidity. High rates of evaporation reduced the time available for leaf surface – raindrop interactions and are probably responsible for the acidification observed in some plots.

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Variation and balance of positive air ion concentrations in a boreal forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-655-2008 ◽

2008 ◽

Vol 8 (3) ◽

pp. 655-675 ◽

Cited By ~ 34

Author(s):

U. Hõrrak ◽

P. P. Aalto ◽

J. Salm ◽

K. Komsaare ◽

H. Tammet ◽

...

Keyword(s):

Steady State ◽

Boreal Forest ◽

Correlation Coefficient ◽

Aerosol Particles ◽

Coniferous Forest ◽

Ionization Rate ◽

Ion Concentration ◽

Air Ions ◽

Ion Concentrations ◽

Charged Aerosol

Abstract. Air ions are characterized on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. The air ions were discriminated as small ions (charged molecular aggregates of the diameter of less than 2.5 nm), intermediate ions (charged aerosol particles of the diameter of 2.5–8 nm), and large ions (charged aerosol particles of the diameter of 8–20 nm). Statistical characteristics of the ion concentrations and the parameters of ion balance in the atmosphere are presented separately for the nucleation event days and non-event days. In the steady state, the ionization rate is balanced with the loss of small ions, which is expressed as the product of the small ion concentration and the ion sink rate. The widely known sinks of small ions are the recombination with small ions of opposite polarity and attachment to aerosol particles. The dependence of small ion concentration on the concentration of aerosol particles was investigated applying a model of the bipolar diffusion charging of particles by small ions. When the periods of relative humidity above 95% and wind speed less than 0.6 m s−1 were excluded, then the small ion concentration and the theoretically calculated small ion sink rate were closely negatively correlated (correlation coefficient −87%). However, an extra ion loss term of the same magnitude as the ion loss onto aerosol particles is needed for a quantitative explanation of the observations. This term is presumably due to the small ion deposition on coniferous forest. The hygroscopic growth correction of the measured aerosol particle size distributions was also found to be necessary for the proper estimation of the ion sink rate. In the case of nucleation burst events, the concentration of small positive ions followed the general balance equation, no extra ion loss in addition to the deposition on coniferous forest was detected, and the hypothesis of the conversion of ions into particles in the process of ion-induced nucleation was not proved. The estimated average ionization rate of the air at the Hyytiälä station in early spring, when the ground was partly covered with snow, was about 6 ion pairs cm−3 s−1. The study of the charging state of nanometer aerosol particles (diameter 2.5–8 nm) in the atmosphere revealed a strong correlation (correlation coefficient 88%) between the concentrations of particles neutralized in the aerosol spectrometer and naturally positively charged particles (air ions) during nucleation bursts. The charged fraction of particles varied from 3% to 6% in accordance with the hypothesis that the particles are quasi-steady state charged.

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The reproductive biology of boreal forest herbs. II. Phenology of flowering and fruiting

Canadian Journal of Botany ◽

10.1139/b87-279 ◽

1987 ◽

Vol 65 (10) ◽

pp. 2047-2056 ◽

Cited By ~ 22

Author(s):

Kaius Helenurm ◽

Spencer C. H. Barrett

Keyword(s):

Boreal Forest ◽

Fruit Set ◽

Pollen Limitation ◽

Fruit Production ◽

Fruit Removal ◽

Cornus Canadensis ◽

Forest Herbs ◽

Pollinator Service ◽

Maianthemum Canadense ◽

Major Factors

The flowering and fruiting phenologies of 12 boreal forest herbs were recorded during 1979 (flowering and fruiting) and 1980 (flowering only) in spruce–fir forests of central New Brunswick. The species studied were Aralia nudicaulis, Chimaphila umbellata, Clintonia borealis, Cornus canadensis, Cypripedium acaule, Linnaea borealis, Maianthemum canadense, Medeola virginiana, Oxalis montana, Pyrola secunda, Trientalis borealis, and Trillium undulatum. Flowering in the community occurred from mid-May to the end of July. The order of flowering was maintained in the 2 years, but the degree of synchronization of inflorescences differed in several species. Fruiting in the community began in mid-July and extended beyond the end of September. The percentage of buds that ultimately bore fruit ranged from 0 (Cypripedium acaule) to 61% (Aralia nudicaulis). With the exception of Cypripedium acaule, which received little pollinator service, the self-incompatible species, Cornus canadensis, Maianthemum canadense, and Medeola virginiana, experienced the lowest levels of fruit-set. Pollen limitation and predation of developing fruit appear to be the major factors limiting percentage fruit-set in boreal forest herbs. Fruit production varied with time of flowering of inflorescences in several species, with periods of low fruit-set tending to coincide with lower densities of flowering inflorescences. Significant rates of fruit removal by herbivores occurred in all sarocochorous species. Disappearance of fruits from infructescences ranged from 31 (Medeola virginiana) to 95% (Aralia nudicaulis), with highest removal rates occurring during periods of greatest fruit availability.

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How do air ions reflect variations in ionising radiation in the lower atmosphere in a boreal forest?

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-14297-2016 ◽

2016 ◽

Vol 16 (22) ◽

pp. 14297-14315 ◽

Cited By ~ 7

Author(s):

Xuemeng Chen ◽

Veli-Matti Kerminen ◽

Jussi Paatero ◽

Pauli Paasonen ◽

Hanna E. Manninen ◽

...

Keyword(s):

Gamma Radiation ◽

Boreal Forest ◽

Ionising Radiation ◽

Ion Concentration ◽

Lower Atmosphere ◽

Air Ions ◽

Long Distance ◽

Ion Concentrations ◽

Depth Analysis ◽

Ion Production

Abstract. Most of the ion production in the atmosphere is attributed to ionising radiation. In the lower atmosphere, ionising radiation consists mainly of the decay emissions of radon and its progeny, gamma radiation of the terrestrial origin as well as photons and elementary particles of cosmic radiation. These types of radiation produce ion pairs via the ionisation of nitrogen and oxygen as well as trace species in the atmosphere, the rate of which is defined as the ionising capacity. Larger air ions are produced out of the initial charge carriers by processes such as clustering or attachment to pre-existing aerosol particles. This study aimed (1) to identify the key factors responsible for the variability in ionising radiation and in the observed air ion concentrations, (2) to reveal the linkage between them and (3) to provide an in-depth analysis into the effects of ionising radiation on air ion formation, based on measurement data collected during 2003–2006 from a boreal forest site in southern Finland. In general, gamma radiation dominated the ion production in the lower atmosphere. Variations in the ionising capacity came from mixing layer dynamics, soil type and moisture content, meteorological conditions, long-distance transportation, snow cover attenuation and precipitation. Slightly similar diurnal patterns to variations in the ionising capacity were observed in air ion concentrations of the cluster size (0.8–1.7 nm in mobility diameters). However, features observed in the 0.8–1 nm ion concentration were in good connection to variations of the ionising capacity. Further, by carefully constraining perturbing variables, a strong dependency of the cluster ion concentration on the ionising capacity was identified, proving the functionality of ionising radiation in air ion production in the lower atmosphere. This relationship, however, was only clearly observed on new particle formation (NPF) days, possibly indicating that charges after being born underwent different processes on NPF days and non-event days and also that the transformation of newly formed charges to cluster ions occurred in a shorter timescale on NPF days than on non-event days.

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The reproductive biology of boreal forest herbs. I. Breeding systems and pollination

Canadian Journal of Botany ◽

10.1139/b87-278 ◽

1987 ◽

Vol 65 (10) ◽

pp. 2036-2046 ◽

Cited By ~ 77

Author(s):

Spencer C. H. Barrett ◽

Kaius Helenurm

Keyword(s):

Boreal Forest ◽

Reproductive Biology ◽

Fruit Set ◽

Experimental Studies ◽

Reproductive Mode ◽

Breeding Systems ◽

Cornus Canadensis ◽

Forest Herbs ◽

Maianthemum Canadense ◽

Floral Syndromes

Detailed observations and experimental studies of the reproductive biology of 12 boreal forest herbs were conducted over a 3-year period (1978–1980) in spruce–fir forests of central New Brunswick. The species examined were Aralia nudicaulis, Chimaphila umbellata, Clintonia borealis, Cornus canadensis, Cypripedium acaule, Linnaea borealis, Maianthemum canadense, Medeola virginiana, Oxalis montana, Pyrola secunda, Trientalis borealis, and Trillium undulatum. All taxa are insectpollinated perennials and most exhibit clonal growth. Floral syndromes of the understory community are relatively unspecialized with many species possessing small white or green flowers. A total of 103 taxa of insects were collected from flowers during the 1979 season. Bombus spp. are the major pollinators of 5 of the 12 species. Syrphid flies, bee flies, and halictid and andrenid bees were also commonly observed. Controlled pollinations were undertaken to determine the breeding systems of herbs. Bagged, self-, cross- and open-pollinated treatments were used to investigate the capacity for self-pollination, compatibility status, and factors influencing fecundity in each species. A diversity of reproductive systems was revealed. Six species are completely dependent on insects for pollination, four species are weakly autogamous, one is strongly autogamous, and one appears to be apomictic. Comparisons of fruit-set and seed set from controlled self- and cross-pollinations indicate that four species are strongly self-compatible, one is dioecious, and the remainder display varying degrees of self-incompatibility. Despite this variation, outbreeding appears to be the most common reproductive mode. In several species there is evidence that low pollinator service limits fruit-set.

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Accumulation Parameters and Seasonal Trends for PCBs in Temperate and Boreal Forest Plant Species

Environmental Science & Technology ◽

10.1021/es800217m ◽

2008 ◽

Vol 42 (16) ◽

pp. 5911-5916 ◽

Cited By ~ 34

Author(s):

Luca Nizzetto ◽

Cristina Pastore ◽

Xiang Liu ◽

Paolo Camporini ◽

Daniela Stroppiana ◽

...

Keyword(s):

Boreal Forest ◽

Plant Species ◽

Seasonal Trends ◽

Forest Plant Species

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Thermal stability of ribosomes from a thermophilic and a mesophilic fungus

Canadian Journal of Microbiology ◽

10.1139/m73-123 ◽

1973 ◽

Vol 19 (6) ◽

pp. 761-763 ◽

Cited By ~ 6

Author(s):

H. M. Miller ◽

M. G. Shepherd

Keyword(s):

Thermal Stability ◽

Ion Concentration ◽

Magnesium Ion ◽

Penicillium Notatum ◽

Ribosomal Subunits ◽

Ion Concentrations ◽

Thermal Stability Of

Ribosomes and ribosomal subunits from the thermophile Penicillium duponti were found to be more thermostable than the corresponding particles from the mesophile Penicillium notatum. The thermostability of the ribosomes from both organisms was dependent on magnesium ion concentration. The dissociation of the 80-S ribosomes into 60-S and 40-S subunits occurred at higher magnesium ion concentrations for the mesophile than the thermophile.

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Phosphate biogeochemical barrier for uranium in situ immobilization in an aquifer nearby sludge repository

10.5194/egusphere-egu21-12410 ◽

2021 ◽

Author(s):

Grigory Artemiev ◽

Alexey Safonov ◽

Nadezhda Popova

Keyword(s):

Essential Elements ◽

Ion Concentration ◽

Soluble Form ◽

High Concentration ◽

Rapid Reduction ◽

Near Surface ◽

Nitrate Ions ◽

Uranium Migration ◽

Storage Facilities

<p>Uranium migration in the oxidized environment of near-surface groundwater is a typical problem of many radiochemical, ore mining and ore processing enterprises that have sludge storage facilities on their territory. Uranium migration, as a rule, occurs against a high salt background due to the composition of the sludge: primarily, nitrate and sulfate anions and calcium cations. One of the ways to prevent the uranium pollution is geochemical or engineering barriers. For uranium immobilization, it is necessary to create conditions for its reduction to a slightly soluble form of uraninite and further mineralization, for example, in the phosphate form. An important factor contributing to the rapid reduction of uranium is a in the redox potential decreasing and the removal of nitrate ions, which can be achieved through the activation of microflora. It should be added that phosphate itself is one of the essential elements for the development of microflora. This work was carried out in relation to the upper aquifer (7-12 m) near the sludge storage facilities of ChMZ, which is engaged in uranium processing and enrichment. One of the problems of this aquifer, in addition to the high concentration of nitrate ions (up to 15 g / l), is the high velocity of formation waters.<br>In laboratory conditions, the compositions of injection solutions were selected containing sources of organic matter to stimulate the microbiota development and phosphates for uranium mineralization. When developing the injection composition, special attention was paid to assessing the formation of calcite deposits in aquifer conditions to partially reduce the filtration parameters of the horizon and reduce the rate of movement of formation waters. This must be achieved to ensure the possibility of long-term deposition of uranium and removal of nitrate. The composition of the optimal solution was selected and in a series of model experiments the mineral phases containing the lowest hydrated form of the uranium-containing phosphate mineral meta-otenite were obtained.<br>In situ mineral phosphate barrier Formation field tests were carried out in water horizon conditions in a volume of 100m3 by injection of an organic and phosphates mixture. As a result, at the first stage of field work, a significant decreasing nitrate ion concentration, and reducing conditions formation coupled with the dissolved uranium concentration of decreasing were noted.</p>

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