Rain Collectors Research Articles

Chemical characterization in coastal fog and rain at Mount Monduver fog-collection station, Mediterranean Iberian Peninsula

An experimental site was selected for fog- and rain-water quality analyses. The selected location corresponds to Mount Monduver of 843 m elevation, being geographically centered in the Mediterranean Iberian Peninsula. Single fog- and rain-water samples were taken manually with a dedicated fog and rain collectors, to prevent any contamination with dry-deposition. Besides, a permanently exposed fog collector and a rain gauge were also used for the collection of water samples affected by dry deposition. Results indicated that all chemical analyses complied with Spanish drinking water regulations, except for the particular case of the dry-deposition contaminated water samples. A further statistical data analysis, together with five-day air mass backward trajectories, was performed. Two sample clusters could be differentiated which were also discriminated against by the two principal components obtained. Cluster-1 members comprised higher levels of conductivity and ion concentration, while cluster-2 members corresponded to lower levels of solutes. The second principal component related to pH levels showed the majority of samples centered at neutral values. The backward trajectory analysis indicated that the origin and route followed by the air masses leading to sample members in cluster-1 were over the Mediterranean Sea and mainly obtained in summer and autumn; while trajectories associated to sample members in cluster-2 had their origin primarily over the Atlantic Sea occurring only in winter and spring. The larger ion loads presented in fogs developed from Mediterranean air masses may be explained through the role of sea breezes on the confinement of pollutants into the atmosphere.

Influence of Slope Direction on the Soil Seed Bank and Seedling Regeneration of Castanopsis hystrix Seed Rain

Objective: To investigate the impact of different slope directions on the quantity and quality of the soil seed bank and seedling germination process of Castanopsis hystrix plantations. Method: Fixed sample plots in forest stands of Castanopsis hystrix were established on different slope directions (sunny slope, semi-sunny slope, semi-shady slope, and shady slope). The characteristics of the forest stand were investigated, and per-wood scaling was carried out. The temporal dynamics of the seed rain and seed bank were quantified using seed rain collectors and by collecting soil samples from different depths. The quantity and quality of the seeds were determined, and the vigor of mature seeds was measured throughout the study. Results: (1) The diffusion of Castanopsis hystrix seed rain started in mid-September, reached its peak from late October to early November, and ended in mid-December. (2) The dissemination process, occurrence time, and composition of the seed rain varied between the different slope directions. The seed rain intensity on the semi-sunny slope was the highest (572.75 ± 9.50 grains∙m−2), followed by the sunny slope (515.60 ± 10.28 grains∙m−2), the semi-shady slope (382.13 ± 12.11 grains∙m−2), and finally the shady slope (208.00 ± 11.35 grains∙m−2). The seed rain on the sunny slope diffused earliest and lasted the longest, while the seed rain on the shady slope diffused latest and lasted the shortest time. Seed vigor and the proportion of mature seeds within the seed rain were greatest on the semi-sunny slope, followed by the sunny slope, semi-shady slope, and the shady slope. (3) From the end of the seed rain to August of the following year, the amount of total reserves of the soil seed banks was highest on the semi-sunny slope, followed by the sunny slope then the semi-shady slope, and it was the lowest on the shady slope. The amount of mature, immature, gnawed seeds and seed vigor of the soil seed bank in various slope directions showed a decreasing trend with time. The seeds of the seed bank in all slope directions were mainly distributed in the litter layer, followed by the 0–2 cm humus layer, and only a few seeds were present in the 2–5 cm soil layer. (4) The seedling density of Castanopsis hystrix differed significantly on the different slope directions. The semi-sunny slope had the most seedlings, followed by the sunny slope, semi-shady slope, and the shady slope. Conclusions: The environmental conditions of the semi-sunny slope were found to be most suitable for the seed germination and seedling growth of Castanopsis hystrix, and more conducive to the regeneration and restoration of its population.

Implications for groundwater recharge from stable isotopic composition of precipitation in Hawai'i during the 2017–2018 La Niña

AbstractThe project captured a subset of the hydrological cycle for the tropical island of O'ahu, linking precipitation to groundwater recharge and aquifer storage. We determined seasonal storm events contributed more to aquifer recharge than year‐round baseline orographic trade wind rainfall. Hydrogen and oxygen isotope values from an island‐wide rain collector network with 20 locations deployed for 16 months and sampled at 3‐month intervals were used to create the first local meteoric water line for O'ahu. Isotopic measurements were influenced by the amount effect, seasonality, storm type, and La Niña, though little elevation control was noted. Certain groundwater compositions from legacy data showed a strong similarity with collected precipitation from our stations. The majority of these significant relationships were between wet season precipitation and groundwater. A high number of moderate and heavy rainfall days during the dry season, large percentage of event‐based rainfall, and wind directions outside of the typical NE trade wind direction were characteristics of the 2017–2018 wet season. This indicates that the majority of wet season precipitation is from event‐based storms rather than typical trade wind weather. The deuterium‐excess values provided the strongest evidence of a relationship between groundwater and different precipitation sources, indicating that this may be a useful metric for determining the extent of recharge from different rain events and systems.

Atmospheric constraints on δ18O and d-excess in precipitation at the middle latitude in the southwestern Atlantic region

ABSTRACT The mid-latitude coastal area at the western South-Atlantic out of the tropics is under the combined effect of different atmospheric circulation patterns at different temporal scales, which can be shown by the isotope composition of precipitation. This pattern effect is more changing and complex than that for the well-studied tropical areas, the isotope studies being an interesting proxy for identifying major processes. This study is focused on the isotope composition of precipitation at a mid-latitude zone, in the western South-Atlantic coastal area of Argentina. δ18O and d-excess were analysed in a data series of 14 years, obtained from the integration of three neighbouring rain collectors at 38°S. A seasonality is observed in both parameters, but with some differences in the extreme months. δ18O showed a seasonality according to the temperature effect, but with a displacement of high values to spring months. Significant linear links between δ18O and Southern Annular Mode (SAM) index and Southern Oscillation Index (SOI) were recognised for the summer and spring seasons, respectively.

Inoculum quantification of canker-causing pathogens in prune and walnut orchards using real-time PCR.

A real-time quantitative PCR (qPCR) assay was established to quantify the inoculum densities in the air and rainwater for six canker-causing pathogen groups in prune and walnut orchards in California. The previously published DNA primers to target six pathogen groups including Botryosphaeria dothidea, Cytospora spp., Diplodia spp., Lasiodiplodia spp., Neofusicoccum spp. and Phomopsis spp. were used in a qPCR assay. Air samples from Burkard spore traps and rain samples from special rain collector devices were collected periodically from various prune and walnut orchards. Using the qPCR approach, we were able to quantify the concentrations of these pathogen groups in rainwater and air samples and study the dynamics of pathogen inoculum in orchards showing severe canker potential. Phomopsis spp. and Diplodia spp. were not found in all rain samples in prune orchards, although they were detected in the 2016 in the walnut orchard. The other four pathogen groups were quantified at varying concentrations in the prune and walnut orchards. Cytospora spp. in some cases showed higher concentrations in the rainwater in prune orchards. The rainy season during winter and early spring is a highly risky period of time for infection by the pathogens when the inoculum of these pathogens can easily spread by air and rain water, thus serving as an important inoculum source for disease initiation. The different studied pathogen groups showed different concentrations during the growing season, indicating the complexity of the components of canker-causing species in various tree crops. This study showed the applicability of the qPCR assay in the quantification of inoculum in tree orchards to help reveal the mechanisms of canker disease epidemics and to help design disease management strategies.

Pest survey card on Phyllosticta citricarpa

The European Commission requested EFSA (M-2017-0137) to assist the Member States to plan annual survey activities of quarantine organisms using a statistically sound and risk-based pest survey approach, in line with current international standards. Phyllostictacitricarpa is a Union quarantine pest and the causal agent of citrus black spot (CBS). It is not known to occur in the EU so special requirements for the import of its host plants and fruit from third countries are in place to prevent its introduction and spread. P. citricarpa produces asexual pycnidia and pycnidiospores on fruit lesions, twigs and leaf litter, but it can also reproduce sexually, giving rise to pseudothecia and ascospores, which are particularly important for long-range dissemination. Most commercial citrus species are susceptible to CBS. Due to the variety of environments in which the fungus is currently distributed, all citrus-growing areas in the EU are potentially suitable for the establishment of the pest. The main pathways for its introduction and spread include production, handling and transport of infected plants for planting or fruit. The goal of the visual examination is to detect the symptoms caused by P. citricarpa. Since symptoms are non-specific and may be highly variable, visual examination should be followed by laboratory testing. Moreover, CBS has a long incubation period and infected fruit may still be asymptomatic at maturity. In this case, symptom induction methods or other early detection approaches (e.g. airborne spore traps or rain collectors for splash-dispersed conidia) could be further explored. For symptomatic fruit, three mainmethods foridentifyingP. citricarpain the laboratoryare presented.Based on the analyses of the information on the pest–host plant system, the variousunits that are needed to design asurvey should be defined and tailored to the situation of each Member State.

Assessment of Atmospheric Deposition and Vitality Indicators in Mediterranean Forest Ecosystems

Considering the fragility of the Mediterranean environment, there is an increasing need to improve the knowledge of this forest environment. The aim of this study was to examine the effects of air pollution on the forest ecosystem’s condition by analyzing tree vitality. The study area was chosen to represent the most important and the most common species in Mediterranean forest ecosystems of the Eastern Adriatic coast. Quercus pubescens, Quercus ilex, Pinus halepensis, and Pinus nigra plots were equipped with rain collectors and dendrometer bands. Sampling, measurements, and analyses of atmospheric deposition, foliar nutrient, defoliation, and growth were all carried out. Results showed that actual N deposition loads were the lowest in Aleppo pine forest and the highest in holm oak forests. This, however, did not have an effect on the concentrations of N in foliage. Most elements’ concentrations were in the plausible range. No relevant differences in mean defoliation between the plots were observed. The plots with a lower percentage of basal area increment (BAI%) were found to have lower defoliation. The research was conducted to bridge the gap in the knowledge of air pollutants and vitality indicators in different forest types. These findings are a valuable contribution to the sustainable forest management of Mediterranean forest.

Contamination of small urban watercourses on the example of a stream in Krakow (Poland)

The urbanization of catchments is consistently accompanied by a decrease of the stream condition. The case study concerns one of the urban streams in Krakow (Poland). The aim was to show the pollutant load which can enter the Vistula River from even a very small inflow. Samples of water, suspended particulate matter and bottom sediment were collected. Values of pH, Eh and electrolytic conductivity were measured in situ and the contents of macroelements—cations and inorganic anions—as well as trace elements were analysed by means of different instrumental methods. The results obtained are related to normative values, geochemical background and different classifications. The exceedance of permissible values for water by electrical conductivity, calcium, chlorides and cadmium concentrations in all of the sampling locations was stated. The high content of heavy metals in the bottom sediment was found especially for zinc (to 929 mg/kg), lead (to 131 mg/kg) and cadmium (to 10 mg/kg). It is shown that pollutants carried along with the waters and sediments of the stream constitute a continuous source of pollution of the Vistula River. It seems important to measure the concentration of some elements not only in the sediment of the biggest rivers but also in the smaller streams, ditches and rain collectors. Only management in the entire catchment system and inventory of pollution sources can give some positive results in improving the quality of urban watercourses.

Collected Rain Water as Cost-Efficient Source for Aquifer Tracer Testing.

Locally collected precipitation water can be actively used as a groundwater tracer solution based on four inherent tracer signals: electrical conductivity, stable isotopic signatures of deuterium [δ2 H], oxygen-18 [δ18 O], and heat, which all may strongly differ from the corresponding background values in the tested groundwater. In hydrogeological practice, a tracer test is one of the most important methods for determining subsurface connections or field parameters, such as porosity, dispersivity, diffusion coefficient, groundwater flow velocity, or flow direction. A common problem is the choice of tracer and the corresponding permission by the appropriate authorities. This problem intensifies where tracer tests are conducted in vulnerable conservation or water protection areas (e.g., around drinking water wells). The use of (if required treated) precipitation as an elemental groundwater tracer is a practical solution for this problem, as it does not introduce foreign matters into the aquifer system, which may contribute positively to the permission delivery. Before tracer application, the natural variations of the participating end members' tracer signals have to be evaluated locally. To obtain a sufficient volume of tracer solution, precipitation can be collected as rain using a detached, large-scale rain collector, which will be independent from possibly existing surfaces like roofs or drained areas. The collected precipitation is then stored prior to a tracer experiment.

Incident Precipitation Partitioning: The Canopy Interactions Enrich Water Solution With Nutrients in Throughfall and Stemflow

Atmospheric deposition is responsible for the ions input, which may be due to dust and aerosols and rainfall. During rainfall a portion is intercepted by the tree canopy and returned to the atmosphere by evapotranspiration, another part crosses the forest canopy called throughfall and stemflow. The objective of the present work was to quantify the nutrient input of the incident rainfall, throughfall, stemflow and canopy enrichment in an Eucalyptus dunnii plantation, established in soil with low natural fertility. Four plots of 20 m × 21 m were demarcated. The rainfall consists 3 rain collectors in an open área. The throughfall consisted 3 collectors per plot in the line, interlining and diagonal positions of the trees. The stemflow consisted in the installation of three systems per plot formed by a hose in the trunk of the tree that leads the solution to a reservoir. Through rainfall, 29.5 kg ha-1 of nutrients were supplied. When we consider the sum of the throughfall and stemflow, the amount of nutrients was 77.6 kg ha-1. After interaction with the tree canopy 48.2 kg ha-1 of nutrients were incorporated. Potassium showed the highest enrichment: 607%. The average nutrient enrichment was 163%. The input of N and K via incident rainfall was 1.8 and 3.1 kg ha-1. Considering the fertilization described in the methodology, this contributed amount represents 6.1 and 2.6% of the total. If we consider the rotation of 7 years for Eucalyptus dunnii, the contribution at the end of rotation represents 42.4 and 18% of N and K2O. The interaction with the canopy of Eucalyptus dunnii enriches the rainwater with nutrients making the solution with a more basic character.

Incident Precipitation Partitioning: Throughfall, Stemflow and Canopy Interception in Eucalyptus dunnii Stand

Atmospheric deposition is responsible for the ions input, which may be due to dust and aerosols and rainfall. During rainfall a portion is intercepted by the tree canopy and returned to the atmosphere by evapotranspiration, another part crosses the forest canopy called throughfall and stemflow. The objective of the study was to quantify incident rainfall partitioning into throughfall, stemflow and canopy interception in a Eucalyptus dunnii stand in southern Brazil. Four plots of 20 m × 21 m were demarcated. The rainfall consists 3 rain collectors in an open area. The throughfall consisted 3 collectors per plot in the line, interlining and diagonal positions of the trees. The stemflow consisted in the installation of three systems per plot formed by a hose in the trunk of the tree that leads the solution to a reservoir. The adjustment of the throughfall, stemflow and canopy interception in function of the incident precipitation was of 99%, 90% and 52%. As the volume of rainfall increases, the coefficient of variation decreases. The annual rainfall was 1903 mm, with a canopy interception average of 8.9%.

Dew, Fog and Rain Collector in a Hyper-arid Climate: Case Study in Abu Dhabi

Dew condensers collect dew via thermal radiation and cooling affect without the use of external energy. The aim of this project was to design the 1m x 1m with 30° angle square funnel dew, fog and rainwater collector to calculate the dew yield in Abu Dhabi urban area. In addition, studies were conducted to determine whether the collected dew quantity is significant for practical use and to verify the cooling effect in condenser surface using temperature sensors. Aluminum was chosen as dew collector material due to its high emissivity. Square funnel was chosen as condenser shape due to easiness of the assembly and feasibility of its design. The quantity of the collected water depended on the weather condition. The average collected water was 0.016 ml/day (0.016 mm/m2 /day). Temperature sensor analysis showed that there was a 3.5 °C temperature difference between condenser top and bottom indicating the cooling effect of square funnel shape.

Detection of Diplodia corticola spores in Ontario and Québec based on High Throughput Sequencing (HTS) methods

A total of 252 aerial spore samples from the provinces of Quebec and Ontario were obtained during an extensive research programme focusing on aerobiology of fungal spores. Samples were collected on 95 sticky rods from rotary arm spore collectors and 157 filters from passive rain collectors. DNA from samples was PCR-amplified for fungal ribosomal ITS and sequenced using High Throughput Sequencing (HTS) methods. After bioinformatics analysis of DNA sequences, the presence of Diplodia corticola, an emerging tree pathogen in North America, was observed. In total, 313 DNA sequence reads from aerial spores of D. corticola were found in the Illumina data set, and 199 DNA sequence reads were obtained from the Ion Torrent data set. DNA of D. corticola was found in 16 of the 32 sampled sites, always less than 10 reads per site, with the exception of three sites – Quebec City, Aylmer and Ottawa – where 287, 125 and 73 DNA reads, respectively, were detected. This is not a first report of the presence of D. corticola causing a tree disease in Canada as symptomatic trees have not been identified. Typically, like many other species of the Botryosphaeriaceae, this fungal pathogen is believed to be an opportunistic plant endophyte capable of living asymptomatically for several years before showing up as a pathogen when conducive conditions arise. Its presence as singletons in nearly half the sampled sites in Quebec and Ontario may be the result of long-distance spore dispersal originating from known infected sites in Massachusetts, Maine and other unknown sites in the north-eastern USA. However, its much higher read counts in three sites may indicate the possibility of a few trees being asymptomatically infected and spreading conidia locally.

Isotopic Characterization of Precipitation, Inflow, and Outflow of Lake Toba as a First Assessment of Lake Water Balance Study

Isotopic characterization of all identified hydrological units in Lake Toba such as precipitation, inflows, outflows, and lake water, as a first assessment of lake water balance study, has been conducted. The isotopic characterization was done through the interpretation of the relationship of d D and d 18 O values of collected samples from various water sources and their variations as a function of time and space. Rain water samples were collected from four rain collectors that were installed in the study area in a monthly sampling for a period of 12 months in 2014. Several samples from various water sources i.e ., inflow streams, outflows, springs, and lake water, were also collected 2-3 times during this sampling period. From monthly sampling of rain water, local meteoric water line ( LMWL ) and the equation of elevations versus d D values have been constructed. Due to the slightly higher temperature in the study area compared with the average temperature on the other parts of the world, the slope of the constructed LMWL is slightly less than the slope of global meteoric water line. Based on the equation of elevations versus d D values, the elevations of four springs around study area have been identified. From the linear relationship of d D and d 18 O values of collected samples from inflow streams, it was found that most of the samples have experienced evaporation process before entering the lake. Due to mixing with other surface water and longer transit time, the d D and d 18 O values of those samples from streams in the Sumatran side are more enriched than those samples from streams in the Samosir side. It was also found that lake water has experienced significant evaporation as indicated by the d D and d 18 O values that were more enriched than any other samples. The d D and d 18 O of Asahan River samples, the only output of Lake Toba, were found to be very close to the d D and d 18 O of the lake. This is because almost all water that flowed in Asahan River originated from the lake. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

Supplementary irrigation at container nursery

AbstractFor the period from the 1st of May to the 30th of October 2014, the water balance for Scots pine, Norway spruce, Pedunculate oak and European beech seedlings in a plantation setting was analysed. The experiment was conducted at the container nursery in the Rudy Raciborskie Forest District, Poland. Water was supplied by natural rainfall as well as a by small-droplet irrigation system and two automatic weather stations combined with 32 rain collectors were used to monitor rainfall throughout this research. Rain gauges were located 25 cm above the metal pallets and 10 cm below the nursery containers. An average of 987 mm∙m−2of water reached the plantation, of which 53% were provided by the irrigation system. Most water was supplied to the oak field, whereas least was given to the spruce plantations and the irrigation water amounted to 535 liters and 422 liters per square meter, respectively. The amount of water percolating through the substrate was approximately 50–65%, depending on the tree species. An average sum of evapotranspiration at the container nursery was estimated to amount to 520 mm∙m−2during the growth season leading to a total water balance of +463 mm.

Correction of Canopy Interception Loss Measurements in Temperate Forests: A Comparison of Necessary Adjustments among Three Different Rain Gauges Based on a Dynamic Calibration Procedure

ABSTRACT Tipping-bucket rain gauges are used widely to measure the amount and intensity of gross rainfall and throughfall in forests, despite the fact that their systematic underestimations are well known. To the knowledge of the authors, no dynamic calibrations for the budget-conscious Davis gauge (Rain Collector II, Davis Instruments, California) have been published. Thus, five Davis gauges were dynamically calibrated under different constant intensities of inflow and a correction equation was derived. The derived correction equation for the Davis rain gauge is V = −0.2005Q2 + 0.702Q + 1 (R2 = 0.95, p < 0.001), where V is the actual volume of a single tip scaled by the static volume of single tip c (cm3 cm−3), and Q is actual inflow scaled by c (s−1). The Davis rain gauge was then compared to the Onset rain gauge and the Ota rain gauge, and the corrections were applied to field observation data of canopy interception loss from a temperate forest in Japan. It is necessary to apply corrections to gross rainfall and throughfall data by tipping-bucket gauges because the results reveal that such corrections change the actual interception loss computed by values from −20% to 40%, depending on the combination of gauges employed. This difference is not trivial. The systematic bias of the Davis gauge is larger than the Onset and Ota gauges. Thus, it is recommended that researchers using Davis rain gauges apply the dynamically calibrated correction equation presented here to ensure more reliable estimates of gross rainfall and canopy interception loss.

QPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments

SummaryThe use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR Ct values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease.

Modern palynological record in the Bay of Brest (NW France): Signal calibration for palaeo-reconstructions

Modern palynological investigations (pollen and non-pollen palynomorphs) have been carried out for the first time in the entire Bay of Brest (BB; NW France), a semi-enclosed oceanic basin flooded during the Holocene that today is exposed to both marine (North Atlantic surface waters) and fluvial (Aulne and Elorn rivers) influences. Palynological analyses were conducted on 41 surface sediments collected in several mudded bays where low-energy conditions prevail, allowing for fine particle decantation, and also on 12 moss samples considered to be pollen rain collectors taken on the periphery of the BB. Furthermore, the BB allows a direct comparison between landscapes and fossilized pollen assemblages in sediments thanks to relatively small watersheds and well-studied vegetation cover on land. Our data display a well-known distortion between pollen taxa percentages calculated from palynological slides and current vegetation cover on land, with a particular overestimation of arboreal taxa as well as an underestimation of herbaceous ones, especially of cereal crops that represent a major component of the regional continental vegetation. Various factors may be involved, including pollen transport issues, taphonomic processes, and different pollination rates according to trees/herbaceous taxa. Under close examination, we find that while all surface sediments show the same major species, palynological maps established in the BB regarding some specific pollen taxa exhibit differences and upstream-downstream gradients. Also, the comparison between the pollen content in BB surface sediments and in mosses supports the hydrodynamic influence acting on the pollen distribution in sediments. More specifically, we suggest that some arboreal taxa reflect a watershed effect, especially Alnus, which seems to be highly correlated to river influences and could therefore be considered as a potential proxy for fluvial Holocene palaeo-discharges within the BB.

USE OF STABLE ISOTOPES IN THE DETERMINATION OF THE MEAN ALTITUDE OF RECHARGE AND THE INVESTIGATION OF FUNCTION MECHANISM OF SPRING WATERS IN ARGOLIS PENINSULA (GREECE)

In the present study, the isotopic composition (δ18Ο) of several spring waters in Argolis peninsula is examined. The use of the specific isotope aimed at the determination of the altitude of recharge areas, while the credibility of the extracted results was verified by in situ geological observations. The applied methodology included the construction of a linear diagram which correlates the stable isotopic values (δ18Ο) in meteoric waters and the altitude. Isotopic data, concerning meteoric waters, came from: a) rain gauge stations of GNIP network (IAEA/WMO), b) rain tanks and selected wells located in Mt. Arachnaio, c) improvised rain collectors which were put in several sites in the peninsula. A decrease of 0.45‰ δ18Ο per 100m altitude was determined. The average isotopic composition of the examined springs, as far as δ18Ο is concerned, resulted from 14 sampling periods between October 2005 and March 2008. This 18O-content of spring waters was used to derive the recharge area and consequently to evaluate the mechanism of water renewal.

NET PRECIPITATION IN A SEMIDECIDUOUS FOREST FRAGMENT IN VIÇOSA CITY, MG

ABSTRACT We aimed to evaluate the net precipitation and rainfall interception in a fragment of semideciduous forest at both early and advanced stages of regeneration in Viçosa city, Minas Gerais state, southeastern Brazil, from January 2012 through July 2013. Six plots were stablished, three in each regeneration stage area. For throughfall and stemflow quantification, 25 rain gauges and collectors were installed in trees having circumference higher than 15 cm, in each plot. An additional rain gauge was installed in an open area to quantify gross precipitation. Gross precipitation in the studied period was 1934 mm. On average, 79.3% and 72.6% of gross precipitation reached the soil via net precipitation in the areas at early and advanced regeneration stages, respectively. Rainfall interception by the forest canopy was higher in the advanced-regeneration area, corresponding to 25.8% of gross precipitation. In the early- regeneration area, on the other hand, rainfall interception accounted for 20.2% of gross precipitation. This suggests that more densely populated areas intercept more rainfall, and consequently have lower net precipitation. Thus, our study shows that rainwater distribution in forest environments changes according to their regeneration status. The replacement of species at different successional stages renders the water to follow different pathways, such as interception, stemflow, and throughfall. This information helps us understand that the succession process can be slow, yet it is the natural way of forest regeneration.