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1.
Sci Total Environ ; 752: 142062, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33207489

RESUMO

We reviewed over 226 studies dealing with arsenic (As) in water bodies (124 sites or regions; 5,834 samples), soils (44; 2,700), sediments (56; 765), rocks (6; 85), mine waste (25; 582), continental plants (17 (77 species); 571), continental animals (10 (32 species); 3,525) and aquatic organisms (27 (100 species) 2,417) in Mexico. In general, higher As concentrations were associated with specific regions in the states of Hidalgo (21 sites), San Luis Potosi (SLP) (19), Baja California Sur (15), Zacatecas (5), and Morelos (4). High As levels have been detected in drinking water in certain locations of Coahuila (up to 435 µg L-1) and Sonora (up to 1004 µg L-1); in continental surficial water in Puebla (up to 780 µg L-1) and Matehuala, SLP (up to 8684 µg L-1); in groundwater in SLP (up to 16,000 µg L-1) and Morelia, Michoacán (up to 1506,000 µg L-1); in soils in Matehuala, SLP (up to 27,945 µg g-1) and the Xichú mining area, Guanajuato (up to 62,302 µg g-1); and in sediments in Zimapán, Hidalgo (up to 11,810 µg g-1) and Matehuala, SLP (up to 28,600 µg g-1). In contaminated arid and semi-arid areas, the plants P. laevigata and A. farnesiana exhibit the highest As levels. These findings emphasize the human and environmental risks associated with the presence of As in such regions. A synthesis of the available techniques for the removal of As in water and the remediation technologies for As contaminated soils and sediments is given. The As occurrence, origin (geogenic, thermal, mining and anthropogenic) and evolution in specific regions is summarized. Also, the mobilization and mechanisms to explain the As variability in continental environments are concisely given. For future research, a stratified regional sampling is proposed which prioritizes critical sites for waters, soils and sediments, and biota, considering the subpopulation of foods from agriculture, livestock, and seafood. It is concluded that more detailed and comprehensive studies concerning pollution levels, as well as As trends, transfer, speciation, and toxic effects are still required.


Assuntos
Arsênico , Poluentes Químicos da Água , Animais , Arsênico/análise , Biota , Monitoramento Ambiental , Humanos , México , Solo , Poluentes Químicos da Água/análise
2.
Chemosphere ; 262: 128360, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182080

RESUMO

Mercury (Hg) is a global pollutant of concern because its organic and more toxic form, methylHg (MeHg), bioaccumulates and biomagnifies through aquatic food webs to levels that affect the health of fish and fish consumers, including humans. Although much is known about trophic transfer of MeHg in aquatic food webs at temperate latitudes in the northern hemisphere, it is unclear whether its fate is similar in biota from coastal zones of the southeastern Pacific. To assess this gap, MeHg, total Hg and food web structure (using δ13C and δ15N) were measured in marine macroinvertebrates, fishes, birds, and mammals from Patagonian fjords and the Antarctic Peninsula. Trophic magnification slopes (TMS; log MeHg versus δ15N) for coastal food webs of Patagonia were high when compared with studies in the northern hemisphere, and significantly higher near freshwater inputs as compared to offshore sites (0.244 vs 0.192). Similarly, in Antarctica, the site closer to glacial inputs had a significantly higher TMS than the one in the Southern Shetland Islands (0.132 vs 0.073). Composition of the food web also had an influence, as the TMS increased when mammals and seabirds were excluded (0.132-0.221) at a coastal site. This study found that both the composition of the food web and the proximity to freshwater outflows are key factors influencing the TMS for MeHg in Patagonian and Antarctic food webs.


Assuntos
Monitoramento Ambiental , Cadeia Alimentar , Compostos de Metilmercúrio/análise , Poluentes Químicos da Água/análise , Animais , Regiões Antárticas , Bioacumulação , Biota , Estuários , Peixes , Água Doce , Humanos , Mercúrio/análise
3.
Sci Total Environ ; 750: 141695, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32861076

RESUMO

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs) were examined in sediments and biota species from two mangrove wetlands of the Pearl River Estuary (PRE) and the Jiulong River Estuary (JRE), South China, to investigate their distribution, bioaccumulation and biomagnification in mangrove food webs. Levels of TBBPA and ΣHBCD (sum of α-, ß- and γ-HBCDs) ranged from 0.003 to 0.31 and not detected (nd) to 1.11 ng/g dry weight in the sediments, and from 0.56 to 22.1 and nd to 56.3 ng/g lipid weight in the biota species, respectively. γ-HBCD was the major diastereoisomer in the PRE sediments, while α- and γ-HBCDs predominated in the JRE sediments. In contrast, α-HBCD was dominant in the biota. Mean enantiomeric fractions (EFs) of α-, ß- and γ-HBCDs in the sediments all followed the trend of JRE > racemic standard > PRE. A significant enrichment of (-)-α-HBCD was found in the biota (p = 0.04), with EFs in the range of 0.297-0.485. Bioaccumulations were seen for TBBPA and α-HBCD as their biota-sediment accumulation factors (BSAFs) were greater than 1. (-)-α-HBCD had significantly greater BSAFs than (+)-α-HBCD (p = 0.04), indicating the preferential bioaccumulation of (-)-α-HBCD. Biomagnification factors (BMFs) of TBBPA ranged from 0.83 to 1.51, which varied among feeding relationships and mangroves. Positive relationships were found between TBBPA concentrations and trophic levels of the biota species with trophic magnification factors of 2.17 for the PRE and 1.22 for the JRE, suggesting that TBBPA biomagnifies in the mangrove food webs. No biomagnifications were observed for ΣHBCD, α-HBCD and its enantiomers.


Assuntos
Retardadores de Chama , Hidrocarbonetos Bromados , Bioacumulação , Biota , China , Monitoramento Ambiental , Retardadores de Chama/análise , Hidrocarbonetos Bromados/análise , Bifenil Polibromatos , Áreas Alagadas
4.
Parasitol Res ; 119(11): 3675-3690, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33001253

RESUMO

In 2018, extensive field studies of diversity and prevalence of helminth infection in synanthropic rodents and non-rodent small mammals from public parks and citified areas in the Bangkok Metropolitan were conducted. Rattus rattus complex was the dominant small mammal in public parks. Of the 197 animals, 147 individuals were infected with one or more species of helminths, yielding an infection prevalence of 74.6%. Twenty-five species of helminths were recovered during necropsy. Pterygodermatites tani was the most prevalent (36.2%); other encountered species included Raillietina celebensis, Hydatigera taeniaformis (metacestode in liver tissue), Gongylonema neoplasticum and Hymenolepis diminuta. Different helminth assemblages infected three different host taxa, i.e. synanthropic Rattus spp., Tupaia belangeri (Northern treeshrew) and Suncus murinus (Asian house shrew). Nine species of possible zoonotic helminths were identified. The focus on synanthropic rats influenced the findings of helminth diversity by either host intrinsic or extrinsic factors. A significant positive correlation was found between host body mass and helminth species richness. Greater helminth species richness was found in rats from public parks compared with animals from citified areas (e.g. inside buildings or offices). Also, helminth species richness was negatively correlated with the proportion of post-flooding/rain-fed land. These results provide essential information for assessing the incidence of potential zoonotic health threats in Bangkok and updating research in parasite ecology.


Assuntos
Biota , Helmintíase Animal/parasitologia , Helmintos/classificação , Doenças dos Roedores/parasitologia , Roedores/parasitologia , Animais , Cidades , Inundações , Helmintíase Animal/epidemiologia , Helmintos/isolamento & purificação , Humanos , Parques Recreativos , Prevalência , Ratos , Doenças dos Roedores/epidemiologia , Musaranhos/parasitologia , Tailândia/epidemiologia
5.
Mar Environ Res ; 161: 105081, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33070934

RESUMO

Concrete is used in marine coastal constructions worldwide. These structures are colonized by specialized hard-bottom biota consisting of macroalgae and benthic macrofauna. As concrete manufacturers face challenges such as limited natural resources and high CO2-emissions, the need for supplementary materials increases. Still, there has been little research on the reaction of species to the differences in concrete composition and what ecological impact these reactions could have. This study addresses the questions (1) if there are differences in settlement communities, depending on differences in concrete constitutes and (2) if so, what are the consequences for the usability of alternative concretes in marine constructions. For the experiment 15 cubes (15 × 15 × 15 cm) made of five different concretes, containing different cements (Portland cement and blast furnace cements) and aggregates (sand, gravel, iron ore and metallurgical slags) were deployed in a natural hard bottom experimental field near Helgoland Island (German Bight) in April 2016. After 12 months, all cubes were examined regarding species composition and coverage, followed by statistical analysis (PERMANOVA, SIMPER, DIVERSE). Results indicate differences in settlement communities for different surface orientation (Top, Front/Back) of the cubes. Significant differences in settlement communities of the Front/Back side were present depending on the used material type. However, the found differences in settlement between the concrete types tested are not sufficiently clear to provide recommendations for their usability in coastal constructions.


Assuntos
Biota , Materiais de Construção
6.
Nat Commun ; 11(1): 5375, 2020 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-33097736

RESUMO

Eutrophication is a widespread environmental change that usually reduces the stabilizing effect of plant diversity on productivity in local communities. Whether this effect is scale dependent remains to be elucidated. Here, we determine the relationship between plant diversity and temporal stability of productivity for 243 plant communities from 42 grasslands across the globe and quantify the effect of chronic fertilization on these relationships. Unfertilized local communities with more plant species exhibit greater asynchronous dynamics among species in response to natural environmental fluctuations, resulting in greater local stability (alpha stability). Moreover, neighborhood communities that have greater spatial variation in plant species composition within sites (higher beta diversity) have greater spatial asynchrony of productivity among communities, resulting in greater stability at the larger scale (gamma stability). Importantly, fertilization consistently weakens the contribution of plant diversity to both of these stabilizing mechanisms, thus diminishing the positive effect of biodiversity on stability at differing spatial scales. Our findings suggest that preserving grassland functional stability requires conservation of plant diversity within and among ecological communities.


Assuntos
Biota , Ecossistema , Eutrofização , Pradaria , Biodiversidade , Biomassa , Fertilização , Modelos Biológicos , Plantas
7.
Science ; 370(6514): 346-350, 2020 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-33060360

RESUMO

Mutualisms, or reciprocally beneficial interspecific interactions, constitute the foundation of many ecological communities and agricultural systems. Mutualisms come in different forms, from pairwise interactions to extremely diverse communities, and they are continually challenged with exploitation by nonmutualistic community members (exploiters). Thus, understanding how mutualisms persist remains an essential question in ecology. Theory suggests that high species richness and functional redundancy could promote mutualism persistence in complex mutualistic communities. Using a yeast system (Saccharomyces cerevisiae), we experimentally show that communities with the greatest mutualist richness and functional redundancy are nearly two times more likely to survive exploitation than are simple communities. Persistence increased because diverse communities were better able to mitigate the negative effects of competition with exploiters. Thus, large mutualistic networks may be inherently buffered from exploitation.


Assuntos
Saccharomyces cerevisiae/fisiologia , Simbiose/fisiologia , Adenina/metabolismo , Biota , Lisina/genética , Lisina/metabolismo , Saccharomyces cerevisiae/genética , Simbiose/genética
8.
Zootaxa ; 4859(3): zootaxa.4859.3.6, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33056191

RESUMO

Species concentration and composition of endosymbiotic ciliates were investigated in the forestomach contents of 12 dromedary camels (Camelus dromedarius) and the ruminal contents of 16 domestic cattle (Bos taurus taurus) living in Ben Gardane, Tunisia. Sixteen species and 8 morphotypes, belonging to 8 genera, were identified from dromedary camels, and 18 species and 13 morphotypes, belonging to 8 genera, were identified from domestic cattle. This is the first report on the endosymbiotic ciliated protozoan biota of dromedary camels and cattle living in Tunisia. The mean density (± SD) of ciliates in the forestomach samples of dromedary camels and the ruminal samples of domestic cattle was 65.4 ± 69.4 × 104 cells mL-1 and 54.2 ± 55.8 × 104 cells mL-1, respectively. Diplodinium cameli and Blepharoconus krugerensis were detected for the first and second time, respectively, from the ruminal contents of cattle. Caloscolex camelinus and B. krugerensis were studied in detail with a scanning electron microscope.


Assuntos
Camelus , Cilióforos , Animais , Biota , Bovinos , Rúmen , Tunísia
9.
Oecologia ; 194(1-2): 237-250, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33009940

RESUMO

Climate change causes species range expansions to higher latitudes and altitudes. It is expected that, due to differences in dispersal abilities between plants and soil biota, range-expanding plant species will become associated with a partly new belowground community in their expanded range. Theory on biological invasions predicts that outside their native range, range-expanding plant species may be released from specialist natural enemies, leading to the evolution of enhanced defence against generalist enemies. Here we tested the hypothesis that expanded range populations of the range-expanding plant species Centaurea stoebe accumulate fewer root-feeding nematodes than populations from the original range. Moreover, we examined whether Centaurea stoebe accumulates fewer root-feeding nematodes in expanded range soil than in original range soil. We grew plants from three expanded range and three original range populations of C. stoebe in soil from the original and from the new range. We compared nematode communities of C. stoebe with those of C. jacea, a congeneric species native to both ranges. Our results show that expanded range populations of C. stoebe did not accumulate fewer root-feeding nematodes than populations from the original range, but that C. stoebe, unlike C. jacea, accumulated fewest root-feeding nematodes in expanded range soil. Moreover, when we examined other nematode feeding groups, we found intra-specific plant population effects on all these groups. We conclude that range-expanding plant populations from the expanded range were not better defended against root-feeding nematodes than populations from the original range, but that C. stoebe might experience partial belowground enemy release.


Assuntos
Nematoides , Rizosfera , Animais , Biota , Plantas , Solo
10.
J Environ Qual ; 49(4): 933-944, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016483

RESUMO

When fertilizer phosphorus (P) is applied to soils, the P can run off fields and cause harmful algal blooms. Due to its chemistry, much of the added P that does not run off can bind to soil particles and become inaccessible to plants. In natural systems, microbial and faunal decomposers can increase soil P accessibility to plants. We tested the hypothesis that this may also be true in agricultural systems, which could increase P application efficiency and reduce runoff potential. We stimulated soil fauna with sodium (Na+ ) and microbes with carbon (C) by adding corn (Zea mays L.) stover and Na+ solution to plots in conventionally managed corn fields in northwestern Ohio. Stover addition increased microbial biomass by 65 ± 12% and respiration by 400-700%. Application of stover with Na+ increased soil detritivore fauna abundance by 51 ± 20% and likely did not affect the other invertebrate guilds. However, soil biological activity was low compared with natural systems in all treatments and was not correlated with instantaneous measures of P accessibility, though cumulative P accessibility over the course of the growing season was correlated with microbial phosphatase activity (slope = 1.01, p < .01) and respiration (slope = 0.42, p = .02). Therefore, in agricultural systems, treatments to stimulate decomposers already in those systems may be ineffective at increasing soil P accessibility in the short term, but in the long term, higher microbial activities can be associated with higher soil P accessibility.


Assuntos
Fósforo/análise , Solo , Biota , Fertilizantes , Ohio
11.
Science ; 370(6513): 164-165, 2020 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-33033201

Assuntos
Biota , Comércio
12.
J Environ Radioact ; 222: 106321, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892897

RESUMO

Although biomagnification of radiocesium (137Cs) has been reported in food webs, most previous research has been limited to select trophic linkages. Few studies have included a comprehensive survey of fauna associated with aquatic, semi-aquatic, and terrestrial habitats within a single study framework. The objectives of this study were to advance our understanding of the dynamics of 137Cs accumulation within food webs by quantifying 137Cs activity across a wide range of biota found within a contaminated canal, as well as test the hypothesis that life-stage and body size influence 137Cs bioaccumulation in select herpetofauna. With extensive sampling across multiple taxa collected from a contaminated canal system and associated floodplain on the Savannah River Site, we assessed 137Cs activity and stable nitrogen isotopes for both aquatic organisms that were restricted to the contaminated effluent canal, and semi-aquatic organisms able to move freely between the contaminated canal and the adjacent uncontaminated terrestrial habitat. We found 137Cs activity to be highly variable among species, with evidence for and against biomagnification in semi-aquatic and aquatic organisms, respectively. Furthermore, 137Cs activity decreased with life stage and body size in bullfrogs (Lithobates catesbeianus), despite post-metamorphic bullfrogs having a more carnivorous diet compared to tadpoles, while cottonmouths (Agkistrodon piscivorus) retained similar 137Cs activity regardless of their age and size. Although evidence of biomagnification has been observed in some contaminated systems, results of our study suggest the extent to which 137Cs biomagnifies within food webs is context-dependent and likely influenced by a suite of biotic and abiotic factors. Further, our data indicate sampling of a broad suite of species and environmental attributes are needed to elucidate the fate and dynamics of anthropogenic pollutants within contaminated ecosystems.


Assuntos
Monitoramento de Radiação , Poluentes Químicos da Água , Poluentes Radioativos da Água , Animais , Biota , Ecossistema , Monitoramento Ambiental , Peixes , Cadeia Alimentar , Rios , Estados Unidos
13.
Bull Environ Contam Toxicol ; 105(4): 650-655, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32889604

RESUMO

Biochar (char-product), generated by pyrolyzing organic materials, is produced for the intended use of land application to promote carbon sequestration, soil improvement and crop-yield. Despite the benefits biochar applications offers, scientific probing on impacts that may result from amendments with biochar is still fragmented. In this study, impact of biochar on Eudrilus eugeniae DNA was investigated. Rice-husk biochar was applied to soil at rates up to 80% d/w and earthworms were exposed for 35-day. Impact on DNA was measured using electrophoresis-gel-extraction-method. Data obtained showed that biochar application over 25% resulted in decreased survival. Electrophoresis-gel-analysis showed that DNA decreased from 450 to 300 bp in biochar soils (p = 0.002). Biochar rates (5%-25%) induced DNA damage. The DNA showed smeared bands or tail; indicating DNA degradation and/or damage. DNA damage is a clear evidence of negative impact of biochar(s) to soil-biota; suggesting that loading of soil with biochar could have serious consequences on soil-fauna.


Assuntos
Carvão Vegetal/toxicidade , Oligoquetos/fisiologia , Poluentes do Solo/toxicidade , Animais , Biota , Carvão Vegetal/química , Dano ao DNA , Oligoquetos/metabolismo , Oryza/metabolismo , Solo , Poluentes do Solo/análise
14.
PLoS Biol ; 18(8): e3000843, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32866143

RESUMO

Interactions between species generate the functions on which ecosystems and humans depend. However, we lack an understanding of the risk that interaction loss poses to ecological communities. Here, we quantify the risk of interaction loss for 4,330 species interactions from 41 empirical pollination and seed dispersal networks across 6 continents. We estimate risk as a function of interaction vulnerability to extinction (likelihood of loss) and contribution to network feasibility, a measure of how much an interaction helps a community tolerate environmental perturbations. Remarkably, we find that more vulnerable interactions have higher contributions to network feasibility. Furthermore, interactions tend to have more similar vulnerability and contribution to feasibility across networks than expected by chance, suggesting that vulnerability and feasibility contribution may be intrinsic properties of interactions, rather than only a function of ecological context. These results may provide a starting point for prioritising interactions for conservation in species interaction networks in the future.


Assuntos
Biota , Simbiose , Animais , Estudos de Viabilidade , Plantas/anatomia & histologia , Risco , Especificidade da Espécie
15.
Nat Commun ; 11(1): 4721, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32948775

RESUMO

The importance of soil age as an ecosystem driver across biomes remains largely unresolved. By combining a cross-biome global field survey, including data for 32 soil, plant, and microbial properties in 16 soil chronosequences, with a global meta-analysis, we show that soil age is a significant ecosystem driver, but only accounts for a relatively small proportion of the cross-biome variation in multiple ecosystem properties. Parent material, climate, vegetation and topography predict, collectively, 24 times more variation in ecosystem properties than soil age alone. Soil age is an important local-scale ecosystem driver; however, environmental context, rather than soil age, determines the rates and trajectories of ecosystem development in structure and function across biomes. Our work provides insights into the natural history of terrestrial ecosystems. We propose that, regardless of soil age, changes in the environmental context, such as those associated with global climatic and land-use changes, will have important long-term impacts on the structure and function of terrestrial ecosystems across biomes.


Assuntos
Biota , Ecossistema , Solo/química , Bactérias/classificação , Biodiversidade , Biomassa , Clima , Fungos/classificação , Microbiota , Plantas/classificação , Fatores de Tempo
16.
Mar Pollut Bull ; 160: 111572, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32920260

RESUMO

Data on the occurrence and abundance of meso and microplastics for the South Pacific are limited and there is urgent need to fill this knowledge gap. The main aim of the study was to apply a rapid screening method, based on the fluorescence tagging of polymers using Nile red, to determine the concentration of meso and microplastics in biota, sediment and surface waters near the capital cities of Vanuatu and Solomon Islands. A spatial investigation was carried out for sediment, biota and water as well as a temporal assessment for sediment for two consecutive years (2017 and 2018). Accumulation zones for microplastics were identified supported by previous hydrodynamic models. Microplastics were detected for all environmental compartments investigated indicating their widespread presence for Vanuatu and Solomons Islands. This method was in alignment with previous recommendations that the Nile red method is a promising approach for the largescale mapping of microplastics in a monitoring context.


Assuntos
Plásticos , Poluentes Químicos da Água , Biota , Cidades , Monitoramento Ambiental , Melanesia , Microplásticos , Poluentes Químicos da Água/análise
17.
Mar Pollut Bull ; 158: 111425, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32753209

RESUMO

Plastic debris is nowadays a well-recognized global threat to marine ecosystems, due to its increasing abundance and pervasiveness. Although the effects of marine plastics on animal wildlife is generally documented, the available studies of plastics affecting seagrasses and their associated biota are relatively scarce. This makes the degree of risk uncertain as regards seagrass ecosystems affected by plastic debris, but also it results in several critical knowledge gaps such as to what extent plastic debris can affect food webs supported by seagrasses. In the age of plastics, the Plasticene, the international political agenda shows great interest in this matter. However, to date, no conservation policies have specifically targeted the protection of seagrasses from plastics debris. Future actions should therefore move in two directions: prompting a radical shift in plastics consumption, and shedding further light on plastics-biota interactions in the marine environment.


Assuntos
Ecossistema , Plásticos , Animais , Biota , Monitoramento Ambiental , Resíduos/análise
18.
Nat Commun ; 11(1): 4086, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32796828

RESUMO

Ecological communities often show changes in populations and their interactions over time. To date, however, it has been challenging to effectively untangle the mechanisms shaping such dynamics. One approach that has yet to be fully explored is to treat the varying structure of empirical communities-i.e. their network of interactions-as time series. Here, we follow this approach by applying a network-comparison technique to study the seasonal dynamics of plant-pollinator networks. We find that the structure of these networks is extremely variable, where species constantly change how they interact with each other within seasons. Most importantly, we find the holistic dynamic of plants and pollinators to be remarkably coherent across years, allowing us to reveal general rules by which species first enter, then change their roles, and finally leave the networks. Overall, our results disentangle key aspects of species' interaction turnover, phenology, and seasonal assembly/disassembly processes in empirical plant-pollinator communities.


Assuntos
Polinização/fisiologia , Animais , Biodiversidade , Biota , Insetos/fisiologia , Estações do Ano
19.
J Environ Radioact ; 222: 106291, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32771855

RESUMO

This study deals with the geology in areas close to a large unexploited uranium deposit and the impact of bedrock characteristics on levels of radionuclides and other elements in soil and biota. Factors influencing soil inventory and ecosystem transfer are discussed, focussing on 238U, 226Ra, and 210Pb. Field work was carried out in Salangen Valley in Northern Norway. Sampling stations for soil and biota covered different habitats - grassland, birch forest and low alpine heathland. The geological survey confirmed uranium-bearing minerals in granitic gneiss and pegmatites. There was large variation in the local occurrence of uranium, reflecting the irregular nature of the pegmatite. Activity concentrations of 238U, 226Ra, and 210Pb in surface soil were elevated at sites close to U-enhanced bedrock, compared to sites with other types of bedrock. Particularly high soil levels were found for 226Ra and 210Pb, whereas activity concentrations of 238U were more variable, depending of local soil characteristics. Levels of other natural radionuclides (40K, 232Th) merely increased with soil mineral content, and concentrations of heavy metals were generally low at all sites. External dose rate (1 m above ground surface) was closely correlated with 226Ra levels in soil. Plant levels of 238U and 226Ra varied by several orders of magnitude depending on soil level and plant species, whereas plant levels of 210Pb and 210Po were largely affected by aerial fallout. Berries generally contained lower levels of 238U and 226Ra than green plant parts. As was the case for plants, the levels of 238U in earthworms were strongly correlated with the respective concentrations in the soil. Soil-to-plant transfer was markedly higher for 226Ra than for 238U. For both radionuclides, a positive correlation was found between concentration ratios of V. myrtillus (heath) and soil organic matter content. The 238U concentration ratios for earthworms were generally two orders of magnitude higher than for plants.


Assuntos
Florestas , Monitoramento de Radiação , Radioatividade , Poluentes Radioativos do Solo , Animais , Biota , Ecossistema , Geologia , Noruega , Solo
20.
PLoS One ; 15(8): e0234830, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32857760

RESUMO

Residential yards constitute a substantive biodiverse greenspace within urban areas. This biodiversity results from a combination of native and non-native species and can contribute to biotic homogenization. Geographical climatic patterns affect the distribution of native species and may differently affect non-native species. In this study, we examined biodiversity and biotic homogenization patterns of yard-dwelling land snails across 12 towns in Oklahoma and Kansas (USA). The 3 x 4 array of towns incorporated a N-S winter temperature gradient (mean low January temperature range = -8.4 to 0.1°C) and an E-W annual rainfall gradient (annual rainfall range = 113.8 to 61.3 cm/yr). Ten yards per town were surveyed. We hypothesized that mild winter temperatures and greater annual rainfall would be associated with greater snail abundance and richness, and that the presence of non-native species would contribute to biotic homogenization. Non-native snails were present and often abundant in all towns. Snail communities varied with both rainfall and cold temperature. Contrary to our prediction, snail abundance was inversely related to annual rainfall-likely because drier conditions resulted in greater yard watering that both augmented rainfall and maintained moist conditions. Sørensen similarity between towns for the entire land snail community and for only non-native species both showed distance-decay patterns, with snail composition becoming less similar with increasing distance-patterns resulting from species turnover. The biotic homogenization index also showed a distance-related pattern, such that closer towns were more likely to have biotic homogenization whereas more distant towns tended to have biotic differentiation. These results support the concept that biotic homogenization is more likely regionally and that climatic changes over distance result in species turnover and can reduce spatially broad biotic homogenization.


Assuntos
Biodiversidade , Biota , Clima , Caramujos/classificação , Animais , Cidades , Ecossistema , Espécies Introduzidas , Kansas , Oklahoma
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