Plant growth promoting bacteria promote rice growth cultivated in two different sandy soils subjected distinct climates conditions.

Sandy soils contain around 70% sand in their composition, making them highly fragile and susceptible to land degradation. Practices such as no-tillage cultivation, the use of bioinoculants, and the application of organic amendments can restore the organic matter in these soils, ensuring sustainable production. In this context, this work aimed to study the microbiological aspects of two sandy soil areas (Brazilian Northeast and South) under contrasting climatic conditions (tropical and temperate). With this purpose, prokaryotic communities were evaluated, and the plant growth-promoting potential of isolated bacteria was assessed by rice inoculation in sandy soil. Despite the high sand content in both soils, soil from the NE was related to the highest phosphorous, calcium, potassium, copper, sodium, zinc, magnesium, and manganese contents, organic matter percentage, and pH. The Shannon diversity index indicated that prokaryotic communities in NE were more diverse than in SU, and PCA revealed that microbial composition exhibited distinct patterns. The rice inoculation experiments were executed to verify if the bacterial isolates displayed a similar growth promotion potential when inoculated in sandy soil areas subjected to different climatic conditions. When all PGP characteristics evaluated were pooled in a PCA, a similar pattern was observed for SU and NE. Burkholderia sp. SU94 was related to highest PGP characteristics evaluated. Paraburkholderia sp. NE32 showed similar results to those of the non-inoculated control. This similar effect of rice growth in the Northeast and South of Brazil suggests that isolate SU94 adapts to different environmental conditions.

Origin of sandy substrates controlling the distribution of open vegetation ecosystems in Amazonia.

Understanding the role of open vegetation, particularly in white-sand ecosystems (WSE) and savannas, is crucial for elucidating their role in Amazonian biotic diversification. These ecosystems predominantly develop on sandy terrains, suggesting that the geological substrate significantly influences the vegetation upon it. Therefore, the interaction between landscape changes and biotic diversification is closely tied to the dynamics and resilience of these sandy substrates. Current WSE and savannas in lowland Amazonia colonized fluvial sediments deposited during the past 120 ka, with marked synchronicity over the last 23 ka, as shown by optically stimulated luminescence (OSL) and radiocarbon ages of such sandy substrates. In contrast, sandy substrates supporting open vegetation in highland areas, unsuitable for Quaternary sand accumulation, would have persisted beyond the Quaternary, as ancient sedimentary rocks in these areas are prone to developing sandy soils. The current distribution of open vegetation ecosystems in lowland Amazonia is coupled with the deposition and erosion of sandy sediments by Quaternary fluvial systems, while weathering sandy substrates in highland areas serve as long-term and resilient refugia beyond the Quaternary. The contrasting spatiotemporal dynamics of landscape changes in lowland and highland areas has implications for biodiversification or extinction events leading to current biogeography patterns in Amazonia.

Isolation and identification of plant growth-promoting rhizobacteria from Spinifex littoreus in Parangkusumo Coastal Sand Dunes, Indonesia.

Utilizing coastal land for agriculture presents challenges such as low water content, high soil salinity, and low organic compound content. To support plant growth under these conditions, biofertilizers composed of plant growth promoting Rhizobacteria (PGPR), especially those inhabiting coastal areas, are needed. The Parangkusumo sand dunes on the southern coast of Java, Indonesia, is a unique coastal ecosystem characterized by arid conditions, high temperatures, and high soil salinity. To date, no studies have reported the isolation of PGPR from this ecosystem. This study is the first to isolate and identify PGPR associated with Spinifex littoreus, a dominant plant species in the Parangkusumo sand dunes, which are adapted to the harsh condition of Parangkusumo sand dunes. Ten rhizobacterial isolates were obtained, with five identified as members of the Bacillaceae family. All isolates demonstrated phosphate solubilization activity, while seven exhibited cellulolytic activity. One isolate, Priestia aryabhattai strain 2, notably showed phosphate solubilization and nitrogen fixation activities. The findings of this PGPR activity screening offer valuable insights for developing biofertilizers tailored for coastal agricultural applications.

Determinants of anuran assemblages in Amazonian White-sand Ecosystems.

Amazonian white-sand ecosystems have predominantly sandy soils and a high amount of endemism, and several species found within them are adapted to long periods of drought. However, little is known about the variation in the structure of anuran assemblages in these ecosystems. Considering that most species are not uniformly distributed in heterogeneous landscapes, we tested the hypothesis that anuran assemblage variation in white-sand ecosystems is related to changes in vegetation structure. Specifically, we focused on a heterogeneous patch of white-sand ecosystems of the central Amazon and evaluated whether vegetation structure and soil characteristics, including root depth, influence the richness, abundance, and composition of anuran assemblages. Our results showed that low amounts of clay in the soil play an important role in structuring vegetation in these ecosystems, and these are the main factors that organize anuran assemblages. The Campinaranas close to the water bodies have a high species richness, while Campina landscapes limit the occupation of most of species. Our findings indicate that anurans undergo environmental filtering in white-sand ecosystems and are organized into hierarchical subgroups, in which only species with specialized reproduction can successfully occupy the most water-restricted environments.

Meiofauna at a tropical sandy beach in the SW Atlantic: the influence of seasonality on diversity.

Background: Sandy beaches are dynamic environments housing a large diversity of organisms and providing important environmental services. Meiofaunal metazoan are small organisms that play a key role in the sediment. Their diversity, distribution and composition are driven by sedimentary and oceanographic parameters. Understanding the diversity patterns of marine meiofauna is critical in a changing world. Methods: In this study, we investigate if there is seasonal difference in meiofaunal assemblage composition and diversity along 1 year and if the marine seascapes dynamics (water masses with particular biogeochemical features, characterized by temperature, salinity, absolute dynamic topography, chromophoric dissolved organic material, chlorophyll-a, and normalized fluorescent line height), rainfall, and sediment parameters (total organic matter, carbonate, carbohydrate, protein, lipids, protein-to-carbohydrate, carbohydrate-to-lipids, and biopolymeric carbon) affect significatively meiofaunal diversity at a tropical sandy beach. We tested two hypotheses here: (i) meiofaunal diversity is higher during warmer months and its composition changes significatively among seasons along a year at a tropical sandy beach, and (ii) meiofaunal diversity metrics are significantly explained by marine seascapes characteristics and sediment parameters. We used metabarcoding (V9 hypervariable region from 18S gene) from sediment samples to assess the meiofaunal assemblage composition and diversity (phylogenetic diversity and Shannon's diversity) over a period of 1 year. Results: Meiofauna was dominated by Crustacea (46% of sequence reads), Annelida (28% of sequence reads) and Nematoda (12% of sequence reads) in periods of the year with high temperatures (>25 °C), high salinity (>31.5 ppt), and calm waters. Our data support our initial hypotheses revealing a higher meiofaunal diversity (phylogenetic and Shannon's Diversity) and different composition during warmer periods of the year. Meiofaunal diversity was driven by a set of multiple variables, including biological variables (biopolymeric carbon) and organic matter quality (protein content, lipid content, and carbohydrate-to-lipid ratio).

Evaluation of heating and liming treatments in sand samples artificially contaminated with Ancylostoma spp. eggs.

Ancylostoma spp. are found worldwide. Infected dog and cat feces can contaminate soil in public places. Despite prophylactic measures being available, studies on direct remediation of Ancylostoma-contaminated soils are scarce. This study aimed to determine the impact of heat treatment and liming on the viability of Ancylostoma spp. eggs in artificially contaminated sandy soil. Sterilized sand samples were contaminated with Ancylostoma spp. eggs extracted from infected dogs' feces. Samples were heated (trial I) to 70 °C or 80 °C, then sieved after 24 hours (212, 90, 38, and 25 µm). Larval cultures were assessed for larval development following heat treatment. Five quicklime concentrations (trial II; 50, 30, 20, 10 and 5%) were used to treat sand. The effect of liming on larval cultures was assessed by measuring embryonic development. Filariform larvae were exposed to 20% quicklime (25 °C and 37 °C, 20 min). Heat treatment destroys Ancylostoma spp. eggs and prevents in vitro larval development. Liming at 50, 30, and 20% concentrations made embryonic development impossible. However, filariform larvae treated with 20% lime solution retained their motility. Heating at 70 °C and liming at 20% were sufficient to make Ancylostoma spp. egg embryogenesis impossible in experimentally contaminated sand samples.

Reduction of Helicobacter pylori cells in rural water supply using slow sand filtration.

Helicobacter pylori is a microorganism that infects 60% of the population and is considered the main cause of atrophic gastritis, gastric and duodenal ulcers, and gastric cancer. Different emerging pathogens have been found in drinking water and their presence is considered to be an important public health problem. For this reason, it is necessary to carry out the validation of reliable technologies for this type of pathogens and evaluate their performance. This paper reports, for the first time, H. pylori reduction in a drinking water pilot plant of two slow sand filters (SSF). Inlet water was taken from a gravel filtration system of a rural water supply in Colombia and then inoculated with viable cells of H. pylori. By determining the Genomic Units (GU) through quantitative Polymerase Chain Reaction (qPCR), the concentration of GU/sample was measured. In the inlet water amplification for SSF1 and SSF2 were 5.13 × 102 ± 4.48 × 102 and 6.59 × 102 ± 7.32 × 102, respectively, while for the treated water they were 7.0 ± 5.6 and 2.05 × 101 ± 2.9 × 101 GU/sample for SSF1 and SSF2, respectively. The SSF pilot plant reached up to 3 log reduction units of H. pylori; therefore, since there is not an H. pylori contamination indicator and its periodic monitoring is financially complicated, the SSF could guarantee the drinking water quality necessity that exists in rural areas and small municipalities in developing countries, where infection rates and prevalence of this pathogen are high.

Clearance rates of sand-burrowed and laterally pressed unburrowed Pismo clam Tivela stultorum (Mawe 1823) in a laboratory open-flow system.

Pismo clam extraction is currently banned in Mexico to help the recovery of natural populations. Thus, the primary objective of this study was to gain insight on its basic biology and husbandry protocols. Growth and clearance rate (CR) of sand-burrowed and sediment-free, laterally pressed adult Pismo clams were quantified in the laboratory as a function of burrowing condition, flow, temperature, and microalgal concentration using open-flow chambers. After 40 days, clams remained healthy regardless of burrowing condition and showed a hyperbolic CR response pattern to increased flow, with CR directly proportional to flows lower than 1000 ml min-1. Maximal asymptotic CR values (300 to 400 ml min-1 org-1) were observed from 1000 to 2000 ml min-1. No significant CR differences were observed between burrowed and laterally pressed clams, yet microalgal concentration effects were detected, with constant maximal CRs of ∼250 ml min-1 in the range of 50 to 200 cells µl-1 and decline at higher concentrations. Maintenance protocols of laterally pressed organisms were validated in the laboratory with both weight and CR data. To our knowledge, this is the first study providing whole-body physiological data translated into effective husbandry protocols for Pismo clams. This approach represents a fresh perspective to traditional research areas, opening the possibility for continued experimentation under controlled conditions.

Drivers of flower visit and resource sharing between the honeybee and native bees in Neotropical coastal sand dunes.

The honeybee (Apis mellifera) is one of the most important pollinator species because it can gather resources from a vast variety of plant species, including both natives and introduced, across its geographical distribution. Although A. mellifera interacts with a large diversity of plants and shares resources with other pollinators, there are some plant species with which it interacts more frequently than others. Here, we evaluated the plant traits (i.e., plant length, abundance of bloomed individuals, number of open flowers, and stamen length) that would affect the honeybee visit frequencies to the flowers in a coastal environment in the Gulf of Mexico. Moreover, we evaluated which native bee species (and their body size) overlap floral resource with A. mellifera. We registered 998 plant-bee interactions between 35 plant species and 47 bee species. We observed that plant species with low height and with high abundances of bloomed individuals are positively related to a high frequency of visits by A. mellifera. Moreover, we found that A. mellifera tends to share a higher number of plant species with other bee species with a similar or smaller body size than with bigger species, which makes them a competitor for the resource with honeybees. Our results highlight that the impacts of A. mellifera on plants and native bees could be anticipated based on its individual's characteristics (i.e., plant height and abundance of bloomed individuals) and body size, respectively.

Urbanization increases the risk of phosphorus loss in sandy soils of tropical ecosystems.

Phosphorus (P) is naturally present in soils. However, urbanization can promote additional inputs of P into the soil that lead to saturation of the binding sites exceeding the maximum sorption capacity. Soils saturated with P act as important diffuse sources of pollution of water resources. The flow of P from the soil to aquatic ecosystems is an aggravating factor for water scarcity, especially in the semiarid region. Knowing phosphorus dynamics in the soil is essential to protect water quality and ensure its multiple uses. In this paper, a total of fifty soil samples, twenty-five from natural soils and twenty-five from urban soils, were evaluated for the effect of urbanization on P sorption characteristics and their relationship with the physical and chemical attributes of the soil. The soil samples were characterized physically and chemically, and the P sorption characteristics were obtained from the adjustment of Langmuir and Freundlich equations by nonlinear regression. Urbanization results in increased soil P saturation and reduced P sorption capacity. Our results show that the sandy texture of the soils studied had a standardizing effect on the soil's physical properties, maintaining, even after urbanization, the physical quality similar to natural soil. In contrast, pH (in water and KCl), base saturation, sodium saturation, potential acidity, exchangeable Al3+, exchangeable Mg2+, available P, and P-rem are valuable indicators in the segregation between natural and urban soils. The reduction of P sorption capacity in urban soils increases the risks related to P loads in aquatic ecosystems that experience urban expansion worldwide. These data serve as a basis for decision-making regarding the appropriate soil monitoring and management of urban expansion areas in watersheds to control P flow to aquatic systems.

Beach sand plastispheres are hotspots for antibiotic resistance genes and potentially pathogenic bacteria even in beaches with good water quality.

Massive amounts of microplastics are transported daily from the oceans and rivers onto beaches. The ocean plastisphere is a hotspot and a vector for antibiotic resistance genes (ARGs) and potentially pathogenic bacteria. However, very little is known about the plastisphere in beach sand. Thus, to describe whether the microplastics from beach sand represent a risk to human health, we evaluated the bacteriome and abundance of ARGs on microplastic and sand sampled at the drift line and supralittoral zones of four beaches of poor and good water quality. The bacteriome was evaluated by sequencing of 16S rRNA gene, and the ARGs and bacterial abundances were evaluated by high-throughput real-time PCR. The results revealed that the microplastic harbored a bacterial community that is more abundant and distinct from that of beach sand, as well as a greater abundance of potential human and marine pathogens, especially the microplastics deposited closer to seawater. Microplastics also harbored a greater number and abundance of ARGs. All antibiotic classes evaluated were found in the microplastic samples, but not in the beach sand ones. Additionally, 16 ARGs were found on the microplastic alone, including genes related to multidrug resistance (blaKPC, blaCTX-M, tetM, mdtE and acrB_1), genes that have the potential to rapidly and horizontally spread (blaKPC, blaCTX-M, and tetM), and the gene that confers resistance to antibiotics that are typically regarded as the ultimate line of defense against severe multi-resistant bacterial infections (blaKPC). Lastly, microplastic harbored a similar bacterial community and ARGs regardless of beach water quality. Our findings suggest that the accumulation of microplastics in beach sand worldwide may constitute a potential threat to human health, even in beaches where the water quality is deemed satisfactory. This phenomenon may facilitate the emergence and dissemination of bacteria that are resistant to multiple drugs.

Phenotypic, genomic and in planta characterization of Bacillus sensu lato for their phosphorus biofertilization and plant growth promotion features in soybean.

Bacillus sensu lato were screened for their capacity to mineralize organic phosphorus (P) and promote plant growth, improving nitrogen (N) and P nutrition of soybean. Isolates were identified through Type Strain Genome Server (TYGS) and Average Nucleotide Identity (ANI). ILBB95, ILBB510 and ILBB592 were identified as Priestia megaterium, ILBB139 as Bacillus wiedmannii, ILBB44 as a member of a sister clade of B. pumilus, ILBB15 as Peribacillus butanolivorans and ILBB64 as Lysinibacillus sp. These strains were evaluated for their capacity to mineralize sodium phytate as organic P and solubilize inorganic P in liquid medium. These assays ranked ILBB15 and ILBB64 with the highest orthophosphate production from phytate. Rhizocompetence and plant growth promotion traits were evaluated in vitro and in silico. Finally, plant bioassays were conducted to assess the effect of the co-inoculation with rhizobial inoculants on nodulation, N and P nutrition. These bioassays showed that B. pumilus, ILBB44 and P. megaterium ILBB95 increased P-uptake in plants on the poor substrate of sand:vermiculite and also on a more fertile mix. Priestia megaterium ILBB592 increased nodulation and N content in plants on the sand:vermiculite:peat mixture. Peribacillus butanolivorans ILBB15 reduced plant growth and nutrition on both substrates. Genomes of ILBB95 and ILBB592 were characterized by genes related with plant growth and biofertilization, whereas ILBB15 was differentiated by genes related to bioremediation. Priestia megaterium ILBB592 is considered as nodule-enhancing rhizobacteria and together with ILBB95, can be envisaged as prospective PGPR with the capacity to exert positive effects on N and P nutrition of soybean plants.

Irrigation level and substrate type on the acclimatization and development of mandacaru (Cereus jamacaru DC.): an emblematic cactus from Brazilian semiarid region.

Mandacaru is a cactus with great socioeconomic potential, but lack of information about its cultivation hinders its domestication. Here, we aimed to evaluate the acclimatization and vegetative development of mandacaru under different substrates and irrigation levels. For this, seeds inoculated in vitro were grown for 120 days, being transplanted to pots containing four types of substrate (S1-caatinga soil + gravel; S2-washed sand + organic matter + soil + charcoal; S3-washed sand + cattle manure + soil + sand; S4-commercial organic substrate). Pots were irrigated with 100% of the field capacity (FC) once-a-week, or with 50% FC twice-a-week, and kept in a greenhouse for six months. The experimental design was completely randomized, in a 4 × 2 factorial scheme, with six replications. Plant height and diameter, axial and radial growth rate, fresh and dry mass of stem and root, water content, and photosynthetic pigments were determined. Growth was affected mainly by the substrate, with S4 resulting in higher growth and pigment content, while S1 was impaired and S2 and S3 resulted in intermediate growth. The use of S4 and 100% FC once per week was the best condition for mandacaru.

Soil-vegetation relationship in savanic formations of the Jalapão, Brazil.

Understanding the influence of fine-scale abiotic filters on plant communities can provide important insights into floristic patterns of the Brazilian Cerrado. We aimed to evaluate the interactions of the soil and the plant community composition with their distribution in different sandy environments of Brazilian Cerrado, the Jalapão region. Eight environments were sampled, each with ten plots of 20 × 50 m. All woody individuals presenting circumference at soil height ≥ 10 cm were sampled. Subplots of 5 × 15 m were demarcated, where woody individuals with a circumference at soil height ≥ 5 and < 10 cm were sampled. Subplots of 2 × 2 m were also demarcated to sample herbaceous individuals. Soil samples varying from 0 to 20 cm of depth were collected for each plot (20 × 50 m). Overall, 20000 individuals that belong to 338 species and 76 families were sampled. The dominant family was Fabaceae. There were significant differences among the environments regarding species richness and soil. The analyzed soils are extremely poor and with a tendency to sandy texture, small chemical and/or physical variations imply differences in the distribution of vegetation. Our study revealed abiotic filters exerted crucial fine-scale effects on plant community in the Jalapão region.

First report of some rare earth elements and trace elements in sands from different islands located in the Marine Natural Monument Archipelago Cayos Cochinos, Caribbean Sea.

Rare earth elements (REEs) are a group of chemicals widely used in emerging technologies today, and are often labeled as potential environmental contaminants. The Cayos Cochinos Archipelago is a protected area of Honduras, Central America, with intertidal and supratidal sands, making it a prime candidate for pollution research. In December 2022, sand samples from the Cayos Cochinos area was collected and analyzed by X-ray fluorescence to determine the levels of REEs and some less-studied trace elements (TEs). Based on the findings, REEs mean contents (µg g-1 d.w.) fluctuated between 2.96 for Y to 667.1 for Nd, while TEs ranged from 10.37 for Th to 3896.2 for Sr. Also, the results showed significantly higher levels of La, Pr, Y, Sr, Ba, and Th in the supratidal zone than in the intertidal zone. The data are useful as a basis for understanding the presence of chemical elements in near-shore marine areas and subsequently help identify sustainable practices that will reduce the impacts of these chemicals.

A Mission Simulating the Search for Life on Mars with Automated Drilling, Sample Handling, and Life Detection Instruments Performed in the Hyperarid Core of the Atacama Desert, Chile.

We report on a field demonstration of a rover-based drilling mission to search for biomolecular evidence of life in the arid core of the Atacama Desert, Chile. The KREX2 rover carried the Honeybee Robotics 1 m depth The Regolith and Ice Drill for Exploration of New Terrains (TRIDENT) drill and a robotic arm with scoop that delivered subsurface fines to three flight prototype instruments: (1) The Signs of Life Detector (SOLID), a protein and biomolecule analyzer based on fluorescence sandwich microarray immunoassay; (2) the Planetary In Situ Capillary Electrophoresis System (PISCES), an amino acid analyzer based on subcritical water extraction coupled to microchip electrophoresis analysis; and (3) a Wet Chemistry Laboratory cell to measure soluble ions using ion selective electrodes and chronopotentiometry. A California-based science team selected and directed drilling and sampling of three sites separated by hundreds of meters that included a light-toned basin area showing evidence of aqueous activity surrounded by a rocky desert pavement. Biosignatures were detected in basin samples collected at depths ranging from 20 to 80 cm but were not detected in the surrounding area. Subsurface stratigraphy of the units drilled was interpreted from drill sensor data as fine-scale layers of sand/clay sediments interspersed with layers of harder material in the basins and a uniform subsurface composed of course-to-fine sand in the surroundings. The mission timeline and number of commands sent to accomplish each activity were tracked. The deepest sample collected (80 cm) required 55 commands, including drilling and delivery to three instruments. Elapsed time required for drilling and sample handling was less than 3 hours to collect sample from 72 cm depth, including time devoted to recovery from a jammed drill. The experiment demonstrated drilling, sample transfer technologies, and instruments that accomplished successful detection of biomolecular evidence of life in one of the most biologically sparse environments on Earth.

Crop rotation and inoculation increase soil bradyrhizobia population, soybean grain yields, and profitability.

Crop rotation and rhizobial inoculation are strategies to increase yield by means of organic matter addition and modulation of microbial diversity. However, the extent to which these agricultural practices change soil Bradyrhizobium populations, soybean grain yield, and economic benefits to farmers is unclear. Thus, this study aimed to evaluate the interaction between crop rotation and inoculation of soybean (Glycine max) cultivated in two contrasting soils (clayey and sandy soil) on biological nitrogen fixation components, grain yields, and profits. Field experiments with a three-year crop rotation system were carried out to compare effects of inoculation and crop rotations on soil chemical attributes, bradyrhizobia most probable number (MPN) and diversity, soybean nodulation, grain yield, and economic indicators of inoculation in different crop rotations. The crop rotation did not affect the soil MPN cells of bradyrhizobia, but the inoculation and the soil sampling time did, ranging from 3.61-4.42 to 4.40-4.82 in the sandy soil, while in the clayey soil they were from 5.19-6.34 to 6.61-7.14 in Log10 per g of soil with higher population after harvest of summer crops. In the clayey soil, crop rotation influenced soybean nodulation. The grain yield of inoculated soybean in the clayey soil was higher than that in the sandy soil. Soybean inoculation with Bradyrhizobium spp. increased the profitability of agricultural production systems by up to 45% in clayey soil and up to 7% in sandy soil.

Distribution of Inorganic Contaminants Along the Coast of Ciudad de la Costa, Uruguay.

The aim of this work was to study the distribution of relevant inorganic contaminants in environmental samples from Ciudad de la Costa, the second most populated city of Uruguay. For this task aluminum (Al), cadmium (Cd), chromium (Cr), nickel (Ni) and lead (Pb) levels were determined in sand, water, and plant material from six beaches that are located in the area. Analytical methods were successfully validated. Accuracy was ensured by using certified reference materials and spiking procedures. Average metal concentrations in sand and water samples were compared with the maximum limits established by international or national regulations (when available), being far below these limits in all cases. This may indicate that the inorganic contamination in the studied area is rather low, despite the rapid increase in anthropic activities in recent years. To give a deeper characterization of the ecosystem, metal accumulation and mobility within a common plant of the zone, Ammophila arenaria, were studied. Results showed that concentrations in roots were one order of magnitude higher in comparison to aerial parts. In addition, the bioaccumulation coefficient (BAC) showed that the plant accumulates Cd, Cr and Ni, while a low accumulation for Pb was observed. Finally, a Cr(VI) speciation analysis in Ammophila arenaria was performed, showing Cr(VI) percentages below 4.6%, which is relevant from the (eco)toxicological point of view due to the high environmental mobility and bioavailability of this valence state. This work constitutes the first environmental surveillance report of this kind, regarding this populated area of the country.

Study of creosote transport properties in sandy and clay soils.

Creosote is an organic pollutant formed by a complex mixture of highly toxic and carcinogenic compounds and classified as a dense non-aqueous phase liquid (DNAPL). Its migration depends on media and fluid properties that control the multiphase flow in the subsurface. Residual saturation and hydraulic conductivity are essential parameters to accurately simulate fluid displacement in porous media. This work shows the behavior of creosote in porous medium for sandy and clay soils, collected in a contaminated area in the state of São Paulo, Brazil. Creosote retention was evaluated and compared to water. The retention curve parameters were obtained based on van Genuchten and Brooks and Corey models. The hydraulic conductivities of creosote and water are presented for both soils. The results show that, in the clay soil, water was more retained than creosote, while in the sandy soil, creosote retention was higher. The hydraulic conductivity values obtained in the clay soil show a difference of two orders of magnitude between creosote and water. Although creosote is a viscous fluid, it presents considerable mobility in the clay soil, which is relevant in remediation processes. This study advances our knowledge about DNAPL behavior in clay and sand, and no other study of creosote parameters in these porous media was found. A more accurate estimate of the time required for a liquid spill to reach groundwater can then be predicted, so that appropriate actions can be taken and risk management can be carried out.

A new species of Pristimantis (Anura: Strabomantidae) from white-sand forests of central Amazonia, Brazil.

The white-sand ecosystems in the Solimões-Negro Interfluve are among the less studied in Amazonia. Recent herpetological surveys conducted west of Manaus, Brazil (central Amazonia) indicate that white-sand forests host a unique anuran fauna comprising habitat specialized and endemic species. In the present study we describe a new species of rain frog belonging to the Pristimantis unistrigatus species group from the white-sand forest locally called "campinarana" (thin-trunked forests with canopy height below 20 m). The new species is phylogenetically close to rain frogs from western Amazonian lowlands (P. delius, P. librarius, P. matidiktyo and P. ockendeni). It differs from its closest relatives mainly by its size (male SVL of 17.3-20.1 mm, n = 16; female SVL of 23.2-26.5 mm, n = 6), presence of tympanum, tarsal tubercles and dentigerous processes of vomers, its translucent groin without bright colored blotches or marks, and by its advertisement call (composed of 5-10 notes, call duration of 550-1,061 ms, dominant frequency of 3,295-3,919 Hz). Like other anuran species recently discovered in the white-sand forests west of Manaus, the new species seems to be restricted to this peculiar ecosystem.