Sites In Southwest Research Articles

Factors associated with study protocol adherence and bio banking participation in reproductive medicine clinical trials and their relationship to live birth.

What demographic and baseline characteristics are predictive of adherence to reproductive medicine clinical trial protocols, live birth or participation in genetic studies? Race, BMI and lower income are associated with likelihood of non-adherent to reproductive medicine clinical trial protocols, while race influences collection of biological samples and non-adherent to study protocols is associated with lower probability of live birth. Although aspects of adherence to study protocol have previously been evaluated as individual factors in infertile women, the factors that affect overall non-adherent to study protocol have not been previously evaluated. A secondary data analysis of 1650 participants from two prospective multicenter, double-blind controlled studies was carried out: Pregnancy in Polycystic Ovary Syndrome II (PPCOS II) and Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation (AMIGOS). The participants were women aged 18-40 years old with either polycystic ovary syndrome (PCOS) with ovulatory dysfunction in combination with either hyperandrogenemia and/or polycystic ovarian morphology (PPCOS II), or regular ovulatory cycles with unexplained infertility (AMIGOS). The study was carried out in 14 clinical sites in the USA. Non-adherence to clinical trial protocol was chosen as the primary outcome for this analysis. To evaluate whether demographic and baseline characteristics were predictive of adherence to study protocols, live birth or participation in blood sampling for DNA and repository, and pregnancy registry, these putative factors were compared between the outcome measures. Logistic regression was used to establish a prediction model using the putative predictors introduced above. Women who self-identified as African American or Asian and those with higher BMI and lower household income were less likely to adhere to protocol. Non-adherence to the study protocol was associated with a lower probability of live birth (odds ratio: 0.180, 95% CI: 0.120, 0.272, P < 0.001). African Americans or Asians were less likely to participate in optional study DNA collection compared to Whites. Participants who were African American or with high annual income or from the Southwest sites or had PCOS were less likely to participate in the blood repository studies. Race and ethnicity were self-reported and such self-classification to strict race and ethnicity may not always be representative of a whole racial or ethnic group. This study included two US multicenter trials and therefore the findings may not be extrapolated to international trials. Identification of populations with low participation is an important initial step, as further investigation can develop specific measures to improve adherence to study protocols and participation in biospecimen banking and thereby extend the representativeness of reproductive medicine clinical trial findings. Supported by NIH Eunice Kennedy Shriver NICHD Grants: U10 HD39005, U10 HD38992, U10 HD27049, U10 HD38998, U10 HD055942, HD055944, U10 HD055936, U10HD055925, PPCOSII: U10 HD27049, U10 HD38992, U10 HD055925, U10 HD39005, U10 HD38998, U10 HD055936, U10 HD055942, U10 HD055944; Clinical Reproductive Endocrine Scientist Training Program (CREST): R25HD075737. Outside this study, M.P.D. received NIH/NIHCD research grant and R.S.L. received research grant from Ferring and was consultant for Bayer, Kindex, Odega, Millendo and AbbVie. ClinicalTrials.gov number: NCT00719186; NCT01044862.

Geographical variation in total phenolics, flavonoids and antioxidant activities of Eucalyptus camaldulensis leaves in Burkina Faso

This study aimed to elucidate the effect of sampling location of Eucalyptus camaldulensis leaves on antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC). Leaves of E. camaldulensis collected at three different locations in Burkina Faso (north, central, south-west) were subjected to hydrodistillation to obtain a water extract and subsequent ethanol extraction of the solid residue. The extracts were analysed for antioxidant activity using 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging, TPC, TFC and high-performance thin layer chromatography (HPTLC) fingerprint. TPC were higher in water extracts and presented considerable variation from 129±9 to 266±4 milligram Gallic Acid Equivalent per gram of extract (mg GAE/g) with the highest value 266±4 mg GAE/g at the south-west site. This aqueous extract also showed high antioxidant activity with EC50 8.3 µg/mL. Furthermore, HPTLC fingerprint of the extracts showed both band intensity and size differences. For TFC, we found a slight differences within both water and ethanolic extracts with the highest value of 38.3 ±4.2 mg QE/g for the south-west ethanolic extract. The noticeable impact of climate on chemical variability of E. camaldulensis leaves needs to be taken into consideration for any further applications based on TPC biological activity of the extracts. Key words: Eucalyptus camaldulensis, total phenolic content, total flavonoid content, antioxidant activity, sample location, chemical variation.

Effects of environmental modification on the diversity and positivity of anopheline mosquito aquatic habitats at Arjo-Dedessa irrigation development site, Southwest Ethiopia

BackgroundIrrigated agriculture is key to increase agricultural productivity and ensure food security in Africa. However, unintended negative public health impacts (e.g. malaria) of such environmental modification have been a challenge. This study assessed the diversity and distribution of breeding habitats of malaria vector mosquitoes around Arjo-Dedessa irrigation development site in Southwest Ethiopia.MethodsAnopheline mosquito larvae were surveyed from two agroecosystems, ‘irrigated’ and ‘non-irrigated’ areas during the dry (December 2017–February 2018) and wet (June 2018–August 2018) seasons. Mosquito habitat diversity and larval abundance were compared between the irrigated and non-irrigated areas. The association between anopheline mosquito larvae occurrence and environmental parameters was analysed using Pearson chi-square. Multiple logistic regression analysis was used to determine primary parameters that influence the occurrence of anopheline larvae.ResultsOverall, 319 aquatic habitats were surveyed during the study period. Around 60% (n = 152) of the habitats were positive for anopheline mosquito larvae, of which 63.8% (n = 97) and 36.2% (n = 55) were from irrigated and non-irrigated areas, respectively. The number of anopheline positive habitats was two-fold higher in irrigated than non-irrigated areas. Anopheline larval abundance in the irrigated area was 16.6% higher than the non-irrigated area. Pearson’s chi-square analysis showed that season (χ2 = 63.122, df = 1, P < 0.001), agroecosystem (being irrigated or non-irrigated) (χ2 = 6.448, df = 1, P = 0.011), and turbidity (χ2 = 7.296, df = 2, P = 0.025) had a significant association with larval anopheline occurrence.ConclusionsThe study showed a higher anopheline mosquito breeding habitat diversity, larval occurrence and abundance in the irrigated than non-irrigated areas in both dry and wet seasons. This indicates that irrigation development activities contribute to proliferation of suitable mosquito breeding habitats that could increase the risk of malaria transmission. Incorporating larval source management into routine malaria vector control strategies could help reduce mosquito population density and malaria transmission around irrigation schemes.

Analysis of Template-Based Detection Algorithms for Inshore Bryde’s Whale Short Pulse Calls

Marine mammals use sound for communication and echolocation within their ecosystems. The detection of these sounds is an important aspect of signal processing, such that we can estimate the spatial position and direction of arrival of these mammals, and have an understanding of their ecology. Passive acoustic monitoring (PAM) is widely used to understand marine mammal movement and vocal repertoire. In PAM, datasets are accumulated over days, months or years. Thus, it is impracticable to manually analyse the datasets because it is very large. This motivated the development of automated sound detection techniques for marine mammals, which most often varies depending on the vocal duration, frequency range and call type. In this paper, continuous recordings of Bryde's whale (Balaenoptera edeni edeni) short pulse calls (<; 3.1s long) were collected on a weekly basis from December 2018 to April 2019 on sighting of the individual in a single site in the endmost South-West of South Africa. The sound, previously not documented off South Africa, was observed on visual confirmation of the presence of inshore Brydes's whale. In addition, the paper develops and analyses two automated template-based detection algorithms for this short pulse call, employing dynamic time warping (DTW) and linear predictive coding (LPC) techniques. These proposed template-based detectors are novel, as they have not being previously used in Bryde's whale sound detection in the literature. When applied to the continuous recordings of the short pulse calls, the DTW-based and LPC-based detection algorithms obtained a sensitivity of 96.04% and 97.14% respectively for high signal-to-noise ratio (about 10dB above the ambient sound). Otherwise, for low SNR, the DTW-based and LPC-based detection algorithms obtained a sensitivity of 94.98% and 96.00% respectively. These detection algorithms exhibit low computational time complexity and can be modified to analyse the movement of obscure but vocal marine species instead of manual identification.

Legacy effects of emerald ash borer on riparian forest vegetation and structure

High levels of ash (Fraxinus spp.) mortality have been reported in areas of North America following invasion of emerald ash borer (EAB) (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), but little is known about the impacts of EAB in riparian forests, particularly along first order streams. We delineated canopy gaps resulting from EAB-caused ash mortality along four first order streams in each of three distinct watersheds, which represented a temporal gradient of the EAB invasion across southern Michigan. Time lapsed aerial imagery showed canopy gaps were apparent by 2005, 2010, and 2012 in southeast, central and southwest sites, respectively. We assessed overstory trees, regeneration, shrubs, herbaceous plants, coarse woody debris, and photosynthetically active radiation in each canopy gap and in forests surrounding the gap. Canopy gaps were originally dominated by green ash (F. pennsylvanica) and black ash (F. nigra) but more than 85% of ash basal area was killed by EAB across all sites. Live basal area was greater in forests than in gaps, but was similar among all three watersheds. A lower percentage of dead ash trees remained standing and volume of ash coarse woody debris was higher in southeastern sites, with the longest history of EAB invasion, than in central and southwestern sites. Species richness of overstory trees was higher in forests (34 species) than in gaps (27 species). Photosynthetically active radiation, measured 1.5 m above ground, was 55% higher in canopy gaps than in adjacent forests during summer, but was similar during winter. Species composition of pre-EAB forest overstories and current saplings were similar among canopy gaps; overall, 66.3% of saplings were ash. Sapling species in forested areas adjacent to gaps were often dominated by Acer rubrum, while Quercus rubra, Prunus serotina, Acer saccharum and A. rubrum were common in overstories. Seedlings were rare within gaps now dominated by dense mats of sedges (Carex spp.). Although ash has been functionally lost from riparian forest overstories in most of southern Michigan, consistently high sapling densities, combined with reduced EAB densities, could facilitate ash persistence in post-invasion areas. If EAB densities increase, however, recruitment of ash saplings into the overstory will be limited. Continued monitoring will be important to assess the future status of ash and overstory dynamics in of post-EAB riparian forests.

Preliminary site characteristics for urban seismic hazard in pasuruan fault from microtremor measurements

The Pasuruan fault is one of active faults in East-Java with the minimum estimated earthquake magnitude to be 6.6 Mw. Although the Pasuruan fault is relatively small in term of estimated earthquake magnitude, because the area is highly populated, earthquake along the fault could pose a significant hazard to the densely populated region and infrastructure. This study mainly focuses on site characteristics of along the Pasuruan fault based on microtremor Horizontal-to-Vertical spectral ratios (HVSR) as a part of the seismic hazard assessment. Through this measurement, the output the site natural frequency, the amplification and the soil vulnerability maps which will be used to make an urban seismic hazard map for along Pasuruan fault. The microtremor measurements were carried out at 48 locations to investigate the natural frequencies and the amplifications at sites. The results showed that the natural frequency (f0) values range from 1 Hz to 10 Hz and the amplification factor (A0) values range from 2 to 8. Correlations between the natural frequency with the geological formation and topographic were established. Variations of both parameters are also indicated as a result of variations in surface soil parameters. The vulnerability index (Kg) is indicated the soil damage level due to ground motions. The weak zone failed during an earthquake on the Southwest site was identified by the highest Kg value.

История изучения среднепалеолитических памятников на югозападе Восточно-Европейской равнины

История изучения среднепалеолитических памятников на югозападе Восточно-Европейской равнины

Compositional analysis of Intermountain Ware pottery manufacturing areas in western Wyoming, USA

In this study we examine 50 sherds from four archaeological sites to understand ceramic vessel source area variation in western Wyoming. Intermountain Ware ceramics are a diagnostic marker of Shoshone ethnicity, and our central hypothesis explores changing mobility during the Late Prehistoric and Historic Periods, ca. 1500–1870 CE. We use neutron activation analysis (NAA) for bulk paste chemical analysis and thin-section petrography to characterize clay and temper mineralogy. NAA places ceramic artifacts into eight groups with little overlap between sites in southwest and northwest Wyoming. Temper composition supports NAA groups indicating that ceramic vessels in this sample were made locally and not transported long distances before their eventual discard.

Adaptive and plastic variation in growth and maturation of the cutlassfish Trichiurus japonicus in the subtropical Pacific Ocean

We investigate d va ria- t ion in growth and maturation in response to 1) spatial variation in climate and 2) exploitation of the subtropical cutlassfish Trichiurus japonicus , an important fishery species whose population ecology i s virtually unknown . Individuals of this cutlassfish species were sampled monthly at 2 primary landing sites: Kengfang, in northeast (NE) Taiwan, and Tsukuan, in southwest (SW ) Taiwan, during 2013–2015. Habitat temperatures were about 1–4°C lower at the NE site t han at the SW site, and the length at age of adult fish had a n inverse pattern with temperature (NE lengths > SW lengths at age). The probabilistic maturation reaction norms did not differ significantly between the 2 areas, but ages and lengths a t maturation were higher for males from NE than for males from SW. Differences in asymptotic lengths (NE>SW) and growth coefficients (NE<SW), tog eth- er with narrower length distribution at the SW site than at the NE site, indicate potentially different mortality between the areas (NE<SW). These results indicate plastic variation in maturation and potentially adaptive variation in growth for this species that are related to the differences in temperature and mortality between the areas, although reliable proxies for mortality are lacking. The observed life-history variation was consistent with the tem perature–size rule that organisms tend to grow faster, mature earlier, and reach smal ler asymptotic sizes at warmer temperatures and may indicate an adaptive divergence of cutlassfish populati

Characteristics and sources of aerosol pollution at a polluted rural site southwest in Beijing, China

Annual average PM2.5 concentration in south Beijing was 30% and 40% higher than the whole Beijing city in 2015 and 2016, respectively. Few studies have been conducted to investigate what leads to the characteristics and sources of heavy pollution in the south rural area of Beijing. This study conducted an observation with Aerosol Chemical Speciation Monitor (ACSM) at a southwest rural site (Liulihe) in Beijing during 2014–2016, to investigate the seasonal aerosol characteristics and their sources. Positive matrix factorization (PMF) algorithm was used to distinguish different components of organic aerosol measured by ACSM. Biomass burning is an important pollution source, mainly due to the open burning after harvest season in autumn, regional transport in spring, and local residential biofuel use in winter. Coal consumption is the largest primary organic aerosol source in winter. Heavy duty diesel trucks contributed significantly to organic aerosol at night-time in the rural area. Results of this study show residential solid fuel burning is the most important source of aerosol pollution in the rural area of Beijing and the results focusing on urban Beijing might have underestimate the contribution from residential emissions in the Beijing-Tianjin-Hebei region.

Occurrence, distribution and possible sources of organochlorine pesticides in peri-urban vegetable soils of Changchun, Northeast China

ABSTRACTThe characterizations of residue levels and sources of organochlorine pesticides (OCPs) in soils are necessary to evaluate the potential pollution and risks of OCPs to the ecosystems and human health. A total of 51 surface soil samples were collected from peri-urban vegetable fields of Changchun and 13 OCPs were analyzed to learn the composition, spatial distribution and sources. The concentrations were in the ranges of 0.94–107.8 ng g−1 for DDTs, 0.89–98.3 ng g−1 for HCHs, 0.22–18.20 ng g−1 for Chlordanes, nd–4.49 ng g−1 for aldrin and nd–9.66 ng g−1 for dieldrin, respectively. The total OCPs concentrations ranged from 2.44 to 177.1 ng g−1 and the higher residues were mainly distributed in northeast and southwest sites, as well as sites along the Yitong River. According to the concentrations and detection frequencies, DDTs and HCHs were the most dominant compounds. Compositional analysis and principal component analysis suggested that DDT, HCH and chlordane in most soil samples derived from historical application except the slight fresh introduction at some locations. There exist a variety of OCPs residues in peri-urban vegetable soils of Changchun, but it is still safe and suitable for agricultural production for the most part, and some specific locations with high OCPs residues ought to be a cause for concern.

Soil properties affect the drought susceptibility of Norway spruce

Norway spruce (Picea abies) is considered to be one of the economically most important coniferous tree species in Europe. It is, however, susceptible to drought and there is concern that anticipated climate change may greatly influence its yield potential. In addition to the climate, soil characteristics are known to play a major role in tree growth rates. Detailed knowledge about the relationships between the soil and tree growth in the face of climate change has started to be generated only recently. As a contribution to this field we investigated the influence of soil on the drought susceptibility of Norway spruce by means of dendrochronology. Tree-ring data were acquired from two sites southwest of Munich, Germany, with rather similar climates but different soil textures. By combining multivariate statistics with climate correlation and pointer year analyses, we were able to show a clear differentiation between the two sites with respect to the growth performance of Norway spruce. That is, trees growing on a shallow, well-drained soil grew less and expressed a relatively higher drought sensitivity compared to trees from a site with a deep, silty soil as indicated by higher correlations with drought related indices and more intense droughts in negative pointer years compared to neutral years. Among the considered drought indices the soil water deficit index explained best the multivariate differentiation between the two sites, wherefore we interpret these findings as a significant impact of soil characteristics on Norway spruce performance. In the context of climate change and an increasing risk of extreme droughts during the 21st century, this finding has important implications for forest management activities since the risk of drought induced tree mortality appears to be affected by soil conditions.

Microbial Nursery Production of High-Quality Biological Soil Crust Biomass for Restoration of Degraded Dryland Soils.

Biological soil crusts (biocrusts) are slow-growing, phototroph-based microbial assemblages that develop on the topsoils of drylands. Biocrusts help maintain soil fertility and reduce erosion. Because their loss through human activities has negative ecological and environmental health consequences, biocrust restoration is of interest. Active soil inoculation with biocrust microorganisms can be an important tool in this endeavor. We present a culture-independent, two-step process to grow multispecies biocrusts in open greenhouse nursery facilities, based on the inoculation of local soils with local biocrust remnants and incubation under seminatural conditions that maintain the essence of the habitat but lessen its harshness. In each of four U.S. Southwest sites, we tested and deployed combinations of factors that maximized growth (gauged as chlorophyll a content) while minimizing microbial community shifts (assessed by 16S rRNA sequencing and bioinformatics), particularly for crust-forming cyanobacteria. Generally, doubling the frequency of natural wetting events, a 60% reduction in sunlight, and inoculation by slurry were optimal. Nutrient addition effects were site specific. In 4 months, our approach yielded crusts of high inoculum quality reared on local soil exposed to locally matched climates, acclimated to desiccation, and containing communities minimally shifted in composition from local ones. Our inoculum contained abundant crust-forming cyanobacteria and no significant numbers of allochthonous phototrophs, and it was sufficient to treat ca. 6,000 m2 of degraded dryland soils at 1 to 5% of the typical crust biomass concentration, having started from a natural crust remnant as small as 6 to 30 cm2 IMPORTANCE: Soil surface crusts can protect dryland soils from erosion, but they are often negatively impacted by human activities. Their degradation causes a loss of fertility, increased production of fugitive dust and intensity of dust storms with associated traffic problems, and provokes general public health hazards. Our results constitute an advance in the quest to actively restore biological soil covers by providing a means to obtain high-quality inoculum within a reasonable time (a few months), thereby allowing land managers to recover essential, but damaged, ecosystem services in a sustainable, self-perpetuating way as provided by biocrust communities.

Prevalence of Anaplasma phagocytophilum in small rodents in France

Anaplasma phagocytophilum is an emerging zoonotic tick-borne pathogen affecting a wide range of mammals. Rodents are suspected to be natural reservoirs for this bacterium, but their role in the epidemiologic cycles affecting domestic animals and wild ungulates has not been demonstrated. This study aimed to improve our knowledge on A. phagocytophilum prevalence in Apodemus sylvaticus, A. flavicollis and Myodes glareolus using data collected in 2010 in one area in eastern France and in 2012–2013 in two others areas in western France. Rodents were captured in each site and infection was tested using qualitative real-time PCR assays on either blood or spleen samples. Prevalence showed high variability among sites. The highest prevalence was observed in the most eastern site (with an average infection rate of 22.8% across all species), whereas no rodent was found to be PCR positive in the south-west site and only 6.6% were positive in the north-west of France. Finally, a significant increase in prevalence was observed in autumn samples compared to spring samples in the north-west, but no change was found in the other two sites.

Macroalgae contribute to the diet of Patella vulgata from contrasting conditions of latitude and wave exposure in the UK

Analysis of gut contents and stable isotope composition of intertidal limpets (Patella vulgata) showed a major contribution of macroalgae to their diet, along with microalgae and invertebrates. Specimens were collected in areas with limited access to attached macroalgae, suggesting a major dietary component of drift algae. Gut contents of 480 animals from 2 moderately wave exposed and 2 sheltered rocky shores in each of 2 regions: western Scotland (55–56°N) and southwest England (50°N), were analysed in 2 years (n = 30 per site per year). The abundance of microalgae, macroalgae and invertebrates within the guts was quantified using categorical abundance scales. Gut content composition was compared among regions and wave exposure conditions, showing that the diet of P. vulgata changes with both wave exposure and latitude. Microalgae were most abundant in limpet gut contents in animals from southwest sites, whilst leathery/corticated macroalgae were more prevalent and abundant in limpets from sheltered and northern sites. P. vulgata appears to have a more flexible diet than previously appreciated and these keystone grazers consume not only microalgae, but also large quantities of macroalgae and small invertebrates. To date, limpet grazing studies have focussed on their role in controlling recruitment of macroalgae by feeding on microscopic propagules and germlings. Consumption of adult algae suggests P. vulgata may also directly control the biomass of attached macroalgae on the shore, whilst consumption of drift algae indicates the species may play important roles in coupling subtidal and intertidal production.

Fish condition factor, peroxisome proliferator activated receptors and biotransformation responses in Sarotherodon melanotheron from a contaminated freshwater dam (Awba Dam) in Ibadan, Nigeria

The relationship between condition factor (CF), peroxisome proliferator-activated receptors (PPARs), phase 1 biotransformation (CYP1A isoforms) and contaminant burden has been studied in Sarotherodon melanotheron from a contaminated tropical freshwater dam (Awba Dam) and compared to a reference site (Modete Dam) in Southwest, Nigeria. A total of 89 fish (57 males and 32 females) was collected from Awba Dam and 95 fish (48 males and 47 females) from the reference site. In general, fish sampled from Awba Dam were bigger than reference site. Sediment samples were also collected from both sites for contaminant analysis. Expression of ppar and cyp1 isoforms was analyzed using validated real-time PCR, while CYP1A and PPAR protein levels were analyzed using immunochemical method with specific antibodies. CYP-mediated catalytic responses (EROD, MROD and BROD) were performed by biochemical methods. We observed significant increases in ppar and cyp1 isoforms mRNA in both male and female fish from Awba Dam, compared to the reference site. Catalytic activities of EROD, MROD and BROD paralleled cyp1 transcript levels. Sex-related differences in PPAR and CYP1A protein levels were also observed, showing higher CYP1A proteins in males, compared with females, and higher PPAR proteins in females compared with males. Principal component analysis (PCA) biplot showed positive relationships between biological responses (ppar isoforms), condition factor (CF) and sediment PCBs, PAHs, OCPs and heavy metal concentrations. The present study shows that S. melanotheron inhabiting Awba Dam are severely affected by different classes of environmental contaminants that target metabolic processes (PPAR) and biotransformation pathways (CYP1A) in male and female fish, compared to a reference site. Interestingly, fish from Awba Dam were exhibiting good growth (evidence by high CF values) that paralleled increases in the transcriptional activation of ppar and cyp1 isoforms, despite the high contaminant burdens, suggesting a possible contaminant-induced obesogenic effects.

Analysis of aerosol scattering properties measured by a nephelometer at a coastal-rural site in the Atlantic southwest of the Iberian Peninsula

Aerosol hemispherical scattering and the backscattering coefficients, σsp, σbsc, have been measured using a 3-wavelength (450, 550 and 700nm) integrating nephelometer over two years (January 2006–May 2008) in the coastal area of the Gulf of Cádiz, in the southwest of the Iberian Peninsula. These coefficients have been carefully analyzed starting with the impact of corrections on the measurements of σsp: i.e., drift calibration constants do not modify the mean value in our data series. However, the selection of dry data (with RH less than 50%) modifies substantially the number of data and the resulting mean value of σsp is now 14% lower, which is compensated when the angular truncation correction is applied. The characterization and features of σsp, σbsc, and the derived parameters αsp (alpha Ångström exponent) and b (the backscatter ratio) has been analyzed, as annual, seasonal and diurnal evolution. A general statistic based on hourly data gives mean values and standard deviation of σsp (500nm)=48±38Mm−1 with a median of 38Mm−1, and σbsc (500nm)=5.6±3.8Mm−1 with a median of 4.6Mm−1. Thus, these values show moderate-low values but with a large range of variation considering the existing measured values over the Iberian Peninsula. The median value of σsp (500nm) is an indicator that events of high aerosol burden are frequent presenting a substantial influence on the daily averages. The alpha Ångström exponent, αsp, derived from the pairs 450/700nm gives a mean value 1.35±0.54 with a median of 1.47 and with the most frequent value of 1.7, thus indicating the prevalence of medium size particles but with a significant influence of fine particles. The b ratio has the same value for mean and median, 0.12±0.02, showing a decrease with increasing values of σsp. Annual and daily cycles have been also analyzed showing the complex behaviour of the optical properties at this coastal site where cold and warn periods show very different characteristics. Besides, the daily cycle is strongly influenced by the breeze conditions. According to the information extracted from the σsp–αsp relationship this rural Atlantic site presents prevalence of mixed marine-continental aerosols but with significant influence of local anthropogenic sources. Desert dust particles were also discriminated which are not frequently reported in the data of “in situ” aerosols.

Spatial and temporal variations of organic matter contents and potential sediment nutrient index in the Sundarbans mangrove forest, Bangladesh

This paper has investigated the total organic carbon contents together with total nitrogen, total phosphorous, electrical conductivity and grain size parameters of the surface sediments of the Sundarbans mangrove forest in Bangladesh. The results showed that the seasonal variations of Total Organic Carbon (TOC) and Total Nitrogen (TN) were significant at all sampling points. TOC and TN content at the monsoon were quite higher than that of the winter season. TOC and TN also showed strong positive correlations between them and negatively correlated with Total Phosphorus (TP). Depending on the distributions of TOC and TN, the studied forest ranges could be arranged at the following order: Sarankhola and Chandpai ranges > Khulna range > Satkhira range. In contrast, TP content showed the reverse order of TOC and TN, where the higher concentrations were generally distributed at the southern parts of Sundarbans. Besides, TOC and TN showed linear positive correlations with grain size distribution where fine grained sediments contain higher amount of TOC and TN. However, in terms of grain size variation, TP reversed the results of TOC and TN. Thus “grain size effect” was an important factor for influencing the distributions of sediment nutrients. Carbon-Nitrogen (C/N) ratios showed the highest contribution of terrestrial organic carbon near the Sarankhola and Chandpai ranges were iso-lines projecting towards northeast, indicating the influence of the upstream river water. Sediment Nutrient Indexes (SNI) were low, although reasonably variable, in forest floor directly receiving effluents from other anthropogenic sources/farms. It was evident that potential nutrient levels changed from the high values at northeast sites to the southwest sites, and this pattern was common across the four forest ranges.

Icebergs not the trigger for North Atlantic cold events.

Abrupt climate change is a ubiquitous feature of the Late Pleistocene epoch. In particular, the sequence of Dansgaard-Oeschger events (repeated transitions between warm interstadial and cold stadial conditions), as recorded by ice cores in Greenland, are thought to be linked to changes in the mode of overturning circulation in the Atlantic Ocean. Moreover, the observed correspondence between North Atlantic cold events and increased iceberg calving and dispersal from ice sheets surrounding the North Atlantic has inspired many ocean and climate modelling studies that make use of freshwater forcing scenarios to simulate abrupt change across the North Atlantic region and beyond. On the other hand, previous studies identified an apparent lag between North Atlantic cooling events and the appearance of ice-rafted debris over the last glacial cycle, leading to the hypothesis that iceberg discharge may be a consequence of stadial conditions rather than the cause. Here we further establish this relationship and demonstrate a systematic delay between pronounced surface cooling and the arrival of ice-rafted debris at a site southwest of Iceland over the past four glacial cycles, implying that in general icebergs arrived too late to have triggered cooling. Instead we suggest that--on the basis of our comparisons of ice-rafted debris and polar planktonic foraminifera--abrupt transitions to stadial conditions should be considered as a nonlinear response to more gradual cooling across the North Atlantic. Although the freshwater derived from melting icebergs may provide a positive feedback for enhancing and or prolonging stadial conditions, it does not trigger northern stadial events.

Atmospheric evolution of sulfur emissions from Kı̅lauea: real-time measurements of oxidation, dilution, and neutralization within a volcanic plume.

The high atmospheric concentrations of toxic gases, particulate matter, and acids in the areas immediately surrounding volcanoes can have negative impacts on human and ecological health. To better understand the atmospheric fate of volcanogenic emissions in the near field (in the first few hours after emission), we have carried out real-time measurements of key chemical components of the volcanic plume from Kı̅lauea on the Island of Hawai'i. Measurements were made at two locations, one ∼ 3 km north-northeast of the vent and the other 31 km to the southwest, with sampling at each site spanning a range of meteorological conditions and volcanic influence. Instrumentation included a sulfur dioxide monitor and an Aerosol Chemical Speciation Monitor, allowing for a measurement of the partitioning between the two major sulfur species (gas-phase SO2 and particulate sulfate) every 5 min. During trade wind conditions, which sent the plume toward the southwest site, sulfur partitioning exhibited a clear diurnal pattern, indicating photochemical oxidation of SO2 to sulfate; this enabled the quantitative determination of plume age (5 h) and instantaneous SO2 oxidation rate (2.4 × 10(-6) s(-1) at solar noon). Under stagnant conditions near the crater, the extent of SO2 oxidation was substantially higher, suggesting faster oxidation. The particles within the plume were extremely acidic, with pH values (controlled largely by ambient relative humidity) as low as -0.8 and strong acidity (controlled largely by absolute sulfate levels) up to 2200 nmol/m(3). The high variability of sulfur partitioning and particle composition underscores the chemically dynamic nature of volcanic plumes, which may have important implications for human and ecological health.