Respirable particulate matter at an urban and nearby industrial location: concentrations and variability and synoptic weather conditions during high pollution episodes

Continuous data of the concentration measurements of respirable suspended particulates (PM10, particles with aerodynamic diameter smaller than or equal to 10 pm) were analyzed. These measurements were carried out at an urban and nearby industrial location in northern Greece for the 5-year period 1996-2000. The time series concentration trend was examined, the seasonal and diurnal variations were identified, and the lognormality of the daily mean concentration data sets was tested. Over the 5-year data-gathering period, the days on which the U.S. Environmental Protection Agency (EPA) 24-hr PM10 standard was exceeded (episode days) were identified and their relation to prevailing synoptic-scale meteorological conditions was studied. The analysis led to useful information concerning the air quality levels, the contribution of the main pollution sources in this area, as well as some of the mechanisms that influence the PM10 concentrations. It also was proved that the measured PM10 concentrations are a result of a combination of processes including local anthropogenic sources, mesoscale transport, and resuspension. A complex system of sources and meteorological conditions modulate the heavy particulate pollution in the area of interest.     

Females reward courtship by competing males in a cannibalistic spider

Despite widespread recognition that intersexual interactions shape reproductive strategies, studies of male competition do not typically include effects imposed by females. In cannibalistic redback spiders, escalated fighting between rival suitors is predicted, as males are unlikely to mate with more than one female, and strong first-male sperm precedence favours mating with virgins. In staged competitions for matings between size mismatched rivals, smaller males adopted an alternative sneaking strategy. However, despite initial agonistic interactions, larger males did not pursue or incapacitate smaller males. When inter-male competition occurred, females struck at males frequently, although strikes were rarely seen when males courted in the absence of a rival. After minimal fighting, larger males engaged in significant courtship (3 h) rather than killing inferior rivals. Prolonged courtship was favoured by female behaviour, as males that attempted rapid copulation (smaller, sneaking males) were cannibalised before mating was completed. This premature cannibalism significantly decreases paternity in redback spiders. Thus, significant features of male competitive behaviour (i.e. prolonged courtship by larger males) may be predicted with consideration of the female’s response to male reproductive strategies. Although the effect of females may be more subtle in systems without the extreme reversed size-dimorphism of redbacks, these results suggest that female interests should be explicitly considered when studying inter-male interactions.     

Overview of temporary ponds in the Mediterranean region: threats, management and conservation issues

Mediterranean temporary ponds (MTPs) comprise an endangered habitat with several endemic species that can be found in many countries, mainly in the Mediterranean region but are disappearing at a high rate. For designing optimal conservation and management strategies for the particular ecosystems, appropriate characterization and classification of these ponds is necessary based on the different type of habitats and on their varying environmental conditions. This paper presents the current ecological status and the threats of Mediterranean temporary ponds and summarizes some management and conservation issues based on the existing experience on a regional level. Emphasis is given in the Greek MTPs with respect to their characteristics and the pressures received mainly from human activities such as agriculture and water overexploitation. Restoration practices should be commenced immediately aiming at the reestablishment of the ponds' hydroperiod and water quality at the natural levels.     

Instream and offstream environmental conditions and stream biotic integrity: Importance of scale and site similarities for learning and prediction

Two different methods to predict biotic integrity were tested and compared in the present paper. The first one tries to predict the fish indices of biotic integrity (IBI) at the state or regional scale based on the most similar observations to a specific target site of interest using the simple to implement k-nearest neighbors (or kNN) method. Two different distance functions were considered to find the k-nearest neighbors: the Euclidean and the Mahalanobis. The second method was applied on the same datasets and consisted of a step-wise multiple regression. The two modeling approaches yielded similar results but kNN proved to be more time-efficient and very fast computationally for the given dataset sizes, which allowed applying a leave-one-out cross validation.In an attempt to reveal the importance of scale in the prediction of IBI, regression models were constructed at the state (or regional) scale and at the more refined cluster of sampling sites scale. Clusters of sites were extracted using Kohonen's self-organizing maps (SOM) followed by k-means clustering of the SOM neurons. Cluster-level regression models, constructed after site patterning, performed better in IBI prediction than global regression models constructed without any previous site patterning. The importance of identifying groups of sites with similar environmental characteristics affecting the IBI was revealed. The combined use of site patterning and regression modeling for IBI prediction also helped identifying important variables acting at the local scale which remain latent at the global scale.     

The effects of field-realistic doses of imidacloprid on Melipona quadrifasciata (Apidae: Meliponini) workers

Environmental Science and Pollution Research - The presence of Brazilian native bees can improve tomato production by increasing pollination effectiveness. However, the extensive use of pesticides...     

Regional climate sensitivity of wetland environments in Rwanda: the need for a location-specific approach

Wetlands are sustaining large communities of people in Rwanda where 10 % of its land surface consists of many local wetlands. Sustainable future management of these numerous wetlands requires a reliable inventory of their location and a dynamic quantitative characterization that allows assessment of their climate change sensitivity. The aim of this study was to assess the importance of climatic factors for determining wetland location at different regional scales. Wetland locations were analyzed and statistically modeled using their location factors with logistic regression. Wetland location probability was determined using topographic (elevation, slope), hydrological (contributing area) and climatic (temperature and rainfall) location factors. A wetland location probability map was made that demonstrated a calibration accuracy of 87.9 % correct at national level compared to an existing inventory, displaying even better fits at subnational level (reaching up to 98 % correct). A validation accuracy of 86.2 % was obtained using an independently collected dataset. A sensitivity analysis was applied to the threshold values used as cutoff value between wetland/non-wetland, demonstrating a robust performance. The developed models were used in a sensitivity scenario analysis to assess future wetland location probability to changes in temperature and rainfall. In particular, wetlands in the central regions of Rwanda demonstrate a high sensitivity to changes in temperature (1 % increase causes a net probable wetland area decline by 12.4 %) and rainfall (+1 % causes a net increase by 1.6 %). This potentially significant impact on wetland number and location probability indicates that climate-sensitive future planning of wetland use is required in Rwanda.     

Assessment of heavy metals in water samples and tissues of edible fish species from Awassa and Koka Rift Valley Lakes, Ethiopia

The Ethiopian Rift Valley Lakes host populations of edible fish species including Oreochromis niloticus, Labeobarbus intermedius and Clarias gariepinus, which are harvested also in other tropical countries. We investigated the occurrence of six heavy metals in tissues of these fish species as well as in the waters of Lake Koka and Lake Awassa. Both lakes are affected by industrial effluents in their catchments, making them ideal study sites. Mercury concentrations were very low in the water samples, but concentrations in the fish samples were relatively high, suggesting a particularly high bioaccumulation tendency as compared with the other investigated metals. Mercury was preferentially accumulated in the fish liver or muscle. It was the only metal with species-specific accumulation with highest levels found in the predatory species L. intermedius. Lower mercury concentrations in O. niloticus could be attributed to the lower trophic level, whereas mercury values in the predatory C. gariepinus were unexpectedly low. This probably relates to the high growth rate of this species resulting in biodilution of mercury. Accumulation of lead, selenium, chromium, arsenic and cadmium did not differ between species, indicating that these elements are not biomagnified in the food chain. Values of cadmium, selenium and arsenic were highest in fish livers, while lead and chromium levels were highest in the gills, which could be related to the uptake pathway. A significant impact of the industrial discharges on the occurrence of metals in the lakes could not be detected, and the respective concentrations in fish do not pose a public health hazard.     

Adverse perinatal outcome in patients screen-positive for neural tube defects and fetal down syndrome

An association between various abnormal mid-trimester maternal serum analyte values and adverse perinatal outcome has been reported. From an original sample of 14 857 women, we observed five women who were ‘screen-positive’ for both neural tube defects [maternal serum alpha-fetoprotein (MSAFP) ≥2·5 multiples of the median] and Down syndrome [risk ≥1/274 using MSAFP, maternal serum unconjugated oestriol (MSuE3), maternal serum human chorionic gonadotropin (MShCG), and maternal age]. The four patients who elected to undergo amniocentesis all demonstrated both normal karyotype and normal amniotic fluid AFP levels. All five cases were associated with intrauterine growth retardation (IUGR) and abnormal pregnancy outcomes. Two cases exhibiting severe IUGR on ultrasound examination were terminated at 19·1 and 21·2 weeks, respectively; the former also exhibited fetal calcifications and positive maternal serology for toxoplasmosis. In another case, fetal demise occurred at 36 weeks' gestation in a patient who had been treated for syphilis in the second trimester. Neither infection was confirmed in fetal tissue studies. Though resulting in live births, the remaining two cases required operative deliveries; emergency Caesarean sections for fetal distress were performed at 38 and 32 weeks, respectively, the latter case being associated with severe pre-eclampsia. We conclude that elevated mid-trimester MSAFP levels concurrent with maternal serum analyte values associated with increased risk for fetal Down syndrome may presage a poor perinatal outcome, particularly IUGR and possibly congenital infection.     

Effects of reduced return activated sludge flows and volume on anaerobic zone performance for a septic wastewater biological phosphorus removal system.

Enhanced biological phosphorous removal (EBPR) performance was found to be adequate with reduced return-activated sludge (RAS) flows (50% of available RAS) to the anaerobic tank and smaller-than-typical anaerobic zone volume (1.08 hours hydraulic retention time [HRT]). Three identical parallel biological nutrient removal pilot plants were fed with strong, highly fermented (160 mg/L volatile fatty acids [VFAs]), domestic and industrial wastewater from a full-scale wastewater treatment facility. The pilot plants were operated at 100, 50, 40, and 25% RAS (percent of available RAS) flows to the anaerobic tank, with the remaining RAS to the anoxic tank. In addition, varying anaerobic HRT (1.08 and 1.5 hours) and increased hydraulic loading (35% increase) were examined. The study was divided into four phases, and the effect of these process variations on EBPR were studied by having one different variable between two identical systems. The most significant conclusion was that returning part of the RAS to the anaerobic zone did not decrease EBPR performance; instead, it changed the location of phosphorous release and uptake. Bringing less RAS to the anaerobic and more to the anoxic tank decreased anaerobic phosphorus release and increased anoxic phosphorus release (or decreased anoxic phosphorus uptake). Equally important is that, with VFA-rich influent wastewater, excessive anaerobic volume was shown to hurt overall phosphorus removal, even when it resulted in increased anaerobic phosphorus release.