Mobilization of arsenic and other trace elements of health concern in groundwater from the Salí River Basin, Tucumán Province, Argentina

The Salí River Basin in north-west Argentina (7,000 km²) is composed of a sequence of Tertiary and Quaternary loess deposits, which have been substantially reworked by fluvial and aeolian processes. As with other areas of the Chaco-Pampean Plain, groundwater in the basin suffers a range of chemical quality problems, including arsenic (concentrations in the range of 12.2–1,660 μg L⁻¹), fluoride (50–8,740 μg L⁻¹), boron (34.0–9,550 μg L⁻¹), vanadium (30.7–300 μg L⁻¹) and uranium (0.03–125 μg L⁻¹). Shallow groundwater (depths up to 15 m) has particularly high concentrations of these elements. Exceedances above WHO (2011) guideline values are 100% for As, 35% for B, 21% for U and 17% for F. Concentrations in deep (>200 m) and artesian groundwater in the basin are also often high, though less extreme than at shallow depths. The waters are oxidizing, with often high bicarbonate concentrations (50.0–1,260 mg L⁻¹) and pH (6.28–9.24). The ultimate sources of these trace elements are the volcanic components of the loess deposits, although sorption reactions involving secondary Al and Fe oxides also regulate the distribution and mobility of trace elements in the aquifers. In addition, concentrations of chromium lie in range of 79.4–232 μg L⁻¹ in shallow groundwater, 129–250 μg L⁻¹ in deep groundwater and 110–218 μg L⁻¹ in artesian groundwater. All exceed the WHO guideline value of 50 μg L⁻¹. Their origin is likely to be predominantly geogenic, present as chromate in the ambient oxic and alkaline aquifer conditions.     

Soft song is a reliable signal of aggressive intent in song sparrows

Animals frequently use signals to modulate aggressive interactions. Establishing that a signal is aggressive or threatening requires demonstrating that it is more commonly used in agonistic contexts, that it predicts subsequent aggressive behaviors by the sender, and that receivers respond differently to this signal. Like many birds, song sparrows (Melospiza melodia) produce a low-amplitude “soft song” vocalization that has been hypothesized to be an aggressive signal. Soft song meets the first two criteria, but previous research has failed to demonstrate that soft song provokes aggression or that receivers even perceive soft song differently from normal loud song. We used a playback experiment with taxidermic mount presentation to test whether territorial male song sparrows respond differently to loud and soft song playbacks. Subjects reacted more strongly to the soft song playback by approaching the mount more closely, increasing wing wave displays, and increasing the proportion of their own songs that were soft songs, with further trends toward increasing the number of flights and attacks. These results confirm that soft song is a conventional signal of aggression in song sparrows and that increased receiver retaliation maintains its reliability.     

Persistent bimodal activity patterns in wild and captive black-tailed godwit <Emphasis Type="Italic">Limosa limosa</Emphasis> under different environmental conditions

There is a large literature dealing with daily foraging routines of wild birds during the non-breeding season. While different laboratory studies have showed that some bird activity patterns are a persistent property of the circadian system, most of field studies preclude the potential role of an endogenous circadian rhythm in controlling bird’s foraging routines. In this study we compared the patterns of diurnal foraging activity and intake rates of migrating black-tailed godwits, Limosa limosa (radio-tagged and non-tagged individuals) at two stopover sites (habitats) with different environmental characteristics, aiming at identifying proximate factors of bird activity routines. To gain insights into the role of food availability in control of such foraging routines, we also estimated foraging activity patterns in captive godwits subjected to constant food availability. Captive and wild black-tailed godwits showed a persistent bimodal activity pattern through daylight period. Food availability had a significant effect on the intake rates, but had a subtler effect on foraging and intake rate rhythms. Temperature and wind speed (combined in a weather index) showed non-significant effects on both rhythms. Although we could not discard a role for natural diurnal changes in light intensity, an important timing cue, our findings support the idea that an endogenous circadian rhythm could be an important proximate factor regulating foraging activity and food items taken per unit time of wild black-tailed godwits during migration.     

Ecological drivers of group living in two populations of the communally rearing rodent, Octodon degus

Intraspecific variation in sociality is thought to reflect a trade-off between current fitness benefits and costs that emerge from individuals' decision to join or leave groups. Since those benefits and costs may be influenced by ecological conditions, ecological variation remains a major, ultimate cause of intraspecific variation in sociality. Intraspecific comparisons of mammalian sociality across populations facing different environmental conditions have not provided a consistent relationship between ecological variation and group-living. Thus, we studied two populations of the communally rearing rodent Octodon degus to determine how co-variation between sociality and ecology supports alternative ecological causes of group living. In particular, we examined how variables linked to predation risk, thermal conditions, burrowing costs, and food availability predicted temporal and population variation in sociality. Our study revealed population and temporal variation in total group size and group composition that covaried with population and yearly differences in ecology. In particular, predation risk and burrowing costs are supported as drivers of this social variation in degus. Thermal differences, food quantity and quality were not significant predictors of social group size. In contrast to between populations, social variation within populations was largely uncoupled from ecological differences.     

Joint use of data and modeling in coastal wave transformation

In the framework of a research project entitled ??BRISA??BReaking waves and Induced SAnd transport??, a methodology was devised to characterize the waves joining together in-situ measurements and numerical wave propagation models. With this goal in mind, a number of in-situ measurements were made, for selected positions in front of Praia de Faro (South Portugal), during four days (25th to 28th March, 2009) by using different types of equipments (e.g., resistive wave gauges, pressure sensors, currentmeters and a new prototype pore pressure sensor using optical fibre). Wave records were obtained simultaneously offshore (at a water depth of 11.7?m below mean sea level, MSL) and at the surf and swash zones. The data processing and analysis were made by applying classical time domain techniques. Numerical simulations of the wave propagation between offshore and inshore for the measurement period were performed with two numerical models, a 1D model based on linear theory and a nonlinear Boussinesq-type model, COULWAVE, both forced by the measured offshore wave conditions of 27th March 2009. Comparisons between numerical results and field data for the pressure sensors placed in the surf and swash zones were made and discussed. This approach enables to evaluate the performance of those models to simulate those specific conditions, but also to validate the models by gaining confidence on their use in other conditions.     

The productivity of mangroves in northwestern Mexico: a meta-analysis of current data

Mangroves constitute highly productive ecosystems that export organic material to surrounding areas. They reach their northernmost distribution on the American Pacific coast in arid northwestern Mexico where they grow under sub-optimal conditions. Nevertheless, they maintain high litterfall rates with important ecological and economical implications. These mangroves are threatened by the region??s accelerated development and population growth. In order to explore and describe large-scale patterns in the production of organic material and to assess their importance in the productivity of coastal ecosystems, we performed a meta-analysis of studies that measured mangrove litterfall in northwestern Mexico. We found that litterfall is strongly associated with latitude, and that evaporation was negatively correlated with it. Additionally, we found high correlation between the presence of Rhizophora mangle and productivity, while the presence of Laguncularia racemosa, showed a less pronounced trend. Despite the harsh conditions, mangroves produce high amounts of organic matter, which is perhaps the most important service of mangroves in these coasts. Their capacity to produce organic matter contrasts with that of their surrounding ecosystems. Substantial reductions in their surface will have consequences for the exchange of energy at the land-sea transition, which will be detrimental for biological communities and human populations.     

Degradation of methyl-phenanthrene isomers during bioremediation of soil contaminated by residual fuel oil

Phenanthrene and methyl-phenanthrenes are major aromatic pollutants originating in particular from fuel oil. Phenanthrene is usually degraded faster than methyl-phenanthrenes under geological and environmental conditions. Here, we report a preferential and accelerated biodegradation of methyl-phenanthrenes versus phenanthrene in soil contaminated by fuel oil. The polluted soil was mixed with sawdust and sand to form a homogenized biopile. The biopile was continuously sprayed with microbial consortia isolated from crude oil?Ccontaminated soil and treated by biosurfactants and nutritive substances for biostimulation. During a 6-month bioremediation experiment, a steady increase in the relative abundance of phenanthrene compared to methyl-phenathrenes was observed by gas chromatography?Cmass spectrometry. The increase was the highest for trimethyl-phenanthrenes, with a phenanthrene/trimethyl-phenanthrenes ratio increasing from 0.42 to 2.45. By contrast, the control, non-stimulated samples showed a ratio decrease from 0.85 to 0.11. Moreover, the results showed that the level of degradability depends on the number of methyl groups.     

衡阳地区樗蚕的发生与防治技术研究

樗蚕(Philosamia cyntia Walker et Felder)是城镇园林植物上的重要害虫.本文研究了该虫在湖南省衡阳地区的生物学特性、发生规律与防治技术.结果表明,该虫在衡阳地区1年发生3代,以蛹在寄主植物上的丝质茧内越冬.5月中下旬是第1代幼虫危害高峰期,也是全年危害最严重的时期,必须采用适当的方法进行防治.在低虫口密度时,采用剪除越冬虫茧的方法,降低越冬代虫口基数.在高虫口密度时,使用高效、低毒、低残留的杀虫剂喷雾防治幼虫,可以迅速压低虫口密度.对于高大树上的樗蚕,可在其幼虫取食期,采用树干打孔注入内吸性杀虫剂的方式,有很好的防治效果.采用克百威、铁灭克等内吸、传导作用强的杀虫剂埋根的方法防治樗蚕幼虫,防效好,药效期长.     

三维植被网预制草毯技术的意义和发展初探

三维植被网预制草毯就其独特的立体网包结构,预植草皮象卷地毯一样整体起运到需要绿化防护的地点,又象铺地毯一样铺贴在需防护的区域,从而达到快速绿化的目的.笔者就其技术的实用效果和发展趋势进行初步的探讨.表1,参3.     

Life history strategy of a southern European population of brown shrimp (Crangon crangon L.): evidence for latitudinal changes in growth phenology and population dynamics

This study provides a comprehensive examination of the life cycle dynamics of the brown shrimp (Crangon crangon L.) in the Mondego estuary, Portugal, a habitat located near the southern edge of the range of this species in European waters. The phenology of all life stages was documented (from the occurrence of ovigerous females, developing embryos, planktonic larvae and benthic post-larvae), and migration patterns of larvae into and out of the estuary were examined. Temperature-dependent functions of egg and larval development were combined with data on field abundance to predict the timing and magnitude of occurrence of larvae and recruits. Compared to brown shrimp at higher latitudes, southern conspecifics grow slower, mature earlier and have smaller brood sizes, and larvae have a more protracted settlement period. The Mondego estuary, besides acting as nursery area, is a dynamic platform for C. crangon to use in different stages, sizes and seasons.