Natural and anthropogenic hydrocarbon inputs to sediments of Patos Lagoon Estuary, Brazil

The Patos Lagoon Estuary, southern Brazil, is an area of environmental interest not only because of tourism, but also because of the presence of the second major port of Brazil, with the related industrial and shipping activities. Thus, potential hydrocarbon pollution was examined in this study. Sediment samples were collected at 10 sites in the estuary, extracted, and analyzed by GC-FID and GC-MS for composition and concentration of the following organic geochemical markers: normal and isoprenoid alkanes, petroleum biomarkers, linear alkylbenzenes (LABs), and polycyclic aromatic hydrocarbons (PAHs). The total concentrations varied from 1.1 to 129.6 microg g(-1) for aliphatic hydrocarbons, from 17.8 to 4510.6 ng g(-1) for petroleum biomarkers, from 3.2 to 1601.9 ng g(-1) for LABs, and from 37.7 to 11,779.9 ng g(-1) for PAHs. Natural hydrocarbons were mainly derived from planktonic inputs due to a usual development of blooms in the estuary. Terrestrial plant wax compounds prevailed at sites located far from Rio Grande City and subject to stronger currents. Anthropogenic hydrocarbons are related to combustion/pyrolysis processes of fossil fuel, release of unburned oil products and domestic/industrial waste outfalls. Anthropogenic hydrocarbon inputs were more apparent at sites associated with industrial discharges (petroleum distributor and refinery), shipping activities (dry docking), and sewage outfalls (sewage). The overall concentrations of anthropogenic hydrocarbons revealed moderate to high hydrocarbon pollution in the study area.     

Reactive transport modeling of remedial scenarios to predict cadmium,copper, and zinc in north fork of Clear Creek,Colorado

The North Fork of Clear Creek (NFCC), Colorado, is an acid‐mine‐drainage‐impacted stream typical of many mountain surface waters affected by historic metal mining in the western United States. The stream is devoid of fish primarily because of high metal concentrations in the water (e.g., copper and zinc) and has large amounts of settled iron oxyhydroxide solids that coat the streambed. The NFCC is part of the Central City/Clear Creek Superfund site, and remediation plans are being implemented that include treatment of three of the main point‐source inputs and cleanup of some tailings and waste rock piles. This article examines dissolved (0.45‐μm filterable) concentrations of cadmium, copper, and zinc following several potential remediation scenarios, simulated using a reactive transport model (WASP4/META4). Results from modeling indicate that for cadmium, remediation of the primary point‐source adit discharges should be sufficient to achieve acute and chronic water‐quality standards under both high‐ and low‐flow conditions. To achieve standards for copper and zinc, however, the modeling scenarios suggest that it may be necessary to treat or remove contaminated streambed sediments in downstream reaches, as well as identify and treat nonpoint sources of metals. Recommendations for improvements to the model for metal transport in acid‐mine drainage impacted streams are made. These recommendations are being implemented by the U.S. Environmental Protection Agency. © 2009 Wiley Periodicals, Inc.     

Benthic foraminiferal response to trace element pollution—the case study of the Gulf of Milazzo, NE Sicily (Central Mediterranean Sea)

The response of benthic foraminiferal assemblages to trace element pollution in the marine sediments of the Gulf of Milazzo (north-eastern Sicily) was investigated. Since the 1960s, this coastal area has been a preferred site for the development of two small marinas and a commercial harbour as well as for heavy industry. Forty samples collected in the uppermost 3–4 cm of an undisturbed layer of sediment in the littoral environment were used for this benthic foraminiferal analysis. The enrichment factors (EFs) of selected trace elements (As, Co, Cr, Cu, Mn, Ni, Pb and Zn) were also calculated. Changes both in benthic foraminiferal assemblages and in some trace elements concentrations have provided evidence that the gulf’s littoral zone can be subdivided into three sectors characterised by environmental changes in the marine ecosystem. In the sector unpolluted, close to the Milazzo Cape, foraminiferal assemblages exhibit high values of species richness and foraminiferal density while trace element concentrations and their EFs are very low. Here, the highest densities of Miliolids and epiphytic species are present. On the contrary, in the sector polluted, from the marinas to the crude oil refinery, foraminiferal density and species diversity are low, and assemblages are dominated, albeit with very low densities, by species that tolerate stressed environmental conditions, such as LOFAs, agglutinants and Ammonia spp. Here, the highest trace elements concentrations of Pb, Zn and Cu and related EFs were detected. Eastwards, in the sector moderately polluted, foraminiferal populations are quite poor. They are characterised by low values of species richness and foraminiferal densities, nevertheless trace element concentrations become lower than in the other sectors and their EFs are often below 1. Deformed foraminifera, with percentages up to 7.14 %, were found in all three of the sectors. Differences in benthic foraminiferal assemblages, coupled with results from statistical analysis, indicate that anthropogenic trace element pollution could be considered as one of the most important causes of the modifications of foraminiferal assemblages in the study area.     

Modeling Effects of Natural Flow Restoration on Metals Fate and Transport in a Mountain Stream Impacted by Mine Waste1

Abstract: The effects of natural flow restoration on metals fate and transport in the Upper Tenmile Creek Watershed, Montana, were modeled using the Water Quality Analysis Simulation Program developed by the U.S. Environmental Protection Agency (USEPA). This 50‐km² watershed has over 150 historic abandoned mines, including mine waste rock and tailings, as well as adits discharging acid mine drainage, and is the primary drinking water supply for the City of Helena. Water supply diversions almost completely dewater some stream reaches during summer low flows, but the city is considering a new drinking water source and restoration of natural flows in Tenmile Creek as part of acid mine drainage remediation and broader aquatic habitat restoration. One dimensional steady‐state simulation of total recoverable cadmium, copper, lead, and zinc in the mainstem was performed, and the model was calibrated to June 2000 base‐flow data. Representative low‐flows in August and high‐flow snowmelt conditions in June were modeled using mean monthly natural flow estimates from the U.S. Geological Survey and representative USEPA metals concentrations data. The modeling showed that total recoverable metals concentrations, and especially loads, can vary significantly among input locations and over time in the watershed. Some data gaps limit evaluation of variability and increase uncertainty in several locations. Model results indicated, however, that natural low‐ and high‐flow restoration by itself can reduce some metals concentrations in the mainstem compared to June 2000 values, which were influenced by significant water diversion. Some values (such as Zn) may still exceed standards during natural August low flow due to the remaining high concentrations and loads in the primary inputs to the mainstem. Others (such as Cu) can increase during high flow due to remaining mine waste sources and loading of particulate Cu associated with erosion and transport of solids. Greater than 50% reduction in concentrations and loads from some of the main tributaries may be necessary to meet all standards, especially for potential particulate loads with higher flows in June.     

Carbon sequestration capacity and productivity responses of Mediterranean olive groves under future climates and management options

The need to reduce the expected impact of climate change, finding sustainable ways to maintain or increase the carbon (C) sequestration capacity and productivity of agricultural systems, is one of the most important challenges of the twenty-first century. Olive (Olea europaea L.) groves can play a fundamental role due to their potential to sequester C in soil and woody compartments, associated with widespread cultivation in the Mediterranean basin. The implementation of field experiments to assess olive grove responses under different conditions, complemented by simulation models, can be a powerful approach to explore future land-atmosphere C feedbacks. The DayCent biogeochemical model was calibrated and validated against observed net ecosystem exchange, net primary productivity, aboveground biomass, leaf area index, and yield in two Italian olive groves. In addition, potential changes in C-sequestration capacity and productivity were assessed under two types of management (extensive and intensive), 35 climate change scenarios (ΔT-temperature from +?0 °C to +?3 °C; ΔP-precipitation from 0.0 to ??20%), and six areas across the Mediterranean basin (Brindisi, Coimbra, Crete, Cordoba, Florence, and Montpellier). The results indicated that (i) the DayCent model, properly calibrated, can be used to quantify olive grove daily net ecosystem exchange and net primary production dynamics; (ii) a decrease in net ecosystem exchange and net primary production is predicted under both types of management by approaching the most extreme climate conditions (ΔT?=?+?3 °C; ΔP?=???20%), especially in dry and warm areas; (iii) irrigation can compensate for net ecosystem exchange and net primary production losses in almost all areas, while ecophysiological air temperature thresholds determine the magnitude and sign of C-uptake; (iv) future warming is expected to modify the seasonal net ecosystem exchange and net primary production pattern, with higher photosynthetic activity in winter and a prolonged period of photosynthesis inhibition during summer compared to the baseline; (v) a substantial decrease in mitigation capacity and productivity of extensively managed olive groves is expected to accelerate between +?1.5 and +?2 °C warming compared to the current period, across all Mediterranean areas; (vi) adaptation measures aimed at increasing soil water content or evapotranspiration reduction should be considered the mostly suitable for limiting the decrease of both production and mitigation capacity in the next decades.

     

The diagnostic potential of fetal renal biopsy

The feasibility of fetal renal biopsy has been investigated in order to assess the diagnostic value of the histological specimen. Two fetuses with a severe bilateral renal abnormality (multicystic dysplastic kidney, Meckel-Gruber syndrome with polycystic kidney) and one fetus with Down syndrome (no detectable structural anomaly) were sampled. Histological findings in the biopsy specimens of cases 1 and 2 were diagnostic of an early obstructive renal disease. In case 3 , the findings were consistent with normal development for gestational age of the kidney. Fetal renal biopsy is technically feasible; histological examination of the samples showed a good correlation with postnatal findings. Further studies of its diagnostic value are required.     

Screening Assessment of Dissolved Zinc from Inactive Mines in a Mountain Watershed

A screening-level assessment of dissolved zinc from inactive and abandoned metal mines in the Cement Creek Basin was performed. The basin is part of the Upper Animas River Basin in the San Juan Mountains of southwestern Colorado. Stream discharge and dissolved zinc concentrations were measured at 49 stations below nonpoint sources including tailings and waste rock, point sources such as adits, and background areas. One measurement was made at a station during three flow events: storm runoff, peak snowmelt runoff, and baseflow. The highest concentrations occurred in the upper part of the basin immediately downstream from nonpoint and point source discharges, especially in the North Fork of Cement Creek. The mean concentration in Cement Creek was highest during baseflow (1350 g l-1) and lowest during snowmelt (796 g l-1). Most exceedances of national acute and chronic criteria for brown trout were chronic criteria exceedances in the upper part of the basin. Subareas with the greatest extent of nonpoint source areas in the upper part of the watershed, especially those contributing to Upper Cement Creek and the North Fork of Cement Creek, generally had the highest loadings and unit area loadings. The greatest loadings from all subareas to Cement Creek occurred during snowmelt (219 000 g day-1 and 17 400 kg for the snowmelt season). The highest unit area loadings from all subareas also occurred during snowmelt (190 g ha-1 day-1 and 15 147 g ha-1 for the snowmelt season). Loadings from subareas with extensive nonpoint source areas were always much greater than those from point sources and background areas.     

Compositional divergence and convergence in arbuscular mycorrhizal fungal communities

In spite of the controversy that they have generated, neutral models provide ecologists with powerful tools for creating dynamic predictions about beta-diversity in ecological communities. Ecologists can achieve an understanding of the assembly rules operating in nature by noting when and how these predictions are met or not met. This is particularly valuable for those groups of organisms that are challenging to study under natural conditions (e.g., bacteria and fungi). Here, we focused on arbuscular mycorrhizal fungal (AMF) communities and performed an extensive literature search that allowed us to synthesize the information in 19 data sets with the minimal requisites for creating a null hypothesis in terms of community dissimilarity expected under neutral dynamics. In order to achieve this task, we calculated the first estimates of neutral parameters for several AMF communities from different ecosystems. Communities were shown either to be consistent with neutrality or to diverge or converge with respect to the levels of compositional dissimilarity expected under neutrality. These data support the hypothesis that divergence occurs in systems where the effect of limited dispersal is overwhelmed by anthropogenic disturbance or extreme biological and environmental heterogeneity, whereas communities converge when systems have the potential for niche divergence within a relatively homogeneous set of environmental conditions. Regarding the study cases that were consistent with neutrality, the sampling designs employed may have covered relatively homogeneous environments in which the effects of dispersal limitation overwhelmed minor differences among AMF taxa that would lead to environmental filtering. Using neutral models we showed for the first time for a soil microbial group the conditions under which different assembly processes may determine different patterns of beta-diversity. Our synthesis is an important step showing how the application of general ecological theories to a model microbial taxon has the potential to shed light on the assembly and ecological dynamics of communities.