Transport,deposition and biodegradation of particle bound polycyclic aromatic hydrocarbons in a tidal basin of an industrial watershed

Polycylic aromatic hydrocarbons (PAHs) are commoncontaminants in industrial watersheds. Their origin,transport and fate are important to scientists,environmental managers and citizens. The Philadelphia NavalReserve Basin (RB) is a small semi-enclosed embayment nearthe confluence of the Schuylkill and Delaware Rivers inPennsylvania (USA). We conducted a study at this site todetermine the tidal flux of particles and particle-boundcontaminants associated with the RB. Particle traps wereplaced at the mouth and inside the RB and in the Schuylkilland Delaware Rivers. There was net particle deposition intothe RB, which was determined for three seasons. Spring andfall depositions were highest (1740 and 1230 kg ofparticles, respectively) while winter deposition wasinsignificant. PAH concentrations on settling particlesindicated a net deposition of 12.7 g PAH in fall and 2.1 gPAH in spring over one tidal cycle. There was nosignificant PAH deposition in the winter. Biodegradationrates, calculated from ¹⁴C-labeled PAH substratemineralization, could attenuate only about 0.25% of the PAHdeposited during a tidal cycle in fall. However, in thespring, biodegradation could be responsible for degrading50% of the settling PAHs. The RB appears to be a sink forPAHs in this watershed.     

Monitoring, assessment and modelling using water quality data in the Saale River Basin, Germany

The European Water Framework Directive (WFD) is the overall driver for this environmental study and currently requires the identification of patterns and sources of pollution (monitoring) to support objective ecological sound decision making and specific measures to enhance river water quality (modelling). The purpose of this paper is to demonstrate in a case study the interrelationship between (1) hydrologic and water quality monitoring data for river basin characterization and (2) modelling applications to assess resources management alternatives. The study deals with monitoring assessment and modelling of river water quality data of the main stem Saale River and its principal tributaries. For a period of 6 years the data, which was sampled by Environmental Agencies of the German states of Thuringia, Saxony and Saxony-Anhalt, was investigated to assess sources and indicators of pollution. In addition to the assessment a modelling exercise of the routing of different pollutants was carried out in the lower part of the test basin. The modelling is a tool to facilitate the evaluation of alternative measures to reduce contaminant loadings and improve ecological status of a water body as required by WFD. The transport of suspended solids, salts and heavy metals was modelled along a selected Saale reach under strong anthropogenic influence in terms of contaminants and river morphology between the city of Halle and the confluence with the Elbe River. The simulations were carried out with the model WASP5 which is a dynamic flood-routing and water quality model package developed by the US Environmental Protection Agency.     

The role of predation in ecosystem models

Ecosystem models must convert a naturally open system into a theoretically closed one. For phytoplankton-herbivore models the form for the parameterization of predation on the herbivores can have a significant effect on the remainder of the model.     

Alpha-thalassaemia prenatal diagnosis by two PCR-based methods

In Cyprus all couples carrying α⁰-thalassaemia mutations are detected in the course of the thalassaemia carrier screening program and prenatal diagnosis is offered to all of them. Prenatal diagnosis for α-thalassaemia is routinely done by two independent molecular methods. With the first method, the mutations of the parents are directly determined by gap-PCR and then the chorionic villus sample (CVS) is examined for the presence of these mutations. With the other method, a (CA)_n repeat polymorphic site located between the ψα₁- and α₂-globin genes is used for determining the presence or absence of the normal and mutant alleles. In the period from 1995 to 1999, molecular analysis of 46 couples in which haematological data were consistent with deletion of two α-globin genes in both partners indicated that only 13 of them were actually at risk for haemoglobin (Hb) Bart's hydrops fetalis and prenatal diagnosis was provided in 16 pregnancies. The molecular diagnosis was possible in all cases with the use of both gap-PCR and (CA)_n repeat polymorphisms analysis. No misdiagnosed cases for α-thalassaemia have been reported to date. Copyright © 2001 John Wiley & Sons, Ltd.     

Using local experts as benchmarks for household local ecological knowledge: Scoring in South African savannas

It is well recognised that local ecological knowledge is an important facet of natural resource management in rural regions of the developing world. However, techniques to assess levels and to integrate it into formal or informal management approaches require further development. In particular, quantitative tools are missing, which would allow more robust analysis of the factors that positively or negatively affect local ecological knowledge and vice versa. This paper reports on a quick assessment approach that provides a quantitative score of generalist local ecological knowledge at the household level. It does so by comparing responses to the knowledge of local people identified as experts within the community. In this way it is both locally constructed and contextualized, and thereby avoids pitfalls of trying to score local ecological knowledge relative to conventional scientific knowledge which frequently cannot account for local constructs. The approach is applied at eight villages throughout the savanna biome in South Africa.     

X-ray absorption spectroscopy studies of reactions of technetium, uranium and neptunium with mackinawite

Technetium, uranium and neptunium may all occur in the environment in more than one oxidation state (IV or VII, IV or VI and IV or V respectively). The surface of mackinawite, the first-formed iron sulfide phase in anoxic conditions, can promote redox changes so a series of laboratory experiments were carried out to explore the interactions of Tc, U and Np with this mineral. The products of reaction were characterised using X-ray absorption spectroscopy. Technetium, added as TcO4(-), is reduced to oxidation state IV and forms a TcS(2)-like species. On oxidation of the mackinawite in air to form goethite, Tc remains in oxidation state IV but in an oxide, rather than a sulfide environment. At low concentrations, uranium forms uranyl surface complexes on oxidised regions of the mackinawite surface but at higher concentrations, the uranium promotes surface oxidation and forms a mixed oxidation state oxide phase. Neptunium is reduced to oxidation IV and forms a surface complex with surface sulfide ions. The remainder of the Np coordination sphere is filled with water molecules or hydroxide ions.     

Distribution and variability of redox zones controlling spatial variability of arsenic in the Mississippi River Valley alluvial aquifer, southeastern Arkansas

Twenty one of 118 irrigation water wells in the shallow (25-30 m thick) Mississippi River Valley alluvial aquifer in the Bayou Bartholomew watershed, southeastern Arkansas had arsenic (As) concentrations (<0.5 to 77 microg/L) exceeding 10 microg/L. Sediment and groundwater samples were collected and analyzed from the sites of the highest, median, and lowest concentrations of As in groundwater in the alluvial aquifers located at Jefferson County, Arkansas. A traditional five-step sequential extraction was performed to differentiate the exchangeable, carbonate, amorphous Fe and Mn oxide, organic, and hot HNO(3)-leachable fraction of As and other compounds in sediments. The Chao reagent (0.25 M hydroxylamine hydrochloride in 0.25 M HCl) removes amorphous Fe and Mn oxides and oxyhydroxides (present as coatings on grains and amorphous minerals) by reductive dissolution and is a measure of reducible Fe and Mn in sediments. The hot HNO(3) extraction removes mostly crystalline metal oxides and all other labile forms of As. Significant total As (20%) is complexed with amorphous Fe and Mn oxides in sediments. Arsenic abundance is not significant in carbonates or organic matter. Significant (40-70 microg/kg) exchangeable As is only present at shallow depth (0-1 m below ground surface). Arsenic is positively correlated to Fe extracted by Chao reagent (r=0.83) and hot HNO(3) (r=0.85). Arsenic extracted by Chao reagent decreases significantly with depth as compared to As extracted by hot HNO(3). Fe (II)/Fe (the ratio of Fe concentration in the extracts of Chao reagent and hot HNO(3)) is positively correlated (r=0.76) to As extracted from Chao reagent. Although Fe (II)/Fe increases with depth, the relative abundance of reducible Fe decreases noticeably with depth. The amount of reducible Fe, as well as As complexed to amorphous Fe and Mn oxides and oxyhydroxides decreases with depth. Possible explanations for the decrease in reducible Fe and its complexed As with depth include historic flushing of As and Fe from hydrous ferric oxides (HFO) by microbially-mediated reductive dissolution and aging of HFO to crystalline phases. Hydrogeochemical data suggests that the groundwater in the area falls in the mildly reducing (suboxic) to relatively highly reducing (anoxic) zone, and points to reductive dissolution of HFO as the dominant As release mechanism. Spatial variability of gypsum solubility and simultaneous SO(4)(2-) reduction with co-precipitation of As and sulfide is an important limiting process controlling the concentration of As in groundwater in the area.     

A meta‐analytic evaluation of diversity training outcomes

The purpose of this meta‐analysis was to use theory and research on diversity, attitudes, and training to examine potential differential effects on affective‐based, cognitive‐based, and skill‐based outcomes, to examine potential moderators of those effects with a focus on affective‐based outcomes, and finally, to provide quantitative estimates of these posited relationships. Results from 65 studies (N = 8465) revealed sizable effects on affective‐based, cognitive‐based, and skill‐based outcomes as well as interesting boundary conditions for these effects on affective‐based outcomes. This study provides practical value to human resources managers and trainers wishing to implement diversity training within organizations as well as interesting theoretical advances for researchers. Practitioners have quantitative evidence that diversity training changes affective‐based, cognitive‐based, and skill‐based trainee outcomes. This study also supports and addresses future research needs. Copyright © 2012 John Wiley & Sons, Ltd.     

Sediment filled fractures in the Permo-Triassic sandstones of the Cheshire basin: observations and implications for pollutant transport

Fracture mapping in a tunnel system and at nearby outcrop on the Runcorn Penninsula, UK, suggests the need for a review of the potential pathways for pollutant transport in Permo-Triassic sandstone aquifers. Sediment infilling is pervasive in the largest sub-vertical multi-layer fractures in the study area, both at the surface and to a depth of about 40 m below ground level. Sediment infill is inferred to have formed in situ. The conventional models of pollutant transport in fracture networks assume that they comprise open fractures, with pollutant mobility depending on fracture connectivity (a function of density, length, orientation and intersection) and aperture. The presence of extensive sediment fills in fractures will materially change their permeability, thereby reducing pollutant flux, and be of significance in the assessment of risks arising from chemical spillages. There has been little or no substantive evidence for such fills in Permo-Triassic sandstones in the UK, apart from observations at outcrop and anecdotes of sand being pumped from boreholes. Here, we report surface and rare, but complementary, subsurface observations of extensive fills in the Cheshire basin, and argue that they will only act as preferential pathways where they crosscut low-permeability horizons such as mudstones.