Field and Laboratory Tests of Flow-Proportional Passive Samplers for Determining Average Phosphorus and Nitrogen Concentration in Rivers

Flow responsive passive samplers offer considerable potential in nutrient monitoring in catchments; bridging the gap between the intermittency of grab sampling and the high cost of automated monitoring systems. A commercially available passive sampler was evaluated in a number of river systems encapsulating a gradient in storm response, combinations of diffuse and point source pressures, and levels of phosphorus and nitrogen concentrations. Phosphorus and nitrogen are sequestered to a resin matrix in a permeable cartridge positioned in line with streamflow. A salt tracer dissolves in proportion to advective flow through the cartridge. Multiple deployments of different cartridge types were undertaken and the recovery of P and N compared with the flow-weighted mean concentration (FWMC) from high-resolution bank-side analysers at each site. Results from the passive samplers were variable and largely underestimated the FWMC derived from the bank-side analysers. Laboratory tests using ambient river samples indicated good replication of advective throughflow using pumped water, although this appeared not to be a good analogue of river conditions where flow divergence was possible. Laboratory tests also showed good nutrient retention but not elution and these issues appeared to combine to limit the utility in ambient river systems at the small catchment scale.

Anthelmintic resistance in Northern Ireland (II): Variations in nematode control practices between lowland and upland sheep flocks

A questionnaire to obtain information on nematode control practices and sheep management was sent to over 1000 farmers in Northern Ireland. Replies were received from 305 flock owners, and data from 252 of them were analysed. Farms were divided into lowland and upland areas. Sizes of pasture and stocking rates on lowland and upland farms were 59.5 hectares, 6.99 sheep/hectare and 62.9 hectares and 10.01 sheep/hectare, respectively. Mean drenching rates for lambs and adults were 2.33 and 2.44, respectively, in lowland flocks and 2.73 and 2.71, respectively, in upland flocks. Between 2008 and 2011, the most frequently identified compounds in use were benzimidazoles and moxidectin in lowland flocks, and benzimidazoles and avermectins in upland flocks. Over the same period the most frequently identified commercial formulations were Tramazole (R), Panacur (R) and Allverm (R) (white drench), Levacide (R) (yellow drench), Oramec (R) (clear drench; avermectin), Cydectin (R) (clear drench; moxidectin) and Monepantel (R) (orange drench).

Most respondents (56.35%) treated their lambs at weaning and the most common time to treat ewes was identified to be pre-mating (67.86% of respondents).

The results of the questionnaire survey revealed that lowland annual drench frequency was 233 and 2.44 in lambs and ewes, respectively, although drench frequencies were higher in upland flocks: 2.73 and 2.71 for lambs and ewes, respectively.

Annual drench rotation was practiced by 43.96% of flock owners, but whether this was true rotation or pseudo-rotation (i.e., substitution of one anthelmintic product by another product belonging to the same chemical group of anthelmintics) could not be explicitly determined. (C) 2012 Elsevier B.V. All rights reserved.

Localized Flux Maxima of Arsenic, Lead, and Iron around Root Apices in Flooded Lowland Rice

In wetland-adapted plants, such as rice, it is typically root apexes, sites of rapid entry for water/nutrients, where radial oxygen losses (ROLs) are highest. Nutrient/toxic metal uptake therefore largely occurs through oxidized zones and pH microgradients. However, the processes controlling the acquisition of trace elements in rice have been difficult to explore experimentally because of a lack of techniques for simultaneously measuring labile trace elements and O2/pH. Here, we use new diffusive gradients in thin films (DGT)/planar optode sandwich sensors deployed in situ on rice roots to demonstrate a new geochemical niche of greatly enhanced As, Pb, and Fe(II) mobilization into solution immediately adjacent to the root tips characterized by O2 enrichment and low pH. Fe(II) mobilization was congruent to that of the peripheral edge of the aerobic root zone, demonstrating that the Fe(II) mobilization maximum only developed in a narrow O2 range as the oxidation front penetrates the reducing soil. The Fe flux to the DGT resin at the root apexes was 3-fold higher than the anaerobic bulk soil and 27 times greater than the aerobic rooting zone. These results provide new evidence for the importance of coupled diffusion and oxidation of Fe in modulating trace metal solubilization, dispersion, and plant uptake.

The 'human revolution' in lowland tropical Southeast Asia:the antiquity and behavior of anatomically modern humans at Niah Cave (Sarawak, Borneo)

Recent research in Europe, Africa, and Southeast Asia suggests that we can no longer assume a direct and exclusive link between anatomically modern humans and behavioral modernity (the 'human revolution'), and assume that the presence of either one implies the presence of the other: discussions of the emergence of cultural complexity have to proceed with greater scrutiny of the evidence on a site-by-site basis to establish secure associations between the archaeology present there and the hominins who created it. This paper presents one such case study: Niah Cave in Sarawak on the island of Borneo, famous for the discovery in 1958 in the West Mouth of the Great Cave of a modern human skull, the 'Deep Skull,' controversially associated with radiocarbon dates of ca. 40,000 years before the present. A new chronostratigraphy has been developed through a re-investigation of the lithostratigraphy left by the earlier excavations, AMS-dating using three different comparative pre-treatments including ABOX of charcoal, and U-series using the Diffusion-Absorption model applied to fragments of bones from the Deep Skull itself. Stratigraphic reasons for earlier uncertainties about the antiquity of the skull are examined, and it is shown not to be an `intrusive' artifact. It was probably excavated from fluvial-pond-desiccation deposits that accumulated episodically in a shallow basin immediately behind the cave entrance lip, in a climate that ranged from times of comparative aridity with complete desiccation, to episodes of greater surface wetness, changes attributed to regional climatic fluctuations. Vegetation outside the cave varied significantly over time, including wet lowland forest, montane forest, savannah, and grassland. The new dates and the lithostratigraphy relate the Deep Skull to evidence of episodes of human activity that range in date from ca. 46,000 to ca. 34,000 years ago. Initial investigations of sediment scorching, pollen, palynomorphs, phytoliths, plant macrofossils, and starch grains recovered from existing exposures, and of vertebrates from the current and the earlier excavations, suggest that human foraging during these times was marked by habitat-tailored hunting technologies, the collection and processing of toxic plants for consumption, and, perhaps, the use of fire at some forest-edges. The Niah evidence demonstrates the sophisticated nature of the subsistence behavior developed by modern humans to exploit the tropical environments that they encountered in Southeast Asia, including rainforest. (c) 2006 Elsevier Ltd. All rights reserved.

Temporal and spatial patterns in α- and γ-hexachlorocyclohexane concentrations in industrially contaminated rivers

Fluxes of HCH isomers α- and γ-HCH dynamics were determined in four industrial U.K. rivers feeding the North Sea. Sampling was conducted weekly basis over a 2-year period. This was complemented by discrete studies of events where two hourly sampling periods were used to investigate the fine time scale dynamics of fluxes. Two intensively industrialized rivers had average isomer concentrations of ~20 ng L^-1 for both isomers, while average concentrations in the two less industrialized rivers ranged between 1.5 and 5.0 ng L^-1. α-HCH concentrations showed no strong temporal patterns on any river, which contrasts with γ-HCH levels that increased considerably during late summer/early autumn following sustained periods of low river flow. Sampling during high river flow events on rivers with differing HCH pollution histories both showed the same dynamics in HCH isomer concentrations. γ-HCH concentrations decreased 4-fold during events while α-HCH-concentrations stayed constant. The increases in γ-HCH concentrations under low flow conditions and the rapid dilution of this isomer during events indicate that γ-HCH has current inputs to these river systems. It was calculated that these four rivers export 30.8 kg yr^-1 of γ-HCH and 14.8 kg yr^-1 of α-HCH to the North Sea.

The frequency of Environmental Quality Standard (EQS) exceedance for chlorinated organic pollutants in rivers of the Humber catchments

The southern industrial rivers (Aire, Calder, Don and Trent) feeding the Humber estuary were routinely monitored for a range of chlorinated micro- organic contaminants at least once a week over a 1.5-year period. Environmental Quality Standards (EQSs) for inland waters were set under the European Economic Community for a limited number of problematic contaminants (18). The results of the monitoring program for seven classes of chlorinated pollutants on the EQS list are presented in this study. All compounds were detected frequently with the exception of hexachlorobutadiene (where only one detectable measurement out of 280 individual samples occurred). In general, the rivers fell into two classes with respect to their contamination patterns. The Aire and Calder carried higher concentrations of micro- pollutants than the Don and Trent, with the exception of hexachlorobenzene (HCB). For Σ hexachlorocyclohexane (HCH) isomers (α + γ) and for dieldrin, a number of samples (~ 5%) exceeded their EQS for both the Aire and Calder. Often, ΣHCH concentrations were just below the EQS level. Levels of p,p'- DDT on occasions approached the EQS for these two rivers, but only one sample (out of 140) exceeded the EQS. No compounds exceeded their EQS levels on the Don and Trent. Analysis of the ratio of γ HCH/αHCH indicated that the source of HCH for the Don and Trent catchments was primarily lindane (γHCH) and, to a lesser extent, technical HCH (mixture of HCH isomers, dominated by α HCH), while the source(s) for the Aire and Calder had a much higher contribution from technical HCH.

The geoarchaeology of Paleolithic rivers of southwest Britain

In Britain, the majority of Lower and Middle Paleolithic archaeological finds come from river terrace deposits. The impressive “staircase” terrace sequences of southeast England, and research facilitated by aggregate extraction have provided a considerable body of knowledge about the terrace chronology and associated archaeology in that area. Such research has been essential in considering rates of uplift, climatic cycles, archaeological chronologies, and the landscapes in which hominins lived. It has also promoted the view that southeast England was a major hominin route into Britain. By contrast, the terrace deposits of the southwest have been little studied. The Palaeolithic Rivers of South West Britain (PRoSWEB) project employed a range of geoarchaeological methodologies to address similar questions at different scales, focusing on the rivers Exe, Axe, Otter, and the paleo-Doniford, all of which were located south of the maximum Pleistocene glacial limit (marine oxygen isotope stage [MIS] 4–2). Preliminary analysis of the fieldwork results suggests that although the evolution of these catchments is complex, most conform to a standard staircase-type model, with the exception of the Axe, and, to a lesser extent, the paleo-Doniford, which are anomalous. Although the terrace deposits are less extensive than in southeast Britain, differentiation between terraces does exist, and new dates show that some of these terraces are of great antiquity (MIS 10+). The project also reexamined the distribution of artifacts in the region and confirms the distributional bias to the river valleys, and particularly the rivers draining southward to the paleo–Channel River system. This distribution is consistent with a model of periodic occupation of the British peninsula along and up the major river valleys from the paleo–Channel River corridor. These data have a direct impact on our understanding of the paleolandscapes of the southwest region, and therefore our interpretations of the Paleolithic occupation of the edge of the continental landmass.

The use of biomarkers to diagnose the ecological impact of pollutants in Mediterranean rivers

Um assunto que requer atenção é a avaliação ecológica da qualidade da água de ecossistemas de água doce. Uma abordagem que surge como promissora é a biomonitorização baseada em biomarcadores, porque pode avaliar a saúde dos organismos e obter sinais de alerta precoce acerca dos riscos ambientais. Até agora, porém, o uso de biomarcadores em espécies de invertebrados, para diagnosticar danos ecológicos nos rios, é escasso. Por essa razão, existe uma necessidade urgente de desenvolver biomarcadores nas principais espécies de macroinvertebrados dos ecossistemas fluviais que são alvo de estudo. Esta tese tem como objectivo averiguar se as respostas in situ, aliadas aos biomarcadores, podem ser um método viável para avaliar os danos ecológicos de contaminantes em ecossistemas de água doce. Numa primeira fase, os biomarcadores foram usados para averiguar os mecanismos fisiológicos de adaptação genética de clones de Daphnia magna ao pesticida organofosforado fenitrothion. Numa segunda fase, os biomarcadores foram usados como ferramentas de diagnóstico de poluição em zonas ribeirinhas. Estes estudos foram realizados com três espécies-chave de macroinvertebrados: Daphnia magna, Corbicula fluminea e Hydropsyche exocellata, nos rios Besós e Llobregat e no Delta do rio Ebro (NE Espanha). Além disso, foram realizados com animais capturados nos rios, ou com ensaios de transplantes, e foram complementados com índices biológicos de macroinvertebrados e análises químicas da água e dos animais. Como os contaminantes químicos têm vários modos toxicológicos de acção e, portanto, afectam várias respostas bioquímicas dos organismos, foram analisados nas três espécies um conjunto de biomarcadores pertencentes a diferentes vias metabólicas. A abordagem experimental indica que o uso combinado de biomarcadores e outras medidas, tais como índices biológicos e testes in situ, contribui para diagnosticar os efeitos prejudiciais de contaminantes nas comunidades ribeirinhas.

The Day Roads Became Rivers: A GIS-Based Assessment of Flash Floods in Worcester

In the last 4 years Worcester, UK has been hit by several intense convective rainstorms, which caused flash floods outside of existing surface drainage networks. This paper addresses two questions related to such events: Firstly to what extent can the occurrence of flash flood flow accumulation can be determined using only commonly available data and tools, assuming the rainfall events caused mainly surface runoff due to their tropical intensity and the relatively impermeable urban catchment surface? Secondly, are the flood in-cidents in Worcester aggravated by roads serving as preferential flow paths under these conditions? The as-sessment results indicated that roads do not have an influence on the flow path of flash flood rainfall in Worcester. Flow accumulation calculated with a 10m DEM, corresponds well with reported flood incidents. This basic assessment method can be used to inform the implementation of non structural flood mitigation and public awareness.

Quantification of the relation between surface morphodynamics and subsurface sedimentological product in sandy braided rivers

This study uses digital elevation models and ground-penetrating radar to quantify the relation between the surface morphodynamics and subsurface sedimentology in the sandy braided South Saskatchewan River, Canada. A unique aspect of the methodology is that both digital elevation model and ground-penetrating radar data were collected from the same locations in 2004, 2005, 2006 and 2007, thus enabling the surface morphodynamics to be tied explicitly to the associated evolving depositional product. The occurrence of a large flood in 2005 also allowed the influence of discharge to be assessed with respect to the processproduct relationship. The data demonstrate that the morphology of the study reach evolved even during modest discharges, but more extensive erosion was caused by the large flood. In addition, the study reach was dominated by compound bars before the flood, but switched to being dominated by unit bars during and after the flood. The extent to which the subsurface deposits (the product') were modified by the surface morphodynamics (the process') was quantified using the changes in radar-facies recorded in sequential ground-penetrating radar surveys. These surveys reveal that during the large flood there was an increase in the proportion of facies associated with bar margin accretion and larger dunes. In subsequent years, these facies became truncated and replaced with facies associated with smaller dune sets. This analysis shows that unit bars generally become truncated more laterally than vertically and, thus, they lose the high-angle bar margin deposits and smaller scale bar-top deposits. In general, the only fragments that remain of the unit bars are dune sets, thus making identification of the original unit barform problematic. This novel data set has implications for what may ultimately become preserved in the rock record.