A preliminary study of the chemistry of pore water extracted from tuff by one-dimensional compression

A specially designed and fabricated one-dimensional compression cell is being used to extract water from nonwelded and densely welded tuffs having degrees of saturation greater than 16 and 37 percent respectively. Chemical analyses of pore water obtained at increasing pressures are used to evaluate possible changes in chemistry caused by compression. The extracted pore water varies form a calcium chloride type to a sodium bicarbonate type. The mean concentration of dissolved ions generally decreases during compression. The relative abundance of the major cations varies little with increasing pressure. Possible causes of the pore-water-chemistry changes include: (1) dilution of pore water by low ionic strength adsorbed water from zeolites and clays; (2) dissolution reactions caused by the increase in dissolved carbon dioxide concentrations that may result from pressurization; (3) membrane filtration by zeolites and clays; and (4) ion exchange with the zeolites and clays

Comparing environmental impacts of deep‐seabed and land‐based mining: A defensible framework

The crises of climate change and biodiversity loss are interlinked and must be addressed jointly. A proposed solution for reducing reliance on fossil fuels, and thus mitigating climate change, is the transition from conventional combustion-engine to electric vehicles. This transition currently requires additional mineral resources, such as nickel and cobalt used in car batteries, presently obtained from land-based mines. Most options to meet this demand are associated with some biodiversity loss. One proposal is to mine the deep seabed, a vast, relatively pristine and mostly unexplored region of our planet. Few comparisons of environmental impacts of solely expanding land-based mining versus extending mining to the deep seabed for the additional resources exist and for biodiversity only qualitative. Here, we present a framework that facilitates a holistic comparison of relative ecosystem impacts by mining, using empirical data from relevant environmental metrics. This framework (Environmental Impact Wheel) includes a suite of physicochemical and biological components, rather than a few selected metrics, surrogates, or proxies. It is modified from the “recovery wheel” presented in the International Standards for the Practice of Ecological Restoration to address impacts rather than recovery. The wheel includes six attributes (physical condition, community composition, structural diversity, ecosystem function, external exchanges and absence of threats). Each has 3–5 sub attributes, in turn measured with several indicators. The framework includes five steps: (1) identifying geographic scope; (2) identifying relevant spatiotemporal scales; (3) selecting relevant indicators for each sub-attribute; (4) aggregating changes in indicators to scores; and (5) generating Environmental Impact Wheels for targeted comparisons. To move forward comparisons of land-based with deep seabed mining, thresholds of the indicators that reflect the range in severity of environmental impacts are needed. Indicators should be based on clearly articulated environmental goals, with objectives and targets that are specific, measurable, achievable, relevant, and time bound

Sediment contamination along desert wash systems from historic mining sites in a hyperarid region of Southern Nevada, USA

Abandoned mining sites in hyperarid environments are generally assumed to present an insignificant risk to water availability. This study investigated the impact abandoned mine sites in Southern Nevada can have on the wider environment. Southern Nevada is characterized with little precipitation and prolonged droughts. Precipitation in Southern Nevada is often in the form of short and intense events with the potential to mobilize and transport contaminated sediments down gradient. This work evaluated the movement of trace elements (Ag, As, Ba, Cd, Cr, Hg, Pb, and Se) and cyanide in surface sediments of three desert washes near the historic mining town of Nelson, a hyperarid region of Southern Nevada. Results indicate trace elements have been mobilized and transported down gradient from sources to areas not directly impacted by mining. Contaminants used in mining operations (Hg and CN−) as well as those of geogenic nature migrated as far as 6000 m, providing evidence of their transport in hyperarid environments, contrary to the generally held belief. Although contaminants in this study are below levels that are environmentally significant, the findings show that transport is possible. This study demonstrates that large amounts of contaminant-laden sediments might be a significant threat in hyperarid environment and to areas down gradient from source materials

ECPPA: Randomised trial of low dose aspirin for the prevention of maternal and fetal complications in high risk pregnant women

Objective To determine the effectiveness of low dose aspirin in women at high risk of adverse outcomes associated with pre-eclampsia.Design A collaborative randomised trial comparing the effects of low dose aspirin (60 mg) with placebo on pre-eclampsia and other materno-fetal complications associated with hypertension.Setting Twelve teaching maternity hospitals and 182 obstetricians' offices in Brazil.Subjects One thousand and nine women considered to be at high risk for the development of preeclampsia, or its complications, entered the study between 12 and 32 weeks of gestation. They were randomly allocated to receive aspirin (498 women) or placebo (511 women) until delivery, and follow up was obtained for 96%.Results There were no significant differences between the treatment groups in the incidence of proteinuric pre-eclampsia (6.7% aspirin-allocated compared with 6.0% placebo-allocated women), of preterm delivery (22.3% compared with 26.1%), of intrauterine growth retardation (8.5% compared with 10.1%), or of stillbirth and neonatal death (7.3% compared with 6.0%), nor were there significant differences in the incidence of proteinuric pre-eclampsia in any subgroup of women studied, including those who had systolic blood pressures of 120 mmHg or above at entry (8.5% compared with 7.3%) or those who were chronically hypertensive (10.0% compared with 7.1%). Aspirin was not associated with a significant excess of maternal or fetal bleeding.Conclusion The results of this study do not support the routine prophylactic administration of low dose aspirin in pregnancy to any category of high risk women (even those who have chronic hypertension or who are considered to be especially liable to early onset pre-eclampsia).ESCOLA PAULISTA MED,DEPT MED,MED CLIN D,RUA BOTUCATU 740,BR-04023900 SAO PAULO,BRAZILESCOLA PAULISTA MED,DEPT MED,MED CLIN D,RUA BOTUCATU 740,BR-04023900 SAO PAULO,BRAZILWeb of Scienc