On the use of the nephelometer in estuarine waters

A study of the problems encountered in nephelometric determinations of suspended sediment loads in the Chesapeake Bay estuary has led to development of a technique which uses nephelometer readings as a guide for sampling at vertical profiles in an estuary. This permits optimum sampling for concentration profiles and allows one to use nephelometer/load ratios to characterize particles.     

Geophysical and hydrogeologic investigation of groundwater in the Karoo stratigraphic sequence at Sawmills in northern Matabeleland,Zimbabwe: a case history

Geophysical and hydrogeological investigations have been carried out around Sawmills in Zimbabwe, Africa. The investigations are components of a larger investigation to assess the groundwater potential of the Karoo sedimentary basin with regards to supplying water to Bulawayo City. The Sawmills area was selected due to the availability of borehole logs indicating favourable stratigraphy for groundwater availability and due to the high yields from the aquifers measured from these boreholes. Data collected using two geophysical methods are presented here: transient electromagnetic (TEM) and continuous vertical electrical sounding (CVES) data. The data have also been processed using laterally constrained inversion (LCI). Because the CVES provides greater detail in the shallow subsurface, whereas TEM is more effective at depth, a more accurate image of the entire subsurface profile is provided based on using both methods. The results suggest that LCI of CVES and TEM data, in the subsurface at the required depths at Sawmills, is able to provide a substantially more accurate image of the subsurface than either method alone. The hydrogeological interpretation of the geophysical data is valuable for determining the depth to and thickness of the potential aquifer horizon(s) and for identifying the position of potential recharge zones.     

Tertiary and Quaternary vegetation history of the Great Salt Lake, Utah, USA

Pollen analysis of 5 wells drilled to bedrock in the Great Salt Lake, Utah, USA provide a record vegetation change over the last ca 13.5 Ma. Over 440 pollen samples have been counted. The longest record presented is for the mid-lake Bridge Well. Close-interval (3–10 Ka) sampling is presented for the upper Indian Cove well. Chronologic control is provided by identification volcanic tephra and by K/Ar, Ar/Ar, and fission-track dates. Ash determinations are based on electron microprobe analyses of iron, calcium, and other elements compared to Neogene ash data at the University of Utah. Sedimentation begins 38 Ma, with good pollen preservation is sediments younger than 13.5 Ma, and no obvious gaps in sedimentation after 6 Ma.The upland vegetation is desert from the late Miocene onward, with Sarcobatus and Ephedra pollen dominance during the late Miocene (<5 Ma). Chenopodiaceae-Amaranthus, and Artemisia gain dominance during the Pliocene (5–2.5 Ma) and early Pleistocene. Pinus and Artemisia sharply increase in the late Pleistocene (0.75 Ma). The pollen of 'Tertiary exotics' (elm, hickory, Ostrya-Carpinus) is rare, but persists into the Pleistocene. Major vegetation – climatic events occur 3.7 and 2.5 Ma. Increased pollen concentration and sedimentation rate after 310 Ka are attributed to the diversion of the Bear River into the Bonneville Basin.Glacial-interglacial cycles appear as alternations of Chenopodiaceae-Amaranthus (interglacial) vs Artemisia (glacial) during the Pliocene and early Pleistocene, and of Cupressaceae, Sarcobatus, and Gramineae (interglacial) vs Picea, Abies, and Pseudotsuga (glacial) during the late Pleistocene. Pluvial cycles are separated by interpluvial peaks in percentages of wetground and aquatic types. Six interpluvials are indicated during the last 759 Ka, with pluvial cycles of ca 100 Ka cyclicity back to 1.5 Ma.     

Workshop on Indices and Indicators for Climate Extremes, Asheville, NC, USA, 3–6 June 1997 Breakout Group A: Storms

The Working Group on Storms considered tropical cyclones, extratropical cyclones, thunderstorms and their associated winds and effects other than on temperatures and precipitation (which are dealt with by the other working groups) to be in their purview. Changes in observing systems and distribution of observers and people impacted by these phenomena confound trend analysis. In light of the difficulty of assembling homogeneous time series of small-scale phenomena such as thunderstorms, tornadoes and hail, and also the problems in wind measurements, the working group recommends that indices of wind be developed by taking advantage of long surface (or sea-level) pressure measurements and analyses. Because wind is a vector, two pairs of readings that are orthogonal are desirable. Instantaneous values over about 1000 km scales are desirable to generate statistics relevant to wind extremes. Recommendations are given on how the data might profitably be processed. Several other recommendations are made concerning data acquisition and processing, some of which apply to reanalysis of past data and some apply to future processing of data. Various "extremes indices" are also suggested.     

Palynological evidence for early Holocene aridity in the southern Sierra Nevada, California

Sediments of Balsam Meadow have produced a 11,000-yr pollen record from the southern Sierra Nevada of California. The Balsam Meadow diagram is divided into three zones. (1) The Artemisia zone (11,000–7000 yr B.P.) is characterized by percentages of sagebrush (Artemisia) and other nonarboreal pollen higher than can be found in the modern local vegetation. Vegetation during this interval was probably similar to the modern vegetation on the east slope of the Sierra Nevada and the climate was drier than that of today. (2) Pinus pollen exceeded 80% from 7000 to 3000 yr B.P. in the Pinus zone. The climate was moister than during the Artemisia zone. (3) Fir (Abies, Cupressaceae, and oak (Quercus) percentages increased after 3000 yr B.P. in the Abies zone as the modern vegetation at the site developed and the present cool-moist climatic regime was established. Decreased fire frequency after 1200 yr B.P. is reflected in decreased abundance of macroscopic charcoal and increased concentration of Abies magnifica and Pinus murrayana needles.     

Modeling the effects of shear on the evolution of the holes in the condensational clouds of Venus

Near-infrared brightness temperature contrasts observed on the night side of Venus indicate variations in the size and distribution of particles in the lower and middle cloud decks. McGouldrick and Toon [McGouldrick, K., Toon, O.B., 2007. Icarus 191, 1-24] have shown that these changes can be explained by large-scale dynamics; in particular, that downdrafts may produce optical depth “holes” in the clouds. The lifetimes of these holes are observed to be moderately short, on the order of ten days. Here, we explore a simple model to better understand this lifetime. We have coupled a microphysical model of the Venus clouds with a simple, two-dimensional (zonal, vertical) kinematical transport model to study the effects of the zonal flow on the lifetime of the holes in the clouds. We find that although wind shear may be negligible within the cloud itself, the shear that is present near the top and the bottom of the statically unstable cloud region can lead to changes in the radiative-dynamical feedback which ultimately lead to the dissipation of the holes.     

Evaluation of Amendments to Control Phosphorus Losses in Runoff from Pig Slurry Applications to Land

If spread in excess of crop requirements, incidental phosphorus (P) losses from agriculture can lead to eutrophication of receiving waters. The use of amendments in targeted areas may help reduce the possibility of surface runoff of nutrients. The aim of this study was to identify amendments which may be effective in reducing incidental dissolved reactive phosphorus (DRP) losses in surface runoff from land applied pig slurry. For this purpose, the DRP losses under simulated conditions across the surface of intact grassland soil cores, loaded with unamended and amended slurry at a rate equivalent to 19 kg P ha^?1, were determined over a 30 h period. The effectiveness of the amendments at reducing DRP in overlying water were (in decreasing order): alum (86%), flue gas desulfurization by‐product (FGD) (74%), poly‐aluminum (Al) chloride (PAC) (73%), ferric chloride (71%), fly ash (58%), and lime (54%). FGD was the most costly of all the treatments (€7.64/m³ for 74% removal). Ranked in terms of feasibility, which takes into account effectiveness, cost, and other potential impediments to use, they were: alum, ferric chloride, PAC, fly ash, lime, and FGD.     

Disputed South China Sea hydrocarbons in perspective

Maritime and territorial disputes have been a source of tension among the states bordering the South China Sea for decades. These disputes are often framed as being at least partially driven by the desire to gain access to much needed seabed hydrocarbon resources. Suggestions that major oil and gas riches are at stake in the South China Sea have arguably encouraged States to be inflexible in their claims and negatively impacted on bilateral relations. Indeed, controversial incidents relating to hydrocarbon exploration have occurred on multiple occasions, and as recently as mid-2011.This paper critically examines the South China Sea ‘hydrocarbon factor’. The wide range of estimates that circulate in the public domain are discussed in detail. Using a hypothetical and optimistic estimate of disputed oil and gas reserves based on the best possible interpretation of available data, depletion and production curve analysis is applied to determine the production profile of disputed reserves, and an evaluation of their potential benefit to energy security for each country with claims in the South China Sea is made. Analysis shows that constraints on production mean that disputed South China Sea oil and gas may only constitute a small part of the solution to Southeast Asia's growing energy security challenges, and does not have the capacity to reverse the trend of growing reliance on imports to the region. Escalating demand for imported hydrocarbons would instead reinforce the importance of sea-lane security to regional energy security.