Goitre and environmental iodine deficiency in the UK — Derbyshire: A review

Endemic goitre was prevalent in the population of Derbyshire in the UK for many centuries until it declined from the 1930s. A contemporary medical survey showed that endemicity of goitre was particularly higher in the Carboniferous limestone areas of the Derbyshire-Peak District. Unlike classical goitrous areas of the world, where the distribution of goitre has been found to be related to the iodine content in the environment, there is no such relationship reported for the Derbyshire-Peak District area. The present study reviews the presence of endemic goitre in this area with reference to iodine in different environmental media using past and present data. In comparison with the world average values, the iodine contents in the soil and sediment in the Peak District are not deficient, but compared to England, Wales and Scotland averages, these levels are low. As no information on the mobility and bioavailability of iodine of this area is available, a cautious approach is necessary before any assumption is made on the aetiology of endemic goitre. The study also discusses some hypotheses relating to the possible cause of endemic goitre in the limestone areas. Further research needs are suggested depending on the land use and geochemistry of the Peak District to determine the underlying causes of the former endemic goitre in this area.     

Predicting ozone levels

This paper presents a statistical model that is capable of predicting ozone levels from precursor concentrations and meteorological conditions during daylight hours in the Shuaiba Industrial Area (SIA) of Kuwait. The model has been developed from ambient air quality data that was recorded for one year starting from December 1994 using an air pollution mobile monitoring station. The functional relationship between ozone level and the various independent variables has been determined by using a stepwise multiple regression modelling procedure. The model contains two terms that describe the dependence of ozone on nitrogen oxides (NOx) and nonmethane hydrocarbon precursor concentrations, and other terms that relate to wind direction, wind speed, sulphur dioxide (SO₂) and solar energy. In the model, the levels of the precursors are inversely related to ozone concentration, whereas SO₂ concentration, wind speed and solar radiation are positively correlated. Typically, 63 % of the variation in ozone levels can be explained by the levels of NOx. The model is shown to be statistically significant and model predictions and experimental observations are shown to be consistent. A detailed analysis of the ozone-temperature relationship is also presented; at temperatures less than 27 °C there is a positive correlation between temperature and ozone concentration whereas at temperatures greater than 27 °C a negative correlation is seen. This is the first time a non-monotonic relationship between ozone levels and temperature has been reported and discussed.     

Fate of disinfection by-products in groundwater during aquifer storage and recovery with reclaimed water

Knowledge on the behaviour of disinfection by-products (DBPs) during aquifer storage and recovery (ASR) is limited even though this can be an important consideration where recovered waters are used for potable purposes. A reclaimed water ASR trial in an anoxic aquifer in South Australia has provided some of the first quantitative information at field-scale on the fate and transport of trihalomethanes (THMs) and haloacetic acids (HAAs). The results revealed that THM half-lives varied from <1 to 65 days, with persistence of chloroform being highest and bromoform lowest. HAA attenuation was rapid (<1 day). Rates of THM attenuation were shown to be highly dependent on the geochemical environment as evidenced by the 2-5 fold reduction in half-lives at the ASR well which became methanogenic during the storage phase of the trial, as compared to an observation well situated 4 m away, which remained nitrate-reducing. These findings agree with previous laboratory-based studies which also show persistence declining with increased bromination of THMs and reducing redox conditions. Modelling suggests that the chlorinated injectant has sufficient residual chlorine and natural organic matter for substantial increases in THMs to occur within the aquifer, however this is masked in some of the field observations due to concurrent attenuation, particularly for the more rapidly attenuated brominated compounds. The model is based on data taken from water distribution systems and may not be representative for ASR since bromide and ammonia concentrations in the injected water and the possible role of organic carbon in the aquifer were not taken into consideration. During the storage phase DBP formation potentials were reduced as a result of the removal of precursor material despite an increase in the THM formation potential per unit weight of total organic carbon. This suggests that water quality improvements with respect to THMs and HAAs can be achieved through ASR in anoxic aquifers.     

The acute and chronic toxicity of lanthanum to Daphnia carinata

The rare earth elements (REEs) are increasingly being used as trace supplements in agriculture. This study measured the acute and chronic toxicity of one REE, lanthanum (La), to Daphnia carinata. The 48-h EC50 of La to Daphnia was measured in three media of differing composition and hardness. Lanthanum was most toxic to Daphnia in soft tap water (TW) with an acute 48-h EC50 of 43 microg/l compared with 1180 microg/l in ASTM hard water (ASTM). In the third daphnid growth medium (DW), based on diluted sea water, the acute 48-h EC50 was 49 microg La/l, however, there was significant precipitation of La in this media. The chronic toxicity of La to Daphnia was measured in the DW and ASTM media. Nominal exposure concentrations were 100, 200, 400, 600, 800, and 1000 microg La/l. Mortality was a more sensitive endpoint than growth or reproduction in both chronic experiments. Very little La was detected in either media after 24 h and the measured concentrations below were estimated by logarithmic mean of nominal and measured values. There was 100% mortality at concentrations > or = 80 microg La/l (400 microg/l nominal) by day six of the experiment using DW media, but no effect on survival growth or reproduction at lower concentrations. In the ASTM media, La caused significant mortality to Daphnia at concentrations > or = 39 microg/l (200 microg/l nominal), however, at least one animal survived to the end of the study at each of the tested concentrations. There was no effect of La on growth of surviving daphnids at concentrations < or = 57 microg/l (400 g/l), however, second brood clutch sizes were significantly increased at 30, 39, and 57 microg/l (100, 200, 400 g/l nominal) compared with controls. Lanthanum also caused a delayed maturation in Daphnia.     

Modelling of physical and reactive processes during biodegradation of a hydrocarbon plume under transient groundwater flow conditions

Numerical experiments of non-reactive and reactive transport were carried out to quantify the influence of a seasonally varying, transient flow field on transport and natural attenuation at a hydrocarbon-contaminated field site. Different numerical schemes for solving advective transport were compared to assess their capability to model low transversal dispersivities in transient flow fields. For the field site, it is shown that vertical plume spreading is largely inhibited, particularly if sorption is taken into account. For the reactive simulations, a biodegradation reaction module for the geochemical transport model PHT3D was developed. Results of the reactive transport simulations show that under the site-specific conditions the temporal variations in groundwater flow do, to a modest extent, affect average biodegradation rates and average total (dissolved) contaminant mass in the aquifer. The model simulations demonstrate that the seasonal variability in groundwater flow only results in significantly enhanced biodegradation rates when a differential sorption of electron donor (toluene) and electron acceptor (sulfate) is assumed.     

The effect of low molecular weight chelators on iron chelation and free radical generation as studied by ESR measurement

The purpose of this work was to improve our current knowledge of the non-enzymatic mechanisms involved in brown rot fungal decay of wood, but also to improve our understanding of chelator-mediated reactions that may occur in other biological systems where low pH conditions may prevail. Several key steps (iron chelation and reduction) during early non-enzymatic wood decay processes have been studied by using electron spin resonance (ESR). It has been proposed that low molecular weight chelators as well as Fenton reagents are involved in brown rot decay, at least in early non-enzymatic stages. In this work, the binding between a catecholate model chelator and ferric iron was studied by ESR spectroscopy. The effects of the model chelator, Fenton reagents, as well as the reaction conditions on free radical generation were also studied using ESR spin-trapping techniques. The results indicate: (1) The relative quantity of the chelator-iron complex can be determined by measurement of the intensities of the characteristic g = 4.3 ESR signal. (2) The effects of the chelator:iron ratio, the pH, and other reaction parameters on the hydroxyl radical generation in a Fenton type system can be determined using ESR spin-trapping techniques. (3) Data support the hypothesis that superoxide radicals are involved in chelator-mediated Fenton processes.     

Multiple paternity in a wild population of northern water snakes,Nerodia sipedon

Summary For most animal species, a single mating is sufficient to fertilize all of a female's offspring. As a result, females do not usually increase their reproductive success with successive matings. However, multiple paternity has been discovered in many animal taxa. We demonstrate that the majority of female water snakes in a wild population mate with more than one male for each litter. Field observations indicated that a highly skewed operational sex ratio (3.6:1 M : F) during the breeding season, while not necessary for multiple paternity to occur, created ample opportunity for females to mate multiply. Protein electrophoretic analysis showed that at least 12 of 14 litters from naturally mated females had more than one father. Since male snakes can not force copulations, multiple matings seem likely to be the result of female choice. Offprint requests to: F.E. Barry     

Provisioning rules and chick competition in asynchronously hatching common terns (Sterna hirundo)

Interactions between nestling birds and their parents are models for examining parent–offspring communication and sibling competition. Most studies have focused on species where young are restricted to a nest. However, offspring of many species are mobile and fed by parents for an extended period post-hatch. These chicks mobility may provide an opportunity to examine the role of signalling and physical competition on parental feeding decisions. We examined parental provisioning rules in relation to offspring behaviour and hatching order (i.e., competitive ability) in a species with mobile young, the common tern. We determined that about 95% of feedings were directed to the first chick to reach the parent when it landed with food. We developed a probabilistic model to predict the likelihood of a chick reaching the parent first, and thus receiving food. Our model showed that begging intensity, feeding history, and the interaction between begging intensity and relative proximity to the parent best predicted which chick would arrive first. Increased begging was associated with arriving first significantly more when a chick was relatively further from the parent than when it was closer than its siblings. Independently of these factors, larger, earlier-hatched chicks were more likely to be fed than smaller, later-hatched chicks. Additional analyses showed that parents landed closer to more intensively begging chicks, however, increased begging did not explain the advantage of earlier-hatched chicks because begging intensity did not vary with hatching order. Instead, earlier-hatched chicks were more likely to outrun later-hatched siblings and reach the parent first.     

In‐well sediment incubators to evaluate microbial community stability and dynamics following bioimmobilization of uranium

An in‐well sediment incubator (ISI) was developed to investigate the stability and dynamics of sediment‐associated microbial communities to prevailing subsurface oxidizing or reducing conditions. Herein we describe the use of these devices at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site. During a seven‐month period in which oxidized Rifle Aquifer background sediment (RABS) were deployed in previously biostimulated wells under iron‐reducing conditions, cell densities of known iron‐reducing bacteria, including Geobacteraceae, increased significantly, showing the microbial community response to local subsurface conditions. Phospholipid fatty acid (PLFA) profiles of RABS following in situ deployment were strikingly similar to those of adjacent sediment cores, suggesting ISI results could be extrapolated to the native material of the test plots. Results for ISI deployment with laboratory‐reduced sediments showed only slight changes in community composition and pointed toward the ability of the ISI to monitor microbial community stability and response to subsurface conditions. © 2009 Wiley Periodicals, Inc.