SEGH Articles

SEGH 2015: a PhD researchers perspective

15 October 2015
Dan Middleton, a PhD student from the University of Manchester, based at the Centre for Environmental Geochemistry at the British Geological Survey, shares his account of the conference proceedings.

June saw the 31st International Conference of the Society for Environmental Geochemistry and hosted by the State Geological Institute of Dionýz Štúr (SGIDŠ) in Bratislava, Slovak Republic. Dan Middleton, a BUFI funded PhD student from the University of Manchester, based at the Centre for Environmental Geochemistry at the British Geological Survey, shares his account of the conference proceedings.

The coming together of our scientific community to disseminate and share recent and ongoing research findings is, in my opinion, a vital aspect of the development process of our rapidly growing field. Our community in particular is a relatively tight-knit group compared to the core scientific disciplines and one which crosses many boundaries, making networking opportunities such as SEGH 2015 essential for sharing expertise and gaining contacts across broad skill sets. A small community it may be, but nevertheless, more than 80 delegates from 24 countries covering 4 continents descended on the Holiday Inn, Bratislava to fuel a fruitful showcase of projects covering  themes of analytical chemistry, geochemistry, environmental epidemiology and medical geology to name but a few.

Of particular interest to me were the health related topics, as they bridge the gap between measurements of inorganic and organic substances in our environment and how they affect our well-being, both detrimentally and beneficially. This matter was addressed early on by Prof. Stanislav Rapant, hosting the event, in his opening presentation. Using a geochemical baseline survey spanning the whole of the Slovak Republic, Prof Rapant and colleagues from SGIDŠ were able to link concentrations of calcium (Ca) and magnesium (Mg) in drinking water to health statistics of cardiovascular disease (CVD), finding an inverse correlation between exposure and outcome. This research highlighted the first of two take-home messages for me personally – drinking water chemistry is often studied in the light of excess concentrations of chemical elements (I myself gave a presentation on arsenic (As) in UK private water supplies) but of equal importance to human health is ensuring a sufficient supply of the elements that underpin key physiological mechanisms, a point reinforced by Dr Alex Stewart in his talk on the negative health implications of iodine (I) deficiency.

BGS’s very own Dr Mark Cave was in attendance and presented a keynote lecture on findings from a recent project examining the links between London’s soil geochemistry and health related deprivation indices. Mark found that the while unemployment showed the strongest link with detrimental health outcomes, tin (Sn) in soils showed a curious relationship out of the elements studied. This relationship requires further investigation as the causal link between the two variables in not established, however the study demonstrates the power of computer based statistical modelling, in this case the random forest method, in unlocking the secrets of large multivariate datasets.

Another standout talk was that of Dr Munir Zia from the Fauji Fertilizer Company in Pakistan, who presented collaborate research with BGS on potentially harmful elements and dietary minerals in vegetable crops grown in wastewater irrigated soils. Dr Zia used a multitude of techniques to measure both the total and bioaccessible concentrations of analytes in soil and vegetable samples as well as estimating daily intake rates based on literature derived figures and comparing with existing guidance values. For me this highlighted the importance of using an interdisciplinary approach to research problems such as these and addressing the question from a number of angles. This allows us to not only quantify the chemical composition of the media we study, but begin to explore the potential impacts that these compositions may or may not have on our health.

This leads me to the second take-home message of the conference. As geochemists, analytical chemists and environmental scientists, we have an abundance of instrumental techniques at our disposal that enable us to generate quantitative chemical data across a diverse range of samples. What many of us lack in our armoury is the medical and epidemiological expertise to compliment such findings. Environmental Geochemistry and Health is an ever important field and as researchers we need to make sure that both sides of the discipline are maintained. This will be achieved through the coming together of those from both the physical and medical sciences and in particular through the continued engagement of the latter. Furthermore, the personal development of skills outside our respective backgrounds will also aid in forming an adhesive bond between the two factions and promote research that gets closer to answering the question of how our environment impacts our health.

Overall, another worthwhile and insightful meeting that demonstrated the ongoing efforts of our community to engage in diverse research problems using techniques, both analytically and statistically, that are cutting-edge and at the forefront of our field. A big thank you to organisers and delegates alike for making SEGH 2015 a memorable event as we look towards Brussels 2016.

Daniel Middleton, PhD Researcher

University of Manchester and British Geological Survey

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Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

• Fertilizer usage and cadmium in soils, crops and food 2018-06-23

Abstract

Phosphate fertilizers were first implicated by Schroeder and Balassa (Science 140(3568):819–820, 1963) for increasing the Cd concentration in cultivated soils and crops. This suggestion has become a part of the accepted paradigm on soil toxicity. Consequently, stringent fertilizer control programs to monitor Cd have been launched. Attempts to link Cd toxicity and fertilizers to chronic diseases, sometimes with good evidence, but mostly on less certain data are frequent. A re-assessment of this “accepted” paradigm is timely, given the larger body of data available today. The data show that both the input and output of Cd per hectare from fertilizers are negligibly small compared to the total amount of Cd/hectare usually present in the soil itself. Calculations based on current agricultural practices are used to show that it will take centuries to double the ambient soil Cd level, even after neglecting leaching and other removal effects. The concern of long-term agriculture should be the depletion of available phosphate fertilizers, rather than the negligible contamination of the soil by trace metals from fertilizer inputs. This conclusion is confirmed by showing that the claimed correlations between fertilizer input and Cd accumulation in crops are not robust. Alternative scenarios that explain the data are presented. Thus, soil acidulation on fertilizer loading and the effect of Mg, Zn and F ions contained in fertilizers are considered using recent $$\hbox {Cd}^{2+}$$ , $$\hbox {Mg}^{2+}$$ and $$\hbox {F}^-$$ ion-association theories. The protective role of ions like Zn, Se, Fe is emphasized, and the question of Cd toxicity in the presence of other ions is considered. These help to clarify difficulties in the standard point of view. This analysis does not modify the accepted views on Cd contamination by airborne delivery, smoking, and industrial activity, or algal blooms caused by phosphates.

• Effects of conversion of mangroves into gei wai ponds on accumulation, speciation and risk of heavy metals in intertidal sediments 2018-06-23

Abstract

Mangroves are often converted into gei wai ponds for aquaculture, but how such conversion affects the accumulation and behavior of heavy metals in sediments is not clear. The present study aims to quantify the concentration and speciation of heavy metals in sediments in different habitats, including gei wai pond, mangrove marsh dominated by Avicennia marina and bare mudflat, in a mangrove nature reserve in South China. The results showed that gei wai pond acidified the sediment and reduced its electronic conductivity and total organic carbon (TOC) when compared to A. marina marsh and mudflat. The concentrations of Cd, Cu, Zn and Pb at all sediment depths in gei wai pond were lower than the other habitats, indicating gei wai pond reduced the fertility and the ability to retain heavy metals in sediment. Gei wai pond sediment also had a lower heavy metal pollution problem according to multiple evaluation methods, including potential ecological risk coefficient, potential ecological risk index, geo-accumulation index, mean PEL quotients, pollution load index, mean ERM quotients and total toxic unit. Heavy metal speciation analysis showed that gei wai pond increased the transfer of the immobilized fraction of Cd and Cr to the mobilized one. According to the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) analysis, the conversion of mangroves into gei wai pond reduced values of ([SEM] − [AVS])/f oc , and the role of TOC in alleviating heavy metal toxicity in sediment. This study demonstrated the conversion of mangrove marsh into gei wai pond not only reduced the ecological purification capacity on heavy metal contamination, but also enhanced the transfer of heavy metals from gei wai pond sediment to nearby habitats.

• Cytotoxicity induced by the mixture components of nickel and poly aromatic hydrocarbons 2018-06-22

Abstract

Although particulate matter (PM) is composed of various chemicals, investigations regarding the toxicity that results from mixing the substances in PM are insufficient. In this study, the effects of low levels of three PAHs (benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene) on Ni toxicity were investigated to assess the combined effect of Ni–PAHs on the environment. We compared the difference in cell mortality and total glutathione (tGSH) reduction between single Ni and Ni–PAHs co-exposure using A549 (human alveolar carcinoma). In addition, we measured the change in Ni solubility in chloroform that was triggered by PAHs to confirm the existence of cation–π interactions between Ni and PAHs. In the single Ni exposure, the dose–response curve of cell mortality and tGSH reduction were very similar, indicating that cell death was mediated by the oxidative stress. However, 10 μM PAHs induced a depleted tGSH reduction compared to single Ni without a change in cell mortality. The solubility of Ni in chloroform was greatly enhanced by the addition of benz[a]anthracene, which demonstrates the cation–π interactions between Ni and PAHs. Ni–PAH complexes can change the toxicity mechanisms of Ni from oxidative stress to others due to the reduction of Ni2+ bioavailability and the accumulation of Ni–PAH complexes on cell membranes. The abundant PAHs contained in PM have strong potential to interact with metals, which can affect the toxicity of the metal. Therefore, the mixture toxicity and interactions between diverse metals and PAHs in PM should be investigated in the future.