SEGH Articles

SEGH2019 Prize Winners Series: Amy Sansby

05 August 2019
Amy Sansby, a veterinary student at the University of Nottingham, won the best overall ECR poster prize and shares a more detailed account of her study with us!

Aquaculture is the fastest-growing livestock sector globally. Between 1961 and 2016 the average increase in global fish consumption was 3.2%, which exceeded the consumption of meat from all terrestrial animals combined (2.8%).  Aquaculture samples can be used to provide a relatively cheap protein source in many countries and is especially important in developing countries where other protein sources may not be available or affordable. Aquaculture also provides income to developing countries, such as Kenya, where 2,500,000 people are employed both directly and indirectly. It can also provide an income too low skilled members of the community who may otherwise not have an income. Therefore, it is important that this sector grows in a safe and sustainable manner in order to ensure that the food is both safe and nutritionally beneficial to all consumers.

Whilst in many countries the use of antibiotics for growth promotion or metaphylaxis is banned, these practices are still occurring in aquaculture. This can lead to an increase in antimicrobial-resistant populations of bacteria, and additionally elevated levels of antimicrobial residues within the food. Other routes to antibiotic exposure include contamination of water with pharmaceutical products; wastewater runoff from humans; and bad agricultural practices.

This study was part of a larger collaborative effort aiming to assess how a range of pollutants, including antibiotics and heavy metals, affect aquaculture samples that are intended for human consumption. The aim was to evaluate the quality of aquaculture produce from Kenya (a growing country within the aquaculture sector) and Vietnam (a large exporter to several European countries, including the UK). Kenyan aquaculture samples were obtained directly from multiple sites around Lake Victoria, and Vietnamese aquaculture samples were purchased in the UK from major supermarkets. This allowed a comparison to be made between aquaculture samples from both countries.

 

Tilapia sampling in Kenya

 

To evaluate antibiotic residues within the fish, a Premi-test 25 kit was used. This test uses a thermophilic bacteria (Bacillus stearothermophilus) which is susceptible to the following antimicrobial compounds: β-lactams, Cephalosporins, Macrolides, Tetracyclines, Sulphonamides, Aminoglycosides, Quinolones, Amphenicoles and Polypeptides. A positive result indicates a residue level above the EU maximum residue level (MRL). Antibiotic resistance was evaluated using polymerase chain reactions (PCR) which amplifies specific genetic elements, if present. The resistance genes for Tetracycline and Ampicillin were examined in this study.

Extracting fish muscle juice for Premi-test 25 on the boat while sampling in Kenya

 

76% of Kenyan samples and 55% of Vietnamese samples tested positive for antibiotic residues. Genetic elements for Tetracycline resistance were present in fish samples from both counties, and all Kenyan fish tested positive for Ampicillin resistance. This highlights the need for further research to investigate the source of the residues and resistance elements, and also the importance of working with aquaculture farmers in order to reduce contamination of their products.

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

  • Ecological impact of the antibiotic ciprofloxacin on microbial community of aerobic activated sludge 2019-08-16

    Abstract

    This study investigated the effects and fate of the antibiotic ciprofloxacin (CIP) at environmentally relevant levels (50–500 µg/L) in activated sludge (AS) microbial communities under aerobic conditions. Exposure to 500 µg/L of CIP decreased species diversity by about 20% and significantly altered the phylogenetic structure of AS communities compared to those of control communities (no CIP exposure), while there were no significant changes upon exposure to 50 µg/L of CIP. Analysis of community composition revealed that exposure to 500 µg/L of CIP significantly reduced the relative abundance of Rhodobacteraceae and Nakamurellaceae by more than tenfold. These species frequently occur in AS communities across many full-scale wastewater treatment plants and are involved in key ecosystem functions (i.e., organic matter and nitrogen removal). Our analyses showed that 50–500 µg/L CIP was poorly removed in AS (about 20% removal), implying that the majority of CIP from AS processes may be released with either their effluents or waste sludge. We therefore strongly recommend further research on CIP residuals and/or post-treatment processes (e.g., anaerobic digestion) for waste streams that may cause ecological risks in receiving water bodies.

  • Source and background threshold values of potentially toxic elements in soils by multivariate statistics and GIS-based mapping: a high density sampling survey in the Parauapebas basin, Brazilian Amazon 2019-08-10

    Abstract

    A high-density regional-scale soil geochemical survey comprising 727 samples (one sample per each 5 × 5 km grid) was carried out in the Parauapebas sub-basin of the Brazilian Amazonia, under the Itacaiúnas Basin Geochemical Mapping and Background Project. Samples were taken from two depths at each site: surface soil, 0–20 cm and deep soil, 30–50 cm. The ground and sieved (< 75 µm) fraction was digested using aqua regia and analyzed for 51 elements by inductively coupled plasma mass spectrometry (ICPMS). All data were used here, but the principal focus was on the potential toxic elements (PTEs) and Fe and Mn to evaluate the spatial distribution patterns and to establish their geochemical background concentrations in soils. Geochemical maps as well as principal component analysis (PCA) show that the distribution patterns of the elements are very similar between surface and deep soils. The PCA, applied on clr-transformed data, identified four major associations: Fe–Ti–V–Sc–Cu–Cr–Ni (Gp-1); Zr–Hf–U–Nb–Th–Al–P–Mo–Ga (Gp-2); K–Na–Ca–Mg–Ba–Rb–Sr (Gp-3); and La–Ce–Co–Mn–Y–Zn–Cd (Gp-4). Moreover, the distribution patterns of elements varied significantly among the three major geological domains. The whole data indicate a strong imprint of local geological setting in the geochemical associations and point to a dominant geogenic origin for the analyzed elements. Copper and Fe in Gp-1 were enriched in the Carajás basin and are associated with metavolcanic rocks and banded-iron formations, respectively. However, the spatial distribution of Cu is also highly influenced by two hydrothermal mineralized copper belts. Ni–Cr in Gp-1 are highly correlated and spatially associated with mafic and ultramafic units. The Gp-2 is partially composed of high field strength elements (Zr, Hf, Nb, U, Th) that could be linked to occurrences of A-type Neoarchean granites. The Gp-3 elements are mobile elements which are commonly found in feldspars and other rock-forming minerals being liberated by chemical weathering. The background threshold values (BTV) were estimated separately for surface and deep soils using different methods. The ‘75th percentile’, which commonly used for the estimation of the quality reference values (QRVs) following the Brazilian regulation, gave more restrictive or conservative (low) BTVs, while the ‘MMAD’ was more realistic to define high BTVs that can better represent the so-called mineralized/normal background. Compared with CONAMA Resolution (No. 420/2009), the conservative BTVs of most of the toxic elements were below the prevention limits (PV), except Cu, but when the high BTVs are considered, Cu, Co, Cr and Ni exceeded the PV limits. The degree of contamination (Cdeg), based on the conservative BTVs, indicates low contamination, except in the Carajás basin, which shows many anomalies and had high contamination mainly from Cu, Cr and Ni, but this is similar between surface and deep soils indicating that the observed high anomalies are strictly related to geogenic control. This is supported when the Cdeg is calculated using the high BTVs, which indicates low contamination. This suggests that the use of only conservative BTVs for the entire region might overestimate the significance of anthropogenic contamination; thus, we suggest the use of high BTVs for effective assessment of soil contamination in this region. The methodology and results of this study may help developing strategies for geochemical mapping in other Carajás soils or in other Amazonian soils with similar characteristics.

  • Uptake of Cd, Pb, and Ni by Origanum syriacum produced in Lebanon 2019-08-06

    Abstract

    Trace metals are found naturally in soil. However, the increase in industrial and agricultural polluting activities has increased trace metal contamination and raised high concerns in the public health sector. The study was conducted on Origanum syriacum, one of the most consumed herbs in the Middle East, and was divided into three parts. (1) Pot experiment: to study the effect of Cd, Pb, or Ni levels in soil on their uptake by O. syriacum. (2) Field samples: collected from major agricultural regions in Lebanon to analyze Cd, Pb, and Ni concentrations in soil and leaves. (3) Sale outlets samples: to measure the levels of Cd, Pb, and Ni in O. syriacum tissues in the market. Results showed that there was a positive correlation between levels of Cd, Pb, and Ni in soil and those in O. syriacum tissues. None of the field samples contained Pb or Ni that exceeded the maximum allowable limits (MAL). Three samples collected from heavily poultry-manured soil contained Cd higher than the MAL. Samples collected from sale outlets did not exceed the MAL for Ni but two exceeded the MAL for Cd and one for Pb. Trace metal contamination is not a major concern in O. syriacum produced in Lebanon. Only one mixture sample from a sale outlet was higher in Pb than the MAL and three samples from heavily manured fields exceeded the MAL for Cd.