Are Chinese consumers at risk due to exposure to metals in crayfish? A bioaccessibility-adjusted probabilistic risk assessment

Freshwater crayfish, the world's third largest crustacean species, has been reported to accumulate high levels of metals, while the current knowledge of potential risk associated with crayfish consumption lags behind that of finfish. We provide the first estimate of human health risk associated with crayfish (Procambarus clarkii) consumption in China, the world's largest producer and consumer of crayfish. We performed Monte Carlo Simulation on a standard risk model parameterized with local data on metal concentrations, bioaccessibility (phi), crayfish consumption rate, and consumer body mass. Bioaccessibility of metals in crayfish was found to be variable (68-95%) and metal-specific, suggesting a potential influence of metal bioaccessibility on effective metal intake. However, sensitivity analysis suggested risk of metals via crayfish consumption was predominantly explained by consumption rate (explaining >92% of total risk estimate variability), rather than metals concentration, bioaccessibility, or body mass. Mean metal concentrations (As, Cd, Cu, Ni, Pb, Se and Zn) in surveyed crayfish samples from 12 provinces in China conformed to national safety standards. However, risk calculation of phi-modified hazard quotient (HQ) and hazard index (HI) suggested that crayfish metals may pose a health risk for very high rate consumers, with a HI of over 24 for the highest rate consumers. Additionally, the phi-modified increased lifetime risk (ILTR) for carcinogenic effects due to the presence of As was above the acceptable level (10(-5)) for both the median (ILTR = 2.5 x 10(-5)) and 90th percentile (ILTR = 1.8 x 10(-4)), highlighting the relatively high risk of As in crayfish. Our results suggest a need to consider crayfish when assessing human dietary exposure to metals and associated health risks, especially for high crayfish-consuming populations, such as in China, USA and Sweden.HZ by the National Natural Science Foundation of China (41273087). LN was supported by European Union Marie Curie Actions, Grant FP People 2010 “IRSES Electroacross” and BG by the SAGE-IGERT Fellowship (US National Science Foundation)

Study of pollution in the El Jadida-Safi Atlantic coastal zone (Morocco) by using PIXE and SSNTD methods

In this work PIXE experiments were performed for measuring heavy and light elements (ranging from aluminium to lead) concentrations inside various polluted and unpolluted soils as well as liquid samples collected from different phosphate factory sewers in the El Jadida-Safi Atlantic coastal region (Morocco). In addition, uranium (238U) and thorium (232Th) contents were evaluated in the same samples studied by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The influence of the phosphate industry wastes on the concentrations of both radioactive and non-radioactive elements of the samples studied was investigated

Geochemistry of As-, F- and B-bearing waters in and around San Antonio de los Cobres, Argentina, and implications for drinking and irrigation water quality

Spring, stream and tap waters from in and around San Antonio de los Cobres, Salta, Argentina, were sampled to characterize their geochemical signatures, and to determine whether they pose a threat to human health and crops. The spring waters are typical of geothermal areas world-wide, in that they are Na-Cl waters with high concentrations of Astot, As(III), Li, B, HCO3, F and SiO2 (up to 9.49, 8.92, 13.1, 56.6, 1250, 7.30 and 57.2 mg L-1, respectively), and result from mixing of deep Na-Cl brines and meteoric HCO3-rich waters. Springs close to the town of San Antonio have higher concentrations of all elements, and are generally cooler, than springs in the Baños de Agua Caliente. Spring water chemistry is a result of mixing of deep Na-Cl brines and meteoric HCO3 waters. Stream waters are also Na-Cl type, and receive large inputs of all elements from the springs near San Antonio, but concentrations decrease downstream through the town of San Antonio due to mineral precipitation. The spring that is used as a drinking water source, and other springs in the area, have As, F and B concentrations in excess of WHO and Argentinian drinking water guidelines. Evaluation of the waters for irrigation purposes suggests that their high salinities and B concentrations may adversely affect crops. The waters may be improved for drinking and irrigation by dilution with cleaner meteoric waters, mineral precipitation or by use of commercial filters. Such recommendations could also be followed by other settlements that draw drinking and irrigation waters from geothermal sources

Mobility of Cr, Pb, Cd, Cu and Zn in a loamy sand soil : a comparative study

Interest in soil contamination has been growing in recent years due to the ongoing degradation of soil environments. Therefore, the development of remediation techniques and the study of contaminant sorption and migration are areas of intense research. In this study, the authors sought to evaluate the scenario of co-contamination of a loamy sand soil by multiple heavy metals. To that end, the sorption and transport of five metals—Cr, Pb, Cd, Cu and Zn—was evaluated using representative samples of a soil from the north of Portugal. The tests were conducted in batch and continuous systems using single- and multiple-metal acid solutions to evaluate the effect of metal competition. In accordance with the type of assay—batch or continuous—Langmuir or Convection Dispersion Two-Site Nonequilibrium models were adjusted to explain the sorption/transport data. FTIR analyses were performed on the final samples of the continuous systems. Generally, the results revealed good fitting of the tested models for the metals in competitive and noncompetitive scenarios, with the exception of Zn that was originally present in soil samples at higher concentrations. As expected, the influence of competition was observed in both batch and continuous systems, but with different tendencies. The FTIR spectra also revealed a strong influence of clay minerals and organic matter on the sorption of the metals.The PhD grants of Bruna Fonseca and Hugo Figueiredo and the research grant of Joana Rodrigues were financially supported by Fundacao para a Ciencia e Tecnologia, Ministerio da Ciencia e Tecnologia, Portugal and Fundo Social Europeu (FSE)

On-line hydraulic state prediction for water distribution systems

World Environmental and Water Resources Congress 2009: Great Rivers Proceedings of World Environmental and Water Resources Congress 2009 May 17–21, 2009 Kansas City, MissouriThis paper describes and demonstrates a method for on‐line hydraulic state prediction in urban water networks. The proposed method uses a Predictor‐Corrector (PC) approach in which a statistical data‐driven algorithm is applied to estimate future water demands, while near real‐time field measurements are used to correct (i.e., calibrate) these predicted values on‐line. The calibration problem is solved using a modified Least Squares (LS) fit method. The objective function is the minimization of the least‐squares of the differences between predicted and measured hydraulic parameters (i.e., pressure and flow rates at several system locations), with the decision variables being the consumers' water demands. The a‐priori estimation (i.e., prediction) of the values of the decision variables, which improves through experience, facilitates a better convergence of the calibration model and provides adequate information on the system's hydraulic state for real time optimization. The proposed methodology is demonstrated on a prototypical municipal water distribution system

Effects of metal-contaminated soils on the accumulation of heavy metals in gotu kola (Centella asiatica) and the potential health risks: a study in Peninsular Malaysia

Centella asiatica is a commonly used medicinal plant in Malaysia. As heavy metal accumulation in medicinal plants which are highly consumed by human is a serious issue, thus the assessment of heavy metals in C. asiatica is important for the safety of consumers. In this study, the heavy metal accumulation in C. asiatica and the potential health risks were investigated. Samples of C. asiatica and surface soils were collected from nine different sites around Peninsular Malaysia. The concentration of six heavy metals namely Cd, Cu, Ni, Fe, Pb and Zn were determined by air-acetylene flame atomic absorption spectrophotometer (AAS). The degree of anthropogenic influence was assessed by calculating the enrichment factor (EF) and index of geoaccumulation (Igeo). The heavy metal uptake into the plant was estimated through the calculation of translocation factor (TF), bioconcentration factor (BCF) and correlation study. Estimated daily intakes (EDI) and target hazard quotients (THQ) were used to determine the potential health risk of consuming C. asiatica. The results showed that the overall surface soil was polluted by Cd, Cu and Pb, while the uptake of Zn and Ni by the plants was high. The value of EDI and THQ showed that the potential of Pb toxicity in C. asiatica was high as well. As heavy metal accumulation was confirmed in C. asiatica, daily consumption of the plant derived from polluted sites in Malaysia was not recommended

Mechanisms of hydrogen sulfide removal by ground granulated blast furnace slag amended soil

Ground granulated blast furnace slag (GGBS) amended soil has been found able to remove gaseous hydrogen sulfide (H2S). However, how H2S is removed by GGBS amended soil and why GGBS amended soil can be regenerated to remove H2S are not fully understood. In this study, laboratory column tests together with chemical analysis were conducted to investigate and reveal the mechanisms of H2S removal process in GGBS amended soil. Sulfur products formed on the surface of soil particle and in pore water were quantified. The test results reveal that the reaction between H2S and GGBS amended soil was a combined process of oxidation and acid-base reaction. The principal mechanism to remove H2S in GGBS amended soil was through the formation of acid volatile sulfide (AVS), elemental sulfur and thiosulfate. Soil pH value decreased gradually during regeneration and reuse cycles. It is found that the AVS plays a significant role in H2S removal during regeneration and reuse cycles. Adding GGBS increased the production of AVS and at the same time suppressed the formation of elemental sulfur. This mechanism is found to be more prominent when the soil water content is higher, leading to increased removal capacity. © 2017 Elsevier Lt

Revisions to the derivation of the Australian and New Zealand guidelines for toxicants in fresh and marine waters

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality are a key document in the Australian National Water Quality Management Strategy. These guidelines released in 2000 are currently being reviewed and updated. The revision is being co-ordinated by the Australian Department of Sustainability, Environment, Water, Population and Communities, while technical matters are dealt with by a series of Working Groups. The revision will be evolutionary in nature reflecting the latest scientific developments and a range of stakeholder desires. Key changes will be: increasing the types and sources of data that can be used; working collaboratively with industry to permit the use of commercial-in-confidence data; increasing the minimum data requirements; including a measure of the uncertainty of the trigger value; improving the software used to calculate trigger values; increasing the rigour of site-specific trigger values; improving the method for assessing the reliability of the trigger values; and providing guidance of measures of toxicity and toxicological endpoints that may, in the near future, be appropriate for trigger value derivation. These changes will markedly improve the number and quality of the trigger values that can be derived and will increase end-users’ ability to understand and implement the guidelines in a scientifically rigorous manner