Geochemical baseline establishment and ecological risk evaluation of heavy metals in greenhouse soils from Dongtai,China

Currently, heavy metal (HM) contamination in greenhouse soils is a significant concern due to the rapid expansion of greenhouse agriculture. However, it is difficult to accurately assess HM pollution in greenhouse soils in China due to the lack of local geochemical baseline concentrations (GBCs) or corresponding background values. In the present study, the GBCs of HMs in Dongtai, a representative greenhouse area of China, were established from subsoils using cumulative frequency distribution (CFD) curves. The pollution levels of HMs and potential ecological risks were investigated using different quantitative indices, such as geo-accumulation index (I_geo), pollution index (PI), pollution load index (PLI) and ecological risk index (RI), based on these regional GBCs. The total concentrations of six metals (Cd, Cr, Cu, Ni, Pb and Zn) in surface soils were determined and shown to be lower than the concentrations reported in other greenhouse regions of China. The GBCs of Cd, Cr, Cu, Ni, Pb and Zn were 0.059–0.092, 39.20–54.50, 12.52–15.57, 20.63–23.26, 13.43–16.62 and 43.02–52.65 mg kg⁻¹, respectively. Based on this baseline criterion, Cd, Pb and Zn accumulated in the surface soils because they were present at concentrations higher than their baseline values. The soils were moderately polluted by Cd according to the I_geo values, and the PI results indicated that moderate Cd contamination was present in this area. The large variation of I_geo value of Cd revealed that Cd in this area was likely influenced by agricultural activities. The PLI showed that most of the study area was moderately polluted. However, an analysis of the RI showed that the investigated HMs had low ecological risks. Correlation analysis and principle component analysis suggested that the Cd, Pb and Zn in the greenhouse soils mainly originated from anthropogenic sources (agricultural activities, atmospheric deposition etc.), while Cr, Cu, and Ni originated from natural sources. The findings of this study illustrated the necessity of GBC establishment at the local scale to facilitate more accurate HM evaluation of greenhouse soils. It is advisable to pay more attention to Cd, which could cause environmental problems in the greenhouse system.     

Probabilistic Forecast and Uncertainty Assessment of Hydrologic Design Values Using Bayesian Theories

Researches on hydrologic extreme events have great significance in reducing and avoiding the severe losses and impacts caused by natural disasters. When forecasting hydrologic design values of the hydrologic extreme events of interest by the conventional hydrologic frequency analysis (HFA) model, the results cannot take uncertainties and risks into account. In this article, in order to overcome conventional HFA model's disadvantages and to improve hydrologic design values’ forecast results, an improved HFA model named AM-MCMC-HFA is proposed by employing the AM-MCMC algorithm (adaptive Metropolis-Markov chain Monte Carlo) to HFA process. Differing with conventional HFA model, which is seeking single optimal forecast result, the AM-MCMC-HFA model can not only get the optimal but also the probabilistic forecast results of hydrologic design values. By applying to two obviously different hydrologic series, the performances of the model proposed have been verified. Analysis results show that four factors have great influence on hydrologic design values’ reliability, and also indicate that AM-MCMC-HFA has the ability of assessing the uncertainties of parameters and hydrologic design values. Therefore, by using the AM-MCMC-HFA model, hydrologic designs tasks can be operated more reasonably, and more rational decisions can be made by governmental decision-makers and public in practice.     

What Biomonitoring Can and Cannot Tell Us about Causality in Human Health and Ecological Risk Assessments

Biomonitoring can provide exposure and effects information on various stressors (chemical or biological) that can be useful for human health and ecological risk assessments. It has been applied over the years where harmful changes in human health or the environment were observed and which may have warranted more detailed investigation. Sometimes biomonitoring programs may have been useful in determining the significance and/or cause of these harmful observations. These data can help to infer, but not confirm, causality as exemplified in classical studies conducted in humans and wildlife. However, in most cases we note that additional work was needed to provide the information necessary to support or refute causality. Today modern technology provides the ability to measure a wide variety of parameters in environmental media, plants, animals, and humans. Finding a chemical in an environmental medium or biological tissue may be helpful in understanding potential exposure (and perhaps to begin estimating hazard) to humans and ecological receptors, but mere presence does not necessarily help to establish effects or assign causality. In this article we evaluate the strengths and weaknesses, in a risk assessment context, of the use of biomonitoring data to support a determination of causality.     

Analysis of Determining Factors of the Public's Risk Acceptance Level in China

This work will characterize risk acceptance in China, based on the psychometric paradigm, and explore the determining factors that influence the risk acceptable level to the Chinese public. For this purpose, a survey was conducted including 12 hazards, 10 risk attributes (including risk acceptance), and demographic variables. First, the research attempted to explore Nanjing citizens’ average risk acceptable level for 12 hazards in China. Second, intercorrelation analysis and factor analysis of nine risk attributes were performed to obtain the suitable risk perception factors as independent variables. Three risk perception models of acceptance were constructed, which were named “Environmental risk model,” “Daily risk model,” and “Technical risk model,” that explained 59.0–69.6% of variance separately. In general, the variables of Knowledge, Benefit, and Trust were found to be significant in all models, implying that these variables are the main determining factors. However, in the environmental risk model, the variable of effect was also significant, which means the determining factors would change for different types of hazards. These results could help the Chinese government to improve the communication of risks with the public and make effective mitigation policies to improve people's rational judgment on the acceptability of risks.     

Extrapolating Growth Reductions in Fish to Changes in Population Extinction Risks: Copper and Chinook Salmon

Fish commonly respond to stress, including stress from chemical exposures, with reduced growth. However, the relevance to wild populations of subtle and sometimes transitory growth reductions may not be obvious. At low-level, sustained exposures, Cu is one substance that commonly causes reduced growth but little mortality in laboratory toxicity tests with fish. To explore the relevance of growth reductions under laboratory conditions to wild populations, we (1) estimated growth effects of low-level Cu exposures to juvenile Chinook salmon (Oncorhynchus tshawytscha), (2) related growth effects to reduced survival in downriver Chinook salmon migrations, (3) estimated population demographics, (4) constructed a demographically structured matrix population model, and (5) projected the influence of Cu-reduced growth on population size, extinction risks, and recovery chances. Reduced juvenile growth from Cu in the range of chronic criteria concentrations was projected to cause disproportionate reductions in survival of migrating juveniles, with a 7.5% length reduction predicting about a 23% to 52% reduction in survival from a headwaters trap to the next census point located 640 km downstream. Projecting reduced juvenile growth out through six generations (～30 years) resulted in little increased extinction risk; however, population recovery times were delayed under scenarios where Cu-reduced growth was imposed.     

Prioritizing Biosecurity Risks Using a Participatory Decision-Making Tool

A decision framework called Deliberative Multi-Criteria Evaluation (DMCE) was developed and deployed to prioritize biosecurity risks using a variety of subjective and objective information. To aid stakeholders in the prioritization of Emergency Plant Pest (EPP) species risk, we presented them with outputs from a Stella-based bio-economic pest risk model, and probable ecological and socioeconomic impacts. The stakeholder participants weighted the consequence criteria they deemed to have the highest expected impact. The methodology featured an uncertain set of parameters, multiple iterations of criteria weighting along with real-time sensitivity analysis. Of the five criteria, economic cost was weighted the highest at 26% while landscape amenity was weighted the lowest at the 10–12% range. The increased understanding and support gained by stakeholders through the DMCE process provided a greater likelihood of the sanctioning of the policies concerned and progress toward desired outcomes.     

Seroprevalence Rates of Helicobacter pylori and Viral Hepatitis A among Adolescents in Three Regions of the Kingdom of Saudi Arabia: Is There Any Correlation?

Background: The seroprevalence rate of Helicobacter pylori in the Kingdom of Saudi Arabia (KSA) was reported to be in the range of 50–80% among mostly symptomatic patients in non‐community‐based studies. However, the seroprevalence of viral hepatitis A (HAV) underwent a marked decline in the last two decades from over 50% in 1989 to 25% in 1997 among Saudi children under the age of 12 years. The aim of this paper was to study seroprevalence rates of H. pylori and HAV among the adolescent population in three regions of KSA and to determine whether there was any correlation between them. Materials and methods: We randomly selected 1200 16–18‐year‐old students from three regions around KSA. Demographic data, including socioeconomic status (SES), were recorded, and each student was tested for the presence of H. pylori‐IgG antibodies and anti‐HAV‐IgG. Results: The results indicate a high H. pylori infection rate (47%) among this age group. Boys had a higher prevalence than girls (p = .03), and the Al‐Qaseem region had the highest prevalence (51%, p = .002). SES did not contribute to the high prevalence rates (p = .83). A cross‐tabulation of data showed that 88 (8%) of the teenagers were seropositive and that 512 (44%) were negative for both H. pylori and HAV antibodies (χ² = 0.03, OR = 0.97, CI = 0.70–1.34). The agreement between H. pylori and HAV seropositivity was lower than would be predicted by chance (κ = ?0.03). The variables that were independently associated with seropositivity to H. pylori were being female (OR = 0.75, 95% CI = 0.60–0.95) and living in the Madinah region (OR = 0.72, 95% CI = 0.55–0.94). Conclusion: The prevalence of H. pylori in this group of adolescents was high. However, there was no correlation between H. pylori and HAV infection rates. Hence, factors contributing to the transmission source and route seem to be different.