Analysis of Spatial Variability of River Bottom Sediment Pollution with Heavy Metals and Assessment of Potential Ecological Hazard for the Warta River, Poland

Pollution of river bottom sediments with heavy metals (HMs) has emerged as a main environmental issue related to intensive anthropopressure on the water environment. In this context, the risk of harmful effects of the HMs presence in the bottom sediments of the Warta River, the third longest river in Poland, has been assessed. The concentrations of Cr, Ni, Cu, Zn, Cd, and Pb in the river bottom sediments collected at 24 sample collection stations along the whole river length have been measured and analyzed. Moreover, in the GIS environment, a method predicting variation of HMs concentrations along the whole river length, not at particular sites, has been proposed. Analysis of the Warta River bottom sediment pollution with heavy metals in terms of the indices: the Geoaccumulation Index (Igeo), Enrichment Factor (EF), Pollution Load Index (PLI), and Metal Pollution Index (MPI), has proved that, in 2016, the pollution was heavier than in 2017. Assessment of the potential toxic effects of HMs accumulated in bottom sediments, made on the basis of Threshold Effect Concentration (TEC), Midpoint Effect Concentration (MEC), and Probable Effect Concentration (PEC) values, and the Toxic Risk Index (TRI), has shown that the ecological hazard in 2017 was much lower. Cluster analysis revealed two main groups of sample collection stations at which bottom sediments showed similar chemical properties. Changes in classification of particular sample collection stations into the two groups analyzed over a period of two subsequent years indicated that the main impact on the concentrations of HMs could have their point sources in urbanized areas and river fluvial process.

The Dilemma of Wildfire Definition: What It Reveals and What It Implies

This paper presents the results of an explorative survey, based on a questionnaire sent by email, about how wildfire experts, operating in different countries, perceive wildfire and express their mindset by defining “wildfire” from a list of 14 terms and how they justify their preference for the term selected as the most important. Using a five-point Likert Scale, results from 221 valid replies indicate a general convergence toward a reduced number of terms. Six of them exhibit a mean >3.20 (Disturbance, Natural hazard, Climate-sensitive hazard, Socio-ecological hazard, Socio-ecological disturbance, and Social-ecological hazard). The three most preferred terms (i.e., Disturbance, Natural hazard, and Climate-sensitive hazard) reflect wildfire as a natural process or phenomenon (about 59% of the replies). The three terms characterized by both the social and ecological adjectives (i.e., Socio-ecological hazard, Socio-ecological disturbance, Social-ecological hazard) occupy relatively less favorable positions in the ranking. For each term, a synthesis of the explanations given by the respondents is provided, together with a critical comment. Our findings show very different perceptions of wildfires inclusively within the same disciplinary field. In addition, for the same term selected, different definitions are often presented. This reflects sectorial, disciplinary, and personal perspectives of the wildfire phenomenon and the lack of a common understanding of wildfire “nature” (i.e., its own identity). The different perceptions on wildfire concept influence the knowledge that can be used by decision makers to improve wildfire management policies. This work puts into perspective one of the most widespread problems in science: the lack of appropriate and similar terminology across different scientific fields dealing with the same problem. A common conceptualization of the nature of wildfires and the creation of a common language across different scientific fields related to wildfires is of paramount importance to address the complexity of the existing problems, and enhance an interactive communication not only among scientific community but also with stakeholders and citizens.

Health Risk Assessment of Heavy Metals in Soils before Rice Sowing and at Harvesting in Southern Jiangsu Province, China

Rice, one of the most important staple crops in China, is easily contaminated by heavy metal pollution from industrial development. In this work, we systematically investigated the heavy metal (Cr, Cd, Pb, Zn, and Cu) and metalloid (Hg and As) concentrations in paddy soils and different rice tissues in southern Jiangsu Province, China. The potential ecological hazard index method and in vitro simulation test were used to evaluate the influence of heavy metals on local resident health. The results showed that, before rice sowing and at the harvesting period, the order of Eri values was EriCd>EriHg>EriAs>EriPb>EriCu>EriCr>EriZn. The low-risk index values (91.63 and 30.29) for the heavy metals indicated the low risk at the two stages in the study area based on the potential ecological hazard index. As determined with Tessier’s five-stage sequential extraction procedure, the proportions of the chemical speciation of the heavy metals were as follows: residual > organic matter-bound > iron-manganese oxide-bound > carbonate-bound > exchangeable. The order of the values of the accumulation and transfer factors was Cd (3.16) > Cu (0.42) > Zn (0.28) > Pb (0.25) > As (0.07) > Cr (0.04) > Cr (0.03) and root > stem > leaves, respectively. In vitro simulation tests showed that, in both adults and children, the daily amount of Pb and Cd intake through the soil-oral cavity route in the study area did not exceed the daily tolerance for Pb and Cd proposed by the WHO. In summary, although there is no obvious danger to local adults and children, it is necessary to be aware of the possibility of rice contamination from Cd in the soil.

Special Issue on Bioconversion, Bioaccumulation and Toxicity of Mercury in a Changing World

Mercury (Hg) is recognized as a persistent global chemical contaminant that accumulates in biota, thus being an ecological hazard, as well as a health risk to fish consumers [...]

Biodegradation of Hydrocarbons by Bacillus cereus Isolated from Indoor and Outdoor Air of Selected Hospitals in Ilorin, Kwara State, Nigeria

Indoor and outdoor air of five (5) hospitals in Ilorin, Kwara state were sampled using settling plate method to isolate fifteen (15) bacteria. Bacillus cereus was the identified spore former. Biodegradation performance of Bacillus cereus on hexadecane and heptane using Mineral Salts Medium (MSM) was studied for 20 days at four days interval using the Jenway 6320D Spectrophotometer to assess the optical density. The degradation and utilization of the hydrocarbons occurred before the fourth day with readings for optical density obtained as 1.051nm and 0.820nm for hexadecane and heptane respectively. After day 4, there was a sharp decline in the utilization of hydrocarbons. A second experiment was setup for optical density with heptane and decane utilization being checked daily for a period of 5days. Bacillus cereus utilized the hydrocarbons till the fourth day as the optical density dropped on the fifth day. The readings for decane obtained on day 4 and day 5 were 0.431nm and 0.338nm respectively. Also, there was a decline in the readings of heptane from 0.451nm obtained on day 4 to 0.343nm obtained on day 5. This study shows that Bacillus cereus is promising in the biodegradation of alkanes and can also be utilized to clean up pollution from petroleum spill which is becoming a prevalent ecological hazard. Keywords: Air, Bacillus cereus, Biodegradation, Hospitals, Hydrocarbons