Correlation of cadmium distribution coefficients to soil characteristics

Cadmium (Cd) distribution between the soil solid phase and the soil solution is a key issue in assessing the environmental effect of Cd in the terrestrial environmental. Previous studies have shown that many individual minerals and other components found in soils can bind Cd, but most studies on whole soil samples have shown that pH is the main parameter controlling the distribution. To identify further the components that are important for Cd binding in soil we measured Cd distribution coefficients (Kd) at two fixed pH values and at low Cd loadings for 49 soils sampled in Denmark. The Kd values for Cd ranged from 5 to 3000 L kg(-1). The soils were described pedologically and characterized in detail (22 parameters) including determination of contents of the various minerals in the clay fraction. Correlating parameters were grouped and step-wise regression analysis revealed that the organic carbon content was a significant variable at both pH values. Cation exchange capacity (CEC) and gibbsite were important at the low pH (5.3) while iron oxides also were important at the high pH (6.7). None of the other clay minerals present in the soils (illite, smectite, kaolinite, hydroxy interlayered clay minerals [HIM], chlorite, quartz, microcline, plagioclase) were significant in explaining the Cd distribution coefficient.     

A comparison of rapid and conventional measures of indicator bacteria as predictors of waterborne protozoan pathogen presence and density

E. coli and enterococci in recreational waters are monitored as indicators of fecal contamination, pathogen presence, and health risk. Quantitative polymerase chain reaction (qPCR) tests for fecal indicator bacteria can provide beach managers with same-day information about water quality, unlike culture methods which provide that information the following day. The abilities of qPCR measurements of indicator bacteria, as compared to culture measurements of indicator bacteria, as predictors of pathogen presence or density in surface waters are not well understood. The purpose of this study was to make such comparisons between water samples collected from Chicago area surface waters, including rivers, inland lakes, Lake Michigan, and the Chicago Area Waterways System, which is dominated by wastewater effluent. A total of 294 twenty-litre samples were collected and analyzed for Giardia and Cryptosporidium. qPCR and membrane filtration methods were used to quantify E. coli and enterococci. Correlation, logistic regression, and zero-inflated Poisson modeling were utilized to evaluate associations between indicators and parasites. qPCR and culture measures of the indicator bacteria were similar in their ability to predict parasite presence and density. Correlations between parasites and indicators were generally stronger at waters not dominated by effluent. Associations between indicator density and Giarida presence were observed more consistently than between indicator density and Cryptosporidium presence. Associations between enterococci and parasites were generally stronger than associations between E. coli and parasites. The use of qPCR monitoring in our setting would generate more timely results without compromising the ability to predict parasite presence or density.     

Theorizing stakeholders of sustainability in the digital age

Stakeholder theory, originally introduced in 1984 by philosopher Edward Freeman, is among the most influential theories today addressing the complex interplay of societal actors. It underwent several transformations and expansions, but the original Freeman model as well as the latest approaches places the corporation at the center positioning the theory as management driven. In this article—from a sustainability science perspective—we argue that sustainability could also be considered as the center, around which societal actors are grouped, because everyone, individuals as well as stakeholders, have a stake in a ‘common future’ that is built on the transformative concept of sustainability. Next to this shift of perspective from corporation to sustainability at the center, we advance the concept of sustainability stakeholders with the new paradigm of the digital age we (are about to) live in: the proposed sustainability-centered stakeholder theory is developed to incorporate novel parameters as brought about by digitalization (such as big data, real-time transparency, algorithmic correlations, predictive analytics, or changing privacy standards). Hence, we classify the stakeholders of sustainability according to their roles as “big data stakeholders:” collectors, generators, and utilizers of big data. This digital sustainability stakeholder model operationalizes the complex interplay between stakeholders focused on their ‘stake’ in sustainability and a common future and illustrates their roles in the digital age. Thus, it offers a normative framework to analyze stakeholders’ responsibility to contribute to, advance, promote, and achieve sustainability.     

The role of rhizofiltration and allelopathy on the removal of cyanobacteria in a continuous flow system

Environmental Science and Pollution Research - A continuous flow filtration system was designed to identify and quantify the removal mechanisms of Cyanobacteria (Microcystis aeruginosa) by...     

Influence of pyrolysis temperature on production and nutrient properties of wastewater sludge biochar

The important challenge for effective management of wastewater sludge materials in an environmentally and economically acceptable way can be addressed through pyrolytic conversion of the sludge to biochar and agricultural applications of the biochar. The aim of this work is to investigate the influence of pyrolysis temperature on production of wastewater sludge biochar and evaluate the properties required for agronomic applications. Wastewater sludge collected from an urban wastewater treatment plant was pyrolysed in a laboratory scale reactor. It was found that by increasing the pyrolysis temperature (over the range from 300 °C to 700 °C) the yield of biochar decreased. Biochar produced at low temperature was acidic whereas at high temperature it was alkaline in nature. The concentration of nitrogen was found to decrease while micronutrients increased with increasing temperature. Concentrations of trace metals present in wastewater sludge varied with temperature and were found to primarily enriched in the biochar.     

Patch Occupancy and Potential Metapopulation Dynamics of Three Forest Mammals in Fragmented Afromontane Forest in South Africa

Abstract: We investigated the persistence of three medium-sized (2–9 kg), rare forest mammals in the fragmented mist-belt Podocarpus forests of the midlands of KwaZulu-Natal Province, South Africa. We recorded patch occupancy of blue duiker (   Philantomba monticola ), tree hyrax (   Dendrohyrax arboreus ), and samango monkey ( Cercopithecus mitis labiatus ) in 199 forest patches. Their rarity is ascribed to the fragmentation and destruction of their forest habitat. Incidence functions, derived from presence and absence data, were formulated as generalized linear models, and environmental effects were included in the fitted logistic models. The small and mostly solitary hyrax and duiker persisted in smaller patches than the large and social monkey. Although this result follows expectations based on relative home-range sizes of each species, the incidence probability of the samango monkey was invariant with increasing isolation, whereas a gradual decrease with increasing isolation was observed for the hyrax and duiker. Group dynamics may inhibit dispersal and increase the isolation effect in social species such as samango monkeys. A mainland-island metapopulation model adequately describes patterns of patch occupancy by the hyrax and duiker, but the monkeys' poor dispersal ability and obvious area-dependent extirpation suggest that they exist in transient, nonequilibrium (declining) metapopulations. Through identification of large forest patches for careful protection and management, the survival of all three species—especially the monkey—could be prolonged. Because no functional metapopulation may exist for the monkey, however, this is an emergency measure. For the duiker and hyrax, larger patches should form part of a network of smaller and closer patches in a natural matrix.     

Dietary exposure to xenoestrogens in New Zealand

Continuing evidence of the feminising effects of xenoestrogens on a range of wildlife species increases the need to assess the human health risk of these estrogen mimics. We have estimated the exposure of New Zealand males, females and young men to a range of naturally occurring and synthetic xenoestrogens found in food. Only estrogenic compounds that act by interaction with the estrogen receptor have been included. Theoretical plasma estrogen activity levels were derived from estrogen exposure estimates and estrogenic potency data. Theoretical plasma levels were compared with published data for specific xenoestrogens. There was surprisingly close agreement. Xenoestrogenicity from dietary intake was almost equally attributed to naturally occurring and synthetic xenoestrogens. Relative contributions for a male, for example were isoflavones (genistein and daidzein) (36%) and bisphenol A (34%) with smaller contributions from alkyl phenols (18%) and the flavonoids (phloretin and kaempferol) (12%). It is suggested that dietary xenoestrogens might have a pharmacological effect on New Zealand males and postmenopausal women, but are unlikely to be significant for pre-menopausal women.