Anaerobic degradation and toxicity of commercial cationic surfactants in anaerobic screening tests

Anaerobic biodegradability and toxicity on anaerobic bacteria of di(hydrogenated tallow) dimethyl ammonium chloride (DHTDMAC) and two esterquats have been investigated. A batch test system containing municipal digester solids as a source of anaerobic bacteria, based on the method proposed by the ECETOC, has been applied. To evaluate the potential toxicity of such surfactants on anaerobic sludge, a co-substrate, an easily biodegradable compound in anaerobic conditions, has been added to the samples to test and the effects on biogas production have been determined. For the esterquats studied high biodegradation levels were obtained and no toxic effects on anaerobic bacteria were observed even at the highest concentrations tested, 100 and 200 mg C/l, respectively. On the contrary, DHTDMAC was not degradated at the same test conditions. However, no inhibitory effects on the biogas production were detected for this surfactant at concentrations <100 mg C/l.     

Structure-activity relationships for association of linear alkylbenzene sulfonates with activated sludge

Sorption of linear alkylbenzene sulfonates (LAS) on sludge particles from wastewater treatment plants was studied. The effect of alkyl chain length and the water hardness were investigated. Sorption on sludge increases with increasing alkyl chain length in the LAS molecules. The results are interpreted in terms of a hydrophobic bonding mechanism being the critical micelle concentration a good index of the surfactant hydrophobicity. The increase in free energy of adsorption for the addition of successive methylene groups to the alkyl chain was estimated as 2.4 kJ/mol. Water hardness clearly enhances the sorption of LAS homologues on sludge and seems to promote cooperative sorption at high surfactant and calcium ion concentrations. An empirical equation was provided that allow to estimate the partition coefficient between aqueous and solid phases for LAS homologues as a function of the alkyl chain length and the water hardness.     

Symbiotic efficiency of autochthonous arbuscular mycorrhizal fungus (G. mosseae) and Brevibacillus sp. isolated from cadmium polluted soil under increasing cadmium levels

The effect of inoculation with indigenous naturally occurring microorganisms (an arbuscular mycorrhizal (AM) fungus and rhizosphere bacteria) isolated from a Cd polluted soil was assayed on Trifolium repens growing in soil contaminated with a range of Cd. One of the bacterial isolate showed a marked PGPR effect and was identified as a Brevibacillus sp. Mycorrhizal colonization also enhanced Trifolium growth and N, P, Zn and Ni content and the dually inoculated (AM fungus plus Brevibacillus sp.) plants achieved further growth and nutrition and less Cd concentration, particularly at the highest Cd level. Increasing Cd level in the soil decreased Zn and Pb shoot accumulation. Coinoculation of Brevibacillus sp. and AM fungus increased shoot biomass over single mycorrhizal plants by 18% (at 13.6 mg Cd kg(-1)), 26% (at 33.0 mg Cd kg(-1)) and 35% (at 85.1 mg Cd (kg(1)). In contrast, Cd transfer from soil to plants was substantially reduced and at the highest Cd level Brevibacillus sp. lowered this value by 37.5% in AM plants. Increasing Cd level highly reduced plant mycorrhization and nodulation. Strong positive effect of the bacterium on inocula, are important in plant Cd tolerance and development in Cd polluted soils.     

Social and hospital costs of patients admitted to a university hospital in Brazil due to motorcycle crashes

Objective: This study aimed to investigate the social and hospital costs of patients treated at a public hospital who were motorcycle crash victims.

Method: This prospective study was on 68 motorcycle riders (drivers or passengers), who were followed up from hospital admission to 6 months after the crash. A questionnaire covering quantitative and qualitative questions was administered.

Results: Motorcycle crash victims were responsible for 12% of the institution's hospital admissions; 54.4% were young (18–28 years of age); 92.6% were the drivers; 91.2% were male; and 50% used their motorcycles as daily means of transportation. Six months afterward, 94.1% needed help from someone; 83.8% had changed their family dynamics; and 73.5% had not returned to their professional activities. Among the injuries, 94.7% had some type of fracture, of which 53.5% were exposed fractures; 35.3% presented temporary sequelae; and 32.4% presented permanent sequelae. They used the surgical center 2.53 times on average, with a mean hospital stay of 18 days. The per capita hospital cost of these victims’ treatment was US$17,481.50.

Conclusion: The social and hospital costs were high, relative to the characteristics of a public institution. Temporary or permanent disability caused changes to family dynamics, as shown by the high numbers of patients who were still away from their professional activities more than 6 months afterward.     

Environmental Surveillance of Enteroviruses in Central Argentina: First Detection and Evolutionary Analyses of E14

Environmental surveillance is an effective approach to investigate the circulation of human enteroviruses in the population. Enteroviruses E14, CVA9, E-6, E16, E20, E25, E13, and CVA24 were detected in sewage and a watercourse in central Argentina. E14 was the most frequent serotype and was found for the first time in environmental samples in our region. Phylogenetic and coalescence analyses showed at least two recent introduction events.     

Socio-cognitive constraints and opportunities for sustainable intensification in South Asia: insights from fuzzy cognitive mapping in coastal Bangladesh

Environment, Development and Sustainability - Appreciating and dealing with the plurality of farmers’ perceptions and their contextual knowledge and perspectives of the functioning and...     

Genetic connectivity of the ecosystem engineer Perumytilus purpuratus north to the 32°S southeast Pacific ecological discontinuity

Connectivity in benthic marine animals with complex life cycles occurs primarily during the pelagic larval stage and depends deterministically on oceanographic dynamics. The scale of such larval dispersal is highly uncertain due the difficulty of direct measurement and poor knowledge of larval dynamics and ocean flow variability. This study characterizes the pattern of genetic connectivity in the ecosystem engineer Perumytilus purpuratus between latitudes 23°S and 33°S, which includes the ecological discontinuity reported for many taxa north to 32°S at the southeast Pacific. The genetic discontinuity observed in P. purpuratus around 26°S is described herein while that detected at 28°S is in line with the ecological discontinuity (in coverage, recruitment and density) previously reported for this mussel between 28°S and 32°S. Both discontinuities delimitate two major gene pools upon Bayesian inferences on geographical variation of five microsatellite loci. Interestingly, marker Pepu1 was responsible for most variation between pools and was potentially under selection. In fact, inferences excluding Pepu1 produced a single gene pool (k = 1) in central-northern Chile. The IBD connectivity pattern observed among P. purpuratus beds distributed in the interval 23°S–33°S is congruent with processes driven by larval dynamics, and the dominant equatorward Humboldt Current along a coast largely unaffected by ice during the last Pleistocene glaciation. However, the selective scenario unveiled by microsatellite Pepu1 inside the 25°S–28°S ecological discontinuity is consistent with selective processes associated with specific mesoscale properties operating in this area. This study highlights the usefulness of integrating different oceanographic scales, ecological data and population genetics to better understand connectivity of benthic marine species.