Intertidal endolithic fauna and it's relationship to the mineralogical,physical and chemical characteristics of the substrate

Mineral composition, granulometry, cohesion, relative and absolute density, and the pH of samples of the Santa Elena sedimentary rock shoal (37°5602 S; 58°1135 W; Argentina) were determined in order to relate the endolithic fauna with the properties of the substrate. Twenty three samples were collected in December 1987, applying a systematic sampling method to an intertidal area of 5 500 m². The mineral composition was determined using x-ray diffraction. Cohesion was determined by visual evaluation of the disintegration of the sample following various periods of immersion in water and by recording the resistance to compressive fracture according to the American Society for Testing and Materials (ASTM) standard. The ASTM standard was also followed for measurement of absolute and relative densities and porosity. The rock was ground up in distilled water and the pH of the resulting liquid measured over a period of 24 h. The data were analysed using numerical taxonomy, and in a supplementary study a granulometric analysis was attempted using five representative samples. The endolithic species selected were: the sipunculanThemiste petricola; the polychaetesPolydora sp. andPherusa sp., and the bivalvesLithophaga patagonica, Petricola patagonica, Saxicava solida, Barnea lamellosa, andPholadidea darwini. The mineral analysis indicated heterogeneous composition and spatial distribution characteristic of a loess. In terms of cohesion, the substrate displayed varying degrees of disintegration, with resistance ranging from zero to very high (254.6 kg/cm²). The endolithic faunaThemiste petricola, Polydora sp.,Pherusa sp.,Lithophaga patagonica, Petricola patagonica, andSaxicava solida were found in areas of low to very high cohesion, with or without calcite. The Pholadidae were found in areas of zero to low cohesion, with absence or traces of calcite. This study indicates the important role of cohesion in determining the distribution of the endolithic fauna.     

A perspective on radical transformations to sustainability: resistances,movements and alternatives

A transformation to sustainability calls for radical and systemic societal shifts. Yet what this entails in practice and who the agents of this radical transformation are require further elaboration. This article recenters the role of environmental justice movements in transformations, arguing that the systemic, multi-dimensional and intersectional approach inherent in EJ activism is uniquely placed to contribute to the realization of equitable sustainable futures. Based on a perspective of conflict as productive, and a “conflict transformation” approach that can address the root issues of ecological conflicts and promote the emergence of alternatives, we lay out a conceptual framework for understanding transformations through a power analysis that aims to confront and subvert hegemonic power relations; that is, multi-dimensional and intersectional; balancing ecological concerns with social, economic, cultural and democratic spheres; and is multi-scalar, and mindful of impacts across place and space. Such a framework can help analyze and recognize the contribution of grassroots EJ movements to societal transformations to sustainability and support and aid radical transformation processes. While transitions literature tends to focus on artifacts and technologies, we suggest that a resistance-centred perspective focuses on the creation of new subjectivities, power relations, values and institutions. This recenters the agency of those who are engaged in the creation and recuperation of ecological and new ways of being in the world in the needed transformation.     

Total soil available nitrogen under perennial grasses after burning and defoliation

Total soil available nitrogen concentrations (NO^–3 + NH ₄ ⁺ ) were determined underneath plants of the more-competitive Poa ligularis, mid-competitive Nassella tenuis and the less-competitive Amelichloa ambigua exposed to various combinations of controlled burning and defoliation treatments. Defoliations were at the vegetative (V), internode elongation (E) or both developmental morphology stages (V + E) during two years after burning in northeastern Patagonia, Argentina. Hypotheses were that (1) concentrations of total soil available nitrogen after burning are greater underneath burned than unburned plants. With time, these differences, however, will gradually disappear; (2) greater total soil available nitrogen concentrations are underneath plants of the more- than less-competitive perennial grasses; and (3) total soil available nitrogen is similar or lower underneath plants defoliated at the various developmental morphology stages in all three study species than on untreated controls at the end of the study. Concentration of total soil available nitrogen increased 35% (p < 0.05) on average after the first six months from burning in comparison to control plants. However, these differences disappeared (p > 0.05) towards the end of the first study year. Total soil available nitrogen concentrations were at least 10% lower underneath the less competitive N. tenuis and A. ambigua than the more competitive P. ligularis on average for all treatments, although differences were not significant (p > 0.05) most of the times. Defoliation had practically no effect on the concentration of total soil available nitrogen. Rather than any treatment effect, total soil nitrogen concentrations were determined by their temporal dynamics in the control and after the experimental fire treatments.     

Environmental degradation and economic growth: evidence for a developing country

This paper examines the relationship between economic growth and environmental degradation in Ecuador from 1971 to 2010. We estimate this relationship in a country with a heavy reliance on revenue from the exploitation of natural resources, the depletion of vegetation cover in recent decades and a low level of participation of industry in GDP. We show the existence of an inverse relationship between real GDP and vegetation cover, indicating that the output of this country is based on environmental degradation. Through Johansen co-integration tests, we check that there is a relationship of long-term equilibrium between the first differences of real GDP, vegetal cover and the urbanization rate. The ECM shows that there is a short-term relationship between vegetation cover, the GDP and the rate of urbanization. Finally, we did not found Granger causality between the variables. A policy implication based on our findings is that policies to protect the environment should not jeopardize economic growth and not limit the rapid urbanization in the country.     

Long-term effects of lead poisoning on bone mineralization in vultures exposed to ammunition sources

Long-lived species are particularly susceptible to bioaccumulation of lead in bone tissues. In this paper we gain insights into the sublethal effects of lead contamination on Egyptian vultures (Neophron percnopterus). Our approach was done on the comparison of two populations (Canary Islands and Iberian Peninsula) differing in exposures to the ingestion of lead ammunition. Blood lead levels were higher in the island population (Canary Islands range: 5.10-1780 μg L⁻¹n = 137; Iberian Peninsula range: 5.60-217.30 μg L⁻¹n = 32) showing clear seasonal trends, peaking during the hunting season. Moreover, males were more susceptible to lead accumulation than females. Bone lead concentration increased with age, reflecting a bioaccumulation effect. The bone composition was significatively altered by this contaminant: the mineralization degree decreased as lead concentration levels increased. These results demonstrate the existence of long-term effects of lead poisoning, which may be of importance in the declines of threatened populations of long-lived species exposed to this contaminant.     

Genotoxic biomonitoring of agricultural workers exposed to pesticides in the north of Sinaloa State, Mexico

Genotoxic damage was evaluated in 70 agricultural workers, 25 women and 45 men, exposed to pesticides in Las Grullas, Ahome, Sinaloa, Mexico, with an average of 7 years of exposure. The effect was detected through the sister chromatid exchanges (SCE) in lymphocytes of peripheral blood and micronuclei (MN) and other nuclear anomalies (NA) in buccal exfoliated cells. Also, the influence on cellular proliferation kinetics (CPK) was studied by means of the replication index (RI) and the cytotoxic effect was examined with the mitotic index (MI). The non-exposed group consisted of 70 other persons, 21 women and 47 men from the city of Los Mochis, Sinaloa, Mexico. Significant differences between the exposed and the non-exposed groups were observed in SCE, CPK, MI, MN and NA. Analysis of variance revealed that age, gender, smoking and alcohol consumption did not have a significant effect on genetic damage. However, there was a correlation between exposure time to pesticides and SCE frequency. These results could have been due to the exposure of workers to pesticides containing different chemical compounds. This study afforded valuable data to estimate the possible risk to health associated with pesticide exposure.     

Building a freshman-year foundation for sustainability studies: Terrascope, a case study

Terrascope is a freshman learning community at the Massachusetts Institute of Technology (MIT) in which teams of students work to find solutions to large ‘unsolvable’ problems and to communicate about those problems with a wide variety of audiences in multiple formats. The program strongly promotes students’ autonomy in focusing and structuring their work, and student projects culminate in public presentations, both to general audiences and to panels of technical specialists. Students who have completed the program tend to show strong engagement with environmental and sustainability issues, as well as the skills and experience to work intensively on such issues within multidisciplinary teams. Here, we present the program as a case study, with some discussion of the factors that are key to its operation.

Protection strategies for drinking groundwater sources in small Quebec municipalities

Awareness of groundwater protection has increased substantially in recent decades. In the Province of Quebec, Canada, the Groundwater Catchment Regulation (GWCR) was promulgated in 2002 to protect water quality in public wells. The goal of the present study was to document groundwater protection in the context of emerging regulations and identify factors explaining the propensity of municipalities applying protection strategies. Two types of information were used in this study: data from a questionnaire-based survey conducted among 665 municipalities in the Province of Quebec and complementary information gathered from various sources. Data from the survey revealed that fewer than half of the municipalities have been able to comply with the GWCR, mainly because of financial limitations. Also, close to half of the municipalities have either identified or are expecting land use conflicts to arise between protection areas required by the GWCR and other land usage, with agriculture being the main conflicting activity. Multivariate logistic regression models served to identify factors explaining the likelihood of municipalities to take groundwater protection measures. Those factors were municipality revenue, history of water contamination in distribution systems, land use near wellheads, location of municipalities within a provincial priority watershed and the importance of groundwater use in a region. Results of the study may prove helpful for government authorities in better understanding the groundwater protection issue and in implementing strategies that improve the ability of municipalities to protect groundwater.     

Assessment of aliphatic-aromatic copolyester biodegradable mulch films. Part I: field study

The objective of this work was to study the use of new biodegradable films in agriculture under open field conditions. Three biodegradable mulch films made from modified biodegradable polyester of different thicknesses and colors (black and white) and a conventional low density polyethylene (LDPE) mulch film were used to cover the beds of tomato plants. Changes in physical appearance of the films were recorded as well as changes in their mechanical, optical, and physical properties. Once tomato harvest was completed, the conventional LDPE mulch film was removed and all the tomato plants were cut using a mower. The biodegradable mulch films were plowed into the soil. The change in the appearance of the film was recorded and samples of each film after plowing were characterized according to the properties mentioned above. After the biodegradable films photodegraded, cross-link formation occurred within the films which promoted brittleness. Titanium dioxide, an additive used to produce white color in the films, catalyzed the photodegradation, while carbon black used for black color stabilized the photodegradation. The white films started to degrade after two weeks while it took about eight weeks for the black films to significantly degrade. The black biodegradable film seems to be a more promising alternative as a mulch film because of the comparable yields and weed suppression ability to conventional mulch film.     

Assessment of aliphatic-aromatic copolyester biodegradable mulch films. Part II: laboratory simulated conditions

In a previous paper, we demonstrated that the main mechanism of degradation of poly(butylene adipate-co-terephthalate) (PBAT) biodegradable mulch films when exposed to field conditions was crosslinking due to the photodegradation from solar radiation. The aim of this work was to determine the effect of crosslinking on the biodegradability of PBAT samples. PBAT films were subjected to UV photodegradation in laboratory simulated conditions to investigate the effects of crosslinking and other major changes in the structure and mechanical properties of the films. Crosslinking caused the films to become more brittle and produced a reduction of the tensile strength and percent elongation. Besides the crosslinking degradation mechanism, chain scission also occurred in the samples. After 45d of biodegradation test, the non-crosslinked PBAT sample reached 60% of mineralization. However, the percent mineralization was reduced when samples were crosslinked. The percent mineralization of samples with 10%, 30%, 50%, and 70% gel content was 36%, 43%, 21%, and 24%, respectively. Our results indicate that crosslinking is a key process underlying the degradation of the PBAT film and did affect the biodegradability of the films, since the samples with greater amount of gel content generally showed less percent mineralization in the biodegradation tests.