Global metrics of land cover and land use provide a fundamental basis to examine the spatial variability of human-induced impacts on freshwater ecosystems. However, microscale processes and site ...specific conditions related to bank vegetation, pollution sources, adjacent land use and water uses can have important influences on ecosystem conditions, in particular in smaller tributary rivers. Compared to larger order rivers, these low-order streams and rivers are more numerous, yet often under-monitored. The present study explored the relationship of nutrient concentrations in 150 streams in 57 hydrological basins in South, Central and North America (Buenos Aires, Curitiba, São Paulo, Rio de Janeiro, Mexico City and Vancouver) with macroscale information available from global datasets and microscale data acquired by trained citizen scientists. Average sub-basin phosphate (P-PO4) concentrations were found to be well correlated with sub-basin attributes on both macro and microscales, while the relationships between sub-basin attributes and nitrate (N-NO3) concentrations were limited. A phosphate threshold for eutrophic conditions (>0.1 mg L-1 P-PO4) was exceeded in basins where microscale point source discharge points (eg. residential, industrial, urban/road) were identified in more than 86% of stream reaches monitored by citizen scientists. The presence of bankside vegetation covaried (rho = -0.53) with lower phosphate concentrations in the ecosystems studied. Macroscale information on nutrient loading allowed for a strong separation between basins with and without eutrophic conditions. Most importantly, the combination of macroscale and microscale information acquired increased our ability to explain sub-basin variability of P-PO4 concentrations. The identification of microscale point sources and bank vegetation conditions by citizen scientists provided important information that local authorities could use to improve their management of lower order river ecosystems.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A mixture of identities, livelihoods and a heterogeneous landscape characterizes the communities located in the rural-urban frontier. The perception of the inhabitants of these communities regarding ...environmental and sociocultural change is linked to their livelihoods and land use decisions. We use the case study of the ancient agricultural chinampa system in the Xochimilco wetland of Mexico City to understand the main threats and opportunities for peri-urban agriculture in megacities, where the rapid displacement of agricultural land by formal and informal settlements makes its future uncertain. We used a household survey and semi-structured interviews to understand: 1) the relationship between agriculture and informal urbanization, and 2) the perception of chinampa users, considering those who are engaged in agriculture and those who are not, regarding the factors that favor or limit agriculture. The information from interviews was coded and conceptualized as pull and push factors for peri-urban agriculture. Sociocultural factors were mentioned as the main reasons that push chinampas into agriculture abandonment, such as community erosion due to conflicts and lack of interest from younger generations. However, those that continue to engage in agriculture maintain a historical connection to farming (whether they are from the region or not), and a willingness to adapt to maintain their agricultural livelihood. We find that while some families abandon their agricultural land, new niches become available for migrants from other surrounding rural areas who find opportunities to continue farming in the peri-urban frontier. Our evidence suggests that the loss of peri-urban agriculture is not a linear process towards urbanization, and that the coexistence of housing, agriculture, and livelihood diversification can produce the conditions needed for innovation to encourage peri-urban agriculture.
•Identity, agricultural livelihoods, and farming adaptation are perceived as pull factors for peri-urban agriculture.•Lack of cooperation, distrust, low profits, and water issues are perceived as push factors for peri-urban agriculture.•As younger generations opt out of agriculture, new niches form to take advantage of the proximity to the city.•Push factors that undermine agriculture for locals could act as pull factors for migrant farmers to farm in the city.•Livelihood diversification, land-use multifunctionality, and innovation are ways for peri-urban agriculture to persist.
As the bulk of the world’s population becomes urban, maintaining urban ecosystem services for environmental and social well-being in cities is crucial. According to resilience theory, maintaining ...such services requires for a complex adaptive systems perspective that helps in identifying key elements and dynamics behind cross-scale social-ecological interactions. In this context, the objective of this article is to use a resilience “lens” to problematize the imminent loss of an urban wetland using the adaptive cycle model as a heuristic tool. Our case study focuses on the Xochimilco wetland, located in the southern periphery of Mexico City. Xochimilco is characterized by the presence of a complex system of raised bed wetland agriculture (the chinampa system), which was established over 1000 years ago; currently, despite having a recognized cultural and environmental value, it is threatened by increasing urban sprawl, over-exploitation of the aquifer, and water contamination. By conducting a historical analysis of the Xochimilco social-ecological system, we assess how it has gone through phases of the adaptive cycle. As a result, we identify critical elements of the system’s historically maintained resilience and main drivers of system change. From such findings, we present some insights on the possibilities of maintaining the system’s resilience and guidance for future management strategies for the Xochimilco wetland. Lastly, we reflect on the scope and limitations of using a resilience-based approach and an adaptive cycle analysis for addressing urban sustainability problems, especially in cities in the Global South.
In the last few years, there has been an interest in understanding the impact of environmental change and degradation on people's affective life. This issue has become particularly pressing for ...populations whose form of life is heavily dependent on ecosystem services and functions and whose opportunities for adaptation are limited. Based on our work with farmers from the Xochimilco urban wetland in the southwest of Mexico City, we begin to draw a theoretical approach to address and explain how environmental degradation impacts people's affective life and sense of agency. Farmers who were part of our project referred to a sense of despair and helplessness toward the loss of the ecosystem and their traditional farming-based form of life. From the perspective of phenomenology, enactivism and ecological psychology, we argue that the loss of this form of life in the area is related to the degradation of socio-ecological systems, limiting the opportunities for people to relate meaningfully to others and the environment. We posit that losing meaningful interaction with the environment generates a feeling of loss of control while leading farmers to feel frustrated, anxious and stressed. Such affective conditions have a direct impact on their sense of agency. In terms of adaptation, the negative interaction between degradation, affective states and a diminished sense of agency can create a downward spiral of vulnerability, including political vulnerability.
Citizen science schemes for environmental monitoring generate benefits for scientists by increasing the capacity of scientists to gather information. Citizen scientist monitoring also benefits the ...citizens involved because they acquire a deeper knowledge and understanding of the benefits of ecosystems and the ways that anthropogenic activities affect them. This study details the efforts of a local non-government organization (Restauración Ecológica y Desarrollo A. C.), the Earthwatch Institute, and the Hongkong and Shanghai Banking Corporation’s Water Program to monitor the water quality in the Xochimilco peri-urban wetland, which is threatened by accelerated urbanization. The Xochimilco wetland includes agricultural areas in which raised beds called chinampas are surrounded by canals and small lakes. These chinampas have been managed for hundreds of years. The water in the canals is mainly used for agricultural irrigation, but it is also the habitat of a variety of aquatic species. In this study, we analyze the water quality of 7 canals and 1 lake located in areas with chinampas that have different uses such as housing, tourism, semi-intensive agriculture, agroecological farming, and abandoned agricultural land. Water samples from these sites were collected by citizen scientists over the course of 4 y. Our aim was to determine how the water quality varies across areas with management differences and between dry and rainy seasons. We found significant differences in pH, temperature, dissolved oxygen, Escherichia coli, and conductivity between seasons. We expected to find suitable water quality for irrigation (based on national and international guidelines) in canals near low-impact activities in the chinampas (such as agroecological farming or chinampas without human activities). Instead, we found that the water in those canals exceeded the recommendations for pH values (>9), total coliforms (>240 CFU/ 100 mL), conductivity (>2000 μS/cm), and dissolved oxygen concentrations (<6.5 mg/L). However, nutrient concentrations were low. The structure of the canals near agroecological farming areas are narrow, shallow, and have low water flow, so alterations in the depth and width of these canals might result in improved water quality. The only sampling site that met most of the international and national guidelines for irrigation use was located in an area with many abandoned chinampas. Volunteers that participated in this study gained insights regarding the importance of being aware of anthropogenic impacts on ecosystems like the Xochimilco wetland, a place that is important to preserve because of its agricultural, ecological, and cultural significance.
Collective agency, the capacity of individuals to mobilise according to shared goals, is crucial for social–ecological transformation. However, in stagnant situations, where individuals in a ...social–ecological system tend to resist transformation due to interests in the status quo, the emergence of collective agency faces numerous barriers. This research asks how to design and implement spaces and methodologies that help to address such barriers. We posit that these spaces and methodologies ought to facilitate processes to reframe shared perceptions of social–ecological situations through: (1) questioning dominant narratives about a situation, (2) building capacities to reframe the situation, and (3) enacting new compelling narratives that support the group’s transformative agency. Our research shows that building a strong bond among participants is key but requires reframing tools that are infrequently used in academically driven participatory research; in particular, tools for reflexivity together with creating safe-enough spaces where participants can be truly open. Reflexivity and openness are conditions for allowing deep transformations of meanings, fostering new collaborations and promoting agency towards novel pathways forward. Through convening diverse social actors—from local farmers, residents in irregular settlements, governmental and non-governmental organisations, to academics—our 2.5-year “Transformation Laboratory” (T-Lab) showed the effectiveness of experiencing reflexive reframing tools to transform both perceived situations, and the participants' agency (i.e., the meanings and values of their role, capacities, and interests) concerning the situation. Our results support the importance of reframing in building collective agency for transformations. Throughout the process, participants deconstructed their narratives, constructed new ones, and enacted them.
Although epileptic crises are equally frequent in women and men, several factors cause female epileptics to present a series of gender-specific problems. To date, few studies have been published on ...the kinetics of carbamazepine (CBZ) and carbamazepine 10,11-epoxide (CBZ-E) active metabolite in a Mexican population, and no information for epileptic women of reproductive age is available. The aim of the present work was to study the pharmacokinetic behavior of this group of women during steady state.
Fourteen epileptic women under chronic treatment receiving only the anticonvulsant CBZ to control their crises were studied. A blood sample was taken before breakfast, before the morning dose of 200 mg, and after the dose at 1, 2, 3, 4, 5, and 8 h.
Serum was separated by centrifugation at 1,350×
g. Serum concentrations of carbamazepine (CBZ) and of the metabolite carbamazepine 10,11-epoxide (CBZ-E) were measured by HPLC. Pharmacokinetic parameters were calculated by statistical moment method after obtaining serum concentrations.
Maximum time (T
max) for CBZ was reached at 2.72±0.71 h and for CBZ-E, it was 3.60±0.79 h. C
max for CBZ was 7.30±2.30 μg/mL, while C
min for CBZ was 6.30±2.49. Maximum serum values for CBZ-E were 1.01±0.57, equivalent to 13.80% of CBZ; t
1
2
value for CBZ and CBZ-E was 18.20 and 16.10 h, respectively. AUC values for CBZ and metabolite were 70.33±17.10 μg/L/h and 9.20±2.50 μg/L/h, respectively. CBZ and CBZ-E clearance did not show differences and were 0.37 mL/kg/min and 0.40 mL/kg/min, respectively. Extraction index for serum concentrations of CBZ and CBZ-E AUC
CBZ/AUC
CBZ-E was 0.13; positive correlation was observed between serum concentrations of CBZ and E-CBZ, with
r
=
0.94.
The schedule we suggest for therapeutic monitoring of serum concentrations of CBZ in chronic treatments is 3 h for maximum peak concentration of C
max after dose administration and for minimum peak concentration, C
min prior to subsequent administration of the dose.
In spite of the progress in synthetic methods to obtain nanoparticles, particularly magnetite either uncoated or coated, the implementation of easier, faster and reproducible protocols to obtain ...well-defined nanoparticles is still a challenge. In this work we present a one-pot approach to synthesize Fe 3 O 4 nanoparticles uncoated and coated with dodecylamine (DDA), starting from a single iron precursor (FeCl 2 ) and incorporating a non-conventional stirring regime into the procedure. The products were characterized by XRD, TEM, TGA, FT-IR and Mössbauer spectroscopy, confirming the obtaining of the target materials. The magnetic measurements showed that the coated nanoparticles (Fe 3 O 4 @DDA) exhibited a higher saturation magnetization ( M s ) and smaller coercivity ( H c ) than the uncoated ones. The compromise between the saturation magnetization displayed by Fe 3 O 4 @DDA nanoparticles and the ease of its synthesis shows the potential of the method to obtain materials applicable to medical therapies.
The agave snout weevil Scyphophorus acupunctatus Gyllenhal (Coleoptera: Curculionidae) is an ubiquitous insect and the main pest of blue tequila agave, Agave tequilana Weber, and other agaves. This ...study reports the repellent effect of the hydroethanolic extract of the castor oil plant, Ricinus communis L. (Euphorbiaceae) wild and ‘Mirante’ cultivar on the adult's behavior. Females and males visited untreated agave tissue more frequently than agave tissue treated with R. communis extracts. Insects visited agaves treated with seed extracts more frequently than those with leave extracts; therefore leaves of R. communis deserve a closer look to identify their properties and gauge their potential use as a repellent.
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