A simple low-cost approach for transport parameter determination in mountain rivers
Castillo, D., Runkel, R.L., Duhalde, D., Pastén, P., Arumí, J.L., Oyarzún, J., Núñez, J., Maturana, H., Oyarzún, R.
A simplified low-cost approach to experimentally determine transport parameters in mountain rivers is described, with an emphasis on the longitudinal dispersion coefficient (DL). The approach is based on a slug injection of table salt (NaCl) as a tracer and specific conductance readings at different locations downstream of the injection spot. Observed specific conductance readings are fit using the advection-dispersion equation with OTIS-P, yielding estimates of cross-sectional area and longitudinal dispersion coefficient for various stream reaches. Estimates of the DL are used to assess the accuracy of several empirical equations reported in the literature. This allowed the determination of complementary transport parameters related to transient storage zones. The empirical equations yielded rather high DL values, with some reaching up an order of magnitude higher to those obtained from tracer additions and OTIS-P. Overall, the proposed approach seems reliable and pertinent for river reaches of ca. 150 m in length.
Mountain streams flushing litter to the sea – Andean rivers as conduits for plastic pollution
Honorato-Zimmera, D., Kiessling, T., Gatta-Rosemary, M., Kroeger Campodónico, C., Núñez-Farías, P., Rechad, S., Thiel, M.
Rivers polluted by anthropogenic litter are major transport routes of litter from inland to the coastal zone and the ocean. However, litter studies have primarily focused on marine environments, and the litter dynamics in rivers are still poorly understood. Herein, we explored the abundances, composition and sources of litter at the riversides and in surface waters of mountain rivers from continental Chile in two different years. Additionally, we evaluated whether different temporal, geographic, topographic, hydrologic or anthropogenic factors influence the abundances of litter. Anthropogenic litter was prevalent in Chilean rivers, both at the riversides and in surface waters. Average abundances of riverside litter, floating macrolitter, and small floating plastics were 1.8 items m−2, 10.1 items h−1 and 5.8 items h−1, respectively, and abundances were generally higher in northern Chile. Plastics dominated in all compartments, comprising 29% of riverside litter and more than 70% of small floating litter, but other litter categories were also present at riversides. Sources of litter in Chilean rivers were mostly local, such as recreational visitors, residents, and illegal dumping, and there were no clear effects of the different tested factors on the abundances of litter. Litter densities in surface waters were low compared to those in lowland slow-flowing rivers in other countries, suggesting that retention of litter is limited in the highly dynamic and rapidly flushing mountain rivers, and thus most litter (primarily plastics) is transported directly to the sea. The results suggest that to adequately address this problem in Chile, prevention measures should be aimed at the identified local sources, by means of education, public policies, legislation, and enforcement.
Palabras claves: Riverine litter, Mountain rivers, Litter sources, Citizen science, Schoolchildren
What if the cold days return? Epigenetic mechanisms in plants to cold tolerance
Hereme, R., Galleguillos, C., Morales-Navarro, S., Molina-Montenegro, M.A.
Low temperatures are one of the most critical environmental conditions that negatively affect the growth, development, and geographic distribution of plants. Exposure to low temperatures results in a suit of physiological, biochemical and molecular modifications through the reprogramming of the expression of genes and transcription factors. Scientific evidence shows that the average annual temperature has increased in recent years worldwide, with cold ecosystems (polar and high mountain) being among the most sensitive to these changes. However, scientific evidence also indicates that there would be specific events of low temperatures, due it is highly relevant to know the capacity for adaptation, regulation and epigenetic memory in the face of these events, by plants. Epigenetic regulation has been described to play an important role in the face of environmental stimuli, especially in response to abiotic stress. Several studies on epigenetic mechanisms have focused on responses to stress as drought and/or salinity; however, there is a gap in the current literature considering those related to low temperatures. In this review, we focus on systematizing the information published to date, related to the regulation of epigenetic mechanisms such as DNA methylation, histone modification, and non-coding RNA-dependent silencing mechanisms, in the face of plant´s stress due to low temperatures. Finally, we present a schematic model about the potential responses by plants taking in count their epigenetic memory; considering a global warming scenario and with the presence or absence of extreme specific events of low temperatures.
Environmental Aspects of a Major ARD Source at El Indio Au-Cu-As District, North-Central Chile
Oyarzún, J., Maturana, H., Paulo, A., Lillo, J., Pastén, P., Núñez, J., Duhalde, D., González, C., Portilla, A., & Oyarzún, R
El Indio, an Au-Cu-As deposit with outstanding gold grades, was mined in the Andes of the Coquimbo region, Chile, between 1975 and 2002. Sediment and water sampling of the rivers in the 2000 s found exceptional As and metal levels in modern and old sediments. The studies also revealed that acid rock drainage (ARD) has been present in the district for nearly 10,000 years and the effect that the mining of the district had in terms of geochemical anomalies. The convergence of mineralogical, structural, and hydrologic conditions has generated a metal-rich ARD, a process followed by transference of metals to the fine sediments. In this context, the study also deals with the risk of metal and metalloid transfers from the sediments to the river waters as a consequence of eventual physical-chemical changes, due for example, to climatic-driven conditions. Water and sediment samplings were carried out to provide materials for selective extraction tests under acidic, acid-reducing, and acid-oxidizing conditions. The different behavior of metals and metalloids was revealed and highlighted the refractory character of As. Additionally, the study included the characterization of the sediment’s mineralogy, and allowed the detection of new geochemical anomalies of Cu, Zn, Co, and Y in the Incaguaz River, along with high dissolved Li concentrations in the Toro and Turbio rivers.
Early transcriptional responses in Solanum peruvianum and Solanum lycopersicum account for different acclimation processes during water scarcity events
Tapia, G., González, M., Burgos, J., Vega, M.V., Méndez, J., Inostroza, L.
Cultivated tomato Solanum lycopersicum (Slyc) is sensitive to water shortages, while its wild relative Solanum peruvianum L. (Sper), an herbaceous perennial small shrub, can grow under water scarcity and soil salinity environments. Plastic Sper modifies the plant architecture when suffering from drought, which is mediated by the replacement of leaf organs, among other changes. The early events that trigger acclimation and improve these morphological traits are unknown. In this study, a physiological and transcriptomic approach was used to understand the processes that differentiate the response in Slyc and Sper in the context of acclimation to stress and future consequences for plant architecture. In this regard, moderate (MD) and severe drought (SD) were imposed, mediating PEG treatments. The results showed a reduction in water and osmotic potential during stress, which correlated with the upregulation of sugar and proline metabolism-related genes. Additionally, the senescence-related genes FTSH6 protease and asparagine synthase were highly induced in both species. However, GO categories such as “protein ubiquitination” or “endopeptidase inhibitor activity” were differentially enriched in Sper and Slyc, respectively. Genes related to polyamine biosynthesis were induced, while several cyclins and kinetin were downregulated in Sper under drought treatments. Repression of photosynthesis-related genes was correlated with a higher reduction in the electron transport rate in Slyc than in Sper. Additionally, transcription factors from the ERF, WRKY and NAC families were commonly induced in Sper. Although some similar responses were induced in both species under drought stress, many important changes were detected to be differentially induced. This suggests that different pathways dictate the strategies to address the early response to drought and the consequent episodes in the acclimation process in both tomato species.
Evolution of physiological performance in invasive plants under climate change
Gianoli, E. and Molina-Montenegro, M.A.
Climate change is expected to promote biological invasions. Invasive species often undergo adaptive evolution, but whether invasive species show greater evolutionary potential than their native counterparts under climate change has rarely been evaluated. We conducted experimental evolution trials comparing the evolution of physiological performance (light-saturated photosynthetic rate, Amax) of coexisting and closely related (1) invasive-native species pairs from Arid, Alpine, and Antarctic ecosystems, and (2) an invasive-naturalized species pair from a Mediterranean ecosystem differing in invasiveness. Experiments were conducted over three generations and under four environments of temperature and water availability resembling typical and climate change conditions in each ecosystem. Amax increased across generations for most species. Invasive species from Arid, Alpine, and Antarctic ecosystems showed similar, greater, and lesser evolution of Amax than their native counterparts, respectively. The Mediterranean invasive species showed greater evolution of Amax than its naturalized congener. Similar patterns were observed in all four experimental environments for each ecosystem, suggesting that comparable responses may be expected under climate change scenarios. All study species showed a positive association between Amax and reproductive output. Results suggest that invasive plants and their native (or naturalized) counterparts would show similar evolutionary responses of physiological performance to global warming and drought.
Toward understanding the long-term persistence of a local governance system among artisanal fishers in Chile
Aburto, J. A., W. Stotz, G. Cundill, and C. Tapia
An important characteristic for the persistence of social-ecological systems (SESs) over time is the adaptation of local institutions to the dynamic of the resources on which they depend, especially when communities face resources with high spatial and temporal variability. Previous studies on Territorial User Rights for Fisheries (TURF) in Chile (Áreas de Manejo y Explotación de Recursos Bentónicos, AMERB) showed that resources with high levels of variability, such as the highly valuable surf clam Mesodesma donacium, can have negative impacts on collective efforts among fishers to govern marine resources under AMERB, resulting in the collapse of local institutions in this boom-and-bust fishery. Here, we reflect on the only known case in Chile (Coquimbo Bay) in which local institutions, its governance mechanisms, and the surf clam M. donacium fishery have persisted over long periods of time, despite disturbances from the natural and social systems. Using participatory techniques, we draw on local fishers' in-depth knowledge of both the resource and their own historical coping mechanisms to understand the potential sources of institutional persistence among local fishers faced with a resource that has high levels of variability. We find that this unique success of a surf clam AMERB in Chile is attributed to the local conditions, such as the roots that fishers have to their village, the support by women and family, and also to the ecological settings of Coquimbo Bay and resource characteristics, that facilitate larval dispersal among the different bays, maintaining recruitment and production that sustains the AMERB. Thus, the persistence of the institution has been built over generations of coping with major disturbances to the SES, directly related to the persistence of M. donacium stocks over time, which has allowed the development of a well-structured institution with a strong fishers' organization, good leaders, a division of labor among members, shared responsibilities, and equitable income distribution.
Palabras claves: AMERB; co-management; governance; resilience; small-scale fishery; traditional ecological knowledge; TURF
Assessment of a conservative mixing model for the evaluation of constituent behavior below river confluences, Elqui River Basin, Chile
Rossi, C., Oyarzún, J., Pastén, P., Runkel, R. L., Núñez, J., Duhalde, D., Maturana, H., Rojas, E., Arumí, J. L., Castillo, D., & Oyarzún, R.
Fate and transport modeling of water-borne contaminants is a data demanding and costly endeavor, requiring considerable expes such, it becomes important to know when a complex modeling approach is required, and when a simpler approach is adequate. This is the main objective herein, where a conservative mixing model is used to characterize the transport of As, Cu, Fe, and SO4. The study area is divided into three sectors, corresponding to the upstream, middle, and downstream portions of the Elqui River Basin, Chile. In Sector 1, acidic conditions result in the conservative transport of constituents that are sourced from acid rock drainage. In Sector 2, pH increases and transport is influenced by pH-dependent reactions and the subsequent settling of the particulate phase. In Sector 3, there are no additional constituent inputs, and the constituents are conservatively transported downstream. Conservative transport within Sector 3 is confirmed through the development of a regression model that provides monthly estimates of SO4 load. Whereas SO4 and Cu concentrations are adequately approximated by the conservative mixing model, estimates of As and Fe concentrations exhibit larger errors, due to the more reactive behavior of these constituents. The fact that the simple, conservative mixing model describes SO4 transport is a valuable result, as this constituent is known to be one of the primary indicators of mining-related contamination in rivers. The approach could also be a useful starting point for further evaluations of the effects of climate change and hydrological variability on the water quality of rivers.
Schoolchildren discover hotspots of floating plastic litter in rivers using a large-scale collaborative approach
Kiessling, T., Knickmeier, K., Kruse, K., Gatta-Rosemary, M., Nauendorf, A., Brennecke, D., Thiel, L., Wichels, A., Parchmann, I., Körtzinger, A., Thiel, M.
Rivers are an important transport route of anthropogenic litter from inland sources toward the sea. A collaborative (i.e. citizen science) approach was used to evaluate the litter pollution of rivers in Germany: schoolchildren within the project “Plastic Pirates” investigated rivers across the entire country during the years 2016 and 2017 by surveying floating macrolitter at 282 sites and taking 164 meso−/microplastic samples (i.e. particles 24.99–5 mm, and 4.99–1 mm, respectively). Floating macrolitter was sighted at 54% of sampling sites and floating macrolitter quantities ranged from 0 to 8.25 items m−1 h−1 (average of 0.34 ± 0.89 litter items m−1 h−1). Floating meso−/microplastics were present at 57% of the sampling sites, and floating meso−/microplastic quantities ranged from 0 to 220 particles h−1 (average of 6.86 ± 24.11 items h−1). As only particles >1 mm were sampled and analyzed, the pollution of rivers in Germany by microplastics could be a much more prevalent problem, regardless of the size of the river. We identified six plastic pollution hotspots where 60% of all meso−/microplastics collected in the present study were found. These hotspots were located close to a plastic-producing industry site, a wastewater treatment plant, at and below weirs, or in residential areas. The composition of the particles at these hotspots indicates plastic producers and possibly the construction industry and wastewater treatment plants as point sources. An identification of litter hotspots would enable specific mitigation measures, adjusted to the respective source, and thereby could prevent the release of large quantities of small plastic particles in rivers. The adopted large-scale citizen science approach was especially suitable to detect pollution hotspots by sampling a variety of rivers, large and small, and enabled a national overview of litter pollution in German rivers.
Palabras claves: Plastic litter; Floating macrolitter; Microplastics; Rivers; Citizen science
COVID lessons from the global south – Face masks invading tourist beaches and recommendations for the outdoor seasons
Thiel, M., de Veer, D., Espinoza-Fuenzalida, N.L., Espinoza, C., Gallardo, C., Hinojosa, I.A., Kiessling, T., Rojas, J., Sanchez, A., Sotomayor, F., Vasquez, N., Villablanca, R.
In response to the COVID-19 pandemic in 2020, Personal Protective Equipment (PPE) has been extensively used, and discarded PPE has been observed in many different environments, including on tourist beaches. Here we examined the distribution and densities of face masks on some of the main tourist beaches in Chile, and we monitored their daily accumulation rates on one beach in northern-central Chile. Face masks were found on beaches across the country with average densities of 0.006 ± 0.002 (mean ± se) face masks m−2, which are higher than densities reported on Peruvian beaches, but lower than those on some Kenyan beaches. Face masks were also found on more remote beaches and rocky shores in northern-central Chile. Daily accumulation rates on one tourist beach were low during austral fall/winter (0.2 face masks km−1 d−1), but were over ten times higher during austral summer (3.0 face masks km−1 d−1). These values are substantially higher than daily accumulation rates reported from urban streets, which is most likely due to the high densities of beach visitors during the summer tourist season. COVID-19 related infrastructure (signposts and PPE waste bins) was present on most beaches, but while signposts about personal protection were abundant, there were few signposts about littering, and only one of the 12 beaches sampled for COVID infrastructure had a signpost that offered recommendations about the proper disposal of used face masks. Specific waste bins for PPE waste were only available at three beaches. Based on these findings it is recommended to provide sufficient PPE-related signs and waste bins, establish general and strict waste disposal regulations, and to improve enforcement. Educational campaigns should aim at recommending proper use and disposal of face masks, litter prevention, reduction of single-use waste and enhanced pro-environmental behaviors.
Palabras claves: COVID-19, Personal Protective Equipment (PPE), Littering, Beach pollution, Waste infrastructure, Waste management.