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Ritter et al. (2018) analyzed the Quaternary history of a purported paleo-lake in the Atacama Desert of northern Chile. They provide a much more thorough analysis than previous publications of the field relationships where there are landform benches surrounding a bedrock knob, Cerro Soledad. They conclude that the benches formed due to shoreline erosion by a paleo-lake while Cerro Soledad rose in elevation due to tectonic activity. Ritter et al. (2018) also used terrestrial cosmogenic nuclide (Neon, Beryllium, and Aluminum) data to determine a history of the landforms, and thus what they conclude is a history of former lake levels and uplift rate. This Comment examines the distribution of mapped geological units, especially Pliocene lake deposits, relative to the locations sampled and described by Ritter et al. (2018). We find that some of the benches sampled for cosmogenic nuclide dating occur on Miocene and Pliocene lacustrine strata, which opens the possibility that clasts were recycled from Miocene-Pliocene lake deposits into the Pleistocene bench clast population. We reach the alternative interpretation that differential resistance to erosion by hillslope processes created most benched forms on the flanks of Cerro Soledad, rather than generation of the benches by shoreline processes. An alternative exhumation scenario which utilizes the cosmogenic exposure ages better explains many of the landforms. In this scenario, the cosmogenic nuclide exposure dates reveal valley-scale denudation in response to tectonic uplift of Cerro Soledad, reduction of valley floor elevation by dissolution of evaporite units, and capture of the valley by the Loa River, rather than shoreline erosion. Irrespective of the alternative interpretation, the exposure history chronological information provided by Ritter et al. (2018) provides new opportunities to examine environmental fluctuations in the central Atacama Desert. [ABSTRACT FROM AUTHOR]

[Display omitted] • We propose a procedure for indoor soiling studies by using spin coating technique. • Dust samples were collected from PV modules installed in the Atacama Desert. • Homogeneous dust deposition was obtained within 25 s using spin coating technique. • Physicochemical characteristics of material allowed understanding the cementation. • As dust amount increased, light attenuation in the UV range became more significant. Soiling affects the economic profitability of solar photovoltaic plants, reducing productivity of the photovoltaic modules and increasing maintenance costs. Typically, studies on the soiling impact on photovoltaic technologies conducted outdoors require long exposure times. This paper deals with a new methodology for accelerated indoor test. Dust samples from the Atacama Desert are used to study physicochemical aspects of local soiling and its effects in the performance of solar cells. The new methodology is based on spin-coating to deposit homogeneous soiling layers on photovoltaic glass. This technique allows different soil mixtures to be deposited, resulting in the desired surface dust densities. X-ray diffraction and scanning electron microscopy of samples with artificially indoor and naturally outdoor deposited dust revealed similar behavior. In both, gypsum was the soluble material supporting the cementation process. The external quantum efficiency of the solar cell under different soiling conditions allowed to evaluate its effect on the photogenerated current density (J ph) for different spectral ranges. As expected from other studies, the influence of soiling is higher in the ultraviolet spectral range than at other wavelengths. It is observed that as the amount of deposited soil increases, the J ph losses are higher in the ultraviolet spectral range than in the visible or infrared. Because of the reduction in current density, efficiency is affected as the surface dust density increases. For instance, the efficiency decreased by 66.5% for 1.37 mg/cm2. [ABSTRACT FROM AUTHOR]

The addition of lithium nitrate is assumed to improve the performance of molten salts, extending the work temperature range. This paper presents an evaluation of the influence of different degrees of purity of LiNO 3 , in a ternary mixture with composition 30 wt%LiNO 3 + 13 wt%NaNO 3 + 57 wt% KNO 3 including a Chilean mixture obtained from the Atacama Desert brines. In addition, the use of synthetic lithium nitrate obtained from the chemical synthesis using Li 2 CO 3 and HNO 3 , was incorporated in the comparison. The melting point results of the 30 wt% LiNO 3 + 13 wt% NaNO 3 + 57 wt% KNO 3 mixture for different purities (128 °C, 124 °C), show a reduction of 92–96 °C with respect to the 223 °C of the solar salt and thermal stability results show maximum temperature are around 594 and 596 °C, which means that this mixture could work at maximum operating temperatures similar to those of solar salt. Finally, it was also determined that for the use of the proposed ternary mixture would mean a reduction of 35% in the volume of inventory with respect to solar salt since the proposed ternary salt presents an improvement about 14–21% in the heat capacity. • Lithium based salts present a higher work temperature range compared to solar salt. • Higher purities show a decrease in viscosity with the temperature. • 35% of reduction could be achieved using LiNO 3 , to reach the current TES capacity. • Melting point shows a reduction close to 90 °C with respect to solar salt. • The heat capacity increases between 14 and 21% respect solar salt. [ABSTRACT FROM AUTHOR]

Based on the premise that textiles can contain information about situations of intercultural contact, including their degree of intensity, a group of textiles recovered from the Doncellas site in Northwest Argentina—some housed in the Ethnographic Museum Juan B. Ambrosetti (Buenos Aires, Argentina) and others in the Archeological Museum Dr. E. Casanova (Tilcara, Argentina)—were examined and related information was updated to bring to light the relational dynamics between the Salar of Atacama and neighboring territories that may have impacted both the Salar and the Loa River basin. In this paper we focus on one of those territories, Northwest Argentina, with the assumption that links established between that region and the Atacama would have intensified in the period ca. A.D. 1350–1500. This analysis led to our proposal that a process of expansion occurred in the Atacama at the time that was linked to the interests of the Inka Empire. [ABSTRACT FROM AUTHOR]

Research on the Late Intermediate Period (AD 900–1450) in northern Chile has been strongly influenced by two mobility models: John Murra's classic vertical ecological archipelago model, with highland colonies in the lowlands; and the gyratory mobility model, with pastoralists and their llama caravans controlling trade. The widespread application of these two models, however, suffers from a lack of supporting archaeological evidence. Stable isotope analysis provides a more direct approach for studying both diet and mobility patterns, complementing material culture studies. The aim of this paper is to evaluate the presence of colonies and/or specialised highland caravans in the lowlands of northern Chile through the application of δ13C, δ15N and δ18O to human tooth enamel, bone collagen and bone apatite. The results show strong local traditions in terms of diet and mobility associated with the Loa-San Pedro, Antofagasta and Pica-Tarapacá cultural groups. Our results suggest a non-local origin for some individuals in Pica-Tarapacá and Loa-San Pedro, but provide little evidence to support either the presence of 'colonies' or of specialised 'caravans'. Mobility patterns were, instead, diverse and flexible, including female and male individuals that moved at different moments of their lives. [ABSTRACT FROM AUTHOR]

Camelid caravans have played a key role in the complex systems of interregional social interaction that characterizes Andean history. In the northernmost region of Chile, the most frequent archaeological indicators of these caravan systems are trails and rock art images. Cruces de Molinos (LL-43), a rock art site in the Lluta valley, 1100 masl, 40 km from the Pacific littoral, expands the ceremonial role of rock art sites, materialized, not only as regards the iconography portrayed and alluding to these practices, but also in terms of articulated carcass remains and detached anatomical units of camelids, intentionally deposited in a cache beneath one of the engraved blocks. This paper analyzes the site considering the visual imagery, spatial location, archaeological deposits and features associated with rock art. Based on the predominance of camelid and caravan motifs in rock art images, the extraordinary setting and location of the site on the valley's upper slopes, which is far removed from local settlements, but closely connected with a llama caravan trade network linking the chaupiyunga ecozone with the highlands (sierra and Altiplano ecozones), we suggest that Cruces de Molinos was not a rest stop for caravanners, but a ceremonial place, and not for local farmers, but for highland herders. According to seven accelerator mass spectrometry (AMS) dates that place the occupation between cal. 1060–1190 CE in the Late Intermediate period. [ABSTRACT FROM AUTHOR]

Although a number of studies have pointed out the remarkable slowness of Earth surface processes in the Atacama Desert, process mechanisms under such extremely limited water availability are poorly understood, and process rates remain unknown. This paper revisits the discussion on the formation of the prominent Atacama-specific hillslope zebra (stone) stripes, previously interpreted to result from palaeo-overland flow (Owen et al., 2013). Compared to this study, our data document different stripe characteristics with regard to stripe form and orientation as well as sorting- and bedding-patterns of stripe-confining surface gravel units. We found a remarkable form-concordance between zebra stripes and deposits from experiments on segregation-induced granular fingering. Hence, we propose a combination of seismic shaking and instantaneous dry granular free surface flows as the key mechanism for zebra stripe formation. Our findings underline the potential significance of seismicity in shaping Atacama landscapes, which bear important analogies to extra-terrestrial surfaces. • Zebra stripes along the Paposo fault show multiple frontal lobes coarsening downslope. • Stripe forms resemble those observed in dry granular flow and granular fingering. • Water is not a necessary precondition for zebra stripe formation. • We assume that zebra stripes originate from seismic shaking. [ABSTRACT FROM AUTHOR]

This paper presents findings from a stochastic benefit-cost analysis (BCA) using Monte Carlo simulations to estimate the probable values for net benefit and benefit cost ratio for a series of proposed strategic and operational water management options under climate change and socioeconomic development. The study is performed in the Tacna region in southern Peru, geographically within the Atacama Desert and under prevailing water scarcity conditions. We examined the benefits and costs to four main water users: urban, agriculture, mining and the environment over a 30-year time horizon. The main scenarios under consideration include reduced water demand from improved water use efficiency in the urban and agriculture sector, and investment in water supply infrastructure including inter-basin infrastructure and dams, a desalination plant, and increased groundwater extraction. Our findings suggest that implementation of demand-side management strategies, which in this instance is investment in water use efficiency technology and water conservation measures result in more favourable net benefit outcomes than investment in water supply infrastructures. The primary outcome of this study is to help the Regional Government of Tacna, Peruvian water authorities and water users, make more informed decisions about water investment options going forward, thereby supporting regional development opportunities. • This paper presents finding from a hydrological and economic model of drought management in Peru. • We performed a benefit cost analysis that accounts for uncertainty and stochasticity. • Our hydrological model includes operational protocols, existing and planned infrastructure, and demand management options. • Our findings suggest that demand-side management strategies are more favourable than water infrastructures investment. [ABSTRACT FROM AUTHOR]

Knowledge of the solar spectrum is essential for the design and study of numerous technologies. Due to the area considered, the harsh conditions and the difficulty for accessing to some zones, information and measurement on local parameters and spectral resource are scarce. This fact, along with the special atmospheric conditions prevailing in Atacama Desert, has led to increasing interest on the part of the solar industry to ascertain the spectral variation respect to that of other places around the world. Considering the standard spectrum for a typical air mass as 1.5, the evaluation of PV module behaviour or device calibration under real conditions can generate a source of uncertainty where spectra may differ. This preliminary paper aims to study the influence of using the standard or local spectra in photovoltaic technologies in Atacama Desert, in order to highlight the necessity for a long-term ground-based measurement campaign. For that purpose, a first approach to the spatio-temporal average of solar spectrum in the Atacama Desert from satellite databases is estimated. Then, local spectra are compared against the Reference Spectra in order to show the differences in studies on solar energy applications. Long-term satellite database information is used to average the atmospheric parameters, such as Aerosol Optical Depth, Ozone, Precipitable Water Vapour, Albedo and Relative Humidity, for the entire Atacama Desert area and is then used to obtain the mean Global tilted Irradiance and Direct plus Circumsolar Irradiance solar spectrum. Finally, to study the influence that the shape of the local spectrum has on the performance of the different solar technologies, the photo-current density of two different solar cell types were studied under Atacama and standard conditions. The results indicate that there are considerable differences with the ASTM G173-03 reference spectra for short wavelengths, especially in the UV spectral range, which is 55% points higher than the reference, which influences in the performance of the solar technologies. [ABSTRACT FROM AUTHOR]

Drylands occupy 31% of the South America. Although diverse, the soils in these environments are fragile and highly vulnerable to anthropogenic pressures. In this study, bibliometric techniques were used to analyze 3309 papers published on soil science in the Caatinga, Patagonia, Gran Chaco, and Atacama Desert, aiming to understand the evolution, map the produced knowledge, and identify future trends of soil science research in the dry environments of South America. The database was obtained from the Web of Science Core Collection, considering the period 1992–2022. Data analysis was performed using regression analysis, descriptive statistics, and cluster analysis. The results indicated that the Caatinga was the biome with the highest number of publications on soil science (n = 1203), followed by Patagonia (n = 1096), Atacama (n = 644), and Gran Chaco (n = 366). EMBRAPA in Caatinga (16.2%), CONICET in Patagonia (55.2%), and the Gran Chaco (42.9%), and NASA in Atacama (15.9%) were the institutions with the highest number of published studies. Citation analysis indicated the strong influence of soil science research conducted in the Atacama for global scientific research, especially in studies related to geochemistry, soil microbiology, and the existence of life on other planets, given the physical-climatic similarity between this environment and the planet Mars. In the Caatinga, research was more related to agriculture (58.0%), while in Patagonia (41.9%) and Gran Chaco (37.4%), research was related to environmental sciences and ecology, as a result of the high level of environmental degradation observed in these environments. In general, the development and use of biological indicators of soil quality and health, subjected to various degradation types (agriculture, overgrazing, deforestation, burning, mining) and climate change, as well as the biotechnological potential of the soil microbiota found under conditions of greater water deficit (arid and hyper-arid regions), can be considered as the main trends of soil science research in the studied environments. The results of this study may be useful for conducting new research and collaborations that contribute to the sustainable use of soils in the dry environments of South America. • Soil science research in the dry environments of South America was reviewed. • Soil science research in the Caatinga accounted for 36.6% of the total studies. • Gran Chaco soils have been the least studied. • Soil science research in the Atacama has shown greater global interest. • Soil microbiology can be considered as the main research trend. [ABSTRACT FROM AUTHOR]

• Brines chlorine calcium type have been identified in deep coastal boreholes in the Atacama Desert. • The combined application of lithium, boron and strontium isotopes has made it possible to recognize an ancient marine origin of deep brines. • The combined application of the isotopes δ11B and δ7Li allows an indirect approximation of the age of groundwater of marine origin to be made. This paper presents a multi-isotopic study to investigate the origin of saline groundwater in the Cordillera de la Costa, in the arid Atacama Desert region in northern Chile. Understanding the origin of deep saline groundwater can be challenging using only hydrogeochemical and common isotope methods. New 87Sr/86Sr, δ11B, δ7Li, and 234U/238U values of dissolved salts have been added to previously known chemical and isotopic compositions of groundwater, inorganic dissolved carbon, and sulfate. In this extremely arid area, the chemical and isotopic compositions of coastal springs primarily reflect the concentration of salts from atmospheric wet and dry deposition, which accumulate in the topsoil and dissolve during the occasional heavy rainfall events. These events recharge the aquifer with sodium-chloride type, high salinity water, with rock weathering contributing minimally to the chemical composition of groundwater. However, high salinity water of the calcium chloride and sodium-calcium chloride types in the deep fractured aquifer have a significantly different chemical and isotopic composition. In this investigation, it has been concluded that the salinity of these last waters is due to remnants of ancient marine water, mineral alteration and interaction with predominantly andesitic volcanic rocks in the Cordillera de la Costa. The deep saline groundwater has δ11B values between 17.3‰ and 20.7‰, and 87Sr/86Sr values below 0.706, suggesting mixing with recharge groundwater. The δ7Li composition of the deep groundwater varies between 23.5‰ and 31.5‰, pointing to a contribution of salts of marine origin and mineral alteration. However, the low Li concentrations relative to B in recharge water and in deep groundwater shows a preferential Li removal from pore water. Uranium and uranium isotopes data are limited to shallow groundwater due to the very low U concentrations in deep groundwater following reduction of U, and point to enhanced water–rock interaction in a rock-dominated environment. The dissolution of old buried saline deposits at shallow depth as a source of salinity is ruled out. [ABSTRACT FROM AUTHOR]

The Atacama Desert is one of the most inhospitable terrestrial environments on Earth, yet the upwelling of the Humboldt Current off the coast has resulted in the presence of a rich marine biota. It is this marine environment which first enabled the human settlement of the northern Atacama Desert, and continues to form the basis of regional economies today. In this paper we explore how the desert has shaped human dietary choices throughout prehistory, using carbon and nitrogen isotope analysis of human bone collagen (n = 80) to reconstruct the diets of the inhabitants of the Arica region of the northern Atacama. This area is one of the driest parts of the desert, but has been generally understudied in terms of dietary adaptation. Statistical analysis using FRUITS has allowed deconvolution of isotopic signals to create dietary reconstructions and highlight the continued importance of marine resources throughout the archaeological sequence. Location also appears to have played a role in dietary choices, with inland sites having 10–20% less calories from marine foods than coastal sites. We also highlight evidence for the increasing importance of maize consumption, coinciding with contact with highland polities. In all periods apart from the earliest Archaic, however, there is significant variability between individuals in terms of dietary resource use. We conclude that marine resource use, and broad-spectrum economies persisted throughout prehistory. We interpret these results as reflecting a deliberate choice to retain dietary diversity as a buffer against resource instability. [ABSTRACT FROM AUTHOR]

Scholars who have critically analyzed the commodification of nature have explored how the specific biophysical features of the objects to be commodified can shape the outcome of the commodification process. Thus, the establishment and behavior of a market system is closer to a political struggle than it is a simple technical and spontaneous process. Despite their contributions, these approaches have not focused on the resistance that cultural exegesis, self-identification, and the affective connection between the human and non-human pose to market systems. In this paper, I show how the Atacameño people from the Atacama Desert (Chile) have subverted the radical pro-water market model imposed by the Chilean military dictatorship in 1981 by relying on their water-related cultural values. In some Atacameño communities, the water market has not operated to ensure that water rights are put to those uses with the highest economic value (e.g., mining or urban water consumption). Indeed, in these communities, internal rules both forbid the sale of water rights to the mining sector and regulate the distribution of water within the community in terms that operate as barriers to other transactions. These rules form part of a moral economy of water that is a concrete ethic based on shared values and affective connections between humans and non-humans, mandating how people should relate to one another in relation to water. Together, these relations have decommodified water and contradict the neoliberal explanation of how a free water market should work. [ABSTRACT FROM AUTHOR]

This paper has been written following the results and reflections of the previously published paper (Viguier et al., 2018) detailing a multidisciplinary assessment of the groundwater resources in the northern part of the Pampa del Tamarugal Aquifer (PTA), at Atacama Desert (Northern Chile). This short note aims to propose an overall review of the PTA conceptual model. Following a brief description of the PTA limit changes over 60 years, the boundary conditions, recharge processes and the 2012–2015 piezometric map are detailed in an updated hydrogeological conceptual model including the northern, central and southern parts of the aquifer. The exploited aquifer contained in El Diablo Fm (Miocene alluvial filling) covers almost 6420 km2, i.e. +87% compared to a previous study. That means that the groundwater resources in the Central Depression are today still underestimated. The Andean Piedmont appears to be a highly interesting target for the groundwater resource exploration and for the long-term water supply in the Central Andes where the regional water demand is continuously increasing. • An overall review of the Pampa del Tamarugal Aquifer conceptual model is proposed. • The updated PTA extent covers almost 6420 km2 (+87%). • Groundwater resources are underestimated in the Central Depression. • The Andean Piedmont is a strategic target for the exploration of groundwater resources. [ABSTRACT FROM AUTHOR]

The emergence of specialized fishers is often considered one of the most distinguishing traits of the Middle Holocene (ca. 8000–6000 cal BP) in the hyperarid Southern Atacama coast. Most of the evidence comes from funerary contexts and artifact typologies, but there are very few systematic zooarchaeological studies from which to understand this process. Considering the importance of marine and coastal resources for communities who inhabited this area in terms of subsistence and social organization, in this paper we analyze ichthyoarchaeological evidence from the Zapatero site (Antofagasta region of Chile), one of the most important Middle Holocene sites of the Taltal area. Our evidence shows a specialized maritime adaptation based on the exploitation of different fish resources from the area, but at the same time an important intensification in the harvesting of one specific taxon, the jack mackerel Trachurus murphyi . Through this systematic ichthyoarchaeological analysis, we reflect on the historical process of adaptation of local communities to the driest coastal desert in the world. [ABSTRACT FROM AUTHOR]

Abstract: This paper briefly summarizes presearch concerning the mid-Holocene in the western slope of the puna de Atacama (20–25°S). Proxy data and dates from palynological, limnological, geomorphological archives were compared with data recovered from the archaeological sites in high altitude basins, intermediate ravines and piemontane paleowetlands. Due to exceptionally favorable conditions, numerous Early Holocene archaeological sites were found. In contrast, the lack of occupations in previously populated areas suggests a decline in human activity during the arid mid-Holocene. In this context, two key concepts are introduced: ecorefuge or ecological refuge, and archaeological silence (silencio arqueológico). The first refers to the particular favorable locations occupied by human groups during the mid-Holocene. The second provides a better understanding about the impact of the arid interval during this period on human adaptations in the most barren territories of the New World. [Copyright &y& Elsevier]

Abstract: In South America, the arid and semiarid subtropical regions through the Atacama Desert and north-central Chile between 19° and 32°S are currently a gap in the tree-ring chronology network. Only a short tree-ring chronology has been published for this vast region and little is known about the suitability of many woody species for tree-ring analysis and dendroclimatology. In this paper we present the first detailed analysis of the climate responses and influences of the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on the tree-rings of three species new to dendrochronology and that typically occur at high elevations in the Andes of central and north-central Chile. Three well-replicated tree-ring chronologies of Kageneckia angustifolia, Proustia cuneifolia and Fabiana imbricata are compared with century-long regional records of precipitation and temperature, and with the N3.4 SST and PDO indices in both time and frequency-domains using correlation and wavelet analysis. The radial growth of these species is controlled by winter precipitation and is also positively correlated with temperature during most of the rainy season from April to September (autumn–spring). The regional climate as well as tree growth is strongly modulated by ENSO and ENSO-like conditions in the equatorial Pacific at both interannual and interdecadal timescales. The decadal and interdecadal variability is not correlated with PDO and appears to be related to the Interdecadal Pacific Oscillation (IPO), a Pacific-wide ENSO-like mode of climate variability. Despite their relatively short lifespans, these three new species have a high potential for dendrochronological and dendroclimatic studies in the semiarid region of Chile over the last two centuries. [Copyright &y& Elsevier]

Abstract: In recent years, longitudinal changes on the thin/thick-skinned tectonic styles of the Central Andes has been intensively discussed while other studies have considered the role of mass transfers on the unloading of the orogen, and on the stress regime along the plate interface arising from changes on the volume of sediment arriving into the Peru–Chile trench. The search for paleo-climate records is therefore crucial for our understanding of the history of the Central Andes. In this paper, we focus on the Atacama Gravels, an extensive blanket of Miocene continental deposits filling a Neogene paleo-valley system along the southern Atacama Desert in northern Chile. An east–west transect, between Pedernales and Chañaral (26°30′S), enabled us to carry out a sedimentological and tectonic study of the Atacama Gravels, based on logging and field observations along the Rio Salado canyon. New 39Ar–40Ar ages obtained on intercalated and overlying ignimbrites date the beginning of the Atacama Gravels sedimentation at around the Oligocene–Miocene boundary and cessation of sedimentation in the Late Miocene. Thirteen lithofacies, included within five facies associations (A1 to A5) were identified. Depositional environments vary from proximal alluvial fan (A1, A2) in the Precordillera through ephemeral fluvial (A3, A4) to distal playa lake (A5) in the Coastal Cordillera. No evidences of synsedimentary deformation have been found, showing that the change from sediment removal to sediment preservation cannot be explained by tectonic causes, and climate change appears to be the dominant controlling factor of sediment preservation. A progressive change from semi-arid towards hyper-arid climatic conditions during the Miocene, led to a reduction on the transport capacity of the fluvial system and sediment preservation along the paleo-valley system formed during the Oligocene. [Copyright &y& Elsevier]

In the Central Atacama Desert (22°-24°S; henceforth CAD), around 3700 cal yrs BP, human economies begin to transition from relying mostly on hunting and gathering to increasingly incorporating horticulture and pastoralism became more intensive during the Late Intermediate Period (LIP; beginning at ca. 1050 cal yrs BP/900 AD). In this extreme environment, the well-being of past and present farming and herding communities is directly tied to water availability. The lack of proper paleoclimatic/environmental records in terms of their temporal/spatial resolution impeded evaluation whether sedentarization was synchronous, in some degree, with the amelioration of dry conditions recorded during the Late Holocene at millennial timescales. The present paper thus aims (1) to reconstruct the past environmental and climatic dynamics in the CAD (22°S) during the late Holocene at millennial to sub-centennial scales based on the pollen record of fossil rodent middens of Cuesta Chita site and; (2) to discuss their possible relationship to changes in cultivation and water management as seen at the archaeological sites of Topaín, Paniri and Turi, located in the Salado River basin. The CCH rodent midden pollen record reflects wetter (drier) than present phases around 4400, 3650, 3000, 2200–2100, 1600, 855–840, 520–450 and 100 cal yrs BP (980, 450-115 cal yrs BP). By the time that wetter-than-present conditions occurred in the CAD (Formative Period, 3500-1050 cal yrs BP), local communities had already developed small-scale horticultural practices, yet they did not develop extensive or intensive agricultural practices. Indeed, historical processes leading to economic transformations and the rapid adoption of intensive agriculture throughout the CAD after 1000 cal yrs BP occurred and were probably favored by wetter than present conditions, suggesting positive correlations between climatic and cultural change. However, these correlations are complex and non-deterministic. In fact, decreased moisture between 650 and 600 cal yrs BP in the Turi Basin was met by agropastoralists at Topaín with complex local strategies that included changing water management practices and significantly extending farmed lands. Similarly, the Topaín fields were abandoned during a period of much-wetter-than-present conditions. The chronologically fine-grained comparison of the CCH and archaeological records reveals that the relationship between climate and culture is complex, non-deterministic, and historically contingent, with examples of agricultural expansion during a time of water stress, and the abandonment of fields during a time of abundance. • Human-environment dynamics in the Central Atacama Desert during the Late Holocene. • Late Holocene climatic variability at millennial to sub-centennial resolution based on pollen records. • Wet (dry) phases occurred ∼4400, 3650, 3000, 2200-2100, 1600, 855-840, 520-450 and 100 (980, 450-115) cal yrs BP. • Human responses to climatic change are various and there is no simple relationship between water availability and land use. [ABSTRACT FROM AUTHOR]

The understanding of soiling processes on photovoltaic modules is a necessary step for the development of cost-effective mitigation methods for the solar industry. This paper analyzes the soiling process for photovoltaic modules installed at the Atacama Desert. For this purpose, the dust deposited on photovoltaic modules and glasses (for one year) was characterized and the location's atmospheric parameters were monitored continuously. The dust samples were separated according to difference in solubility, obtaining three samples: soluble (recrystallized), insoluble (filtered), and original. Through x-ray diffraction measurements it was detected that the soluble part corresponds to gypsum and the other dust components are insoluble or low-solubility salts such as albite, anhydrite, calcite, quartz, and orthoclase. Scanning electron microscopy and energy dispersive x-ray spectroscopy of the dust on photovoltaic glasses show the presence of gypsum with a monoclinic prismatic structure covered with smaller dust particles. These prismatic crystals are also observed after recrystallization of the soluble sample suggesting that gypsum, as a soluble hygroscopic material, has a key role in the cementation process. Atmospheric parameters of each season were characterized through wind velocity, temperature, and relative humidity. All these parameters show large daily oscillation, which trigger a cementation process in which gypsum crystallization, after being completely or partially solubilized, causes the encapsulation of insoluble material. • This article reports on the cementation process for photovoltaic (PV) modules. • Soluble and hygroscopic salts present in the place accelerate the cementation. • SEM/EDX and XRD were used to characterize soluble and non-soluble material. • Environmental parameters were measured and related to the cementation process. • The broadband transmittance of PV glass reduced by 44.3% after 4 months of exposure. [ABSTRACT FROM AUTHOR]

Chile is host to one of the most considerable Cu resources in the world. The primary source of Cu is from porphyry deposits. However, associated "exotic-Cu" deposits are also significant in the Atacama Desert of northern Chile. The critical processing issue for these ores is that they are refractory to dissolution under acidic and oxidative conditions, and consequently their dissolution kinetics are relatively slow. This paper reports a study on the extraction of copper and manganese from exotic-Cu ores using cane molasses as a reducing agent in the presence of chloride ions and diluted sulfuric acid media. The effects of concentrations of cane molasses, chloride ion, and sulfuric acid are discussed. Leaching tests on ground ore in shake flasks were studied, as well as the agglomeration and curing stages of a coarse ore sample. The dissolution of the exotic copper ore is enhanced when 50 g/L of NaCl and 60 g/L of cane molasses are added to the leaching solution. The dissolution of copper associated with copper wad appears independent of the Mn dissolution. Tests with the ore agglomerated with acid, chloride ions, and cane molasses showed enhanced dissolution of manganese contained in the copper wad, but not copper. It is thus confirmed that cane molasses is a suitable reductant in the leaching of Mn, especially in the presence of chloride ions. The behavior and fate of the wad-associated copper requires further investigation. • The presence of molasses provides a suitable reductant to leach the Mn phase. • Addition of chloride ions enhances the dissolution of exotic-Cu ore. • The use of cane molasses increases the Mn dissolution. • Chloride ions enable the Cu(II)/Cu(I) couple to be a redox shuttle/catalyst. [ABSTRACT FROM AUTHOR]

The Chilean water model imposed by the Chilean dictatorship in 1981 is broadly known as a radical example of neoliberal water management. Several studies have focused their analyses on this model, and its relation to mining, from a political ecology perspective; however, this has minimized the broader historical context. In this paper, we followed a geohistorical standpoint to gain an extensive understanding of the processes of mining development and the related water extraction in the Atacama Desert. By analyzing different official documents, historical sources and scientific discourses of the 19th and early 20th centuries, we aimed to denaturalize the idea of the Atacama Desert as hyper-arid space, rich in mineral resources. By doing so, from a political ecology perspective, and with a critical approach to territory, we interrogated the mining development in the Taltal district (1840–1920). This exercise led us to understand the Atacama Desert as a socially-produced mining territory, or miningscape, where foreign actors have produced hegemonic discourses and uneven materialities. Here, water, minerals, global markets, scientific knowledge, political and legal discourses, and colonialism have inevitably become interwoven in a territorial long-standing production process. Thus, we propose that the production of miningscapes and waterscapes are entangled process in the Andes mining territories. In turn, this process has enabled the reproduction of the Chilean state, capital accumulation, and the consolidation of a modern project at the expense of local populations and rationalities, which have been invisibilized. [ABSTRACT FROM AUTHOR]

The Atacama Desert in northern Chile is the driest place on Earth. In this region, climate models are subject to large biases, especially precipitation is significantly overestimated. Meteorological observations in the region are sparse and limited to inhabited places at the coast or the foothills of the Andes. To fill this gap, a new network of 15 automatic weather stations has been established beginning April 2017. These stations do not only record standard meteorological parameters such as temperature, humidity and wind, but also soil temperatures and humidity, additionally a wetness sensor gives information about the occurrence of fog. Data from the first year(s) of this network show a very regular wind pattern with easterly winds during night and morning and westerly winds from noon to evening. This wind transports moisture from the Pacific Ocean into the desert which forms fog during the night which may account for a moisture supply on the order of the rare precipitation events in the region. A few precipitation events have been observed during the first years. The recorded data allows to distinguish between different sources: convective precipitation above the Altiplano, which in some cases extended to the western slope of the Andes, and troughs extending from mid latitudes to the region, directing moist air from the pacific into the region. Both of these mechanisms brought only some tenths of mm precipitation. In one case the accidental combination of flow over the Andes and a weak cut-off low above the Pacific led to moisture convergence off the coast of northern Chile and initiated a convective system moving south-east ward which brought for the region extreme precipitation of 3-10 mm. • We present a new network of climate stations in the Atacama Desert • 15 Stations have been installed between the coast and 2500m AMSL and between 20°S and 25°S. • Wind measurements of the stations support the existence of the Rutlland circulation cell driven by the Andes. • Fog is a regular occurring phenomenon mainly during night with frequency and duration depending on location. • Precipitation occured on some occasions and is driven by certain synoptic situtations described in the paper. [ABSTRACT FROM AUTHOR]