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Ozone layer depletion on the west coast of South America, map of stratospheric ozone distribution obtained from NASA (Jan 31st, 2005). Notice the depletion of the ozone layer over the west coast FO South America.
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UV absorption in Valparaíso, Chile, is analyzed during the passage of a smoke column from a nearby forest fire. Total solar absorption is measured, UVB and UVA radiation, UV nanometre to nanometre between 295 nm and 315 nm. With the purpose of seeing what factors intervene in this absorption, tropospheric ozone and PM10 particulate material are mea...
Context in source publication
Context 1
... city of Valpara ́ ıso is located on the central coast of Chile, with the following geographic coordinates: 33 01 S; 71 ◦ 38 W. The climate is subtropical, similar to moderate Mediterranean, with an average maximum temperature of 20 ◦ C. The coolest months are July and August even though the winter is benign due to the influence of offshore marine breezes which penetrate the Aconcagua valley. The rainy season occurs in the months of May, June and July, during which periods of rain of great intensity are possible. Predominant winds blow mainly towards South-Southeast throughout the year. This condition is interrupted during the rainy winter months during which the winds blow predominantly North-Northwest. Valpara ́ ıso, being on the west coast of South America, is exposed to an increase of UV radiation during the summer as a result of the presence of a stratospheric ozone layer depletion which runs the length of Chile as can be appreci- ated in fig. 1 (see [1]). UVB irradiance values during the summer and winter solstice of 2006 were 33 . 3 μ W / m 2 and 6 . 2 μ W / m 2 , respectively. For more detailed UV climatology information on Valpara ́ ıso see [2]. The city of Valpara ́ ıso is surrounded by an extensive forest area and is prone to forest wildfires during the summer months. Wildfires dam- aged 5 157 . 7 hectares (51 . 58 km 2 ) only in the Valpara ́ ıso province in 2005, of which 3 472 . 23 hectares (34 . 72 km 2 ) were destroyed in January. These forest fires, apart from producing particulate material and smoke, produce allergenic and toxic compounds which affect the population. The area of this study has a population of approximately 800 000 people. The smoke and particulate produced by these forest fires has an effect on the UV radiation which at this time of year is high because it happens during the summer, in addition to the stratospheric ozone depletion in this region as previously mentioned. In this publication, results of the analysis done to determine the action of smoke and principally the PM 10 particulate material generated by forest fires in the region of Valpara ́ ıso and their effect upon UV radiation are shown. A forest fire was reported in Casablanca (33 19 S; 71 24 W) located approximately 30 km Southeast of Valpara ́ ıso in the morning of January 31st, 2005. At about 12:30 p.m. local time, a decrease in solar UVA and UVB irradiance was detected by the spectroradiometer EKO model MS-701, property of the Universidad Técnica Federico Santa Mar ́ ıa (UTFSM). In fig. 2, the wind direction from 03:00 to 21:00 is shown. In this graph, it can be observed the wind direction was variable, between 60 ◦ and 350 ◦ from 03:00 to 10:00. At 10:00, the wind shifted to 170 ◦ SE and remained at this direction until 21:00. This data was taken at the UTFSM meteorological station by the Wind Monitor model 05103 manufactured by Young Instruments. It also registered the wind speed throughout the day. Wind speed is low between 03:00 and 10:00, approximately 1 m / s. On the other hand, wind speed starts to increase at 10:00, 5.5 m / s and reaches a maximum of 7.0 m / s at 19:00, see fig. 3. This wind direction and wind speed data over Valpara ́ ıso establishes the fact that the smoke from this fire passed over Valpara ́ ıso and as a result generated low solar and UV irradiance. In addition, meteorological data for this day indicated clear skies over the area of Valpara ́ ıso, corroborated by satellite images. Solar radiation is measured once a minute using spectral piranometer from Eppley Lab model PSP series No. 32108F3, belonging to the Solar Evaluation Laboratory at UTFSM. When the decline of solar irradiance is analyzed in the graph in fig. 4, it can be observed that this decline commenced at approximately 12:30 and that it lasted until 20:00, this decline is relatively rapid, at 12:30 the irradiance value was 937 W / m 2 whereas the irradiance value at 14:40 was 437 . 9 W / m 2 which corresponds to a 53% decline. In fig. 5 the total irradiance graph is shown, direct plus diffused of the UVB band. The band’s irradiance value at 12:30 was 26 . 9 μ W / m 2 and at 14:40 it was 2 . 2 μ W / m 2 which is a 92% decrease. In the case of the UVA band, the decrease is on the order of 84%. Both UVB and UVA declines were greater than that of the Solar Spectrum as indicated previously. In fig. 6 the behaviour of UV irradiance for distinct wavelengths by the EKO spectroradiometer for every nm between 295 and 315 nm is shown. In all of the wavelengths, the behaviour is similar over time which indicates that all are altered in the same way, not noting any great absorption for any particular wavelength. During the afternoon, fluctuations of all bands can be noticed. This is due to the variation in the thickness of the layer smoke. This type of alteration suggests that the absorption is more the black-body ...
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Citations
... Wildfires have been increasing in the western US over the past few decades (Abatzoglou and Williams 2016), and particulate matter in the air during wildfires can increase by more than 100 μg m −3 (Wu et al. 2006). Elevated concentrations of particulate matter can decrease air and water temperatures, attenuate solar radiation, and reduce photolysis (Da Silva et al. 2012;David et al. 2018;Williamson et al. 2016). Throughout the 10 days prior to the target pesticide application in 2020, hourly particulate matter (with diameters ≤ 2.5 µm) measured in Sacramento fluctuated from 5 to 264 μg m −3 and averaged 46 μg m −3 (station number: 060670006; US EPA 2022a). ...
Naled, an organophosphate insecticide, is applied aerially at ultra-low volumes over aquatic ecosystems near Sacramento, California, USA, during summer months for mosquito control. Two ecosystem types (rice fields and a flowing canal) were sampled in 2020 and 2021. Naled and its primary degradation product (dichlorvos) were measured in water, biofilm, grazer macroinvertebrates, and omnivore/predator macroinvertebrates (predominantly crayfish). Maximum naled and dichlorvos concentrations detected in water samples one day after naled application were 287.3 and 5647.5 ng/L, respectively, which were above the U.S. Environmental Protection Agency’s aquatic life benchmarks for invertebrates. Neither compound was detected in water more than one day after the application. Dichlorvos, but not naled, was detected in composite crayfish samples up to 10 days after the last aerial application. Detections in water from the canal showed that the compounds were transported downstream of the target application area. Factors such as vector control flight paths, dilution, and transport through air and water likely affected concentrations of naled and dichlorvos in water and organisms from these aquatic ecosystems.
Graphical Abstract
... On the other hand, the presence of atmospheric aerosols during fog events at GOB and RAN monitoring sites may affect the spectral distribution of solar radiation (da Silva et al. 2012;Lapere et al. 2021). However, during most of the year, the mean UVER values at solar noon were higher than 0.20 Wm −2 , indicating a "very high risk" of developing sunburn according to the World Health Organization (WHO 2002). ...
... Cloudy sky conditions during the morning are common features of the coastal area of Central Chile, which reduces the UVER or UVI levels. da Silva et al. (2012) reported an hourly UVER value of 0.33Wm −2 (equivalent to UVI = 12) for the coastal areas of Valparaiso (GOB). According to the WHO, this condition is considered an "extreme risk" to human and ecosystem life (WHO 2002). ...
Solar ultraviolet radiation (UVR) plays an important role in environmental and occupational health. Although the importance of UVR and its spectral bands is well established, the characterization of spatio-temporal distributions has not been documented in Central Chile. This research estimated ultraviolet erythemal radiation (UVER) doses for the Mediterranean Region of Chile (MRCh) sites by using a simple model developed previously by us based on ground-based global solar irra-diance. This provides monthly, seasonal, and annual basis maps of UVER exposure across MRCh. The model was validated using ground-based solar radiation measurements in three sites. The spatio-temporal distributions of UVER daily doses for MRCh on a monthly and annual were analyzed. The evolution of standard and minimal erythemal doses (SED/MED) for skin phototypes I-IV was calculated for the years 2015-2020. The UVER doses in the MRCh were greater than 2.6 kJm −2 during most of the year and were relatively similar for the study area. The mean annual standard cumulative doses ranged from 14,149 to 10,146 SED, whereas the most common skin type in Chile (III-IV) receives an annual cumulative dose between 4,073 MED III and 3,161 MED IV in the mountains (El Colorado) and between 2,926 MED III and 2,276 MED IV in the coastal area (Valparaiso). The results can be used for public health awareness and to predict UVER levels at locations without measurement, providing useful information for decision-makers to offer insight into potential skin damage among the most populated area of Chile.
... Water transparency in many mountainous regions is being affected by climatedriven changes in dissolved organic carbon inputs, glacial cover, and watershed vegetation due to treeline advancement (Desloges 1994;Sadro and Melack 2012;Macias-Fauria and Johnson 2013). In addition, incident UV irradiance is sensitive to variation in stratospheric ozone, cloud cover, and forest fire frequency (Estupiñ an et al. 1996;Silva et al. 2012;Williamson et al. 2014). Our findings together with these environmental changes suggest that the vertical distribution of zooplankton is being altered, with more pronounced effects in transparent lakes. ...
The transparency regulator hypothesis (TRH) proposes that water transparency determines the relative importance of visual predation vs. ultraviolet radiation (UVR) in driving zooplankton out of the surface waters during the day. To test this hypothesis, we used a combination of observational and experimental approaches to examine the effects of UVR, photosynthetically active radiation (PAR), fish, temperature, and food resources on the daytime vertical distribution and diel vertical migration (DVM) of the copepod Hesperodiaptomus arcticus in a set of lakes in the Canadian Rocky Mountains. Across lakes, H. arcticus daytime vertical distribution increased with both UVR transparency and depth of food resources, and was not related to PAR, thermal structure, or the presence of fish. We also observed a strong positive relationship between UVR and H. arcticus daytime depth distribution in a single lake that varied in transparency over time. The presence of substantial DVM in H. arcticus in two transparent lakes coupled with the lack of DVM in a less transparent lake indicated a weakening effect of UVR in lower transparency conditions. Finally, we deployed open-bottomed vertical columns constructed of UVR-blocking and UVR-transmitting material overnight in two lakes of contrasting transparency. The following day, we observed significantly more copepods in UVR-blocking columns in the more transparent lake but no UVR effect in the less transparent lake. Collectively, our results provide multiple lines of evidence supporting the TRH by highlighting the changing role of UVR as a driver of DVM across lakes of varying transparency.
