Wet scavenging of black carbon (BC) is essential for evaluating their atmospheric lifetime and radiative forcing. However, it is crucial to differentiate atmospheric BC into char and soot subgroups, given their significant disparities in physicochemical properties and potential impacts. We first conducted a comparative study of char/soot in PM10 and rainwater, collected over a year in urban Guangzhou, China. The mean char/soot ratio in PM10 (similar to 2.5) is obviously higher than that in rainwater (similar to 0.8), corresponding to higher wet scavenging efficiency of soot. Through sequence rainwater sampling during individual rainfall events, we further distinguished the contributions of in-cloud and below-cloud scavenging, with in-cloud scavenging predominantly contributed to the distinct difference between char and soot. Such a distinct wet scavenging behavior of char and soot would have substantial implications for the atmospheric behavior of BC, which should be considered in future models for accurate evaluation of its lifetime and climate impact.

This study investigated the degradation behavior of concrete properties in the saline soil region of Northwest China through indoor tests conducted in the corrosive environment of Lake Taitama, Xinjiang. A damage degree was established using the loss rates of compressive strength, dynamic elastic modulus, and mass as variables. The factors influencing the variation in damage degree were elucidated by examining the evolution of microscopic pore structure, internal sulfate content, and corrosion products over time. Additionally, a concrete service life prediction model was formulated based on Wiener's theory, with the damage index as a variable. Results indicated that compressive strength, dynamic elastic modulus, and mass initially increased but subsequently declined over time under erosion. Damage degree exhibited a non-linear variation as a quadratic function of corrosion time, characterized by a gradual acceleration in damage rate and interdependence between damage degrees. The concentration of sulfate ions within concrete increased with erosion time and diminished with erosion depth. The sulfate ion diffusion coefficient decreased exponentially with corrosion age and damage severity. Total porosity initially decreased before increasing, exhibiting an S-curve relationship with damage. The X-ray diffraction tests revealed that the chemical reaction between sulfate and hydration products resulted in a decrease in calcium hydroxide content and an increase in ettringite and gypsum content, elucidating the microscopic mechanism underlying damage evolution. The concrete service life prediction curve exhibited a three-stage variation, with the damage index based on compressive strength loss demonstrating a higher sensitivity in concrete life prediction. The findings from this study can serve as a valuable reference for predicting concrete corrosion resistance and service life in the saline soil region of Northwest China.

The increasing global demand for renewable energy necessitates a comprehensive understanding of solar photovoltaic (PV) system performance and reliability, particularly in harsh climates such as Iraq. Despite ambitious targets to diversify its energy sector, Iraq faces challenges in the deployment of PV projects due to limited field experience. In this study, we assess the reliability and performance of two different PV systems installed in Basrah and Baghdad, aged 3.5 and 8 years, respectively. Field analysis reveals prevalent issues including glass and cell breakage, delamination, solder bond fatigue, and encapsulant discoloration, contributing to medium degradation rates of 0.91 %/year and 2.6 %/year in Basrah and Baghdad, respectively. Our investigation attributes higher degradation rates not only to ageing but also to suboptimal operation and maintenance (O&M) practices. Additionally, since the two systems are from different manufacturers, we verify that the measured higher degradation rates are mainly attributed to harsh operating conditions rather than differences in manufacturing processes. To extrapolate our findings countrywide, we employ a physics-based model to simulate the degradation rates. Based on the simulated degradation, we proposed four degradation rate zones across the country with degradation rates ranging from 0.62 %/year to 0.96 %/year. By applying these rates to estimate lifetime energy yield across different zones, we demonstrate the trade-offs between higher irradiance zones with reduced PV lifetime and low irradiance zones with longer PV lifetimes. In the study, we compared energy yield simulations using fixed degradation rates with those employing climate-dependent degradation rates. Our analysis revealed that in certain locations in Iraq, employing a fixed degradation rate underestimates the yield by approximately 9.7 %. Conversely, in other locations, it results in overestimations ranging from approximately 10.5 %-31.1 %, highlighting the importance of accurate degradation rate modelling for PV system assessment. Furthermore, we simulate the impact of soiling losses on energy yield, revealing potential losses of up to 70 % depending on location and cleaning schedules. Our findings contribute valuable insights into PV system degradation across harsh climates, addressing critical gaps in global degradation rate data and facilitating more accurate climate-dependent assessments of PV performance and reliability.

Black carbon (BC) in the atmosphere contributes to the human health effects of particulate matter and contributes to radiative forcing of climate. The lifetime of BC, particularly the smaller particle sizes (PM2.5) which can be transported over long distances, is therefore an important factor in determining the range of such effects, and the spatial footprint of emission controls. Theory and models suggest that the typical lifetime of BC is around one week. The frequency distributions of measurements of a range of hydrocarbons at a remote rural site in southern Scotland (Auchencorth Moss) between 2007 and 2010 have been used to quantify the relationship between atmospheric lifetime and the geometric standard deviation of observed concentration. The analysis relies on an assumed common major emission source for hydrocarbons and BC, namely diesel-engined vehicles. The logarithm of the standard deviation of the log-transformed concentration data is linearly related to hydrocarbon lifetime, and the same statistic for BC can be used to assess the lifetime of BC relative to the hydrocarbons. Annual average data show BC lifetimes in the range 4-12 days, for an assumed OH concentration of 7 x 10(5) cm(-3). At this site there is little difference in BC lifetime between winter and summer, despite a 3-fold difference in relative hydrocarbon lifetimes. This observation confirms the role of wet deposition as an important removal process for BC, as there is no difference in precipitation between winter and summer at this site. BC lifetime was significantly greater in 2010, which had 23% less rainfall than the preceding 3 years. (C) 2012 Elsevier Ltd. All rights reserved.