The response of Betula pubescens Ehr., B. pendula Roth and two provenances of Pinus sylvestris L. to solar ultraviolet radiation were investigated in a UV exclusion field experiment during the 1997-1999 growing seasons in Finnish Lapland. The seed-grown seedlings were grown under UV-B exclusion and UV-B/UV-A exclusion as compared to control treatment and ambient plants. The only significant impacts of UV exclusion were found in P. sylvestris provenance Enontekio. Longer-term field studies are needed to detect the cumulative characteristics of the UV responses

Ground-based Multi-Axis Differential Optical Absorption Spectroscopy (Max-DOAS) measurements of nitrogen dioxide (NO₂) were continuously obtained from January to November 2019 in northeastern China (NEC). Seasonal variations in the mean NO₂ vertical column densities (VCDs) were apparent, with a maximum of 2.9 × 10¹⁶ molecules cm⁻² in the winter due to enhanced NO₂ emissions from coal-fired winter heating, a longer photochemical lifetime and atmospheric transport. Daily maximum and minimum NO₂ VCDs were observed, independent of the season, at around 11:00 and 13:00 local time, respectively, and the most obvious increases and decreases occurred in the winter and autumn, respectively. The mean diurnal NO₂ VCDs at 11:00 increased to at 08:00 by 1.6, 5.8, and 6.7 × 10¹⁵ molecules cm⁻² in the summer, autumn and winter, respectively, due to increased NO₂ emissions, and then decreased by 2.8, 4.2, and 5.1 × 10¹⁵ molecules cm⁻² at 13:00 in the spring, summer, and autumn, respectively. This was due to strong solar radiation and increased planetary boundary layer height. There was no obvious weekend effect, and the NO₂ VCDs only decreased by about 10% on the weekends. We evaluated the contributions of emissions and transport in the different seasons to the NO₂ VCDs using a generalized additive model, where the contributions of local emissions to the total in the spring, summer, autumn, and winter were 89 ± 12%, 92 ± 11%, 86 ± 12%, and 72 ± 16%, respectively. The contribution of regional transport reached 26% in the winter, and this high contribution value was mainly correlated with the northeast wind, which was due to the transport channel of air pollutants along the Changbai Mountains in NEC. The NO₂/SO₂ ratio was used to identify NO₂ from industrial sources and vehicle exhaust. The contribution of industrial NO₂ VCD sources was >66.3 ± 16% in Shenyang due to the large amount of coal combustion from heavy industrial activity, which emitted large amounts of NO₂. Our results suggest that air quality management in Shenyang should consider reductions in local NO₂ emissions from industrial sources along with regional cooperative control.

Eyes convey important information about the external and internal worlds of animals. Individuals can follow the gaze of others to learn about the location of salient objects as well as assess eye qualities to evaluate the health, age or other internal states of conspecifics. Because of the increasing prevalence of artificial lighting at night (ALAN), urbanized individuals can potentially garner information from conspecific eyes under both daylight and ALAN. We tested this possibility using a visual modeling approach in which we estimated the maximum distance at which individuals could detect conspecific eyes under daylight and high levels of ALAN. We also estimated the minimum light level at which individuals could detect conspecific eyes. Great-tailed grackles (Quiscalus mexicanus) were used as our study species because they are highly social and are unusual among birds in that they regularly gather at nocturnal roosts in areas with high levels of ALAN. This visual modelling approach revealed that grackles can detect conspecific eyes under both daylight and ALAN, regardless of iris coloration. The grackles could detect conspecific eyes at farther distances in daylight compared to ALAN. Our results highlight the potential importance of lighting conditions in shaping social interactions.

Forest soils are among the world’s largest repositories for long-term accumulation of atmospherically deposited mercury (Hg), and understanding the potential for remobilization through gaseous emissions, aqueous dissolution and runoff, or erosive particulate transport to down-gradient aquatic ecosystems is critically important for projecting ecosystem recovery. Forestry operations, especially clear-cut logging where most of the vegetaiton is removed, can influence Hg mobility/fluxes, foodweb dynamics, and bioaccumulation processes. This paper measured surface-air Hg fluxes from catchments in the Pacific Northwest, USA, to determine if there is a difference between forested and logged catchments. These measurements were conducted as part of a larger project on the impact of forestry operations on Hg cycling which include measurements of water fluxes as well as impacts on biota. Surface-air Hg fluxes were measured using a commonly applied dynamic flux chamber (DFC) method that incorporated diel and seasonal variability in elemental Hg (Hg⁰) fluxes at multiple forested and harvested catchments. The results showed that the forested ecosystem had depositional Hg⁰ fluxes throughout most of the year (annual mean: −0.26 ng/m²/h). In contrast, the harvested catchments showed mostly emission of Hg⁰ (annual mean: 0.63 ng/m²/h). Differences in solar radiation reaching the soil was the primary driver resulting in a shift from net deposition to emission in harvested catchments. The surface-air Hg fluxes were larger than the fluxes to water as runoff and accounted for 97% of the differences in Hg sequestered in forested versus harvested catchments.

High particulate matter (PM) and ozone (O₃) concentration in Hong Kong are frequently observed during the summertime typhoon season. Despite the critical effect of a typhoon on air pollution, contributions of vertical wind profile and cloud movement during transboundary air pollution (TAP) on surface PM and O₃ concentration have yet to be fully understood. This work is the first study to apply a network of Doppler light detection and ranging (LiDAR) as well as back trajectory analysis to comprehensively analyze the effect of a weak Typhoon (Danas) occurring during 16–19 July 2019 on different variations in PM and O₃ concentration. During the typhoon Danas, three types of surface air pollution with five episodes were identified: (1) low PM and high O₃ concentration; (2) co-occurring high PM and O₃ concentration and (3) high PM and low O₃ concentration. Employing our 3D Real-Time Atmospheric Monitoring System (3DREAMs) along with surface observations, we found the important role of TAP in the increases in surface PM and O₃ concentration with significant vertical wind shear that transported air pollutants at upper levels, and strong vertical mixing that brought air pollutants to the ground level. Cloud movement related to typhoon periphery, as well as high solar radiation due to sinking motion and remote transport by continental wind, have an impact on local O₃ concentration. For the substantial difference in O₃ concentration between two air quality measurement sites, the similar vertical aerosol distributions and wind profiles suggest the comparable TAP contributions at the two sites and thus infer the critical role of local O₃ photochemical process in the O₃ difference. This work comprehensively reveals the influences of a weak typhoon on variations in PM and O₃ during the five episodes, providing important references for air quality monitoring and forecast in regions under the influence of typhoon.

As a volatile organic compound existing in the atmosphere, methanol plays a key role in atmospheric chemistry due to its comparatively high abundance and long lifetime. Croplands are a significant source of biogenic methanol, but there is a lack of systematic assessment for the production and emission of methanol from crops in various phases. In this study, methanol emissions from spring wheat during the growing period were estimated using a developed emission model. The temporal and spatial variations of methanol emissions of spring wheat in a Canadian province were investigated. The averaged methanol emission of spring wheat is found to be 37.94 ± 7.5 μg·m⁻²·h⁻¹, increasing from north to south and exhibiting phenological peak to valley characteristics. Moreover, cold crop districts are projected to be with higher increase in air temperature and consequent methanol emissions during 2020–2099. Furthermore, the seasonality of methanol emissions is found to be positively correlated to concentrations of CO, filterable particulate matter, and PM₁₀ but negatively related to NO₂ and O₃. The uncertainty and sensitivity analysis results suggest that methanol emissions show a Gamma probabilistic distribution, and growth length, air temperature, solar radiation and leafage are the most important influencing variables. In most cases, methanol emissions increase with air temperature in the range of 3–35 °C while the excessive temperature may result in decreased methanol emissions because of inactivated enzyme activity or increased instant methanol emissions due to heat injury. Notably, induced emission might be the major source of biogenic methanol of mature leaves. The results of this study can be used to develop appropriate strategies for regional emission management of cropping systems.

Northern China is a significant source of dust source in Central Asia. Thus, high-resolution analysis of dust storms and comparison of dust sources in different regions of northern China are important to clarify the formation mechanism of East Asian dust storms and predict or even prevent such storms. Here, we analyzed spatiotemporal trends in dust storms that occurred in three main dust source regions during 1960–2007: Taklimakan Desert (western region [WR]), Badain Jaran and Tengger Deserts (middle region [MR]), and Otindag Sandy Land (eastern region [ER]). We analyzed daily dust storm frequency (DSF) at the 10-day scale (first [FTDM], middle [MTDM], and last [LTDM] 10 days of a month), and investigated the association of dust storm occurrences with meteorological factors. The 10-day DSF was greatest in the FTDM (accounting for 77.14% of monthly occurrences) in the WR, MTDM (45.85%) in the MR, and LTDM (72.12%) in the ER, showing a clear trend of movement from the WR to the ER. Temporal analysis of DSF revealed trend changes over time at annual and 10-day scales, with mutation points at 1985 and 2000. We applied single-factor and multiple-factor analyses to explore the driving mechanisms of DSF at the 10-day scale. Among single factors, a low wind-speed threshold, high solar radiation, and high evaporation were correlated with a high DSF, effectively explaining the variations in DSF at the 10-day scale; however, temperature, relative humidity, and precipitation poorly explained variations in DSF. Similarly, multiple-factor analysis using a classification and regression tree revealed that maximum wind speed was a major influencing factor of dust storm occurrence at the 10-day scale, followed by relative humidity, evaporation, and solar radiation; temperature and precipitation had weak influences. These findings help clarify the mechanisms of dust storm occurrence in East Asia.

Since the Industrial Revolution, the global ambient O3 concentration has more than doubled. Negative impact of O3 on some common crops such as wheat and soybeans has been widely recognized, but there is relatively little information about maize, the typical C4 plant and third most important crop worldwide. To partly compensate this knowledge gap, the maize cultivar (Zhengdan 958, ZD958) with maximum planting area in China was exposed to a range of chronic ozone (O3) exposures in open top chambers (OTCs). The O3 effects on this highly important crop were estimated in relation to two O3 metrics, AOT40 (accumulated hourly O3 concentration over a threshold of 40 ppb during daylight hours) and POD6 (Phytotoxic O3 Dose above a threshold flux of 6 nmol O3 m−2 s−1 during a specified period). We found that (1) the reduced light-saturated net photosynthetic rate (Asat) mainly caused by non-stomatal limitations across heading and grain filling stages, but the stomatal limitations at the former stage were stronger than those at the latter stage; (2) impact of O3 on water use efficiency (WUE) of maize was significantly dependent on developmental stage; (3) yield loss induced by O3 was mainly due to a reduction in kernels weight rather than in the number of kernels; (4) the performance of AOT40 and POD6 was similar, according to their determination coefficients (R2); (5) the order of O3 sensitivity among different parameters was photosynthetic parameters > biomass parameters > yield-related parameters; (6) Responses of Asat to O3 between heading and gran filling stages were significantly different based on AOT40 metric, but not POD6. The proposed O3 metrics-response relationships will be valuable for O3 risk assessment in Asia and also for crop productivity models including the influence of O3.

The carbon dots (C-dots) mediated Sn₂Ta₂O₇/SnO₂ heterostructures with spongy structure were successfully assembled by simple hydrothermal route. The photocatalytic removal efficiency of amoxicillin (AMX, 20 mg L⁻¹) over C-dots/Sn₂Ta₂O₇/SnO₂ was estimated to reach up 88.3% within 120 min simulated solar light irradiating. Meanwhile, the HPLC-MS/MS analysis and density functional theory (DFT) computation were examined to clarify the photo-degradation pathway of AMX. The mechanism investigation proposed that with the modification of C-dots, the photocatalysts improves the utilization of solar energy by harvesting the long wavelength solar light due to their unique up-converted photoluminescence (UCPL). In addition, the porous spongy structure and plenty of tiny C-dots promote the ability of adsorption by enlarged specific surface area. Furthermore, the C-dots mediated Z-type heterojunction of Sn₂Ta₂O₇/SnO₂ facilitates the efficient separation and transfer of photo-induced carriers. Our work affords a promising approach for the design of the high-efficient photocatalysts to remedy poisonous antibiotics in aqueous environment.

Molting is a crucial physiological process in arthropods development, growth, and adult reproduction, where the chitinolytic enzyme chitobiase (CB) and the apoptosis process (caspase-3 activity) play crucial roles. Both molecular endpoints have been observed to be affected by different toxics that may be present in aquatic environments. However, the role of ultraviolet radiation (UVR) in the molting process remains with poor evidence and the possible effect of the previous exposure on F1 generation is unknown. Here, we conducted laboratory experiments with chronic UVR exposure to test the effect on the molting process of Daphnia commutata. Our results showed a clear negative effect of the UVR that affected the molting process with a reduction in individual growth. This trend was also observed in CB and caspase-3 activities. Our results also suggest that the UV dose received by the mother and eggs has an additive effect with the dose received by the offspring. These results imply that the cumulative impact of small UVR doses (2 h per day, daily dose: 2520 J m⁻² of 340 nm) on mothers and eggs (which cannot be discriminated in our experiments) can have an additive or synergistic effect along with the generations through a potential increase in lethal effect. Finally, the observed desynchronization in the molting process by UVR will affect the fitness of individuals and population dynamics.