Summer Solar Radiation Research Articles

Temporal variations in gaseous elemental mercury concentrations at a contaminated site: Main factors affecting nocturnal maxima in daily cycles

Abstract Mercury is considered to be a global pollutant and it has been globally transported as gaseous elemental mercury (GEM). International networks for the continuous monitoring of mercury, all of which are based on background sites, study the dispersion pattern of this metal and trends in its evolution in time and space. However, information about seasonal and daily cycling of polluted sites is scarce. The aim of the work described here was to cover this gap in knowledge. For this purpose, continuous (GEM) measurements were carried out in Almaden town from November 2011 to September 2013. Meteorological data were also collected during this time. GEM data show an average concentration during the sampling period (2011–2013) of 27.4 ng m−3, with a range of 0.8–686.9 ng m−3. The results highlighted seasonal and daily cycles of GEM in Almaden town, with seasonally higher levels in summer (686.9 ng m−3) and significantly daily higher levels during the night. A multiple linear regression model has established wind speed as the best GEM predictor in all seasons during the night, while the best predictor in winter is relative humidity, temperature in spring, solar radiation in summer and wind speed in autumn during the day. These results provide evidence that, in mining polluted sites like Almaden, photochemical reactions have a negligible impact on GEM levels during the daytime and that meteorological parameters are more relevant. Further studies on diurnal GEM cycling in polluted sites must be carried out to obtain a realistic local risk assessment, taking into account night GEM levels and their importance in each case study.

Aquatic metabolism response to the hydrologic alteration in the Yellow River estuary, China

Summary Successful artificial hydrologic regulation and environmental flow assessments for the ecosystem protection require an accurate understanding of the linkages between flow events and biotic responses. To explore an ecosystem’s functional responses to hydrologic alterations, we analysed spatial and temporal variations in aquatic metabolism and the main factors influenced by artificial hydrologic alterations based on the data collected from 2009 to 2012 in the Yellow River estuary, China. Gross primary production (GPP) ranged from 0.002 to 8.488 mg O2 L−1 d−1. Ecosystem respiration (ER) ranged from 0.382 to 8.968 mg O2 L−1 d−1. Net ecosystem production (NEP) ranged from –5.792 to 7.293 mg O2 L−1 d−1 and the mean of NEP was −0.506 mg O2 L−1 d−1, which means that the trophic status of entire estuary was near to balance. The results showed that seasonal variations in the aquatic metabolism are influenced by the hydrologic alteration in the estuary. High water temperature and solar radiation in summer are associated with low turbidity and consequently high rates of GPP and ER, making the estuary net autotrophic in summer, and that also occurred after water–sediment regulation in August. Turbidity and water temperature were identified as two particularly important factors that influenced the variation in the metabolic balance. As a result, metabolism rate did not decrease but increased after the regulation. ER increased significantly in summer and autumn and reached a maximum after the water–sediment regulation in September. GPP and NEP reached a maximum value after the water–sediment regulation in August, and then decreased in autumn. Estuarine ecosystem shifted from net heterotrophy in spring to net autotrophy in summer, and then to net heterotrophy in autumn. Our study indicated that estuarine metabolism may recover to a high level faster in summer than that in other seasons after the short-term water–sediment regulation due to higher water temperature and nutrients.

Spatiotemporal characteristics of anthropogenic heat in an urban environment: A case study of Tsinghua Campus

In this study, a detailed investigation of the spatiotemporal characteristics of anthropogenic heat (AH) from different sectors (i.e. human metabolism, transportation and building energy consumption) in an urban environment (the Tsinghua Campus in Beijing, China) is conducted using inventory and building energy modeling methods. The AH is estimated as large as 220.0 W m−2 (at about local time 7pm) in summer and 221.0 W m−2 (at about local time 6am) in winter. The results indicate that AH on Tsinghua Campus (TC) displays clear diurnal and seasonal cycles. Among the three sectors on TC, building energy consumption contributes the most to the total AH (about 97.4%), whereas metabolism and transportation accounts for 1.4% and 1.2% respectively. The spatial distribution of AH on TC indicates that higher AH is generally observed in more densely built-up areas with the hourly maximum value of 474.3 W m−2. Comparison between AH and incoming solar radiation shows that the magnitude of AH is about 43% and 92% of the incoming solar radiation in summer and winter, respectively. Therefore, AH should be considered as an important component of the urban representation in numeric weather prediction models and should be carefully accounted for when considering the urban surface energy balance. This study provides evidence of the significance of AH in urban environment and suggestions for improvement of urban module in numeric weather prediction models.

Elemental mercury (Hg(0)) in air and surface waters of the Yellow Sea during late spring and late fall 2012: Concentration, spatial-temporal distribution and air/sea flux

The Yellow Sea in East Asia receives great Hg input from regional emissions. However, Hg cycling in this marine system is poorly investigated. In late spring and late fall 2012, we determined gaseous elemental Hg (GEM or Hg(0)) in air and dissolved gaseous Hg (DGM, mainly Hg(0)) in surface waters to explore the spatial-temporal variations of Hg(0) and further to estimate the air/sea Hg(0) flux in the Yellow Sea. The results showed that the GEM concentrations in the two cruises were similar (spring: 1.86±0.40ngm−3; fall: 1.84±0.50ngm−3) and presented similar spatial variation pattern with elevated concentrations along the coast of China and lower concentrations in the open ocean. The DGM concentrations of the two cruises were also similar with 27.0±6.8pgL−1 in the spring cruise and 28.2±9.0pgL−1 in the fall cruise and showed substantial spatial variation. The air/sea Hg(0) fluxes in the spring cruise and fall cruise were estimated to be 1.06±0.86ngm−2h−1 and 2.53±2.12ngm−2h−1, respectively. The combination of this study and our previous summer cruise showed that the summer cruise presented enhanced values of GEM, DGM and air/sea Hg(0) flux. The possible reason for this trend was that high solar radiation in summer promoted Hg(0) formation in seawater, and the high wind speed during the summer cruise significantly increased Hg(0) emission from sea surface to atmosphere and subsequently enhanced the GEM levels.

Diatom response to climate forcing of a deep, alpine lake (Lugu Hu, Yunnan, SW China) during the Last Glacial Maximum and its implications for understanding regional monsoon variability

The Yunnan Plateau of southwest China is strongly influenced by the Asian monsoon and is a critical area in terms of determining its development and variability since the Last Glacial Maximum. High-resolution diatom analysis of a 14C-dated sediment core retrieved from Lugu Lake, Yunnan provides a detailed history of palaeoenvironment changes from 30,000 to 10,000 cal. yr BP. A model of climate–diatom interactions (linking thermal stratification, ice cover and catchment-derived nutrients) is proposed to explain the observed changes. Prior to 24,500 cal. yr BP the dominance of the planktonic Cyclotella rhomboideo-elliptica indicates a period of stable stratification and low nutrient levels, with a moderate change of temperature and precipitation in the southwest monsoon region. During the LGM (24,500–14,500 cal. yr BP), the loss of the planktonic diatoms and a switch to small Fragilaria spp. suggest an altered thermal regime in the lake (i.e. weaker stratification and possibly ice cover). From ∼18,000 cal. yr BP, the expansion of planktonic taxa (Stephanodiscus and the Asterionella formosa) and increased %TOC are indicative of increased nutrient availability reflecting altered vegetation and soil processes due to rising regional temperatures. After 14,500 cal. yr BP, a rapid reversal to dominance by planktonic diatoms indicates a further increase in temperature and continued development of catchment vegetation and soils. The abrupt changes in diatom species composition around 24,500 and 14,500 cal. yr BP suggest that the ecological status of the lake exceeded limnological thresholds. Interestingly, however, the Younger Dryas event is not clearly recognizable in either the diatom or pollen records in the Lugu Lake sediment record. In a partial redundancy analysis, 44.2% of the variability in the total diatom assemblages in the period 30,000–10,000 cal. yr BP was accounted for by changes in summer solar radiation. The relationships between the diatom assemblages and the C/N and pollen data are further evidence of climate–catchment–vegetation interactions and their impact on lake functioning. The composition of diatom assemblages in the Lugu Lake sediment core reflects direct and indirect (i.e. via catchment processes) climate forcing and in particular, the strength of the southwest monsoon, which in turn corresponds to orbitally-induced variability in Northern Hemisphere summer solar insolation from 30,000 cal. yr BP to 10,000 cal. yr BP.

Estimating the actual transpiration rate with compensated levels of accumulated radiation for the efficient irrigation of soilless cultures of paprika plants

Water management directly affects the productivity of paprika plants and is currently determined based on accumulated radiation levels. However, the amount of water used by the plants, which can be determined by their transpiration rates, does not always increase proportionally to the accumulated radiation levels, depending on the region and climate as well as crop growth stages and development. This effect is observed because the transpiration rate is also related to light intensity, which varies with the time of day and season. To develop a more efficient irrigation strategy, both factors should be analyzed based on the relationship between light intensity and transpiration rate in the short-term. In this study, a sigmoidal relationship between light intensity and transpiration rate at an interval of 10min was observed using a consecutive transpiration monitoring system. From this relationship, a compensated equation that can calibrate the light intensity was developed. When a modified irrigation was applied using this compensated equation, less water was used compared to a conventional irrigation that supplies water proportional to accumulated radiation, especially in summer. Moreover, there were no significant differences in the transpiration rates and plant growth between plants watered with either the conventional or modified with compensated equation irrigation method. From these results, it was concluded that water was used more efficiently with the modified irrigation method without affecting plant growth. In a region with a high solar radiation in summer, such as Korea, using our equation to calculate for light intensity can prevent water waste, resulting in energy-saving and a reduction of environmental pollution in open-loop soilless cultures.

Dwelling on Courtyards. Exploring the energy efficiency and comfort potential of courtyards for dwellings in the Netherlands

Dwelling on Courtyards. Exploring the energy efficiency and comfort potential of courtyards for dwellings in the Netherlands

Dwelling on Courtyards

Dwelling on Courtyards

Dwelling on Courtyards. Exploring the energy efficiency and comfort potential of courtyards for dwellings in the Netherlands

Dwelling on Courtyards. Exploring the energy efficiency and comfort potential of courtyards for dwellings in the Netherlands

Dwelling on Courtyards. Exploring the energy efficiency and comfort potential of courtyards for dwellings in the Netherlands

Dwelling on Courtyards. Exploring the energy efficiency and comfort potential of courtyards for dwellings in the Netherlands

1218 夏期炎天下駐車時における車室内温度低減 : 吹出し角度と換気流量の検討(GS05-4 熱工学・流体工学)

1218 夏期炎天下駐車時における車室内温度低減 : 吹出し角度と換気流量の検討(GS05-4 熱工学・流体工学)

Signatures of diversifying selection at EST‐SSR loci and association with climate in natural Eucalyptus populations

Understanding the environmental parameters that drive adaptation among populations is important in predicting how species may respond to global climatic changes and how gene pools might be managed to conserve adaptive genetic diversity. Here, we used Bayesian FST outlier tests and allele-climate association analyses to reveal two Eucalyptus EST-SSR loci as strong candidates for diversifying selection in natural populations of a southwestern Australian forest tree, Eucalyptus gomphocephala (Myrtaceae). The Eucalyptus homolog of a CONSTANS-like gene was an FST outlier, and allelic variation showed significant latitudinal clinal associations with annual and winter solar radiation, potential evaporation, summer precipitation and aridity. A second FST outlier locus, homologous to quinone oxidoreductase, was significantly associated with measures of temperature range, high summer temperature and summer solar radiation, with important implications for predicting the effect of temperature on natural populations in the context of climate change. We complemented these data with investigations into neutral population genetic structure and diversity throughout the species range. This study provides an investigation into selection signatures at gene-homologous EST-SSRs in natural Eucalyptus populations, and contributes to our understanding of the relationship between climate and adaptive genetic variation, informing the conservation of both putatively neutral and adaptive components of genetic diversity.

Analysis of the Application Potential of Climate Adaptive Window Materials

This paper gives the numerical analysis method for heat transfer through climate adaptive window materials. Using the weather data in a typical city in hot summer and cold winter zone, an analysis of the application potential of climate adaptive window materials is given. The result shows that climate adaptive windows are capable of blocking solar radiation in summer while penetrating sunlight in winter and thus are suitable for building applications in this area.

Non-Uniform Thermal Behaviour of Suspen-Dome with Stacked Arch Structures

In recent years, the arch has been introduced into other structures to form new spatial structures. Typical is the suspen-dome with stacked arches (SDSA), which has been adopted for the Chiping Gymnasium. SDSAs consist of upper arches and a lower suspen-dome. The temperature distribution of the SDSA structure is non-uniform and temperatures are higher than ambient air temperature because of the exposure of the upper arches to solar radiation. The structural behaviour of SDSAs is very complex, therefore, under non-uniform thermal loading with solar radiation taken into account. The variation of thermal behaviour over time under summer solar radiation was studied as well as the effect of cable sliding friction and healing temperature (i.e. the ambient temperature at completion of construction) on the non-uniform thermal behaviour. The analysis results indicate that (1) solar radiation significantly affects SDSAs; (2) the structural behaviour of SDSAs with non-sliding cable–strut joints (i.e. the friction is too large to slide) is better than those with sliding cable–strut joints (i.e. the friction is zero) under non-uniform thermal loading; (3) the healing temperature of the upper arches and the lower suspen-dome significantly affects thermal response, and the optimal healing temperature for the SDSA structure can be determined.

内部ケルビン波の砕波による水平循環の発生機構解明

In enclosed bays, a two-layer system is likely to be formed due to the fresh water from rivers and solar radiation in summer. External forces, such as wind and tide, cause internal waves in a two-layers system, in which the Coriolis effect induces internal Kelvin waves. When internal Kelvin waves propagate over a slope, they break and cause turbulence, which results in the occurrence of horizontal circulation. However, previous studies have not revealed how breaking induces horizontal circulation. Therefore, this study aims to clarify the mechanisms of horizontal circulation induced by the breaking of internal Kelvin waves by using numerical analysis and laboratory experiments.

0514 夏期炎天下駐車時における車室内温度低減 (吹出し角度が温度低減効果に与える影響)(GS02-2 熱工学,オーガナイズドセッション 10:「バイオエンジニアリング(3)バイオメカニクスとバイオミメティクス」)

0514 夏期炎天下駐車時における車室内温度低減 (吹出し角度が温度低減効果に与える影響)(GS02-2 熱工学,オーガナイズドセッション 10:「バイオエンジニアリング(3)バイオメカニクスとバイオミメティクス」)

완도 양식장 해역의 수온변동

Abalone culture is one of important coastal fisheries off Wando in the southeast coast of Korea. Since cage culture for abalones was popularized, Understanding of temperature variation, which is important to raise abalones and to prevent their mass mortalities, is necessary. We analyzed temperature data from 2005 to 2009 obtained at Sinji-do and Cheongsan-do off Wando. Sinji-do, which is relatively close to land, had yearly wide range of temperature and rate of temperature variation. It is likely to be caused by heating of solar radiation in summer and cooling in winter at the shallow area. Rate of temperature variation in autumn was higher than that in spring. In summer short term variation of temperature corresponding tidal period was distinguished clearly. Diurnal temperature range, abrupt temperature change, was larger open sea. Comparison between temperatures of two stations and favorable raising conditions of abalones showed that Cheongsan-do, located out to sea, appears to be more appropriate than Sinji-do.

Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

Abstract. The carbon balance of an 80-yr-old deciduous oak plantation in the temperate oceanic climate of the south-east of Great Britain was measured by eddy covariance over 12 yr (1999–2010). The mean annual net ecosystem productivity (NEP) was 486 g C m−2 yr−1 (95% CI of ±73 g C m−2 yr−1), and this was partitioned into a gross primary productivity (GPP) of 2034 ± 145 g C m−2 yr−1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m−2 yr−1. Although the maximum variation of NEP between years was large (333 g C m−2 yr−1), the ratio of Reco/GPP remained relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular weather events, such as low summer solar radiation and low soil moisture content (values below 30% by volume). The European-wide heat wave and drought of 2003 did not reduce the NEP of this woodland because of good water supply from the surface-water gley soil. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p < 0.001) was found between peak leaf area index and annual GPP, which modified the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these two years. Inter-annual variation in the sensitivity of Reco to temperature was found to be strongly related to summer soil moisture content. The eddy covariance estimates of NEP closely matched mensuration-based estimates, demonstrating that this forest was a substantial sink of carbon over the 12-yr measurement period.

Seasonal variation in floating persistence of detached Durvillaea antarctica (Chamisso) Hariot thalli

Abstract Several large kelp species are capable of long-distance dispersal via rafting. However, seasonal changes in environmental conditions at the sea surface may variably affect the physiological status of the floating thalli; challenging conditions during summer may accelerate disintegration and cause rapid sinking. We used the bull kelp Durvillaea antarctica from northern-central Chile (30°S) to test seasonal variation in floating persistence. Experiments with tethered specimens were conducted in all seasons to assess how variable environmental conditions influence the morphology and photosynthetic characteristics of floating D. antarctica. Floating specimens stayed afloat at the surface for more than 1 month during moderate environmental conditions that prevailed in winter, spring, and fall. However, higher water temperatures and intense solar radiation in summer resulted in significant biomass losses and rapid disintegration of the floating kelps; consequently, they sank within <1 month. These strong seasonal effects were reflected in decreasing maximal quantum yield as well as in maximum relative electron transport rates of photosynthesis. Understanding physiological responses of floating algae is important because increasing global temperatures and shifts in solar radiation may strongly affect the survival of floating algae, potentially reducing the distances and frequencies of rafting dispersal.

Shaded pavements in the urban environment – a case study

This article presents a study on the surface temperature of three types of pavements in urban environments with and without vegetation, located in the city of Passo Fundo, Rio Grande do Sul, Brazil. Some of the assessed pavements are exposed to direct sunlight, and some others are in the shade. We estimate the reduction of their surface temperature when shaded by trees. The method used was numerical modeling, including verification measurements. The pavement made from open cell concrete blocks filled with vegetation had a thermal performance similar to the grass, making it an ideal surface for use in adjacent areas to passages (street side and adjacent sidewalk). The shading influence of the dense canopy trees on the surface temperature of the floor exposed to solar radiation in summer was significant, 9°C and 10°C. Its use is recommended in urban environments.