Seasonal Temperature Fluctuations Research Articles

Effect of Seasonality for Optimization of Germ Cell Extraction from Mature Blue Catfish

AbstractXenogenesis is an innovative tool for hybrid catfish (female Channel Catfish Ictalurus punctatus × male Blue Catfish I. furcatus) seed production, accomplished by transplanting undifferentiated germ cells derived from a donor diploid fish into a sterile recipient, which then enables recipient fish to produce donor‐derived gametes. There is potential to collect donor‐derived germ cells from mature fish during certain times of the year depending upon seasonal temperature and serum sex steroid hormonal fluctuations. The objective of this study was to evaluate seasonal variations in germ cell counts and serum sex steroid hormonal profiles in mature Blue Catfish. Mature fish were collected monthly over the full annual cycle to quantify the number of live germ cells (spermatogonia A, oogonia), viability of germ cells, and levels of serum sex steroid hormones, including testosterone, 11‐ketotestosterone, and 17β estradiol. Extracted spermatogonia A counts were highest from April to June, whereas a significant decline was detected from July to November. Extracted live oogonia counts were highest in April and gradually decreased to zero over the months of May to August. Seasonal variations in serum testosterone, 11‐ketotestosterone, and 17β estradiol followed a similar pattern as the live spermatogonia A and oogonia counts. Even though spermatogonia A counts were relatively lower in mature than in immature Blue Catfish males, extracting spermatogonia A from mature Blue Catfish males during April to June provides an added advantage to the process of artificial fertilization, as it is required to sacrifice these fish to collect sperm.

Dual-Mode Integrated Janus Films with Highly Efficient NaH2 PO2 -Enhanced Infrared Radiative Cooling and Solar Heating for Year-Round Thermal Management.

The currently available materials cannot meet the requirements of human thermal comfort against the hot and cold seasonal temperature fluctuations. In this study, a dual-mode Janus film with a bonded interface to gain dual-mode functions of both highly efficient radiative cooling and solar heating for year-round thermal management is designed and prepared. The cooling side is achieved by embedding NaH2 PO2 particles with high infrared radiation (IR) emittance into a porous polymethyl methacrylate (PMMA) film during pore formation process, which is reported for the first time to the knowledge. A synergistic enhancement of NaH2 PO2 and 3D porous structure leads to efficient radiant cooling with high solar reflectance (R̅solar ≈ 92.6%) and high IR emittance (ε̅IR ≈ 97.2%), especially the ε̅IR value is much greater than that of the reported best porous polymer films. In outdoor environments under 750 mW cm-2 solar radiation, the dual-mode Janus film shows subambient cooling temperature of ≈8.8 °C and heating temperature reaching ≈39.3 °C, indicating excellent thermal management capacity. A wide temperature range is obtained only by flipping the dual-mode Janus film for thermal management. This work provides an advanced zero-energy-consumption human thermal management technique based on the high-performance dual-mode integrated Janus film material.

Commercial Quality, Biological Indices and Biochemical Composition of Queen Scallop Aequipecten opercularis in Culture

Market demand for scallops has considerably increased in recent decades. Although natural populations of scallops are vulnerable, the queen scallop, Aequipecten opercularis, can represent a possible alternative to at-risk species. The aim of this study was to determine the effect of seawater parameters on the commercial quality, biological indices and nutritional quality of the scallop A. opercularis in 1900 L tanks in ex situ conditions. The condition index (CI) and meat yield (MY) peaked in autumn (89.92% and 40.29%, respectively). The muscle index (MI) showed the highest peak during the winter season (5.96%), while the gonadosomatic index (GSI) (34.06%) peaked in the spring months. Protein content (6.89–9.56 g/100 g), lipids (2.58–2.79 g/100 g) and carbohydrates (0.12–0.33 g/100 g) varied during the study period. Seasonal fluctuations in seawater temperature and pH negatively influenced the CI, MY and protein and lipid content, while positively affecting carbohydrate and moisture content. The most suitable period of the year for the consumption of the scallop A. opercularis was found to be the winter and spring periods, when the scallops achieved their highest nutritional value. It can be stated from this study that queen scallops in the Adriatic Sea have a high nutritional quality and that they can be proposed for higher human consumption.

Lime Hemp Concrete with Unfired Binders vs. Conventional Building Materials: A Comparative Assessment of Energy Requirements and CO2 Emissions

This work assesses the energy requirements and CO2 emissions of a building made of Lime Hemp Concrete (LHC) with alternative unfired binders as lime replacement, compared to buildings made of standard LHC, and several conventional building materials. The assessment is based on ISO 14040, which deals with Life Cycle Assessment (LCA), and examines two aspects: energy, including pre-use phase Embodied Energy (EE), and use phase Operational Energy (OE); and CO2 emissions, including pre-use phase Embodied Carbon (EC), and use phase Operational Carbon (OC). The EE and EC calculations are based on published databases, while OE and OC were obtained with EnergyPlus simulations. The assessment refers to a specific case study in an arid region, with extreme diurnal and seasonal fluctuations of temperature and relative humidity. Using LHC with 100% unfired binder as lime replacement was shown to save up to 90% of the total energy consumption and CO2 emissions, as compared to conventional building materials. The findings of this research clearly demonstrate the high potential of LHC with unfired binders as lime replacement, which possesses the lowest energy requirements and CO2 emissions, illustrating the potential for a building with significantly low environmental impact over its life cycle, i.e., when calculating both EE and EC, and OE and OC.

House-warming: Wild king cobra nests have thermal regimes that positively affect hatching success and hatchling size

Incubation temperature in nests of oviparous reptiles affects reproductive success indicators, including hatching time and success, offspring size, fitness, and behaviour. The female king cobra builds an above ground nest to incubate and protect its eggs. However, it is not clear how thermal regimes inside king cobra nests respond to external environmental temperature regimes, especially in subtropical regions that witness high diel and seasonal temperature fluctuations. To better understand the relationship between inside nest temperatures and hatching outcomes for this snake, we monitored the thermal regimes of 25 natural king cobra nests in the subtropical forests of the Western Himalayas in Uttarakhand state, northern India. We hypothesized that inside nest temperatures would be higher than outside (ambient) temperatures and that thermal regimes inside nests would affect hatching success and hatchling size. Internal and external temperatures at nest sites were measured every hour until hatching, via automatic data loggers. We then calculated hatching success of eggs and measured hatchling length and weight. Mean inside nest temperatures were consistently higher by about 3.0 °C than outside environmental temperatures. External temperature reduced with increasing elevation of nest sites and was the best determinant of inside nest temperature, which had a smaller range of variability. Physical characteristics of nests (size and leaf materials used) did not influence nest temperature significantly, but nest size was positively related to clutch size. Mean inside nest temperature was the best predictor of hatching success. Average daily minimum nest temperature, which indicates a possible lower threshold for thermal tolerance by eggs, was also correlated positively with hatching success. Mean daily maximum temperature was a significant predictor of mean length of hatchlings, but not of mean hatchling weight. Our study provides unequivocal evidence for the critical thermal benefits of king cobra nests for increased reproductive success, in subtropical environments with lower and sharply fluctuating temperature regimes.

Thermal conductivity of compacted Opalinus Clay at different degrees of saturation

Tunnelling in bedded shale rocks induces damage around the excavation. Consequently, the rock mass in the excavation damaged zone (EDZ) shows different thermo-hydro-mechanical (THM) properties from the intact rock. In turn, the damaged material close to the tunnel wall is affected by seasonal fluctuations in temperature and relative humidity (RH) variations associated with tunnel ventilation, impacting the total suction and the saturation state of the EDZ. The monitoring data at the new Swiss BelchenA2 highway tunnel excavated in Opalinus Clay (OPA) captured these seasonal variations in the total stressacting on the lining associated with this temperature and RH fluctuation. Within this context, assessing the temperature field in the EDZ requires determining the thermal conductivity of the damaged rock at different degrees of saturation. However, obtaining good-quality cores of OPA from the EDZ is not straightforward, and partially desaturating them using controlled RH techniques is time-consuming. Consequently, instead of testing damaged OPA, statically compacted samples of OPA powder at different degrees of saturation have been considered to study the thermal conductivity. In addition, two natural OPA samples (with different bedding orientations) retrieved from the Belchen tunnel have been tested to cross-check the experimental procedure and results, which indicated a consistent increase in thermal conductivity with the degree of saturation.

Monitoring of Seasonal Variations in Ground Temperature

The paper considers the problem of monitoring seasonal changes in soil temperature in northern and mountainous areas in the light of ongoing climate changes. To study seasonal changes in soil temperature, a model site of the Moscow State University Meteorological Observatory was used with the ability to monitor air temperature, snow cover thickness, and ground freezing temperature and depth, which was a prototype of a system for monitoring the state of permafrost soils used in the Arctic and mountain territories. The paper presents the results of monitoring seasonal changes in soil temperature based on the results of numerical modeling of the penetration of seasonal fluctuations in soil temperature in 2014-2017 in MATLAB environment at the model site of the MSU Meteorological Observatory. The results of numerical simulation of the penetration of seasonal temperature fluctuations in the ground at the MSU meteorological site in 2014-2017 in the MATLAB environment are in good agreement with the thermometry data and, therefore, the developed calculation scheme shows fairly good simulation results. This makes it possible to use the calculation scheme to assess the thermal state of frozen soils and assess the stability of foundations and buildings and linear structures located on them in the conditions of the North and mountainous territories. Therefore, the presented methodology can serve as a good help for monitoring and preventing the destruction of the studied structures in the conditions of climate warming.

Monitoring of seasonal variations in ground temperature at the observation site of Lomonosov MSU

The paper considers the problem of monitoring seasonal variations of ground temperature in northern and mountainous areas in the light of ongoing climate changes. To study seasonal variations of ground temperature, a model site of the Moscow State University Meteorological Observatory was used with the ability to monitor air temperature, snow cover thickness, and ground freezing temperature and depth, which was a prototype of a system for monitoring the state of permafrost soils used in the Arctic and mountain territories. The paper presents the results of monitoring seasonal variations of ground temperature based on the results of numerical modelling of the propagation of seasonal fluctuations of ground temperature in 2014-2017 in MATLAB environment which are in good agreement with the thermometry data and, therefore, the developed calculation scheme shows fairly good simulation results. This makes it possible to use the calculation scheme to assess the thermal state of frozen grounds and the stability of foundations and buildings and linear constructions located on them in the conditions of the North and mountainous territories. Therefore, the presented methodology can serve as a good help for monitoring and preventing the destruction of the observed structures in the conditions of climate warming.

The occurrence of the jellyfish Aequorea cf. forskalea in the Adriatic Sea

Jellyfish are becoming an increasingly important component of studies of the global marine environment, as their frequent mass phenomena affect ecosystem performance and have economic and health consequences. Recent research has focused primarily on mass occurrences of scyphozoans and ctenophores, while less attention has been paid to hydromedusae blooms, which can also have significant impacts on the marine ecosystem with economic consequences. Like many members of the Scyphozoa and Ctenophora, Aequorea species can be numerous and form blooms. Based on surveys from 2000 to 2020 and information provided by marine professionals, we examine the (multiannual) variability, seasonality, and spatial distribution patterns of the poorly studied temperate species Aequorea cf. forskalea (Hydrozoa: Leptothecata). We hypothesized that this macrogelatinous jellyfish with a bipartite life cycle (benthic polyps and planktonic medusae) is sensitive to seasonal and long-term temperature fluctuations, particularly because temperature has been shown to play a critical role in mediating transitions in the life cycle of cnidarians. The cold-water affinity of A. cf. forskalea was confirmed by a significant negative correlation with temperature and the most frequent occurrence during the winter-spring period. For the northern Adriatic (Gulf of Trieste), sea temperature data and semi-quantitative plankton data are available for the first decade of the 20th century, allowing comparison of the historical data (1900-1911) with our current data set. Compared to historical records, the current occurrence of A. cf. forskalea differs significantly. With the warming of the northern Adriatic Sea since the beginning of the 20th century, the current phenology of A. cf. forskalea has changed, probably related to the delayed production of medusae by hydroids in autumn, the absence of medusae in this season and their less frequent occurrence in winter.

Dynamic numerical investigation of the long-term performance of a GSHP system considering groundwater seepage and layered subsurface coupling conditions

This study presents a novel analytical model for ground source heat pump (GSHP) which comprehensively considers the dynamic interaction between building load, borehole heat exchanger (BHE) and heat pump unit, and the BHE under groundwater seepage and layered subsurface coupling conditions, as well as the impact of seasonal ground temperature fluctuation. The model achieved comprehensively reflect the influence of complex geological condition, interaction of unit system and seasonal fluctuation on GHSP performance. The model is utilized to simulate and analyze the long-term dynamic performance and the evaluation index (SCOP) is introduced to evaluate it, the results indicate that, after the 20 years of operation, the SCOP decreases by 9.1% from 4.81 to 4.37. Moreover, by analyzing the influence of load variation on outlet liquid temperature, it can find that the maximum value of the outlet temperature of the circulating fluid and the building cooling load appear at different times, with a difference of 44 days. Finally, the effect of seepage and seasonal ground temperature fluctuates on GSHP performance is investigated, the results reveal that the seepage effect is beneficial to it, and the seasonal ground temperature fluctuate will have an adverse effect on it.

One-Year Monitoring of a Ground Heat Exchanger Using the In Situ Thermal Response Test: An Experimental Approach on Climatic Effects

The use of renewable energies, and of geothermal energy in particular, is increasingly being applied in Germany and Europe for the development of new residential districts. The use of geothermal borehole heat exchangers (BHE), in combination with ground-source heat pumps (GSHP), represents an important part of shallow geothermal systems, which are used, among other systems, in urban areas due to their small space requirements. Over the course of planning BHE systems, performance must be determined via the parameters of thermal conductivity, thermal capacity, undisturbed ground temperature, and borehole thermal resistance. These can be identified by the experimental approach known as thermal response testing (TRT). The thermal parameters change due to the influences of the seasonal temperature fluctuations that take place in the ground. In this paper, a pilot double-U BHE heat exchanger field with a depth of 120 m was investigated from this perspective. TRT was carried out using monthly measurements taken over the period of one year using an electrically powered mobile TRT device. The evaluation of the individual tests was carried out using the line-source, moving-line-source, and cylinder-source theories. Our results show that the season in which TRT was implemented had an influence on the determined thermal parameters, with better thermal conditions being obtained in winter months. This is especially visible for thermal conductivity, with monthly deviations of 0.1 W/(m∙K), independent of the evaluation approaches used.

Paleophytogeography of the Siberian Paleofloristic Region in the Early Jurassic and First Half of the Middle Jurassic

The results of a comparative analysis of taphofloras of the Early Jurassic and first half of the Middle Jurassic of the Siberian paleofloristic region are considered. For this time interval, a significant similarity in the systematic composition of the taphofloras of Western Siberia and Northern China is revealed. Based on the author's data and the published data, the position of the boundary in the south and southwest of the Siberian paleofloristic region and the boundary between its West Siberian and North China provinces are corrected. The refined systematic composition of paleofloras, the constant presence of numerous remains of leaves of deciduous gymnosperms in the sediments, and the sedimentological features of flora-bearing strata taken together convincingly confirm the fact that the climate throughout the entire Siberian region in the Early Jurassic and first half of the Middle Jurassic was humid with seasonal fluctuations in temperature and humidity. The paleogeographic features of the northeast of the Siberian paleofloristic region are briefly considered.

Isotopic time-series (δ13C and δ18O) obtained from the columnar layer of Permian brachiopod shells are a reliable archive of seasonal variations

In this paper, we develop a robust palaeo-proxy technique for inferring seasonal fluctuations in Phanerozoic seawater temperature. Specifically, we report δ13C and δ18O values across the columnar layer (inner shell) of Permian brachiopods, including five genera of the Order Spiriferida (Ingellarella, Martinia, Permophricodothyris, Cartorhium, and Trigonotreta) and two genera of the Order Athyridida (Araxathyris and Comelicania). These brachiopod specimens are inferred to have inhabited varied palaeo-depths, based on facies analysis, and were collected from low, middle and high palaeolatitudes. To obtain high-resolution ontogenetic isotopic time-series, a handheld microdrill was used to collect low-magnesium calcite samples along the longitudinal axis of the mid-valve for each specimen. Intrageneric and intergeneric comparison of statistics (mean values, variance, and range) reveals that δ18O values are consistent within and between genera although δ13C values are more variable. In specimens obtained from low palaeolatitudes (Julfa Formation, Iran; Bellerophon Formation, Italy; Late Permian), the range of δ18O values is small and consistent with weak seasonal temperature variations, irrespective of water depth. In specimens obtained from middle palaeolatitudes (Qarari Formation, Oman; Early-Middle Permian), we found a range of δ18O values dependent on inferred water depth, possibly reflecting a change in thermocline structure between warm and cold seasons. In specimens obtained from high palaeolatitudes (Wasp Head and Wandrawandian Siltstone formations, Australia; Early-Middle Permian), brachiopods from glacial and interglacial climate phases show significant variations of δ18O values, probably caused by seasonal changes in the seawater surface temperature. Based on these findings, the technique developed in this paper appears to provide reliable paleoclimate and paleoenvironmental data for Permian sites, and should be also applicable for Phanerozoic studies in general. However, we caution that δ18O values vary dependent on the growth direction, resulting in differences of up to 5 °C in seawater paleotemperature calculations, and emphasise that a consistent sampling strategy accounting for shell structure and growth direction is required.

Geospatial alternatives for quantification of bio-thermal influence zone in the vicinity of a solid waste dump.

Owing to the release of toxic gases, leachate and thermal emissions that originate from waste dumps, these sites significantly impact environmental sustainability. The study attempts to assess the deleterious impact of municipal solid waste (MSW) dump on surrounding forested landscape by employing geospatial technologies, which are cost and time-effective. For this purpose, temporal period ranging from 2015 to 2020, having 41 valid satellite observations has been selected for study. Firstly, the radii of intense hazardous zone and hazardous zone have been measured, as two separate parameters, which are 580 ± 30 m and 1260 ± 30 m, respectively. Secondly, average spatial extent of bio-influence zone is measured to be 1262 m while the average thermal influence zone extends up to 530 m around the MSW dumping site. A detailed analysis of influence zone variations reveals that the bio-influence zone depends on multitude of meteorological parameters, whereas the thermal influence zone relies mainly on seasonal temperature fluctuations. Moreover, the level of severity of emissions from MSW decomposition directly depends upon temperature. The long-term variability analysis of these hazardous zones reveals the stationarity of their spatial extents, signifying forest resilience. This study has proved significance of geospatial techniques as an alternate of expensive and time intensive assessment methods involving in situ measurements. So the proposed technique is beneficial for environmentalists, decision-makers and municipal authorities for analysing the extent and severity of MSW pollutants for forest community to address the problem of ecological degradation.

THE IMPACT OF AGRO-CLIMATIC FACTORS ON THE PRODUCTIVITY OF AGRICULTURAL LANDS OF ORENBURG REGION

Currently, the shortage of fresh water is an important abiotic factor limiting the survival, growth and distribution of plants in semi-arid areas. The productivity of natural forage lands is influenced by seasonal fluctuations in temperature and precipitation, especially characteristic of the steppe Orenburg region. The uneven intra-annual distribution of precipitation does not meet the water needs of the phytocenosis in the vegetative phase of development. The aim of the study was to analyze the effect of atmospheric precipitation on agricultural forage lands of Orenburg region. An important and necessary task is to assess the interaction of agro-climatic factors on the development of agricultural land is an important and necessary task. The research area is located in a zone with a semiarid (semi-arid) climate of temperate latitudes of the Orenburg Urals of the Orenburg region (Orenburg region, Russia). Studies of agricultural land were carried out on 4 plots in the vicinity of the village of Nezhinka, Orenburg district, Orenburg region. For this purpose, various facies of agricultural lands located on the supports of watershed surfaces are identified and analyzed. To study local geosystems of various facies, we used camera methods, aerospace images and in-kind observations. Statistical and mathematical processing of digital data was carried out according to the StatsoftStatisticav 6.1 RUS program. Elements of descriptive statistics of average annual indicators (total precipitation per year, precipitation during the growing season, productivity of natural lands) revealed that the theory of normality was not rejected. The analysis of the average long-term data on the amount of precipitation and their relationship with the productivity of natural forage lands shows a reliable positive correlation between these parameters, at r2 = 0.95. In the conditions of the semi-arid zone during the growing season, plants use the moisture of atmospheric precipitation most effectively

Hydrologic Sensitivities and ENSO Variability Across Hydrological Regimes in Central Chile (28°–41°S)

AbstractThere is strong evidence of El Niño‐Southern Oscillation (ENSO) teleconnections in the South Pacific and related impacts on the precipitation regime in Chile; nonetheless, many aspects of the hydrological propagation and temperature responses to ENSO remain unclear in this region. We examine fluctuations across 59 near‐natural catchments in central Chile (28°–41°S) under contrasting ENSO phases during the period 1981–2019. Our results show statistically significant ENSO‐related hydroclimatic anomalies in almost all watersheds analyzed, which confirms the major influence of ENSO within this domain. By comparing El Niño phases against La Niña, we observe generally wetter conditions, warmer winters, cooler late springs, lower (higher) runoff ratios in snowmelt‐driven (rainfall‐driven) basins, and longer storm durations while storm frequencies (i.e., number of events of consecutive days with precipitation) are preserved. Additionally, low (high) elevation catchments are related to positive (negative) streamflow sensitivities to winter temperature, which increase in magnitude with the evaporative index; besides, catchments with sharp warm‐and‐dry conditions yield largely negative sensitivities to late spring temperature. Further, positive streamflow anomalies in rainfall‐driven catchments are explained by temperature and precipitation ENSO‐related amplitudes (El Niño minus La Niña) that separately favor streamflow; however, in mixed regimes and snowmelt‐driven basins these results are spatially scattered. Hence, this study supports that meteorological, hydrological, and physiographic attributes modulate the translation of climate variability into river hydrology. The results presented here unravel the joint effects of precipitation and seasonal temperature fluctuations through different hydrological regimes, across a region that encloses populated cities and water‐intensive activities.

Tritium transport in non-saturated concrete under temperature fluctuations

This work studies the effect of the environmental conditions on tritium transport in concrete cells storing radioactive waste. Water with high concentration of tritium was leaking from drains situated in these concrete cells, which indicates flow of water and tritium transport in these cells. 2D numerical models together with temperature and humidity measurements suggested that this leak of tritiated water is caused by a combination of thermo-hydraulic processes occurring in the unsaturated concrete, that comprise capillary rise from the groundwater, evaporation and condensation due to temperature gradients caused by seasonal temperature fluctuations outside. Following this conceptual model, numerical models have been developed to study the tritium transport in the concrete. Model results show that tritium concentration varies according to evaporation and condensation processes inside the concrete cell. An analysis of tritium fluxes revealed that differences in transport mechanisms in liquid and gas can cause concentration gradients of tritium in zones of high water content very different or even opposite to those in zones with low water content. From our numerical calculations, we conclude that there is no release of tritiated water to the groundwater.

Growth, lipids, proteins, and carotenoid contents of some freshwater green microalgae under simulated day/night temperature fluctuation

Day/night or seasonal temperature fluctuation is a major factor during outdoor cultivation of microalgae. In the present study, we investigated the impact of simulated day/night temperatures (20oC night and 30oC day) on the growth, lipid, protein and carotenoid contents of four local oleaginous microalgae strains under mixotrophic and heterotrophic conditions. The impact of simulated day/night temperatures on the growth and biochemical compositions varied across species and culture conditions (mixotrophic or heterotrophic). The lipid productivity by Dictyosphaerium sp. under heterotrophic condition was twice the value obtained at constant temperature but showed no significant (p > 0.05) impact under mixotrophic condition. Desmodesmus subspicatus elicited higher lipid (15%) and carotenoid (56%) contents under simulated day/night temperature regime than at constant temperature (30oC) (p<0.05). There was a negative impact on the protein content of the microalgal species under mixotrophic and heterotrophic conditions. The above results have shown that these species have high potentials for co-production of lipids, protein and carotenoid under outdoor conditions.

Recent Climatic Change Research in the Chukchi and Beaufort Seas Based on Numerical Simulation

This study analyses climatic changes in the Chukchi Sea and the Beaufort Sea based on numerical modeling using a regional ice-ocean model. Numerical experiments were carried out for the period 2000–2019. NCEP/NCAR reanalysis data were used to determine the ocean and sea ice surface fluxes. The temperature, salinity, and transport of Pacific waters entering the Arctic Ocean were specified as boundary conditions in the Bering Strait. Three types of boundary values were used for the experiments: a) monthly average climate data averaged over the period 1990–2003; b) monthly average climate data averaged over the period 2003–2015; c) average monthly measurement data since 2016 to 2019. The sensitivity of the model to the variability of the transport and temperature of the incoming Pacific waters was studied, and the effect on the ocean heat content, the volume and sea ice extent was analyzed.Numerical experiments simulate the transport of warm Pacific water across the Chukchi shelf in the north direction and onto the Beaufort Sea shelf, the process of warm water sinking on the continental slope in the autumn-winter period. In recent years, at the points on the boundary of the shelf and deep-water areas, the amplitude of seasonal temperature fluctuations in the surfacelayer increases and the temperature rises significantly at a depth of 100 m.The simulation results demonstrate an increase in the ocean heat content and decrease in the ice volume in the Beaufort and Chukchi Seas, caused by an increase in atmospheric temperature. We also showed that the increase in temperature and transport of the Pacific water, which began after 2003, contributed to an additional increase in the ocean heat content of both seas, a reduction in the ice cover area, and a delay in the ice formation in the Chukchi Sea.

Efficacy of a large-scale integrated constructed wetland for pesticide removal in tail water from a sewage treatment plant

The higher and higher detection frequencies of micro-pollutants such as pesticides in water are nowadays intensifying the investigation for strategies to provide effective engineering methods that could mitigate such substances. Traditional sewage treatment plants (STP) do not design specific processes for micro-pollutants removal in water. As an environmentally-friendly measure, some laboratory-scale wetlands have been proved to be effective in the removal of pesticides in water, but such studies are rarely carried out in large-scale wetlands, especially when they are adopted as a polishing step of STPs. Therefore, the further removals of micro-pollutants in tail water of STPs through the large-scale wetlands and the relevant removal mechanism are still knowledge gaps. In this study, 44 target pesticides were detected in the water of a large-scale integrated constructed wetland (ICW) for four seasons. The ICW was established to further process the tail water from a STP, whose drainage was from domestic sewage of local residents. There were 19, 16, 17, and 19 pesticides detected in spring, summer, autumn, and winter, respectively. The removal values for Σ19 pesticides ranged from 49.99% to 84.96% during the study period, and the removal of these pesticides followed significant seasonal trends, which was likely because the microorganisms responsible for biotic degradation were markedly influenced by seasonal temperature fluctuations. Proteobacteria, Chloroflexi, Acidobacteria, Planctomycetes, and Bacteroidetes were the dominant phyla, and might be associated with the biodegradation of organic pollutants in the ICW. Removal of pesticides by the ICW resulted in overall toxicity reductions in water, but butachlor and chlorpyrifos were still at non-ignorable ecological risks. This study highlights the potential of constructed wetlands for micro-pollutants removal in water as a polishing step in STPs.