Oxygen Concentration In Water Research Articles

How do natural and socio-economic factors influence the sustainable development of the ecological environment in the World Natural Heritage Sites? Evidence from the Jiuzhaigou, China

With the rapid development of tourism in the World Natural Heritage Sites (WNHSs), it made ecological environment issues increasingly become prominent while boosting regional economic development. Exploring the influence and evolution of natural and socio-economic factors will help to maintain the authenticity and integrity of the WNHSs, and promote sustainable development. Here, to better understand the sustainable development situation of the WNHSs, we construct a nature-society-based comprehensive evaluation framework, and combining the remote sensing-based ecological index (RSEI) with the spatial autocorrelation model, and employed the obstacle factor diagnostic model, to reveal the spatial–temporal characteristics and the key driving factor of ecological environment in the Jiuzhaigou. Meanwhile, we assess the integrated ecological sensitivity of the Jiuzhaigou and determine the key conservation area. Through the analysis of results, we find that RSEI from 2013 to 2020 exhibits a fluctuation trend resembling an ”N-shape”, high RSEI points tend to cluster in the southern part of the study area, while low RSEI points cluster in the northern part, it has a significant spatial heterogeneity. We shed further light on that when the number of tourists exceeds the population carrying capacity of the heritage site, the negative impacts of tourism development on the natural environment will outweigh the positive impacts of tourism revenue growth on regional economic development and constrain the sustainable development of the site as a whole. Specifically, dissolved oxygen concentration in water, nitrogen dioxide concentration, and noise are the main drivers of nature. The proportion of tertiary industry, fixed asset investment, and total tourism consumption are the main drivers of society. Furthermore, the ecological sensitivity of Jiuzhaigou is moderately low. Therefore, we suggest that the government should improve and refine the existing disaster early warning mechanism, dynamically adjust and control the number of tourists received per day, harmonize the relationship between economic development and environmental protection, and strengthen the protection of authenticity and integrity in areas of high ecological sensitivity.

Understanding how high stocking densities and concurrent limited oxygen availability drive social cohesion and adaptive features in regulatory growth, antioxidant defense and lipid metabolism in farmed gilthead sea bream (Sparus aurata).

The study combined the use of biometric, behavioral, physiological and external tissue damage scoring systems to better understand how high stocking densities drive schooling behavior and other adaptive features during the finishing growing phase of farmed gilthead sea bream in the Western Mediterranean. Fish were grown at three different final stocking densities (LD, 8.5kg/m3; MD, 17kg/m3; HD, 25kg/m3). Water oxygen concentration varied between 5 and 6ppm in LD fish to 3-4ppm in HD fish with the summer rise of water temperature from 19°C to 26°C (May-July). HD fish showed a reduction of feed intake and growth rates, but they also showed a reinforced social cohesion with a well-defined endogenous swimming activity rhythm with feeding time as a main synchronization factor. The monitored decrease of the breathing/swimming activity ratio by means of the AEFishBIT data-logger also indicated a decreased energy partitioning for growth in the HD environment with a limited oxygen availability. Plasma glucose and cortisol levels increased with the rise of stocking density, and the close association of glycaemia with the expression level of antioxidant enzymes (mn-sod, gpx4, prdx5) in liver and molecular chaperones (grp170, grp75) in skeletal muscle highlighted the involvement of glucose in redox processes via rerouting in the pentose-phosphate-pathway. Other adaptive features included the depletion of oxidative metabolism that favored lipid storage rather than fatty acid oxidation to decrease the oxygen demand as last electron acceptor in the mitochondrial respiratory chain. This was coincident with the metabolic readjustment of the Gh/Igf endocrine-growth cascade that promoted the regulation of muscle growth at the local level rather than a systemic action via the liver Gh/Igf axis. Moreover, correlation analyses within HD fish displayed negative correlations of hepatic transcripts of igf1 and igf2 with the data-logger measurements of activity and respiration, whereas the opposite was found for muscle igf2, ghr1 and ghr2. This was indicative of a growth-regulatory transition that supported a proactive instead of a reactive behavior in HD fish, which was considered adaptive to preserve an active and synchronized feeding behavior with a minimized risk of oxidative stress and epidermal skin damage.

The removal of ammonia-nitrogen from aquaculture water based on cavitation effect of ultrasonic vibration

This paper mainly studies the mechanism and efficiency of ammonia-nitrogen removal from circulating sewage in closed fish tank system. According to some factors affecting the removal efficiency (ultrasonic power, ultrasonic time and water oxygen concentration). Simulated circulating sewage mixed with oxygen through a venturi tube and then entered a closed experiment box for ultrasonic experiments. Finally, the removal efficiency was determined by Knott's reagent photometry. In the experiment, the PH value of the simulated sewage was 7.5, the indoor water temperature was 20 °C, and the free ammonia was selected as 0.02 mg/L (total ammonia-nitrogen was 1.6 mg/L) according to the standard. The experiment found that when the ultrasonic power is 400 W, the action time is 2 h, and the oxygen concentration of water is 23.8 mg/L, the efficiency of removing ammonia-nitrogen in water is about 65 %. When applied on fishing vessels, increasing the power can increase the removal efficiency.

Shale Gas: An Undepletable Energy Resource

Water is aptly described as the mother of life. It contains one oxygen and two hydrogen atoms connected by covalent bonds. Oxygen remains dissolved in water. All aquatic organisms depend on the dissolved oxygen for the respiration. Dissolved oxygen (DO) is a measure of how much oxygen in the water- the amount of oxygen available to living aquatic organisms. The present work mainly concentrates the comparative study of Dissolved oxygen content in different water samples. The Dissolved oxygen content in the river water is 5.071 mg/lr, rain water is 4.226 mg/lr, sea water is 3.099 mg/lr, well water is 2.817 mg/lr, tap water is 1.972 mg/lr, pond water is 0.845 mg/lr and the sewage water is 0.282 mg/lr. In the present study the Dissolved oxygen content in river water is higher when compared to other water samples and the Dissolved oxygen content in sewage water is very low when compared to other water samples. Key Words: Dissolved oxygen, Aquatic organisms, Water samples, River water, Sewage water.

Sedimentary molybdenum and uranium cycling under seasonally contrasting redox conditions on the Namibian Shelf

Sedimentary molybdenum (Mo) and uranium (U) enrichments have been widely used as a proxy for redox conditions in oxygen-depleted marine paleo-environments. However, in a dynamic upwelling system the seasonal fluctuations from oxic to completely anoxic-sulfidic bottom waters and lateral sediment transport can modify the primary Mo and U signal of the sediment, which in turn may impact paleo-redox interpretations. In this study we present pore water and solid phase data collected at two cross shelf transects during the ‘more oxygenated’ austral winter and ‘anoxic’ austral summer to study the influence of spatially and seasonally contrasting redox conditions on the formation of authigenic Mo and U enrichments in organic carbon (TOC) rich mud belt sediments on the Namibian shelf. A mass balance was established for each element based on diffusive fluxes and element mass accumulation rates to evaluate the respective mechanisms of trace metal delivery, accumulation and recycling.Mo is delivered to the sediment in its dissolved form via diffusion across the sediment–water interface, especially during austral summer when bottom waters are anoxic and surface sediments are highly sulfidic. In the center of the inner shelf mud belt, the benthic Mo fluxes of up to 37 nmol cm−2 yr−1 into sulfidic surface sediments are the highest ever reported for reducing sulfidic systems and agree with the rate of Mo accumulation in the solid phase. Concurrently, high sedimentation rates and low terrigenous input limit solid phase Mo accumulation on the Namibian shelf. In ancient marine sediments, this mode of Mo cycling can be identified by low Mo/TOC ratios of ∼2 similar to those found in sediments deposited below the perennial oxygen minimum zone on the Peruvian shelf and to those found in deposits of the Cretaceous Oceanic Anoxic Event 2. Diffusive U fluxes into the sediment are generally too low to account for the sedimentary enrichment leading to the conclusion that U is delivered mainly in particulate form. In areas with anoxic bottom water, shallow dissolved U maxima directly below the sediment water interface and rather low sedimentary U content indicate that particulate U is recycled and largely released back into the bottom water. At sites where bottom water oxygen concentrations vary from anoxic to completely oxic on seasonal timescales, the depth at which Mo and U are removed from pore waters moves vertically within the sediment column thus defining a layer between the sediment surface and ∼20 cm depth, in which Mo and U accumulate in the solid phase. Our results emphasize the importance of short-term redox fluctuations in the bottom waters and underlying sediments, as well as lateral sediment transport for the authigenic enrichment of redox-sensitive trace metals in reducing shelf sediments. The relative enrichment patterns identified might be useful for the reconstruction of open marine anoxia in the geological past.

Distribution of modern benthic foraminiferal assemblages across the Northeast Greenland continental shelf

Analysis of benthic foraminifera in surface samples from 23 sites on the Northeast Greenland continental shelf reveal key assemblage differences between sites. Cluster analysis creates two clear geographical faunal assemblage zones: the 1) inner shelf, and 2) mid and outer shelf sites. These assemblages differ significantly, with the inner shelf sites being characterised by a high percentage and concentration of calcareous species, whilst the mid and outer shelf sites are dominated by agglutinated taxa. At almost all sites, the calcareous assemblages are dominated by Cassidulina neoteretis and Cassidulina reniforme, suggesting that they thrive across the shelf. Stetsonia horvathi, Oridorsalis tener, as well as Glomulina oculus and other miliolid species are found to be key calcareous species at many sites in the inner shelf zone, but they are rare-to-absent on the mid and outer shelf. Canonical correspondence analysis shows that September sea-ice cover and bottom water oxygen content are positively correlated with benthic foraminiferal assemblages at inner shelf sites, whereas organic carbon content is correlated with those in the mid and outer shelf. The formation of seasonal sea-ice and the Northeast Water polynya rejects brine into surrounding waters and transports CO2 to the seafloor, creating a highly corrosive environment for calcium carbonate. These environments are also highly productive, as indicated by the high organic carbon content and low bottom water oxygen content. The oxidation of this organic material creates CO2. We propose that these processes are key drivers in the dissolution of calcareous tests. In contrast, extensive sea-ice, high bottom water oxygen content and low primary productivity in the glacier-proximal region facilitates carbonate preservation.

Spatial and Seasonal Variations in Dissolved Methane Across a Large Lake

AbstractLakes process large volumes of organic carbon (OC), are important sources of methane (CH4), and contribute to climatic warming. However, there is a lack of data from large lakes >500 km2, which creates uncertainty in global budgets. In this data article, we present dissolved CH4, OC bioreactivity measurements, water chemistry, and algal biovolumes at 11 stations across Lake Mälaren, the third largest (1,074 km2) Swedish lake. Total phosphorus concentrations show that during the study period the lake was classed as mesotrophic/eutrophic. Overall mean CH4 concentration from all stations, sampled five times to cover seasonal variation, was 2.51 μg l−1 (0.98–5.39 μg l−1). There was no significant seasonal variation although ranges were greatest during summer. Concentrations of CH4 were greatest in shallow waters close to anthropogenic nutrient sources, whilst deeper, central basins had lower concentrations. Methane correlated positively with measures of lake productivity (chlorophyll a, total phosphorus), and negatively to water depth and oxygen concentration, with oxygen emerging as the sole significant driver in a linear mixed effects model. We collated data from other lakes >500 km2 (n = 21) and found a significant negative relationship between surface area and average CH4 concentration. Large lakes remain an understudied contributor to the global CH4 cycle and future research efforts should aim to quantify the spatial and temporal variation in their diffusive and ebullitive emissions, and associated drivers.

Multi-proxy reconstruction of climate changes in the Lower St. Lawrence Estuary, Canada, during the Middle and Late-Holocene

The micropaleontological and palynological content, and geochemical and isotopic composition of a marine sediment core collected off Pointe-des-Monts in eastern Québec, Canada, reveal regional palaeoclimatic and paleoceanographic conditions in the Lower St. Lawrence Estuary over the last ~8200 years. The pollen and spore content allows comparison with the terrestrial palynostratigraphy, whereas dinoflagellate cysts and benthic foraminifera are used to reconstruct sea-surface conditions and bottom water properties, respectively. The dinocyst-based reconstructions indicate shifts between estuarine and oceanic conditions with important changes in sea-surface temperature, salinity, and primary productivity. Both the dinocyst assemblages and the quantitative sea-surface estimates highlight a distinct transition at ca. 4200 cal years BP. It is notably marked by a change towards higher salinity, which suggests reduced freshwater discharge, hence lower precipitation in the watershed, during the Late-Holocene. The isotopic composition (δ18O and δ13C) and assemblages of the benthic foraminifera indicate centennial to millennial frequency variability of bottom water properties, over a general trend towards decreasing temperatures and increasing ventilation from the beginning of the Middle Holocene until the last century. Since then, reverse trends with abrupt warming and decreasing dissolved oxygen content in bottom water have been observed.

Research and Application of Airlift Pump to Operate Aquaponics

This paper presents the results of a study on the use of an airlift pump in aquaponics, a model that has been applied and developed for organic food production. Airlift pumps, which are commonly used in the mining industry for pumping liquids such as water and oil, have recently been adopted for use in aquaponics systems. Airlifts offer several advantages over other types of pumps, including a simple and compact design with no moving parts, making them suitable for hanging systems in shallow water. Airlifts also play a dual role in transporting liquids and saturating dissolved oxygen content in water, which is essential for the organisms in the aquaponics system to thrive. To promote these benefits, it is crucial to choose the correct mode of operation for the aeration pump; otherwise, it may decrease efficiency and increase operating costs. In this study, an airlift pump, which combines an aquaponic pump, aerator, and duct system into one compact unit, was used. The experiment was conducted using a riser pipe of different diameters (D = 24, 30, 36, 48 mm), a height (h + H) of 2000 mm, an air pipe with a diameter of 15 mm, compressed air pressure ranging from 0.5 to 4.0 kg/cm2, gas consumption (V) between 0.1 to 1.0 m3/h, and a pump capacity (Q) of 5-39 L/min. The results show that the greatest lifting height can be achieved with a riser pipe diameter of 30-36 mm. At an airflow rate of 0.8-0.9 m3/h and various compression pressures, the dip coefficient of 0.285 produces a maximum pumping capacity of 25-30 L/min.

Wastewater treatment with algal based membrane bioreactor for the future: Removing emerging contaminants

The difficulty of developing pollutants in aquatic ecosystems and their potential effects on animals and plants have been raised. Sewage effluent can seriously harm a river's plant and animal life by reducing the water's oxygen content. Due to their increasing use and poor elimination in traditional municipal wastewater treatment plants (WWTPs), pharmaceuticals are one of the developing pollutants that have the potential to penetrate aquatic ecosystems. Due to undigested pharmaceuticals and their metabolites, which constitute a significant class of potentially hazardous aquatic pollutants. Using an algae-based membrane bioreactor (AMBR), the primary objective of this research was to eliminate emerging contaminants (ECs) identified in municipal wastewater. The first part of this research covers the basics of growing algae, an explanation of how they work, and how they remove ECs. Second, it develops the membrane in the wastewater, explains its workings, and uses the membrane to remove ECs. Finally, an algae-based membrane bioreactor for removing ECs is examined. As a result, daily algal production using AMBR technology might range from 50 to 100 mg/Liter. These kinds of machines are capable of nitrogen and phosphorus removal efficiencies of 30–97% and 46–93%, respectively.

Environmental DNA in the Kuroshio reveals environment-dependent distribution of economically important small pelagic fish

IntroductionSmall pelagic fishes constitute large proportions of fisheries and are important components linking lower and higher trophic levels in marine ecosystems. Many small pelagic fishes in the Northwest Pacific spawn upstream in the Kuroshio and spend their juvenile stage in the Kuroshio Front area, indicating that the Kuroshio Current system impacts their stock fluctuations. However, the distribution of these fish relative to the Kuroshio has not been determined due to dynamic spatio-temporal fluctuations of the system. Here, the recent development of environmental DNA (eDNA) monitoring enabled us to investigate the distribution patterns of four economically important small pelagic fishes (Japanese sardine Sardinops melanostictus, Japanese anchovy Engraulis japonicus, chub mackerel Scomber japonicus, and blue mackerel Scomber australasicus) in the Kuroshio Current system. MethodsThe influence of environmental factors, such as sea water temperature, salinity, oxygen concentration, chlorophyll-a concentration, and prey fish on the occurrence and quantity of target fish eDNA was analyzed using generalized additive models. In addition, the detection (presence) of target fish eDNA were compared between the offshore and inshore side areas of the Kuroshio axis.ResultsSea water temperature showed important effect, especially on the distribution of Japanese sardine and Japanese anchovy, whereas the distribution pattern of chub mackerel and blue mackerel was greatly influenced by the eDNA quantity of Japanese sardine and Japanese anchovy (especially potential prey fish: Japanese anchovy). In addition, we found that the four target fish species could be observed in areas on the inshore side or around the Kuroshio axis, while they were hardly found on the offshore side.ConclusionBased on eDNA data, we succeeded in revealing detailed spatial distribution patterns of small pelagic fishes in the Kuroshio Current system and hypothesized predator–prey relationships influence their distribution in small pelagic fish communities.

The Middle-Upper Eocene benthic foraminifera from north-west Fayoum area, Egypt: Paleoecology and their similarity to the Tethyan provinces

This study deals with the Middle–Late Eocene benthic foraminiferal assemblage from the Um Rigl succession that is exposed in the northwest of Fayoum area, Egypt. Stratigraphically, two rock units are recognized from base to top as the Gehannam Formation and Birket Qarun Formation. The examination of benthic foraminiferal community identifies 63 species belonging to 36 genera, 22 families and four suborders. Their distribution aids to recognize one benthic foraminiferal biozone, Bulimina jacksonensis-Uvegerina jacksonensis Zone. To detect the paleocological conditions that prevailed during the deposition of the studied succession, a quantitative analysis is done on the foraminiferal assemblage, including the number of taxa, the relative abundances of the recorded suborders, calcareous species, agglutinated species and common species. The morphology of benthic foraminiferal tests is strongly associated with their microhabitat preferences. Therefore, the percentages of epifaunal and infaunal species are also calculated to detect the level of oxygenation. Accordingly, two ecozones are established, ecozone 1 represents the Gehannam Formation, whereas ecozone 2 represents the Birket Qarun Formation (excluding the barren zone in the upper part). Ecozone 1 is dominated by calcareous species (90–100%) and infaunal species (38–99%), while epifaunal species range from 2 to 62%. The most abundant taxa are Bolivina, Bulimina, Uvigerina, Nonion and Lenticulina. Therefore, the ecozone 1 was deposited under an inner-outer neritic environment, with normal salinity and eutrophic to mesotrophic conditions. On the other side, ecozone 2 is characterized by changes in the composition of foraminiferal assemblage, where infaunal species dominate the base of this ecozone, followed by a strong decline in the middle part and then increase again in the upper part. Also, a notable increase in epifaunal species is documented in this ecozone. This variation in foraminiferal assemblage reflects changes in water depth and oxygen content. Consequently, ecozone 2 was deposited under an inner to middle neritic environment, with normal salinity and mesotrophic to oligotrophic conditions. Regarding the paleobiogeographic outline, the results of multivariate analyses indicate that the Egyptian species show a strong similarity to those from the Southern Tethyan Province (Tunisia and Libya), whereas they show a reasonable similarity to the Western Tethyan Province (Spain, Italy, France). This deduction reflects a probable marine connection between both provinces during Eocene.

The effects of sodium sulfite on Helicobacter pylori by establishing a hypoxic environment

Helicobacter pylori (H. pylori) is an obligate microaerobion and does not survive in low oxygen. Sodium sulfite (SS) reacts and consume oxygen in solutions. The present study aimed to investigate the effects of SS on H. pylori. The effects of SS on oxygen concentrations in solutions and on H. pylori in vivo and in vitro were examined, and the mechanisms involved were explored. The results showed that SS decreased the oxygen concentration in water and artificial gastric juice. In Columbia blood agar and special peptone broth, SS concentration-dependently inhibited the proliferation of H. pylori ATCC43504 and Sydney strain-1 in Columbia blood agar or special peptone broth, and dose-dependently decreased the number of H. pylori in Mongolian gerbils and Kunming mouse infection models. The H. pylori was relapsed in 2 weeks withdrawal and the recurrence in the SS group was lower than that in the positive triple drug group. These effects were superior to positive triple drugs. After SS treatments, the cell membrane and cytoplasm structure of H. pylori were disrupted. SS-induced oxygen-free environment initially blocked aerobic respiration, triggered oxidative stress, disturbed energy production. In conclusion, SS consumes oxygen and creates an oxygen-free environment in which H. pylori does not survive. The present study provides a new strategy and perspective for the clinical treatment of H. pylori infectious disease.

Pre-aeration promotes nutrient removal in a pilot-scale duckweed-based pond by influencing the duckweed growth and bacterial community

Duckweed-based ponds (DPs) are widely used to treat wastewater due to the rapid growth and high-value biomass of duckweed. However, their performance at nutrient removal is restricted by low dissolved oxygen (DO) concentrations in pond water, and direct aeration of a DP is impracticable because floating duckweed is vulnerable to interference by bubbles. Thus, we developed an influent pre-aeration treatment process for a DP and investigated its effect on the DO concentration and performance of the pilot-scale (12 m2) DP, as well as the underlying mechanism over a 9-month period. Pre-aeration increased the DO concentration (by 478 %) and oxidation reduction potential (by 55 %) in pond water, and promoted duckweed growth (by 33 %) and total phosphorous, total nitrogen, and NH4+-N removal (by 84 %, 80 %, and 91 %, respectively). It also increased the contributions of microorganisms to nitrogen and phosphorous removal (13.37 % and 35.52 % greater, respectively), indicating that it had greater beneficial effects on microorganisms than on duckweed. In the bacterial community, pre-aeration likely promoted nutrient removal by improving the growth and activity of bacterial assemblages involved in nutrient cycling (e.g., Rhodopseudomonas, Cloacibacterium, Candidatus_Limnoluna, and Novosphingobium in pond water), and by improving duckweed growth by altering the relative abundances of bacterial assemblages attached to duckweed. These findings help clarify the beneficial effects and mechanisms of influent pre-aeration, providing a new insight into the improvement and application of DPs.

Identification of high oxygen-consuming substances in stormwater drainage systems illicitly connected with sewage system

The dissolved oxygen content in water is an important indicator for assessing the quality of the water environment, and maintaining a certain amount of dissolved oxygen is essential for the healthy development of the ecological environment. When a water body is anoxic, the activity of anaerobic microorganisms increases and organic matter is decomposed to produce a large number of blackening and odorizing substances, resulting in black and odorous water bodies, which is a very common and typical phenomenon in China. Presently, there is still a relatively universal occurrence of illicitly connected stormwater and sewage pipes in the urban drainage pipe network in China, which makes oxygen-consuming substances be directly discharged into rivers through stormwater pipes and consume the dissolved oxygen in the water bodies, resulting in an oxygen deficiency of the water. This induces seasonal or year-round black and stink phenomena in urban rivers. Hence, identifying high oxygen-consuming substances, which lays the foundation for the subsequent removal of oxygen-consuming substances, is essential. Through a series of comparisons of water quality indicators and analysis of organic characteristics, it was found that the oxygen consumption capacity of domestic sewage was higher than that of industrial wastewater in the selected area of this study, and the oxygen-consuming substances of domestic sewage were small molecular amino acids. By comparing 20 conventional free amino acids, it was found that seven of them consumed oxygen easily, and compared with chemical oxygen consumption, biological oxygen consumption was in a leading position.

The Late Miocene‐Early Pliocene Biogenic Bloom: An Integrated Study in the Tasman Sea

AbstractThe Late Miocene‐Early Pliocene Biogenic Bloom (∼9–3.5 Ma) was a paleoceanographic phenomenon defined by anomalously high accumulations of biological components at multiple open ocean sites, especially in certain regions of the Indian, and Pacific oceans. Its temporal and spatial extent with available information leaves fundamental questions about driving forces and responses unanswered. In this work, we focus on the middle part of the Biogenic Bloom (7.4–4.5 Ma) at International Ocean Discovery Program Site U1506 in the Tasman Sea, where we provide an integrated age model based on orbital tuning of the Natural Gamma Radiation, benthic foraminiferal oxygen isotopes, and calcareous nannofossil biostratigraphy. Benthic foraminiferal assemblages suggest changes in deep water oxygen concentration and seafloor nutrient supply during generally high export productivity conditions. From 7.4 to 6.7 Ma, seafloor conditions were characterized by episodic nutrient supply, perhaps related to seasonal phytoplankton blooms. From 6.7 to 4.5 Ma, the regime shifted to a more stable interval characterized by eutrophic and dysoxic conditions. Combined with seismic data, a regional change in paleoceanography is inferred at around 6.7 Ma, from stronger and well‐oxygenated bottom currents to weaker, oxygen‐depleted bottom currents. Our results support the hypothesis that the Biogenic Bloom was a complex, multiphase phenomenon driven by changes in ocean currents, rather than a single uniform period of sustained sea surface water productivity. Highly resolved studies are thus fundamental to its understanding and the disentanglement of local, regional, and global imprints.

Cause Analysis of Extreme High Temperature Weather in Nanjing in 2022 and Its Impact on Crab Breeding in the Gucheng Lake Waters

In 2022, extreme high temperature weather occurred in Nanjing, which had a great adverse impact on aquaculture such as crabs in the waters of Gucheng Lake in Nanjing. This study analyzes the temperature situation in Nanjing in August 2022 through field survey and literature research, and compares it with the weather in the same period in history. Through the analysis of the background of global warming and the study of the atmospheric circulation during the abnormal high temperature weather, the causes of the abnormal high temperature weather in Nanjing are revealed; Study the adverse effects of high temperature weather on water temperature and oxygen content, aquatic organisms, and aquaculture, especially crab aquaculture in Gucheng Lake, and put forward corresponding countermeasures.

Reconstructing ocean oxygenation changes from U/Ca and U/Mn in foraminiferal coatings: Proxy validation and constraints on glacial oxygenation changes

Deep-sea oxygen concentrations reflect combined effects of air-sea exchange in high-latitude surface waters, ventilation through ocean circulation and the organic carbon remineralization at depth. Reconstruction of past bottom water oxygen (BWO) concentrations has been challenging due to limitations of each existing BWO proxy whose fidelity may be complicated by diagenetic or depositional factors. Therefore, evaluations on BWO changes with multi-proxy approach are always preferred. In this study, we exploit the authigenic uranium content on mixed planktonic foraminiferal coatings as a BWO proxy by presenting new foraminiferal U/Ca and U/Mn ratios of the Holocene and last glacial maximum (LGM) sediments from 54 sites throughout the Pacific Ocean, covering a range of modern BWO from 8 to 210 μmol/kg. Distinct correlation between Holocene foraminiferal U/Ca and U/Mn with BWO is observed in the modern Pacific Ocean, which has not been obscured by other complicating factors such as sedimentation rate and organic carbon flux. Based on the comparison of our foraminiferal U/Ca and U/Mn ratios between the Holocene and LGM and existing redox proxy data, we provide new constraints on Equatorial and South Pacific oxygenation changes during the LGM. First, the boundary between better oxygenated upper ocean and less oxygenated deeper ocean in the Eastern Equatorial Pacific was limited to a narrower water depth range between ∼0.6 and 0.7 km surrounding the Panama Basin. Second, our data imply better oxygenation in the upper and bottom waters of the Pacific Ocean and mid-depth deoxygenation, which contrasts with findings in the deep Atlantic and Indian Oceans. After excluding influences from other factors such as sedimentation rates and productivity, our study demonstrates foraminiferal U/Ca and U/Mn provide a useful proxy for BWO reconstruction in the Pacific, thus helping to constrain the glacial-interglacial oceanic carbon cycle.

Combined effect of physico-chemical and microbial quality of breeding habitat water on oviposition of malarial vector Anopheles subpictus.

Mosquitoes prefer diverse water bodies for egg laying and larval survival. Present study was performed with an objective to characterize physico-chemical properties and microbial profiling of breeding habitat water bodies of Anopheles subpictus mosquitoes. A field survey was accomplished to check the presence of An. subpictus larvae to record per dip larval density in various breeding habitats throughout the year. Physico-chemical and bacteriological properties in relation to mosquito oviposition were assessed. Dissolved oxygen content, pH and alkalinity were found to have major impacts and ponderosity on the prevalence of An. subpictus larvae. Larval density showed significant positive correlation with dissolved oxygen content of water and significant negative correlation with pH and alkalinity of habitat water. Comparatively higher population (cfu/mL) of Bacillus spp. competent with starch hydrolyzing and nitrate reducing properties were recorded all the breeding habitat water bodies of An. subpictus. Higher amplitude of anopheline larvae was portrayed during monsoon and post-monsoon season in clear water with an inclining trend to high dissolved oxygen content and neutral pH. B. cereus, B. megaterium, B. subtilis and B. tequilensis prevalent in all habitat water bodies were marked as oviposition attractants of gravid An. subpictus mosquitoes. Microbial population played key roles in the modulation of physico-chemical parameters of habitat water with a view to enhance its acceptability by gravid mosquitoes in relation to their oviposition. Better understanding of the interactions along with the control of oviposition attractant bacterial strains from mosquito breeding habitats might contribute to the vector management programme.

Development of a new design of deironing granulated filter for joint removal of iron and ammonium nitrogen from underground water

ABSTRACT Providing the population with high-quality drinking water is one of the main state tasks. Rural water supply systems and water supply systems of small settlements in the region require special attention, namely, the development of technologies for individual, small-sized water treatment equipment, as well as equipment for collective use, designed to purify groundwater for drinking purposes. In many areas, there are groundwaters containing excess levels of several pollutants, which makes their purification much more difficult. Elimination of shortcomings in the known methods of water iron removal is possible by reconstructing existing water supply systems from underground sources in small settlements. A rational solution is to search for groundwater treatment technologies that make it possible to provide the population with high-quality drinking water at a lower cost. The result of increasing the concentration of oxygen in water was obtained in the process of modifying the filter by changing the excess air exhaust system, which was made in the form of a perforated pipeline located in the lower half of the granular filter layer connected to the upper branch pipe. At the same time, high-quality groundwater treatment, sufficient simplicity and reliability in operation are ensured, local conditions and the inaccessibility of many objects and settlements in the region are taken into account as much as possible. After the filter was upgraded, the concentration of iron decreased from 4.4 to 0.27 mg/L and ammonium nitrogen from 3.5 to 1.5 mg/L.