Climate and Human-Driven Variability of Summer Hypoxia on a Large River-Dominated Shelf as Revealed by a Hypoxia Index

Coastal hypoxia has become common especially in large river dominated coastal ecosystems. To better quantify the severity of hypoxia and the contribution of hypoxia drivers, we applied principal component analysis (PCA) on observable properties from eight summer hypoxia events in the East China Sea and defined the first principal component as the hypoxia index (HI). Multiple linear regression showed that the HI significantly correlated with three direct hypoxia drivers including water column stratification, subsurface water residence time, and respiration rates, which accounted for 5.7, 55.3, and 34.5%, respectively, of the total variance of PCA derived HI. We further reconstructed the HI over the past 60 years using available long-term data of stratification, model-derived residence times and respiration rates. The results show that summer hypoxia has become more severe since the 1960s. ENSO and global warming may have exacerbated hypoxia by affecting the river discharge, resulting in freshening in the plume-impacted shelf area, while anthropogenic activities may have exacerbated hypoxia by elevating fluvial nutrient concentrations, resulting in higher respiration rates. In addition, warming of the bottom water from the Kuroshio Current accounts for an additional increasing rate for HI, which made hypoxia more severe by means of decreasing oxygen solubility. Overall, our results indicate that stratification, water residence and oxygen solubility resulting from climate change can explain about 80% while higher respiration resulting from higher nutrient inputs can explain about 20% of the variation in the severity of hypoxia during the past half century.

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Diatom- and Chironomid-Inferred Eutrophication of Bouchie Lake, British Columbia

Water Quality Research Journal ◽

10.2166/wqrj.2005.045 ◽

2005 ◽

Vol 40 (4) ◽

pp. 418-430 ◽

Cited By ~ 2

Author(s):

Markus L. Heinrichs ◽

Brian F. Cumming ◽

Kathleen R. Laird ◽

J. Sanford Hart

Keyword(s):

British Columbia ◽

Land Use Changes ◽

Head Capsule ◽

Relative Increase ◽

Nutrient Concentrations ◽

The Past ◽

Nutrient Levels ◽

Lower Head ◽

Lower Oxygen ◽

Historical Land Use

Abstract Diatom and chironomid analysis of sediments encompassing the past 400 years from Bouchie Lake, British Columbia, suggests two distinct periods of limnological conditions. Prior to 1950 AD, Fragilaria construens and F. pinnata are the most common diatom species, and Chironomus, Procladius and Tanytarsini dominate the chironomid record. Moderately low nutrient concentrations consistent with oligo-mesotrophic lakes are inferred. From 1950, the diatom assemblage is dominated by Stephanodiscus parvus, a eutrophic indicator, whereas the chironomid communities show a relative increase in littoral taxa coincident with lower head capsule abundance. Higher nutrient levels, specifically total phosphorus, which increased from 8 µg L-1 prior to 1950 to 20 µg L-1 currently, are coincident with midge communities indicative of lower oxygen concentrations. Observed biotic changes and nutrient levels inferred from the sediment core correspond to historical land-use changes.

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A European scale monitoring system to assess water quality of multi-national river basins in the accession countries

Water Science & Technology ◽

10.2166/wst.2003.0550 ◽

2003 ◽

Vol 48 (10) ◽

pp. 103-110 ◽

Cited By ~ 2

Author(s):

J. Fehér ◽

A. Lázár

Keyword(s):

Water Resources ◽

Subsurface Water ◽

Nutrient Concentrations ◽

Environmental Assessments ◽

Data Collecting ◽

Accession Countries ◽

Catchment Size ◽

Environment Agency ◽

Collecting System

In the middle of the 1990s the European Environment Agency (EEA) started to develop a data collecting system for surface and subsurface water resources for assessing pressures, states and impacts on European water resources. The main objective of this system was to provide reliable, comparable, homogenous information, and support integrated environmental assessments at European level. The data collecting system for water is called Eurowaternet. The extent and information content of the network makes not only pan-European, but also regional or thematic environmental assessments possible. An extensive programme started in 1997 to support the Phare countries in their accession to the EU with implementation of this data collecting system in their countries. The paper briefly introduces the methodology of the system, but it focuses more on the application of the system in the accession countries, highlighting, through examples, the usefulness of the implemented network and assembled database. The examples present - among several other possible ones - trends of average nutrient concentrations; relationships between catchment size and annual average nutrient concentrations; relationships between catchment size and agricultural usage.

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Research Trends of Biodegradation of Cooking Oil in Antarctica from 2001 to 2021: A Bibliometric Analysis Based on the Scopus Database

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18042050 ◽

2021 ◽

Vol 18 (4) ◽

pp. 2050

Author(s):

Khadijah Nabilah Mohd Zahri ◽

Azham Zulkharnain ◽

Suriana Sabri ◽

Claudio Gomez-Fuentes ◽

Siti Aqlima Ahmad

Keyword(s):

Bibliometric Analysis ◽

Anthropogenic Activities ◽

Drainage System ◽

The United States ◽

Waste Cooking Oil ◽

Oil Degradation ◽

Carcinogenic Effect ◽

Cooking Oil ◽

The Past ◽

Scopus Database

In the present age, environmental pollution is multiplying due to various anthropogenic activities. Pollution from waste cooking oil is one of the main issues facing the current human population. Scientists and researchers are seriously concerned about the oils released from various activities, including the blockage of the urban drainage system and odor issues. In addition, cooking oil is known to be harmful and may have a carcinogenic effect. It was found that current research studies and publications are growing on these topics due to environmental problems. A bibliometric analysis of studies published from 2001 to 2021 on cooking oil degradation was carried out using the Scopus database. Primarily, this analysis identified the reliability of the topic for the present-day and explored the past and present progresses of publications on various aspects, including the contributing countries, journals and keywords co-occurrence. The links and interactions between the selected subjects (journals and keywords) were further visualised using the VOSviewer software. The analysis showed that the productivity of the publications is still developing, with the most contributing country being the United States, followed by China and India with 635, 359 and 320 publications, respectively. From a total of 1915 publications, 85 publications were published in the Journal of Agricultural and Food Chemistry. Meanwhile, the second and third of the most influential journals were Bioresource Technology and Industrial Crops and Products with 76 and 70 total publications, respectively. Most importantly, the co-occurrence of the author’s keywords revealed “biodegradation”, “bioremediation”, “vegetable oil” and “Antarctic” as the popular topics in this study area, especially from 2011 to 2015. In conclusion, this bibliometric analysis on the degradation of cooking oil may serve as guide for future avenues of research in this area of research.

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An Introduction to Development of Centralized and Distributed Stochastic Approximation Algorithm with Expanding Truncations

Algorithms ◽

10.3390/a14060174 ◽

2021 ◽

Vol 14 (6) ◽

pp. 174

Author(s):

Wenxiao Zhao

Keyword(s):

Approximation Algorithm ◽

Stochastic Approximation ◽

Probabilistic Method ◽

Principal Component ◽

Stochastic Approximation Algorithm ◽

The Past ◽

Systems And Control ◽

Ode Method ◽

Centralized Algorithm ◽

And Control

The stochastic approximation algorithm (SAA), starting from the pioneer work by Robbins and Monro in 1950s, has been successfully applied in systems and control, statistics, machine learning, and so forth. In this paper, we will review the development of SAA in China, to be specific, the stochastic approximation algorithm with expanding truncations (SAAWET) developed by Han-Fu Chen and his colleagues during the past 35 years. We first review the historical development for the centralized algorithm including the probabilistic method (PM) and the ordinary differential equation (ODE) method for SAA and the trajectory-subsequence method for SAAWET. Then, we will give an application example of SAAWET to the recursive principal component analysis. We will also introduce the recent progress on SAAWET in a networked and distributed setting, named the distributed SAAWET (DSAAWET).

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Centennial mineral dust variability in high-resolution ice core data from Dome C, Antarctica

Climate of the Past ◽

10.5194/cp-8-609-2012 ◽

2012 ◽

Vol 8 (2) ◽

pp. 609-623 ◽

Cited By ~ 97

Author(s):

F. Lambert ◽

M. Bigler ◽

J. P. Steffensen ◽

M. Hutterli ◽

H. Fischer

Keyword(s):

High Resolution ◽

Southern Ocean ◽

Mineral Dust ◽

Ice Core ◽

Principal Component ◽

Dominant Factor ◽

Core Data ◽

The Past ◽

Dust Flux ◽

Soluble Calcium

Abstract. Ice core data from Antarctica provide detailed insights into the characteristics of past climate, atmospheric circulation, as well as changes in the aerosol load of the atmosphere. We present high-resolution records of soluble calcium (Ca2+), non-sea-salt soluble calcium (nssCa2+), and particulate mineral dust aerosol from the East Antarctic Plateau at a depth resolution of 1 cm, spanning the past 800 000 years. Despite the fact that all three parameters are largely dust-derived, the ratio of nssCa2+ to particulate dust is dependent on the particulate dust concentration itself. We used principal component analysis to extract the joint climatic signal and produce a common high-resolution record of dust flux. This new record is used to identify Antarctic warming events during the past eight glacial periods. The phasing of dust flux and CO2 changes during glacial-interglacial transitions reveals that iron fertilization of the Southern Ocean during the past nine glacial terminations was not the dominant factor in the deglacial rise of CO2 concentrations. Rapid changes in dust flux during glacial terminations and Antarctic warming events point to a rapid response of the southern westerly wind belt in the region of southern South American dust sources on changing climate conditions. The clear lead of these dust changes on temperature rise suggests that an atmospheric reorganization occurred in the Southern Hemisphere before the Southern Ocean warmed significantly.

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Geochemical and statistical evaluation of groundwater in the Thamirabarani river basin, south India

10.21203/rs.3.rs-163816/v1 ◽

2021 ◽

Author(s):

Gajendran Chellaiah ◽

Basker ◽

Hima Pravin ◽

Suneel Kumar Joshi ◽

Sneha Gautam

Keyword(s):

River Basin ◽

Tamil Nadu ◽

Statistical Evaluation ◽

Anthropogenic Activities ◽

Monsoon Season ◽

Principal Component ◽

Chloride Ion ◽

Temporal Analysis ◽

Point Sources ◽

International Standards

Abstract In the present study, an attempt has been made to develop the dictate metrics using a multi-proxy approach, i.e., spatial-temporal analysis, statistical evaluation, and hydrogeochemical analysis for 45 water samples located in the Thamirabarani river basin in Tamil Nadu, India. In order to evaluate the aptness of developed metrics for agriculture and domestic needs, eleven years dataset was analyzed and compared with national and international standards. Monitoring and analysis results revealed that the concentration of calcium and chloride ion was on the higher side in all the selected locations. These higher values may be attributed to the regional point sources such as untreated water disposal and off-peak sources such as agriculture practices. The principal component analysis resulted in 84.2% of the total variance in the post-monsoon season dataset. The major analyzed cations and anions were observed in the following order: Na+> Ca2+> Mg2+> K+ and Cl−> HCO3−> SO42−> NO3−, respectively. Overall, this study revealed that the studied area's groundwater quality was significantly affected by the high salinity in the region, probably due to anthropogenic activities and unprotected river sites.

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Hydrology controls recruitment of two invasive cyprinids: bigheaded carp reproduction in a navigable large river

PeerJ ◽

10.7717/peerj.3641 ◽

2017 ◽

Vol 5 ◽

pp. e3641 ◽

Cited By ~ 10

Author(s):

Daniel K. Gibson-Reinemer ◽

Levi E. Solomon ◽

Richard M. Pendleton ◽

John H. Chick ◽

Andrew F. Casper

Keyword(s):

Mississippi River ◽

Silver Carp ◽

Monitoring Program ◽

Large River ◽

Asian Carp ◽

Bighead Carp ◽

Illinois River ◽

Hypophthalmichthys Molitrix ◽

The Past ◽

Causative Factors

In the Mississippi River Basin of North America, invasive bigheaded carp (silver carpHypophthalmichthys molitrixand bighead carpH. nobilis, also referred to as Asian carp) have spread rapidly over the past several decades. In the Illinois River, an important tributary of the Upper Mississippi River, reproduction appears to be sporadic and frequently unsuccessful, yet bigheaded carp densities in this river are among the highest recorded on the continent. Understanding the causative factors behind erratic recruitment in this commercially-harvested invasive species is important for both limiting their spread and managing their harvest. We analyzed weekly catch records from 15 years of a standardized monitoring program to document the emergence of age-0 bigheaded carp in relation to environmental conditions. The appearance of age-0 fish was generally linked to hydrographic attributes, which probably serve as a cue for spawning. However, we found profound differences in the number of age-0 fish among years, which varied by as much as five orders of magnitude in successive years. The strong link between summer flooding and age-0 fish production we observed emphasizes the importance of understanding the hydrologic context in which sustained invasions occur. Despite evidence of sporadic recruitment, bigheaded carp populations in the Illinois River appear to be consistent or increasing because of particularly strong, episodic year classes.

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The site Vavilino 1 on the right bank of the Derkul River in Western Kazakhstan (materials of 2018)

Samara Journal of Science ◽

10.17816/snv201983209 ◽

2019 ◽

Vol 8 (3) ◽

pp. 166-173

Author(s):

Talgat Basarbaevich Mamirov

Keyword(s):

Anthropogenic Activities ◽

Past Century ◽

Stone Age ◽

Cultural Layer ◽

Stone Artifacts ◽

The Past ◽

Western Kazakhstan ◽

The Right ◽

Bone Remains ◽

Excavation Area

The paper is devoted to preliminary data from a study of the Vavilino 1 site in Western Kazakhstan. The monument was first opened by N.M. Malov in 1986, later he picked artifacts from the surface in 1988. In 1991 N.L. Morgunova carried out excavations on the site, which showed the importance of this monument study to understand the Neolithic Volga-Ural interfluve. The monument is located on the right bank of the Derkul River and is currently classified as an emergency. In 2018, employees of the Institute of Archeology named after A.Kh. Margulan in the framework of the Stone Age study in Western Kazakhstan started to work on the monuments of Yeshkitau, Derkul 1 and Vavilino 1. At the Vavilino 1 site a small excavation area - 16 square meters was made, more than a thousand stone artifacts were received; fragments of ceramics and bone remains of animals were poorly diagnosed. Excavations have shown the presence of a 15-20 cm thick cultural layer belonging to the Neolithic time. The upper layer of the monument with a capacity of up to 30 cm was destroyed by anthropogenic activities in the past century. The material from the cultural layer is not numerous; tip scrapers, fragments of plates with retouching, geometrical microliths, prismatic nucleus for plates, etc. are typologically distinguished.

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Comparison of Land Surface Temperature During and Before the Emergence of Covid-19 using Modis Imagery in Wuhan City, China

Forum Geografi ◽

10.23917/forgeo.v34i1.10862 ◽

2020 ◽

Vol 34 (1) ◽

Author(s):

Hamim Zaky Hadibasyir ◽

Seftiawan Samsu Rijal ◽

Dewi Ratna Sari

Keyword(s):

Surface Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

Anthropogenic Activities ◽

Temporal Analysis ◽

The Past ◽

Modis Imagery ◽

Rapid Transmission ◽

The Mean ◽

Spatio Temporal

Coronavirus disease (COVID-19) was firstly identified in Wuhan, China. By 23rd January 2020, China’s Government made a decision to execute lockdown policy in Wuhan due to the rapid transmission of COVID-19. It is essential to investigate the land surface temperature (LST) dynamics due to changes in level of anthropogenic activities. Therefore, this study aims (1) to investigate mean LST differences between during, i.e., December 2019 to early March 2020, and before the emergence of COVID-19 in Wuhan; (2) to conduct spatio-temporal analysis of mean LST with regards to lockdown policy; and (3) to examine mean LST differences for each land cover type. MODIS data consist of MOD11A2 and MCD12Q1 were employed. The results showed that during the emergence of COVID-19 with lockdown policy applied, the mean LST was lower than the mean LST of the past three years on the same dates. Whereas, during the emergence of COVID-19 without lockdown policy applied, the mean LST was relatively higher than the mean LST of the past three years. In addition, the mean LST of built-up areas experienced the most significant differences between during the emergence of COVID-19 with lockdown policy applied in comparison to the average of the past three years.

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Spatial Distribution of Fluoride in Drinking Water in Dhamar City, Yemen

International Journal of Environment ◽

10.3126/ije.v10i1.38402 ◽

2021 ◽

Vol 10 (1) ◽

pp. 49-63

Author(s):

Hefdhallah Al Aizari ◽

Rachida Fegrouche ◽

Ali Al Aizari ◽

Saeed S. Albaseer

Keyword(s):

Drinking Water ◽

Anthropogenic Activities ◽

Groundwater Resources ◽

Principal Component ◽

World Health ◽

Residential Areas ◽

Central Plateau ◽

The World ◽

Pca Method ◽

Health Organization

The fact that groundwater is the only source of drinking water in Yemen mandates strict monitoring of its quality. The aim of this study was to measure the levels of fluoride in the groundwater resources of Dhamar city. Dhamar city is the capital of Dhamar governorate located in the central plateau of Yemen. For this purpose, fluoride content in the groundwater from 16 wells located around Dhamar city was measured. The results showed that 75% of the investigated wells contain fluoride at or below the permissible level set by the World Health Organization (0.5 – 1.5 mg/L), whereas 25% of the wells have relatively higher fluoride concentrations (1.59 – 184 mg/L). The high levels of fluoride have been attributed to the anthropogenic activities in the residential areas near the contaminated wells. Interestingly, some wells contain very low fluoride concentrations (0.30 – 0.50 mg/L). Data were statistically treated using the principal component analysis (PCA) method to investigate any possible correlations between various factors. PCA shows a high correlation between well depth and its content of fluoride. On the other hand, health problems dominating in the study area necessitate further studies to investigate any correlation with imbalanced fluoride intake.

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