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Hailong Li

Bio: Hailong Li is an academic researcher from Southern University of Science and Technology. The author has contributed to research in topics: Aquifer & Submarine groundwater discharge. The author has an hindex of 34, co-authored 125 publications receiving 2979 citations. Previous affiliations of Hailong Li include Temple University & China University of Geosciences (Wuhan).


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors present field data and numerical simulations of a two-layered beach with a small freshwater recharge in the contaminated area, where a high permeability upper layer is underlain by a low-permeability lower layer, and find that the upper layer temporarily stored the oil, while it slowly and continuously filled the lower layer wherever the water table dropped below the interface of the two layers, as a result of low freshwater recharge from the land.
Abstract: Oil spilt from the tanker Exxon Valdez more than 20 years ago still persists in the gravel beaches of Prince William Sound, Alaska. Field data and numerical modelling indicate that some of the oil was trapped in the anoxic environment of the lower layers of the beaches when the water table was low. Oil spilled from the tanker Exxon Valdez in 1989 (refs 1, 2) persists in the subsurface of gravel beaches in Prince William Sound, Alaska. The contamination includes considerable amounts of chemicals that are harmful to the local fauna3. However, remediation of the beaches was stopped in 1992, because it was assumed that the disappearance rate of oil was large enough to ensure a complete removal of oil within a few years. Here we present field data and numerical simulations of a two-layered beach with a small freshwater recharge in the contaminated area, where a high-permeability upper layer is underlain by a low-permeability lower layer. We find that the upper layer temporarily stored the oil, while it slowly and continuously filled the lower layer wherever the water table dropped below the interface of the two layers, as a result of low freshwater recharge from the land. Once the oil entered the lower layer, it became entrapped by capillary forces and persisted there in nearly anoxic conditions that are a result of the tidal hydraulics in the two-layered beaches. We suggest that similar dynamics could operate on tidal gravel beaches around the world, which are particularly common in mid- and high-latitude regions4,5, with implications for locating spilled oil and for its biological remediation.

199 citations

Journal ArticleDOI
30 Mar 2021
TL;DR: In this article, the authors examine SGD nutrient fluxes in over 200 locations globally, explain their impact on biogeochemistry and discuss broader management implications, with median total SGD fluxes of 60mmolm−m−2 per day for dissolved inorganic nitrogen.
Abstract: Submarine groundwater discharge (SGD) links terrestrial and marine systems, but has often been overlooked in coastal nutrient budgets because it is difficult to quantify In this Review, we examine SGD nutrient fluxes in over 200 locations globally, explain their impact on biogeochemistry and discuss broader management implications SGD nutrient fluxes exceed river inputs in ~60% of study sites, with median total SGD fluxes of 60 mmol m−2 per day for dissolved inorganic nitrogen, 01 mmol m−2 per day for dissolved inorganic phosphorus and 65 mmol m−2 per day for dissolved silicate SGD nitrogen input (mostly in the form of ammonium and dissolved organic nitrogen) often mitigates nitrogen limitation in coastal waters, since SGD tends to have high nitrogen concentrations relative to phosphorus (76% of studies showed N:P values above the Redfield ratio) It is notable that most investigations do not distinguish saline and fresh SGD, although they have different properties Saline SGD is a ubiquitous, diffuse pathway releasing mostly recycled nutrients to global coastal waters, whereas fresh SGD is occasionally a local, point source of new nutrients SGD-derived nutrient fluxes must be considered in water quality management plans, as these inputs can promote eutrophication if not properly managed Submarine groundwater discharge transports nutrients from terrestrial to marine systems, but is often ignored in coastal biogeochemistry In this Review, the fluxes, impacts and management implications of this discharge are examined and compared with riverine fluxes globally

126 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the seawater-groundwater circulation in shallow beach aquifers using the finite element model MARUN, and obtained results that apply to a wide range of beach permeabilities from 10 � 4 m/s to 10 � 3 m /s, beach slopes from 3.16% to 31.6%, tidal amplitude (0.3 m-2 m) and period (diurnal or semidiurnal).

120 citations

Journal ArticleDOI
TL;DR: In this paper, an analytical solution of groundwater response to tidal fluctuation in a coastal multilayer aquifer system consisting of a leaky confined aquifer, a semipermeable layer, and an unconfined aquifer was presented.
Abstract: This paper presents the analytical solution of groundwater response to tidal fluctuation in a coastal multilayer aquifer system consisting of a leaky confined aquifer, a semipermeable layer, and an unconfined aquifer. The semipermeable layer, or the roof of the leaky confined aquifer, extends under the sea. Comparisons are made with solutions derived previously, which considered only a single aquifer, zero extension of the roof, or infinite roof length, and demonstrate that the previous solutions are special cases of the solution presented here. A hypothetical example is used to discuss the impact of the dimensionless roof length, dimensionless leakage, and tidal efficiency on the groundwater level fluctuations in the inland part of the confined aquifer. The fluctuation decreases significantly with the roof length when the roof length is small but is insensitive to the change of roof length when the roof length is greater than a threshold. The impacts of leakage from the offshore and inland portions of the confining unit are different. Leakage from the offshore portion tends to increase the fluctuation of the groundwater level, while leakage from the inland portion tends to decrease the fluctuation. The fluctuation increases as the tidal efficiency increases. This fact is significant only when the roof length is great and leakage is small.

106 citations

Journal ArticleDOI
TL;DR: In this paper, the authors synthesize the published literature on subsurface airflow driven by natural forcings such as atmospheric pressure fluctuations, topographic effect, water table fluctuations, and water infiltration.
Abstract: [1] Subsurface airflow in unsaturated zones induced by natural forcings is of importance in many environmental and engineering fields, such as environmental remediation, water infiltration and groundwater recharge, coastal soil aeration, mine and tunnel ventilation, and gas exchange between soil and atmosphere. This review synthesizes the published literature on subsurface airflow driven by natural forcings such as atmospheric pressure fluctuations, topographic effect, water table fluctuations, and water infiltration. The present state of knowledge concerning the mechanisms, analytical and numerical models, and environmental and engineering applications related to the naturally occurring airflow is discussed. Airflow induced by atmospheric pressure fluctuations is studied the most because of the applications to environmental remediation and transport of trace gases from soil to atmosphere, which are very important in understanding biogeochemical cycling and global change. Airflow induced by infiltration is also an extensively investigated topic because of its implications in rainfall infiltration and groundwater recharge. Airflow induced by water table fluctuations is important in coastal areas because it plays an important role in coastal environmental remediation and ecological systems. Airflow induced by topographic effect is studied the least. However, it has important applications in unsaturated zone gas transport and natural ventilation of mines and tunnels. Finally, the similarities and differences in the characteristics of the air pressure and airflow are compared and future research efforts are recommended.

88 citations


Cited by
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Journal ArticleDOI
TL;DR: To the best of our knowledge, there is only one application of mathematical modelling to face recognition as mentioned in this paper, and it is a face recognition problem that scarcely clamoured for attention before the computer age but, having surfaced, has attracted the attention of some fine minds.
Abstract: to be done in this area. Face recognition is a problem that scarcely clamoured for attention before the computer age but, having surfaced, has involved a wide range of techniques and has attracted the attention of some fine minds (David Mumford was a Fields Medallist in 1974). This singular application of mathematical modelling to a messy applied problem of obvious utility and importance but with no unique solution is a pretty one to share with students: perhaps, returning to the source of our opening quotation, we may invert Duncan's earlier observation, 'There is an art to find the mind's construction in the face!'.

3,015 citations

01 Dec 2013
TL;DR: This paper found that the most intensive glacier shrinkage is in the Himalayan region, whereas glacial retreat in the Pamir Plateau region is less apparent, due to changes in atmospheric circulations and precipitation patterns.
Abstract: Glacial melting in the Tibetan Plateau affects the water resources of millions of people. This study finds that—partly owing to changes in atmospheric circulations and precipitation patterns—the most intensive glacier shrinkage is in the Himalayan region, whereas glacial retreat in the Pamir Plateau region is less apparent.

1,599 citations

Journal ArticleDOI
TL;DR: A review of the state of the art in sea intrusion research can be found in this article, where the authors subdivide SI research into three categories: process, mea- surement, prediction and management.

1,055 citations

Journal ArticleDOI
TL;DR: These oil degrading indigenous microorganisms played a significant role in reducing the overall environmental impact of both the Exxon Valdez and BP Deepwater Horizon oil spills.
Abstract: Oil biodegradation and bioremediation: A tale of the two worst spills in U. S. history. Ronald M. Atlas, University of Louisville, Louisville KY 40292 Terry C. Hazen, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 Biography Ronald Atlas is Professor of Biology at the University of Louisville. He has over 40 years experience studying the role of microorganisms in oil biodegradation and helped pioneer the field of bioremediation. He has worked extensively on the bioremediation the Exxon Valdez spill. Terry Hazen is DOE BER distinguished scientist in the Earth Sciences Division at Lawrence Berkeley National Laboratory. He has studied oil, chlorinated solvent, and metal and radionuclide bioremediation for more then 30 years. He has been extensively studying the microbial degradation of the BP Deepwater Horizon Spill in the Gulf of Mexico. Abstract The devastating environmental impacts of the Exxon Valdez spill in 1989 and its media notoriety made it a frequent comparison to the BP Deepwater Horizon spill in the popular press in 2010, even though the nature of the two spills and the environments impacted were vastly different. Fortunately, unlike higher organisms that are adversely impacted by oil spills, microorganisms are able to consume petroleum hydrocarbons. These oil degrading indigenous microorganisms played a significant role in reducing the overall environmental impact of both the Exxon Valdez and BP Deepwater Horizon (MC252) oil spills. Introduction to Biodegradation of Petroleum Hydrocarbons Petroleum hydrocarbons in crude oils, such as those released into marine ecosystems by the Exxon Valdez and BP Deepwater Horizon spills, are natural products derived from aquatic algae laid down between 180 and 85 million years ago. Crude oils, composed mostly of diverse aliphatic and aromatic hydrocarbons, regularly escape into the environment from underground reservoirs. Because petroleum hydrocarbons occur naturally in all marine environments there has been time for numerous diverse microorganisms to evolve the capability of utilizing hydrocarbons as sources of carbon and energy for growth. Oil-degrading microorganisms are ubiquitous, but may only be a small proportion of the pre-spill microbial community. Bacteria, archaea, and fungi each have hundreds of species that can degrade petroleum. Most petroleum hydrocarbons are biodegradable under aerobic conditions; though a few compounds found in crude oils, e.g. resins, hopanes, polar molecules, and asphaltenes, have practically imperceptible biodegradation rates. Lighter crudes, such as the oil released from the BP Deepwater Horizon spill, contain a higher proportion of simpler lower molecular weight hydrocarbons that are more readily biodegraded than heavy crudes, such as the oil released from the Exxon Valdez. The polycyclic aromatic hydrocarbons (PAH) are a minor constituent of crude oils; however, they are among the most toxic to plants and animals. Bacteria can convert PAHs completely to biomass, CO 2 , and H 2 O, but they usually require the initial insertion of O 2 via dioxygenase enzymes. Anaerobic degradation of petroleum hydrocarbons can also occur albeit at a much slower rates. Petroleum hydrocarbons can be biodegraded at temperatures below freezing to more than 80°C. Microorganisms require elements other than carbon for

721 citations