Other affiliations: Ocean University of China, University of Hawaii, Huazhong University of Science and Technology ...read more
Bio: Hongbin Liu is an academic researcher from Hong Kong University of Science and Technology. The author has contributed to research in topics: Phytoplankton & Environmental science. The author has an hindex of 48, co-authored 308 publications receiving 7735 citations. Previous affiliations of Hongbin Liu include Ocean University of China & University of Hawaii.
Papers published on a yearly basis
TL;DR: It is concluded that biochar can be used under conditions where NH4 +-N (or NH3) pollution is a concern, but further research is needed in terms of applying biochars to reduce NO3 −-N pollution.
Abstract: Biochar produced by pyrolysis of biomass can be used to counter nitrogen (N) pollution. The present study investigated the effects of feedstock and temperature on characteristics of biochars and their adsorption ability for ammonium N (NH4+-N) and nitrate N (NO3−-N). Twelve biochars were produced from wheat-straw (W-BC), corn-straw (C-BC) and peanut-shell (P-BC) at pyrolysis temperatures of 400, 500, 600 and 700°C. Biochar physical and chemical properties were determined and the biochars were used for N sorption experiments. The results showed that biochar yield and contents of N, hydrogen and oxygen decreased as pyrolysis temperature increased from 400°C to 700°C, whereas contents of ash, pH and carbon increased with greater pyrolysis temperature. All biochars could sorb substantial amounts of NH4+-N, and the sorption characteristics were well fitted to the Freundlich isotherm model. The ability of biochars to adsorb NH4+-N followed: C-BC>P-BC>W-BC, and the adsorption amount decreased with higher pyrolysis temperature. The ability of C-BC to sorb NH4+-N was the highest because it had the largest cation exchange capacity (CEC) among all biochars (e.g., C-BC400 with a CEC of 38.3 cmol kg−1 adsorbed 2.3 mg NH4+-N g−1 in solutions with 50 mg NH4+ L−1). Compared with NH4+-N, none of NO3−-N was adsorbed to biochars at different NO3− concentrations. Instead, some NO3−-N was even released from the biochar materials. We conclude that biochars can be used under conditions where NH4+-N (or NH3) pollution is a concern, but further research is needed in terms of applying biochars to reduce NO3−-N pollution.
TL;DR: The results suggest Prochlorococcus are not severely nutrient-limited in the oligotrophic environment and rapid nutrient recycling by grazing activity permits Pro chlorococcus to contribute a significant fraction of the total primary production.
Abstract: DNA synthesis and cell division of Prochlorococcus are tightly synchronized to the daily light cycle, therefore, cell division rates can be estimated from the fraction of cells in each cell cycle stage during a 24 h sampling period. The total mortality rate of Prochlorococcus can also be estimated from the difference between the observed cell abundance and the expected cell number projected from growth rate in that sampling period, providing an estlmate of grazing impact. Growth and mortality rates of Prochlorococcus were investigated at 2 statlons In the equatorial Pacific, as well as Station ALOHA in the subtropical North Pacific Ocean. Growth rate of Prochlorococcus remained high at all sites independent of the nitrate concentration. The maximum growth rate (up to 1 doubling d-') occurred at 70 m depth at the western equatorial Pacific site (166' E) and at 40 to 45 nl at the eastern equatorial Pacific site (150' W) and at Station ALOHA (22" 45' N, 158' W). Total mortality rates were roughly balanced by Prochlorococcus growth at all stations. Because of the phased cell cycle and continuous (if not evenly distributed) mortality, the abundance of Prochlorococcus at each depth could vary up to 2-fold between afternoon and midnight. Prochlorococcus production was estimated to contribute 9 and 39% to the total gross primary production in the eastern and western equatorial Pacific, respectively, and up to 82% in the subtropical North Pacific Ocean at Station ALOHA. Our results suggest Prochlorococcus are not severely nutrient-limited in the oligotrophic environment. Rapid nutrient recycling by grazing activity permits Prochlorococcus to contribute a significant fraction of the total primary production.
01 Feb 1997
TL;DR: Time-series data on community structure in the upper 200 m at Station ALOHA in the subtropical North Pacific were collected at approximately monthly intervals from December 1990 through to March 1994 during an extended El Niiio-Southern Oscillation (ENSO) event, with significant interannual variation in the total 200-m integrated microbial carbon estimates.
Abstract: Time-series data on community structure in the upper 200 m at Station ALOHA in the subtropical North Pacific were collected at approximately monthly intervals from December 1990 through to March 1994 during an extended El Niiio-Southern Oscillation (ENSO) event. Samples were analyzed by flow cytometry to enumerate Prochlorococcus, Synechococcus, picoeucaryotes, 3–20 μm algae, and heterotrophic bacteria, as well as to quantify cellular chlorophyll fluorescence for the autotrophic components. A significant seasonal cycle was evident in cellular chlorophyll fluorescence for each of the autotrophic components, with maxima occurring each winter as a consequence of photoacclimation. Abundance of each picophytoplankton component exhibited temporal variability on both seasonal and interannual scales. Although the magnitude of the seasonal cycles in the abundance was relatively small, the cycles appeared to be out of phase. Typically, abundance maxima of Synechococcus occurred in winter, of picoeucaryotes in spring, and of Prochlorococcus during summer/fall. The different timing in these cycles may explain why the presence of a seasonal pattern in total phytoplankton biomass has been difficult to establish. Abundance of the larger 3–20 μm algae varied over two orders of magnitude during the time series, with no obvious seasonal pattern. The 3–20 μm algae were a small percentage of the total estimated carbon biomass (∼8%). Heterotrophic bacteria were the most numerous of the picoplankton, and the seasonal pattern in their 200-m integrated abundance paralleled Prochlorococcus over the time series. Together, the procaryotes contributed 60–90% of the total estimated microbial carbon. Significant interannual variation in the total 200-m integrated microbial carbon estimates may be related to the effects of the extended ENSO event, which began in 1991.
••15 Jul 2008
TL;DR: The Pearl River Estuary is a subtropical estuary and the second largest in China based on discharge volume from the Pearl River as mentioned in this paper, which shows a remarkable capacity to cope with excessive nutrients.
Abstract: The Pearl River Estuary is a subtropical estuary and the second largest in China based on discharge volume from the Pearl River. Processes in the estuary vary spatially and temporally (wet vs dry season). In the dry season at the head of the estuary, hypoxic and nearly anoxic conditions occur and NH4 reaches > 600 mu M, NO3 is similar to 300 mu M and nitrite is similar to 60 mu M indicating that nitrification and denitrification may be important dry season processes in the region extending 40 km upstream of the Humen outlet. There are very few biological studies conducted in this upper section of the estuary in either the dry or wet seasons and hence there is a need for further research in this region of the river. In the wet season, the salinity wedge extends to the Hongqimen outlet and oxygen is low (35-80% saturation). Nitrate is similar to 100 mu M, silicate similar to 140 mu M: and phosphate is relatively low at similar to 0.5 mu M, yielding an N:P ratio up to similar to 200:1 in summer. Nutrients decrease in the lower estuary and primary productivity may become potentially P-limited. Eutrophication is not as severe as one would expect from the nutrient inputs from the Pearl River and from Hong Kong's sewage discharge. This estuary shows a remarkable capacity to cope with excessive nutrients. Physical processes such as river discharge, tidal flushing, turbulent dispersion, wind-induced mixing, and estuarine circulation play an important role in controlling the production and accumulation of algal blooms and the potential occurrence of hypoxia. Superimposed on the physical processes of the estuary are the chemical and biological processes involved in the production of the bloom. For example, the 100N:1P ratio indicates that P potentially limits the amount of algal biomass (and potential biological oxygen demand) in summer. While extended periods of hypoxia are rare in Hong Kong waters, episodic events have been reported to occur during late summer due to factors such as low wind, high rainfall and river discharge which result in strong density stratification that significantly dampens vertical mixing processes. Nutrient loads are likely to change over the next several decades and monitoring programs are essential to detect the response of the ecosystem due to the future changes in nutrient loading and the ratio of nutrients. (c) 2008 Elsevier Ltd. All rights reserved.
University of California, Santa Cruz1, Texas A&M University2, University of South Carolina3, Woods Hole Oceanographic Institution4, University of Hawaii5, University of Texas at Austin6, University of California, San Diego7, Monterey Bay Aquarium Research Institute8, College of William & Mary9, University of Rhode Island10
TL;DR: In this article, the biomass of planktonic organisms, ranging from heterotrophic bacteria through microplankton-sized organisms, was estimated using a variety of methods including #ow cytometry and microscopy.
Abstract: One of the main objectives of the Joint Global Ocean Flux Studies (JGOFS) program is to develop an understanding of the factors controlling organic carbon production in the ocean and the time-varying vertical #ux of carbon from surface waters (US JGOFS (1990) US JGOFS Planning Report Number 11; Sarmiento and Armstrong (1997) US JGOFS Synthesis and Modeling Project Implementation Plan). A considerable amount of evidence suggests that carbon cycling and the potential for exporting carbon from ocean systems is a function of food web structure. As part of the US JGOFS Arabian Sea Studies, the biomass of planktonic organisms, ranging from heterotrophic bacteria through microplankton-sized organisms, was estimated using a variety of methods including #ow cytometry and microscopy. This is a "rst attempt to combine biomass data from a number of sources, evaluate the structure of the food
01 Jun 2012
TL;DR: SPAdes as mentioned in this paper is a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler and on popular assemblers Velvet and SoapDeNovo (for multicell data).
Abstract: The lion's share of bacteria in various environments cannot be cloned in the laboratory and thus cannot be sequenced using existing technologies. A major goal of single-cell genomics is to complement gene-centric metagenomic data with whole-genome assemblies of uncultivated organisms. Assembly of single-cell data is challenging because of highly non-uniform read coverage as well as elevated levels of sequencing errors and chimeric reads. We describe SPAdes, a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler (specialized for single-cell data) and on popular assemblers Velvet and SoapDeNovo (for multicell data). SPAdes generates single-cell assemblies, providing information about genomes of uncultivatable bacteria that vastly exceeds what may be obtained via traditional metagenomics studies. SPAdes is available online ( http://bioinf.spbau.ru/spades ). It is distributed as open source software.
TL;DR: In this article, a new method for metagenomic biomarker discovery by way of class comparison, tests of biological consistency and effect size estimation is described and validated, which addresses the challenge of finding organisms, genes, or pathways that consistently explain the differences between two or more microbial communities.
Abstract: This study describes and validates a new method for metagenomic biomarker discovery by way of class comparison, tests of biological consistency and effect size estimation. This addresses the challenge of finding organisms, genes, or pathways that consistently explain the differences between two or more microbial communities, which is a central problem to the study of metagenomics. We extensively validate our method on several microbiomes and a convenient online interface for the method is provided at http://huttenhower.sph.harvard.edu/lefse/.
United States Environmental Protection Agency1, University of Maryland Center for Environmental Science2, North Carolina State University3, Woods Hole Oceanographic Institution4, San Francisco State University5, National Oceanic and Atmospheric Administration6, Stony Brook University7, University of South Florida St. Petersburg8, Delaware Department of Natural Resources and Environmental Control9, University of South Carolina10, South Carolina Department of Natural Resources11, Maryland Department of Natural Resources Police12, Old Dominion University13, Chesapeake Research Consortium14, University of Alaska Fairbanks15
TL;DR: In January 2003, the US Environmental Protection Agency sponsored a "roundtable discussion" to develop a consensus on the relationship between eutrophication and harmful algal blooms, specifically targeting those relationships for which management actions may be appropriate.
Abstract: In January 2003, the US Environmental Protection Agency sponsored a ‘‘roundtable discussion’’ to develop a consensus on the relationship between eutrophication and harmful algal blooms (HABs), specifically targeting those relationships for which management actions may be appropriate. Academic, federal, and state agency representatives were in attendance. The following seven statements were unanimously adopted by attendees based on review and analysis of current as well as pertinent previous data: