scholarly journals Variations in in situ Fluorescence of Phytoplankton Pigments and Turbidity during Winter in the Chikugo River Estuary, Ariake Bay, Japan

2004 ◽  
Vol 13 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Katsuhisa Tanaka ◽  
Masashi Kodama ◽  
Kaori Kumagai ◽  
Hisanobu Fujimoto
Keyword(s):  
River Estuary ◽  
Ariake Bay ◽  
Phytoplankton Pigments ◽  
Chikugo River

scholarly journals Major role of ammonia-oxidizing bacteria in N<sub>2</sub>O production in the Pearl River estuary

2019 ◽  
Vol 16 (24) ◽  
pp. 4765-4781 ◽  
Author(s):  
Li Ma ◽  
Hua Lin ◽  
Xiabing Xie ◽  
Minhan Dai ◽  
Yao Zhang
Keyword(s):  
River Estuary ◽  
Amoa Gene ◽  
Pearl River Estuary ◽  
Pearl River ◽  
N2o Production ◽  
The Pearl River Estuary ◽  
Incubation Experiments ◽  
In Situ Incubation ◽  
The Pearl River

Abstract. Nitrous oxide (N2O) has significant global warming potential as a greenhouse gas. Estuarine and coastal regimes are the major zones of N2O production in the marine system. However, knowledge on biological sources of N2O in estuarine ecosystems remains controversial but is of great importance for understanding global N2O emission patterns. Here, we measured concentrations and isotopic compositions of N2O as well as distributions of ammonia-oxidizing bacterial and archaeal amoA and denitrifier nirS genes by quantitative polymerase chain reaction along a salinity gradient in the Pearl River estuary, and we performed in situ incubation experiments to estimate N2O yields. Our results indicated that nitrification predominantly occurred, with significant N2O production during ammonia oxidation. In the hypoxic waters of the upper estuary, strong nitrification resulted in the observed maximum N2O and ΔN2Oexcess concentrations, although minor denitrification might be concurrent at the site with the lowest dissolved oxygen. Ammonia-oxidizing β-proteobacteria (AOB) were significantly positively correlated with all N2O-related parameters, although their amoA gene abundances were distinctly lower than ammonia-oxidizing archaea (AOA) throughout the estuary. Furthermore, the N2O production rate and the N2O yield normalized to amoA gene copies or transcripts estimated a higher relative contribution of AOB to the N2O production in the upper estuary. Taken together, the in situ incubation experiments, N2O isotopic composition and concentrations, and gene datasets suggested that the high concentration of N2O (oversaturated) is mainly produced from strong nitrification by the relatively high abundance of AOB in the upper reaches and is the major source of N2O emitted to the atmosphere in the Pearl River estuary.

scholarly journals Merkuri (Hg) di Permukaan Perairan Muara Sungai Banyuasin, Sumatera Selatan, Indonesia

2018 ◽  
Vol 5 (2) ◽  
pp. 177 ◽  
Author(s):  
Yulianto Suteja ◽  
Anna Ida Sunaryo Purwiyanto ◽  
Fitri Agustriani
Keyword(s):  
Water Quality ◽  
River Estuary ◽  
Quality Standards ◽  
Quality Standard ◽  
Marine Biota ◽  
Distance Weighted ◽  
Seawater Quality ◽  
Inverse Distance ◽  
Temperature Depth

The purposes of this study were to determine the water quality, concentration and distribution of Hg in the surface water of Banyuasin river estuary. This research was conducted in June 2016 with 26 sampling stations. Measurement of in situ water quality was done using Conductivity Temperature Depth (CTD) multiparameter profiler while Hg metal was measured using Atomic Absorption Spectroscopy (AAS).  The data obtained was interpolated by Inverse Distance Weighted (IDW) and then mapped spatially. The results showed that in general the water quality in Banyuasin river estuary still meets the seawater quality standards for marine biota based on KepMenLH no. 51 in 2004. The concentration of Hg in Banyuasin river estuary ranges from 0.001-0.032 mg/L with a distribution pattern that generally increases towards the ocean. The Hg concentration at the Banyuasin river estuary is on the maximum limit and exceeds the quality standard for marine biota.

scholarly journals Effects of Tidal Scenarios on the Methane Emission Dynamics in the Subtropical Tidal Marshes of the Min River Estuary in Southeast China

2019 ◽  
Vol 16 (15) ◽  
pp. 2790 ◽  
Author(s):  
Jiafang Huang ◽  
Min Luo ◽  
Yuxiu Liu ◽  
Yuxue Zhang ◽  
Ji Tan
Keyword(s):  
High Tide ◽  
River Estuary ◽  
Tidal Marshes ◽  
Tidal Wetlands ◽  
Ch4 Emission ◽  
Air Exposure ◽  
Southeast China ◽  
Min River ◽  
Min River Estuary

In order to accurately estimate the effects of tidal scenarios on the CH4 emission from tidal wetlands, we examined the CH4 effluxes, dissolved CH4 concentrations, and environmental factors (including in situ pH, Eh and electrical conductivity, porewater SO42−, NO3−, and NH4+) during inundation and air-exposure periods in high- and low-tide seasons in the Min River Estuary in southeast China. By applying static and floating chambers, our results showed that the CH4 effluxes during the inundation periods were relatively constant and generally lower than those during the air-exposed periods in both seasons. When compared, the CH4 effluxes during the air-exposed periods were significantly higher in the high-tide season than those in the low-tide season. In contrast, CH4 effluxes during the inundation periods were significantly lower in the high-tide season than those in the low-tide season. During the inundation periods, dissolved CH4 concentrations were inversely proportional to in situ Eh. Under air-exposed conditions, CH4 effluxes were proportional to in situ pH in both seasons, while the dissolved CH4 concentrations were negatively correlated with the porewater SO42− concentrations in both seasons. Our results highlighted that CH4 effluxes were more dynamic between inundation and air-exposure periods compared to low- and high-tide seasons.

scholarly journals MODIS observed phytoplankton dynamics in the Taiwan Strait: an absorption-based analysis

2011 ◽  
Vol 8 (4) ◽  
pp. 841-850 ◽  
Author(s):  
S. Shang ◽  
Q. Dong ◽  
Z. Lee ◽  
Y. Li ◽  
Y. Xie ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Sea Water ◽  
River Estuary ◽  
Taiwan Strait ◽  
Percentage Error ◽  
Nutrient Loads ◽  
Phytoplankton Dynamics ◽  
Average Percentage ◽  
The Taiwan Strait

Abstract. This study used MODIS observed phytoplankton absorption coefficient at 443 nm (Aph) as a preferable index to characterize phytoplankton variability in optically complex waters. Aph derived from remote sensing reflectance (Rrs, both in situ and MODIS measured) with the Quasi-Analytical Algorithm (QAA) were evaluated by comparing them with match-up in situ measurements, collected in both oceanic and nearshore waters in the Taiwan Strait (TWS). For the data with matching spatial and temporal window, it was found that the average percentage error (ε) between MODIS derived Aph and field measured Aph was 33.8% (N=30, Aph ranges from 0.012 to 0.537 m−1), with a root mean square error in log space (RMSE_log) of 0.226. By comparison, ε was 28.0% (N=88, RMSE_log = 0.150) between Aph derived from ship-borne Rrs and Aph measured from water samples. However, values of ε as large as 135.6% (N=30, RMSE_log = 0.383) were found between MODIS derived chlorophyll-a (Chl, OC3M algorithm) and field measured Chl. Based on these evaluation results, we applied QAA to MODIS Rrs data in the period of 2003–2009 to derive climatological monthly mean Aph for the TWS. Three distinct features of phytoplankton dynamics were identified. First, Aph is low and the least variable in the Penghu Channel, where the South China Sea water enters the TWS. This region maintains slightly higher values in winter (~17% higher than that in the other seasons) due to surface nutrient entrainment under winter wind-driven vertical mixing. Second, Aph is high and varies the most in the mainland nearshore water, with values peaking in summer (June–August) when river plumes and coastal upwelling enhance surface nutrient loads. Interannual variation of bloom intensity in Hanjiang River estuary in June is highly correlated with alongshore wind stress anomalies, as observed by QuikSCAT. The year of minimum and maximum bloom intensity is in the midst of an El Niño and a La Niña event, respectively. Third, a high Aph patch appears between April and September in the middle of the southern TWS, corresponding to high thermal frontal probabilities, as observed by MODIS. Our results support the use of satellite derived Aph for time series analyses of phytoplankton dynamics in coastal ocean regions, whereas satellite Chl products derived empirically using spectral ratio of Rrs suffer from artifacts associated with non-biotic optically active materials.

Estimation of Chlorophyll-a Concentrations in the Pearl River Estuary Using In Situ Hyperspectral Data: A Case Study

2008 ◽  
Vol 42 (4) ◽  
pp. 22-27 ◽  
Author(s):  
Qianguo Xing ◽  
Chuqun Chen ◽  
Heyin Shi ◽  
Ping Shi ◽  
Yuanzhi Zhang
Keyword(s):  
Chlorophyll A ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Second Order ◽  
Hyperspectral Data ◽  
Order Derivative ◽  
Pearl River ◽  
Strong Light ◽  
Turbid Waters

Taking Pearl River Estuary (PRE), China as an example, we explored the potential of in situ hyperspectral data in estimating chlorophyll-a concentrations of turbid waters. Two cruises were conducted on August 21, 2006 and May 18, 2004 to collect the data of water quality and remote sensing reflectance (Rrs). The field surveys showed that: chlorophyll-a concentration ranged from 2.97μg/L to 49.97μg/L, and turbidity 13.6-128.9 NTU. The Rrs spectra were binned to 10 nm resolution, and then processed to be first-order and second-order derivatives. A linear algorithm is developed to estimate chlorophyll-a concentrations based on second-order derivative at 670 nm; its mean relative error of estimation is less than 58%, and the root mean square error is 6.69 μg/L, which is better than other popular algorithms for turbid waters, i.e., the ratio of Rrs at 700 nm and 670 nm. The Case-I algorithm of blue-green band ratio is also proved to be a failed application in PRE, and so does the algorithm of fluorescence line height (FLH), which is questionable for its application in waters with strong light scattering and absorption. All the above work was done without classification of cloud conditions. This suggests that the second-order derivative at 670 nm could be effective for estimation of chlorophyll-a concentrations in turbid waters, especially in situ.

scholarly journals Improved MODIS-Aqua Chlorophyll-a Retrievals in the Turbid Semi-Enclosed Ariake Bay, Japan

2018 ◽  
Vol 10 (9) ◽  
pp. 1335 ◽  
Author(s):  
Meng Meng Yang ◽  
Joji Ishizaka ◽  
Joaquim I. Goes ◽  
Helga do R. Gomes ◽  
Elígio de Raús Maúre ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Red Tide ◽  
Atmospheric Correction ◽  
Ariake Bay ◽  
Band Ratio ◽  
Simple Method ◽  
Chl A ◽  
Switching Algorithm ◽  
Economic Significance

The accurate retrieval of chlorophyll-a concentration (Chl-a) from ocean color satellite data is extremely challenging in turbid, optically complex coastal waters. Ariake Bay in Japan is a turbid semi-enclosed bay of great socio-economic significance, but it suffers from serious water quality problems, particularly due to red tide events. Chl-a derived from the MODerate resolution Imaging Spectroradiometer (MODIS) sensor on satellite Aqua in Ariake Bay was investigated, and it was determined that the causes of the errors were from inaccurate atmospheric correction and inappropriate in-water algorithms. To improve the accuracy of MODIS remote sensing reflectance (Rrs) in the blue and green bands, a simple method was adopted using in situ Rrs data. This method assumes that the error in MODIS Rrs(547) is small, and MODIS Rrs(412) can be estimated from MODIS Rrs(547) using a linear relation between in situ Rrs(412) and Rrs(547). We also showed that the standard MODIS Chl-a algorithm, OC3M, underestimated Chl-a, which was mostly due to water column turbidity. A new empirical switching algorithm was generated based on the relationship between in situ Chl-a and the blue-to-green band ratio, max(Rrs(443), Rrs(448)/Rrs(547), which was the same as the OC3M algorithm. The criterion of Rrs(667) of 0.005 sr−1 was used to evaluate the extent of turbidity for the switching algorithm. The results showed that the switching algorithm performed better than OC3M, and the root mean square error (RMSE) of estimated Chl-a decreased from 0.414 to 0.326. The RMSE for MODIS Chl-a using the recalculated Rrs and the switching algorithm was 0.287, which was a significant improvement from the RMSE of 0.610, which was obtained using standard MODIS Chl-a. Finally, the accuracy of our method was tested with an independent dataset collected by the local Fisheries Research Institute, and the results revealed that the switching algorithm with the recalculated Rrs reduced the RMSE of MODIS Chl-a from 0.412 of the standard to 0.335.

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