•Analysis of satellite data reveals the synoptic characteristics of water quality.•Biogeochemical processes affect the seasonality and heterogeneity in chlorophyll a.•Seasonality and heterogeneity in ...suspended solids result from physical processes.
The structure of 9-year time series data for Sea Surface Temperature (SST), Chlorophyll a (Chl-a) and Total Suspended Solids (TSS), derived from the Visible Infrared Imaging Radiometer Suite (VIIRS), was examined in this study. Authors found that there exists strong seasonality among the three variables with spatial heterogeneity along the Korean South Coast (KSC). In specific, SST was in phase with Chl-a, but out of phase with TSS by six months. A strong inversed spectral power with six-month phase-lag was found between Chl-a and TSS. This could be attributed to different dynamics and environmental settings. For example, Chl-a concentration seemed to have strong positive correlation with SST indicating typical seasonality of marine biogeochemical processes such as primary production; while a strong negative correlation between TSS and SST might have been influenced by changes in physical oceanographic processes, such as stratification and monsoonal wind-driven vertical mixing. In addition, the strong east–west heterogeneity of Chl-a suggests that the marine coastal environments are predominantly governed by distinct local hydrological conditions and human activities associated with land cover and land use, while the east–west spatial pattern revealed in TSS timeseries was associated with the gradient of tidal forcings and topographical changes keeping tidally induced resuspension low eastward.
Coastal disasters due to storms and related prevention and prediction are key issues in coastal environmental management and planning. In the present study, the coupled storm surge–tide–wave model ...has been used for studying the effects of several factors on the storm surges in the West Korean Bay during the 1997 Winnie. The results have shown that the coupled model is capable of predicting the total water level under storm events with reasonable accuracy. The results have also shown that the river discharge plays an important role in the storm surge development. The peak surges at stations 1 and 2 located in the river estuaries were 0.2–1.5 m larger than those at the stations 3 and 4. Especially, the peak surge at the station 3 located in the Taedong River estuary was much smaller compared to those at the stations 1 and 2, due to the control of the river discharge by barrages such as the West Sea Barrage. The peak surge at the station 1 located in the Amrok River estuary was 12% larger than that at the station 2 located in the Chongchon River estuary, due to the considerable difference in the river discharges. In summary, our results have shown that integrating the coupled storm surge–tide–wave model technology with the real-time river discharge forecast is feasible for predicting the inundation under both storm surge and riverine floods for the West Korean Bay.
This study aims to understand population dynamics and secondary production of a nereid polychaete Hediste diadroma in the Bongam tidal flat. Samples were collected on a monthly basis over two ...distinct periods: from May 2015 to April 2016 and from March 2018 to February 2019. The annual mean values for temperature, sand content, and total organic carbon in surface sediments were 18.1±9.6 ℃, 79.8±12.4% and 0.53±0.36%, respectively. Relationships between parameters such as body length (BL) versus the width of the third setiger (WS3), and dry weight (DW) versus WS3 were analyzed using a sample group of 56 intact individuals. The resulting equations were determined as BL=(28.575×WS3)-7.6462 with an R2 value of 0.93, and DW=1.3435×WS33.252 with an R2 value of 0.83. There was a notable decrease in annual mean density observed in 2018 (1096±901 ind. m−2) compared to 2015 (1938±1724 ind. m−2), which could be attributed to higher temperatures and interspecies competition in 2018. Recruitment events were singular within each year, occurring in June 2015 and July 2018. The estimated secondary production (P) was 8.40 g DW m−2 yr−1 with a mean biomass (B̅) of 5.18 g DW m−2 (P/B̅= 1.6) from May 2015 to April 2016, and P= 3.38 g DW m−2 yr−1 with B̅= 1.97 g DW m−2 (P/B̅= 1.7) from March 2018 to February 2019. Based on these findings, it is suggested that the contribution of H. diadroma to energy flows in the benthic ecosystem of the study area accounts for approximately 3% (1.7 g C m−2 yr−1) of the total energy flows (54.5 g C m−2 yr−1).
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•The initial assessment on the secondary production of Hediste diadroma.•Singular recruitment within a given year took place during the summer months.•The P/B̅ ratio was lower compared to other Hediste species studied globally.•Hediste diadroma accounted for approximately 3% of the secondary production of the macrobenthos community.
The sources of halogenated compounds in East Asia associated with stratospheric ozone depletion and climate change are relatively poorly understood. High-precision in situ measurements of 18 ...halogenated compounds and carbonyl sulfide (COS) made at Gosan, Jeju Island, Korea, from November 2007 to December 2011 were analyzed by a positive matrix factorization (PMF). Seven major industrial sources were identified from the enhanced concentrations of halogenated compounds observed at Gosan and corresponding concentration-based source contributions were also suggested: primary aluminum production explaining 37% of total concentration enhancements, solvent usage of which source apportionment is 25%, fugitive emissions from HCFC/HFC production with 11%, refrigerant replacements (9%), semiconductor/electronics industry (9%), foam blowing agents (6%), and fumigation (3%). Statistical trajectory analysis was applied to specify the potential emission regions for seven sources using back trajectories. Primary aluminum production, solvent usage and fugitive emission sources were mainly contributed by China. Semiconductor/electronics sources were dominantly located in Korea. Refrigerant replacement, fumigation and foam blowing agent sources were spread throughout East Asian countries. The specified potential source regions are consistent with country-based consumptions and emission patterns, verifying the PMF analysis results. The industry-based emission sources of halogenated compounds identified in this study help improve our understanding of the East Asian countries’ industrial contributions to halogenated compound emissions.
We reconstruct atmospheric abundances of the potent
greenhouse gas c-C4F8 (perfluorocyclobutane, perfluorocarbon
PFC-318) from measurements of in situ, archived, firn, and aircraft air
samples with ...precisions of ∼1 %–2 % reported on the SIO-14
gravimetric calibration scale. Combined with inverse methods, we found near-zero atmospheric abundances from the early 1900s to the early 1960s, after
which they rose sharply, reaching 1.66 ppt (parts per trillion dry-air mole
fraction) in 2017. Global c-C4F8 emissions rose from near zero in
the 1960s to 1.2±0.1 (1σ) Gg yr−1 in the late 1970s to
late 1980s, then declined to 0.77±0.03 Gg yr−1 in the mid-1990s
to early 2000s, followed by a rise since the early 2000s to 2.20±0.05 Gg yr−1 in 2017. These emissions are significantly larger than
inventory-based emission estimates. Estimated emissions from eastern Asia
rose from 0.36 Gg yr−1 in 2010 to 0.73 Gg yr−1 in 2016 and 2017,
31 % of global emissions, mostly from eastern China. We estimate
emissions of 0.14 Gg yr−1 from northern and central India in 2016 and
find evidence for significant emissions from Russia. In contrast, recent
emissions from northwestern Europe and Australia are estimated to be small
(≤1 % each). We suggest that emissions from China, India, and Russia
are likely related to production of polytetrafluoroethylene (PTFE,
“Teflon”) and other fluoropolymers and fluorochemicals that are based on
the pyrolysis of hydrochlorofluorocarbon HCFC-22 (CHClF2) in which
c-C4F8 is a known by-product. The semiconductor sector, where
c-C4F8 is used, is estimated to be a small source, at least in
South Korea, Japan, Taiwan, and Europe. Without an obvious correlation with
population density, incineration of waste-containing fluoropolymers is
probably a minor source, and we find no evidence of emissions from
electrolytic production of aluminum in Australia. While many possible
emissive uses of c-C4F8 are known and though we cannot
categorically exclude unknown sources, the start of significant emissions
may well be related to the advent of commercial PTFE production in 1947.
Process controls or abatement to reduce the c-C4F8 by-product were
probably not in place in the early decades, explaining the increase in
emissions in the 1960s and 1970s. With the advent of by-product reporting
requirements to the United Nations Framework Convention on Climate Change
(UNFCCC) in the 1990s, concern about climate change and product stewardship,
abatement, and perhaps the collection of c-C4F8 by-product for use
in the semiconductor industry where it can be easily abated, it is
conceivable that emissions in developed countries were stabilized and then
reduced, explaining the observed emission reduction in the 1980s and 1990s.
Concurrently, production of PTFE in China began to increase rapidly. Without
emission reduction requirements, it is plausible that global emissions today
are dominated by China and other developing countries. We predict that
c-C4F8 emissions will continue to rise and that c-C4F8
will become the second most important emitted PFC in terms of
CO2-equivalent emissions within a year or two. The 2017 radiative
forcing of c-C4F8 (0.52 mW m−2) is small but emissions of
c-C4F8 and other PFCs, due to their very long atmospheric
lifetimes, essentially permanently alter Earth's radiative budget and should
be reduced. Significant emissions inferred outside of the investigated
regions clearly show that observational capabilities and reporting
requirements need to be improved to understand global and country-scale
emissions of PFCs and other synthetic greenhouse gases and ozone-depleting
substances.
Data for the TOMS aerosol index and SeaWiFS chlorophyll a clearly indicate that an early spring bloom in the northern East/Japan Sea can be initiated during the Asian dust event in association with ...precipitation. Spring bloom is normally initiated in this area as the surface mixed layer becomes shallower than critical depth, in accordance with Sverdrup's critical depth hypothesis. However, after the passage of Asian dust accompanied by precipitation, spring bloom was initiated about one month earlier than the bloom during non‐dust event years. We found that deepening of critical depth coincided with the early spring bloom observed during wet‐dust events. This early initiation of spring bloom indicates that the supply of bio‐available nutrients such as iron through wet deposition induces deepening of the critical depth, which results in such an early initiation of the bloom in the area.
Methyl Chloride (CH
3
Cl) is a chlorine-containing trace gas in the atmosphere contributing significantly to stratospheric ozone depletion (Carpenter et al.
2014
). In the global CH
3
Cl budget, the ...atmospheric CH
3
Cl emissions is predominantly maintained by natural sources, of which magnitudes have been relatively well-constrained. However, significant uncertainties still remain in the CH
3
Cl emission strengths from anthropogenic sources. High-frequency and high-precision in situ measurements of atmospheric CH
3
Cl concentrations obtained since 2008 at Gosan station (a remote background site in the East Asia) reveal significant pollution events superimposed on the seasonally varying regional background levels. Back trajectory statistics showed that air masses corresponding to the observed CH
3
Cl enhancement largely originated from regions of intensive industrial activities in China. Based on an inter-species correlation method, estimates of CH
3
Cl emissions from manufacturing industries including coal combustion, use of feedstocks, or process agents in chemical production for China (2008–2012) are 297 ± 71 Gg yr.
−1
in 2008 to 480 ± 99 Gg yr.
−1
in 2009, followed by a gradual decrease of about 25% between 2009 and 2012 (398 ± 92 Gg yr.
−1
for 2010; 286 ± 68 Gg yr.
−1
for 2011; 358 ± 92 Gg yr.
−1
for 2012). The annual average of industrial CH
3
Cl emissions for 2008–2012 (363 ± 85 Gg yr.
−1
) in China is comparable to the known total global anthropogenic CH
3
Cl emissions accounting only for coal combustion and indoor biofuel use. This may suggest that unless emissions from the chemical industry are accounted for, global anthropogenic emissions of CH
3
Cl have been substantially underestimated. In particular, since industrial production and use of CH
3
Cl have not been regulated under the Montreal Protocol (MP) or its successor amendments, continuous monitoring of Chinese CH
3
Cl outflow is important to properly evaluate its anthropogenic emissions.
The East/Japan Sea (hereafter, East Sea (ES)) is a semi-enclosed marginal sea and considered as a miniature ocean with oceanic features (e.g., currents, eddies, fronts, upwelling) and dynamic marine ...environments. The ES is significantly influenced by the global ocean warming with fast increases in sea surface temperature during the last several decades. The climate-induced environmental changes can affect marine ecosystem and food webs in the ES. Therefore, more accurate estimates in phytoplankton biomass in the ES with high spatial and temporal resolutions are necessary to investigate phytoplankton production, fisheries, and carbon budget as well as biological responses to the environmental and climate changes. The NASA ocean chlorophyll-type (OCx) chlorophyll-a (Chl-a) algorithms based on blue to green band ratio for the satellite ocean color data in the global ocean have been evaluated using the in situ radiometric and Chl-a measurements in the ES. The model-derived Chl-a data using the OC Chl-a algorithms present systematic overestimation in the lower Chl-a concentrations between about 0.1 and 1.0 mg/m3 in the ES (with ∼40% uncertainties). New Chl-a algorithms for the ES has been derived from the 3rd polynomial regression fits of in situ Chl-a and maximum band ratios of remote sensing reflectance (Rrs). The revised Chl-a algorithms considerably improve the Chl-a data in the ES from the satellite ocean color data in the lower Chl-a concentrations. Thus, the new Chl-a algorithms can provide more accurate assessments in biological and biogeochemical processes such as primary productivity, phytoplankton phenology, phytoplankton dynamics, and carbon cycles.
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