Clay mineral nanostructures regulate sequestration of organic carbon in typical fluvial sediments.

The association between clay minerals and organic carbon is pivotal for understanding transport, burial, and preservation processes of sedimentary organic carbon. However, fine-scale microscopic studies are still limited in assessing the effect of diverse clay mineral structures and properties on organic carbon sequestration. In this study, we employed X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy coupled with energy dispersive spectroscopy and electron energy loss spectroscopy analyses to investigate the nanoscale interaction between clay minerals and organic carbon of two typical fluvial sediment samples with contrasting clay mineral compositions and organic carbon origins. Sample from Taiwan shows abundant illite and chlorite with petrogenic organic carbon, while sample from Luzon has significant smectite with pedogenic organic carbon. We observed that the nanostructure of the clay minerals controls the distribution of organic carbon. In the Luzon sample, the organic carbon is tightly associated with smectite, occupying expandable interlayer spaces. In the Taiwan sample, however, the organic carbon is primarily confined on the surface and edge of illite. These findings offer valuable insights into the selective association of organic carbon with clay minerals and underscore the role of clay mineral nanolayer structures in governing the occurrence and preservation of organic carbon in sediments. A comprehensive understanding of these interactions is crucial for accurate assessments of carbon cycling and sequestration in the natural environment.

3D X-ray computed tomography gray value and age model datasets of coral cores Baler 2 and 3 (Philippines).

The datasets here contain the 3D X-ray computed tomography (3DXCT) gray values and age models of coral cores Baler 2 and 3, taken from Baler, Aurora, Philippines. 3DXCT was used to analyze 5 mm-thick slabs of the coral cores. From the resulting 3DXCT images, gray values were determined per pixel from top to bottom of the slabs. The gray value profiles across the length of the slabs were then matched with records of sea surface temperature (SST) of the Baler site to construct the age model of the coral cores. Daily SST records from October 2018 to February 1982 were from the Optimum Interpolation Sea Surface Temperature or OISST [1,2], while monthly SST records from February 1982 to May 1945 were from the Extended Reconstructed Sea Surface Temperature or ERSST [3]. The gray value datasets of coral cores Baler 2 and 3 present historical records of the corals' response to changing environments through the years and may be used in studies related to such. An example of this can be seen in the relationship between coral gray values and SST. Furthermore, the age model datasets of Baler 2 and 3 serve as the basis for interpretation for all current and future studies on these coral cores. These datasets were originally produced for the research work titled "A historical record of the impact of nuclear activities based on 129I in coral cores in Baler, Philippines: an update" [4].

A historical record of the impact of nuclear activities based on 129I in coral cores in Baler, Philippines: An update.

In a previous study in 2016, we presented how 129I in coral cores from the east (Baler) and west (Parola) sides of the Philippines recorded the impacts of human nuclear activities, including nuclear weapons testing, nuclear fuel reprocessing, and nuclear accidents. However, the 2016 Baler dataset only had a two-year time resolution and a crude age model based on growth band counting. Here we present a new 2020 Baler 129I/127I atomic ratio dataset that features at least annual time resolution and a more accurate age model constructed using 3D X-ray Computed Tomography. Results show that the bomb peaks in Baler primarily came from the Pacific Proving Grounds or PPG with a time lag of about 1.8 years (or more specifically, between 1.3 and 2.4 years). Moreover, a review of the Parola dataset shows that PPG signals may have been transported to Parola in the West Philippine Sea via two pathways: the northward and southward bifurcations of the North Equatorial Current, reaching Parola about 4.5 and 8.5 years after detonation, respectively. Moreover, a prominent peak in the year 2014.7 in Baler possibly came from the 2011 Fukushima Accident, transported by the Kuroshio Recirculation Gyre and the North Pacific Mode Waters with a 3.5-year time lag. This study contributes to the understanding of the impact and transport of human-made radionuclides to the Philippines and the relevant oceanographic processes in the Western Equatorial Pacific region.

Spatial variability in benthic assemblage composition in shallow and upper mesophotic coral ecosystems in the Philippines.

Mesophotic coral ecosystems (MCEs) have received increasing attention in recent years in recognition of their unique biodiversity and also their potential importance as refuges from disturbance events. However, knowledge of the composition of MCEs and how they vary in space is lacking in many regions, particularly the Coral Triangle biodiversity hotspot. Here, we compared the benthic components and coral genera composition between shallow-water reefs (SWRs, 8-13 m depth) and upper MCEs (30-40 m) in four locations in the Philippines that are exposed to differing environmental conditions. Coral cover, abundance, and generic diversity were lower in MCEs than SWRs at three of the four locations. Benthic composition and coral generic composition also varied significantly among locations for both shallow and deep sites. Differences in benthic composition among sites was due primarily to variation in hard corals, macroalgae, sand and silt, while variation in coral assemblage was due to differences in abundance of encrusting Porites, branching Acropora, branching Seriatopora. Our results showed that the composition of MCE communities varied significantly from adjacent shallow reefs, but also among MCEs in differing geographic locations. Furthermore, our results suggest disturbances affecting shallow-water reefs, particularly sedimentation, also negatively impact MCEs, and that depth therefore provides no potential refuge from these disturbances. We recommend that conservation of MCEs consider spatial variability in community composition among sites, and urge further research to better understand the spatial variation in the composition of MCE communities in the Philippines.

Spatial variability in reef-fish assemblages in shallow and upper mesophotic coral ecosystems in the Philippines.

The variability in reef-fish species assemblages was examined at three geographic locations in the Philippines (Apo, Abra and Patn), each showing varying levels of disturbances (low to high) at two depths, shallow-water reef (SWR; 8-20 m) and the upper mesophotic coral ecosystem (MCE; 30-35 m). Fish species assemblages varied among locations and between depths. Differences in fish assemblages among locations corresponded to the variability in benthic assemblages and levels of disturbances, wherein locations with higher coral cover and less disturbances had the highest fish species richness, abundance and biomass. Variation in fish assemblages between depths was also associated with changes in benthic assemblages and possibly inaccessibility to local fishing techniques. Fish species richness decreased with depth in all locations, but biomass increased only in the MCEs of Apo and Abra, which is a similar pattern exhibited in many MCEs. Our results suggest that despite location differences, depth had a relatively consistent influence on fish species assemblages, particularly in locations exposed to low and intermediate disturbance. Under high disturbance, MCEs exhibit similar vulnerability to SWRs.

Historical record of nuclear activities from 129I in corals from the northern hemisphere (Philippines).

Iodine-129 is a long-lived fission product that is majorly released in human nuclear activities (HNA) such as nuclear bomb testing, nuclear fuel reprocessing, and nuclear accidents. It is a good environmental tracer and former measurements of 129I in corals from the southern hemisphere show the increasing trend of 129I concentrations in the marine environment caused by HNA. Here we show time series of 129I/127(stable)I isotopic ratios in two coral cores from the northern hemisphere (Philippines) and how these record 129I released from HNA in even greater, unprecedented detail. Corals were taken from the Pacific Ocean (Baler) and South China Sea (Parola) sides of the Philippines. We observed nearly identical peaks (129I/127I âˆ¼ 31.5 × 10-12) in both the Baler and Parola records, each attributed to the year 1962 - the year with the highest recorded amount of 129I release from nuclear bomb testing. This 1962 129I bomb signal offers a new time marker that can be used to establish or confirm age models of corals, comparable to or possibly better than the well-known coral 14C bomb peak. We also observed nuclear fuel reprocessing and Chernobyl accident 129I signals in years 1977, 1980, and 1986, concurrently in Parola and with 9 to 11-year lags in Baler. This discrepancy in timing suggests that 129I was transported to the South China Sea and Pacific Ocean sides of the Philippines directly from the atmosphere and through prevailing ocean currents, respectively. Lastly, we observed surprisingly high 129I/127I isotopic ratios (i.e., 22.8 to 38.9 × 10-12) in the Parola record after the year 1996, which is in contrast to the decreasing trend observed in the Baler record and in published 129I releases of different HNA. These results possibly indicate the presence of unknown sources of 129I in the South China Sea region.

I-C-SEA Change: A participatory tool for rapid assessment of vulnerability of tropical coastal communities to climate change impacts.

We present a synoptic, participatory vulnerability assessment tool to help identify the likely impacts of climate change and human activity in coastal areas and begin discussions among stakeholders on the coping and adaptation measures necessary to minimize these impacts. Vulnerability assessment tools are most needed in the tropical Indo-Pacific, where burgeoning populations and inequitable economic growth place even greater burdens on natural resources and support ecosystems. The Integrated Coastal Sensitivity, Exposure, and Adaptive Capacity for Climate Change (I-C-SEA Change) tool is built around a series of scoring rubrics to guide non-specialists in assigning scores to the sensitivity and adaptive capacity components of vulnerability, particularly for coral reef, seagrass, and mangrove habitats, along with fisheries and coastal integrity. These scores are then weighed against threat or exposure to climate-related impacts such as marine flooding and erosion. The tool provides opportunities for learning by engaging more stakeholders in participatory planning and group decision-making. It also allows for information to be collated and processed during a "town-hall" meeting, facilitating further discussion, data validation, and even interactive scenario building.

Levels and distribution of organophosphorus flame retardants and plasticizers in fishes from Manila Bay, the Philippines.

Organophosphorus compounds (OPCs) and stable isotope ratios (δ(13)C and δ(15)N) were determined in 58 fishes belonging to 20 species collected from Manila Bay, the Philippines. OPCs were detected in most of the samples and found up to µg/g lw (lipid weight) level, suggesting their ubiquitous presence in the coastal marine environment of the Philippines. Higher levels (>1000 ng/g lw) of total OPCs were determined in yellowstriped goatfish, silver sillago, tripletail wrasse and bumpnose trevally indicates either their active uptake from ambient water or lower metabolic capacity of these species. Levels of triphenyl phosphate (TPhP) in demersal species showed a positive correlation with δ(15)N, indicating that TPhP was adsorbed onto the particle, settled down to the bottom sediment and accumulated through the benthic food web rather than the pelagic. Estimated dietary intake of OPCs in Manila Bay fishes were four to five orders of magnitude lower than the proposed reference dose (RfD).

Contamination and bioaccumulation of benzotriazole ultraviolet stabilizers in fish from Manila Bay, the Philippines using an ultra-fast liquid chromatography-tandem mass spectrometry.

Benzotriazole ultraviolet stabilizers (BUVSs) used in plastic products, building materials and personal hygiene products were analyzed in fishes collected from Manila Bay, the Philippines. BUVSs were detected at ng g⁻¹ level in all the fish samples, indicating their ubiquitous contamination in coastal waters. Among the targeted eight BUVSs, UV-328 was predominantly found with a mean concentration of 34.2 ng g⁻¹ lipid weight, implying large scale production and use of this compound in the Philippines. High concentrations of ∑BUVSs were found in bumpnose trevally (Carangoides hedlandensis), bluetail mullet (adult) (Valamugil buchanani), common ponyfish (Leiognathus equulus) and coral grouper (adult) (Epinephelus corallicola) indicating their active uptake and/or lower metabolic capacity to eliminate BUVSs. Among BUVSs, UV-P showed significant positive relationship (p<0.05) between concentration and fish length (r=0.29) and fish weight (r=0.31). Levels of UV-P in demersal species had positive correlation with δ¹5N, indicating that possibile sink of UV-P is bottom sediment in the bay, and ultimately accumulate through benthic food web rather than pelagic food web. To our knowledge, this is the first study on BUVSs distribution in fish from developing countries.

Determination of preservative and antimicrobial compounds in fish from Manila Bay, Philippines using ultra high performance liquid chromatography tandem mass spectrometry, and assessment of human dietary exposure.

Ultra high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of four paraben preservatives (methyl, ethyl, propyl and butyl) and two antimicrobial agents (triclosan and triclocarban) belonging to personal care products (PCPs) in 20 species of fish from Manila Bay (Philippines) was performed. Detection of PCPs with greater frequency indicates the ubiquitous contamination of Manila Bay. Concentrations of total paraben were one order of magnitude higher than the antimicrobials in almost all fish, except in Stolephorus indicus and Leiognathus equulus. A positive correlation was observed between parabens concentration and fish length (r = 0.31-0.49; p<0.05 to <0.001) and fish weight (r = 0.28-0.49; p<0.05 to <0.001), but not for the antimicrobials. The estimated dietary exposure values of the four parabens in the Philippines through fish is four orders of magnitude lower than the acceptable daily intake (ADI) of 10mg/kg/day, but the values of antimicrobials are just half of the ADI of TCS. To our knowledge, this is the first report of PCPs contamination in fish from Philippines.

Global sea-level rise is recognised, but flooding from anthropogenic land subsidence is ignored around northern Manila Bay, Philippines.

Land subsidence resulting from excessive extraction of groundwater is particularly acute in East Asian countries. Some Philippine government sectors have begun to recognise that the sea-level rise of one to three millimetres per year due to global warming is a cause of worsening floods around Manila Bay, but are oblivious to, or ignore, the principal reason: excessive groundwater extraction is lowering the land surface by several centimetres to more than a decimetre per year. Such ignorance allows the government to treat flooding as a lesser problem that can be mitigated through large infrastructural projects that are both ineffective and vulnerable to corruption. Money would be better spent on preventing the subsidence by reducing groundwater pumping and moderating population growth and land use, but these approaches are politically and psychologically unacceptable. Even if groundwater use is greatly reduced and enlightened land-use practices are initiated, natural deltaic subsidence and global sea-level rise will continue to aggravate flooding, although at substantially lower rates.