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Taiwan is particularly sensitive to changes in monsoonal precipitation and to typhoon-induced heavy precipitation events, however, rainfall variability in Taiwan on centennial and millennial time scales during the Holocene has not been well understood. This study describes mid-Holocene rainfall features of Taiwan based on pollen, total organic carbon (TOC), total nitrogen (TN), and C/N ratio records of core MD05-2908. The step-wise increase in sedimentation rate, fern spore percentage and concentration, TOC content, and C/N ratio suggests an increasing terrestrial material supply due to the intensified rainfall in Taiwan since 6800 cal. yr BP. This rainfall pattern shows an inverse pattern to the decreasing East Asian summer monsoon (EASM) strength represented by the multi-proxy records from North China. Variation of the East Asian summer circulation and associated moisture transport may account for the long-term rainfall changes in Taiwan. Superimposed on this trend, we interpreted three prominent rainfall changes, which focus on the periods of 6800–6600, 1090–880 and 490–190 cal. yr BP. These centennial time scale rainfall variations in our records are linked to the intensity of El-Nino Southern Oscillations.

This study investigated the bulk sediment geochemistry, U–Pb ages and rare earth element (REE) geochemistry of one hundred detrital zircons recovered from the Brujas beach sands in southwestern Gulf of Mexico to understand the provenance and age spectra. The bulk sediments are high in Zr and Hf contents (∼1400–3773 ppm and ∼33–90 ppm, respectively) suggested the abundance of resistant mineral zircon. The chondrite normalized REE patterns of the bulk sediments are less fractionated with enriched low REE (LREE; La CN /Sm CN = ∼491–693), depleted heavy REE (HREE; Gd CN /Yb CN = ∼44–69) and a negative Eu anomaly (Eu/Eu ∗ = ∼0.44–0.67) suggested that the source rock is felsic type. The results of this study revealed highly varied contents of Th (∼4.2–321 ppm), U (∼20.7–1680 ppm), and Hf (∼6970–14,200 ppm) in detrital zircons compared to bulk sands. The total REE content (∼75 and 1600 ppm) and its chondrite-normalized pattern with positive Ce and negative Eu anomalies as well as low Th/U ratio of zircon grains indicated that they were dominantly of magmatic origin. U–Pb data of zircons indicated two age populations, with predominance of Permian-Triassic (∼216–286 Ma) and Neoproterozoic (∼551–996 Ma). The Permian-Triassic zircons were contributed by the granitoids and recycled metasedimentary rocks of the Chiapas Massif Complex. The major contribution of Neoproterozoic zircons was from the Chaucus, Oaxacan, and Chiapas Massif Complexes in Grenville Province, southern Mexico. U–Pb ages of zircons from the Brujas beach are consistent to the reported zircon ages from the drainage basins of Usumacinta, Coatzacoalcos, and Grijalva Rivers in southern Mexico, suggesting that the sediments delivered by the rivers to the beach area are vital in defining the provenance of placers.

•Chennai (India) received the highest rainfall of 490 mm on 1 Dec 2015.•This study looked at NOAA/NESDIS global analysis of SST anomaly (°C).•Revival of 769 km long Buckingham Canal essential for flood mitigation.•Renovating canals, ponds, and lakes crucial for flood prevention.•India needs better strategies to adapt to future extreme weather situations.

Sediment core OS03-1 retrieved from the Akademia Nauk Rise in Southern Okhotsk Sea was analyzed for the contents of rare earth elements (REEs) and combined with carbon isotope (δ13C) time series of benthic foraminifera to infer changes in terrigenous accumulation and bottom water ventilation on glacial–interglacial timescales in the study area. The age model of OS03-1 was constructed by a combination of foraminifer δ18O stratigraphy and 14C AMS dating, revealing that the 380 cm long core provides a window on climate change in the southern Okhotsk Sea since ∼180 ka. A grain size-controlled-REE content shows strong glacial–interglacial changes. The Cerium and Europium anomalies vary from 0.89 to 1.32 and from 1.14 to 1.37, respectively. The (La/Yb)N values range between 0.55 to 0.92. Both results suggest a significant contribution of volcanic debris in the core sediments. In addition, the relationships between Sm vs. Nd suggest main contribution origin from the Amur River and sea ice during warm intervals and from the sea ice during cold intervals, indicating that the sea ice played an important role in transporting terrigenous materials to the study site in the southern Okhotsk Sea. During the last 180 ka, the mass accumulation rates (MAR) of ∑REEs are relatively higher during glacials and lower during interglacials with a peak accumulation during the early deglacial period. We infer that an intensified Mongolia High is responsible for the first-order accumulation pattern of ∑REEs in the southern Okhotsk Sea by mediating the dynamic changes in sea ice extent. Furthermore, six δ13C minima are associated with intensified Asian monsoon (AM) precipitation and maximum MARs of ∑REEs, indicating that the dominance of barrier layer effects by high fresh water input through sea ice melting. The maximum MAR of ∑REEs during the Marine Isotope Stage (MIS) 5c coincides with the minimum of benthic foraminiferal δ13C, indicating a major interruption of ventilation in the bottom water in the Okhotsk Sea. The major low ventilation event in the deep water of the Okhotsk Sea appears to be dampened by a cooling condition and a major blooming of surface productivity preceded the event.

We used multi-decadal pollen and diatom records from sediment core TFL-1 from Tsuifong Lake to reconstruct the vegetation dynamics and hydroclimate in northeastern Taiwan during the past 3500 cal BP. Coarse grained sediments in association with higher percentages of wetland pollen (Cyperaceae) and upper conifer pollen (Tsuga and Pinus) in the lower part of the core indicate low lake levels and a relatively cold/dry climate between 3500 and 2030 cal BP, reflecting a decline of the East Asian summer monsoon (EASM). Muddy sediments coupled with reduction of wetland pollen represent the rise of lake levels, implying the re-strengthening of the EASM during the past 2000 years. Paleotemperature was inferred from the variation of pollen origin from the upper and lower mountain forest, indicating the global temperature anomalies of the Medieval Warm Period (MWP) and the Little Ice Age (LIA). In comparison to the main climate forces in the North Pacific, we suggest that the long-term climatic trend in Taiwan was controlled by variations in EASM intensity, while increased precipitation over the past 2000 years may also be linked to warmer sea surface temperature (SST) of the western Pacific Warm Pool (WPWP) and increased El Nino-Southern Oscillation (ENSO) events, which increased typhoon intensity. Higher diatom-inferred pH during 2930–2030 cal BP and the LIA suggest strong hydrological disturbances, reflecting more typhoons passing over Taiwan. The frequent typhoon events could be linked by an abrupt shift of typhoon track, due to the reduction of the WPWP and expansion of the Northwestern Pacific High, which move typhoons in a more westerly direction.

The global export of organic carbon (OC) is intimately linked to the total flux of terrestrial sediment to the ocean, with the continental margins receiving ~ 90% of the sediment generated by erosion on land. Recent studies suggest that a substantial amount of particulate OC (POC) might escape from the shelf and be exported to the continental slope-deep sea sector, although the mechanisms and magnitude of such deep sea POC transfer remain unknown. Here we investigate hyperpycnal flow-associated total suspended matter (TSM) collected from water depths of ~ 3000 m, near the bottom of sea floor, in the Gaoping Submarine Canyon (GSC) off southwestern Taiwan. Elemental (C, N), isotopic (δ 13 C, δ 15 N) and biomarker compositions of TSM were investigated to understand its biogeochemical characteristics. A two end-member δ 13 C mixing model indicates that deep sea TSM contains ~ 90% terrigenous OC, while a similar mixing model using δ 15 N reveals a lower proportion (~ 58%). Organic biomarkers of TSM suggest contributions from a mixture of resuspended, continental-margin derived marine organic matter (OM MAR ) and terrigenous sources, revealing that terrestrial OC likely mixes with nitrogen-rich marine material during rapid transport. This study documents that rapid transfer of terrigenous organic matter (OM TERR ) into the deeper regions of GSC occurred within a week of typhoon Morakot, likely through hyperpycnal injection of sediment-laden, warm freshwater from southern Taiwan. Evidence from this typhoon Morakot-induced hyperpycnal plume event in Taiwan demonstrates that extreme storm events provide an efficient way to export terrigenous OC without oxidation to hitherto unknown water depths of deep sea in the Oceania region.

article i nfo Wereportontheexistenceandnature of Holocene solar andclimaticvariationson centennialto millennial time- scales. We introduce a new solar activity proxy, based on nitrate (NO3 − ) concentration from the Talos Dome ice core, East Antarctica. We also use a new algorithm for computing multiple-cross wavelet spectra in time-fre- quency space that is generalized for multiple time series (beyond two). Our results provide a new interpretive framework for relating Holocene solaractivity variations on centennial to millennial timescales to co-varying cli- mate proxies drawn from a widespread area around the globe. Climatic proxies used represent variation in the North Atlantic Ocean, Western Pacific Warm Pool, Southern Ocean and the East Asian monsoon regions. Our wavelet analysis identifies fundamental solar modes at 2300-yr (Hallstattzeit), 1000-yr (Eddy), and 500-yr (unnamed) periodicities, leaves open the possibility that the 1500-1800-yr cycle may either be fundamental or derived, and identifies intermediary derived cycles at 700-yr and 300-yr that may mark rectified responses of the Atlantic thermohaline circulation to external solar modulation and pacing. Dating uncertainties suggest that the 1500-yr and 1800-yr cycles described in the literature may represent either the same or two separate cycles, but in either case, and irrespective too of whether it is a fundamental or derived mode in the sense of Dima and Lohmann (2009), the 1500-1800-yr periodicity is widely represented in a large number of paleoclimate proxy records. It is obviously premature to reject possible links between changing solar activity at these multiple scales and the variations that are commonly observed in paleoclimatic records.

Protein concentrate (PC) of Kappaphycus alvarezii (cultivated on the West coast of India), was extracted and its functional properties were evaluated. The K. alvarezii PC contained 62.3 ± 1.62% proteins. At pH 12, the nitrogen solubility of this PC was 58.72 ± 1.68% in the presence of 0.5 M NaCl. The emulsifying and foaming properties of this PC varied with time and pH. However, it formed remarkably stable emulsions with Jatropha oil after 720 min (i.e. E 720 = 53.67 ± 1.59). On the other hand, maximum foaming ability (53.33 ± 2.31%) of the PC was recorded at pH 4.0. This PC had high oil (1.29 ± 0.20 ml oil/g PC) and water absorption capacity (2.22 0.04 ml H 2 O/g PC). DSC analysis revealed thermal transitions at about 109.25 °C at neutral pH. The results obtained in this investigation suggest the suitability of K. alvarezii PC as an inexpensive source of protein; thus this PC could be incorporated into several value-added food products.

Small mountainous rivers in Oceania typically have higher sediment yields than larger rivers because of their steep gradients and frequent tropical storm-induced high rainfall. The high sediment yields of these small mountainous rivers enable them to transport a large amount of terrigenous material to the oceans. However, data are unfortunately sparse on this topic. In this study, we investigated the water quality and sediment geochemistry of 35 small rivers in Taiwan and compared these data with that of the large Pearl River. Although Taiwan and the Pearl River Basin are both traversed by the Tropic of Cancer, and thus have similar weather patterns, their water chemistry is quite different. The most notable difference is that despite higher rainfall in Taiwan, and hence, a larger dilution effect, the total dissolved solid concentration (TDS), Mg+2, Na++K+, Cl−, and SO 4 - 2 are generally higher in the Taiwanese rivers compared to the Pearl River. On the other hand, the sediment load in Taiwanese rivers is higher compared with the Pearl River, as expected. These observations reflect the higher rate of chemical weathering and denudation in Taiwan due to its steeper terrain and the larger impact of typhoons, hence episodic heavy rains in that region. The pattern of distribution vs. altitude is also different, with higher TDS, Ca+2, Mg+2, SO 4 - 2 , HCO 3 - and pH values at higher altitudes in the Pearl River Basin, whereas these values are lower at higher elevations in Taiwan. We see this difference because the upper reaches of the Pearl River are primarily covered with limestone, whereas the high mountains of Taiwan are mainly composed of slate and schist that are more resistant to chemical weathering and less affected by acid rain compared with limestone. Pollution-related parameters such as non-sea-salt SO 4 - 2 ( nss- SO 4 - 2 ) , nss-SO4/(Na++K+) and Cl−/(Na++K+) also suggest that rivers in Taiwan are much more polluted than the Pearl River Basin, perhaps due to the widespread burning of coal and plastic-laden refuse in Taiwan.

National Science Council of Taiwan [NSC 97-2629-M-001-025, NSC 99-2116-M-001-011]; National Science Foundation of China [41176059, 41121091]

Multi-proxy records in two sediment cores (R and Rd) from the subalpine Retreat Lake in NE Taiwan document 5 centennial-scale periods (∼7.3–6.9, 6.35–5.9, 5.8–5.1, 4.5–∼2.1, and 2.0–1.6 ka BP) of relatively reduced summer East Asian monsoon (EAM) precipitation that were superimposed on the long-term decreasing monsoon trend from ∼8 ka BP onwards. The first three intervals of weak summer EAM indicated by low TOC, C/N ratio and water content within the Holocene optimum (∼8.6–4.5 ka BP) correlate with solar activity, revealing that the centennial-scale summer monsoon variations in a warm climate were related to weak solar irradiance. The desiccation of the lake (4.5–∼2.1 ka BP), followed by a weak monsoon event at ∼2.0–1.6 ka BP, may coincide with decreased sea surface temperature in the tropical Pacific. High water content and low dry bulk density in core Rd at ∼7.6, 7.46, 6.8–6.54, 6.1, 5.8, 5.6, and 5.0 ka BP imply a significant increase of summer EAM during these periods, and thus suggest an unstable optimum climate in Taiwan. A possible linkage of weak summer EAM with the tropical Pacific and North Atlantic cooling during these intervals may be driven by coupled ocean–atmosphere interactions, especially reduced heat and moisture transport and enhanced El Nino-Southern Oscillation in the tropical Pacific, as well as solar activity. The centennial-scale reorganizations in the tropical Pacific climate dynamics may have played an important role in the summer EAM instability, particularly during the late Holocene.

Slag material was dumped in two sites off southwestern Taiwan by the China Steel Corporation during 1984-1995. By geochemically analyzing four sediment cores, we investigate the impact of slag on the sediment chemistry. Elemental profiles from the dumping sites show a strong depletion in detrital elements and enrichment in alkaline and redox-sensitive elements, especially for the top ~20 cm of sediments. The relative enrichment factor (EFrel) exhibits wider range for Ca (0.73-13.33), Fe (0.883.03), Mg (0.94-9.58), and Mn (1.22-33.30) due to contamination of sediments by slag. Sediment weathering indicators also show a distinct change with lower values in sediments influenced by dumping due to Ca and Sr addition. Higher EFrel for As, Cd and Pb in the top sections of the cores indicate an additional modern/industrial input of these elements since ~1950. Our study suggests that slag dumping may have a localized effect on biogeochemical processes by inducing the diagenetic remobilization of certain elements.

article i nfo Results of clay mineralogy in 140 samples collected in major rivers and lakes in southwestern Taiwan and on the seafloor off Taiwan in the northeastern South China Sea (SCS), combined with clay mineral records of the Pearl River drainage basin, rivers in Luzon, and the South China shelf and slope, are used to semi- quantitatively evaluate the detrital fine-grained sediment contribution of Taiwan to the northern SCS. The clay mineral assemblage of the Taiwan-sourced sediments consists dominantly of illite (average 56%) and chlorite (41%), with very scarce kaolinite and smectite. Their respective distribution from the rivers and lakes to the seafloor off Taiwan does not show obvious basin-wide differences. Linear correlations of illite chemistry index with illite crystallinity and of illite crystallinity with kaolinite (%) present two end-members of provenances, the Pearl River and Taiwan, for the South China shelf and slope. Assuming that kaolinite in the northern SCS is provided completely from the Pearl River, the contribution of Taiwan in clay minerals is evaluated as 29% to the South China shelf and 23% to the South China slope, respectively. Accordingly, the contribution of the Pearl River to the South China shelf and slope is 52% and 31%, respectively. The Luzon Arc accounts for the rest of clay mineral components for the northern SCS mainly by providing smectite. The Bashi Strait-crossed branches of the southward deep North Pacific Deep Water and the northward surface Kuroshio Current in the western Pacific may transport Taiwan-sourced suspended sediments westwards to the northern SCS.

Three sediment cores near the spreading axis in the Andaman backarc basin (ABB) were studied for bulk and clay mineralogy, major, trace and rare earth element (REE) geochemistry in bulk and three selective leaches, to identify sediment sources to this region and to decipher probable hydrothermal contribution. REE and other geochemical data suggest a strong influence of the Irrawaddy River as a major continental source to the ABB sediments. Low carbonate content in the sediments is due to dilution by higher detrital input as well as reduced foraminiferal carbonate contribution because of low sea surface salinity. The contribution from local volcanic sources was identified from the presence of volcanic glass in the sand-sized sediment fraction; higher smectite content in the clay fraction and the trace element data. Mn concentrations in the upper 12 cm are well above those found in pelagic carbonate-free sediments. Mn distribution pattern and oxide nature suggest a hydrothermal source. Other discriminants such as Eu anomaly and Y/Ho ratio also suggest the role of hydrothermal activity. In addition, the association of Mo with Pb, Zn and Cu in the HCl-insoluble residue suggests the presence of sulfidic material probably of hydrothermal origin.

Distribution of 10Be in systematically collected (degree × degree interval at 10 to 16 °S; 73.5 to 76.5 °E) surficial siliceous ooze, siliceous clay and pelagic clay sediments (top 2 cm) from the abyssal Central Indian Basin and the Andaman Sea is used to evaluate sources and to decipher the transport pathways of sediment particles, demarcate sediment depocenters and erosional areas. While 10Be concentrations display a wide variation (0.12–5.56 × 109 atoms g−1) with an average of 3.58 × 109 atoms g−1 in the Central Indian Basin, the values in the Andaman Sea are uniform with an average of 1.49 × 109 atoms g−1. The 10Be/9Be values in the Central Indian Basin sediments range between 0.06 and 2.99 × 10−8 atoms atoms−1 and average to ∼1.56 × 10−8 atoms atoms−1. Correlation of 10Be data with some selected major (Al, Mn, Ti) and trace (Rb and Ba) elements suggest that large part of the isotope has been supplied through direct atmospheric fallout from the water column and minor part from lithogenic detrital flux. Significantly lower 10Be accumulation rates in the Central Indian Basin and an order of magnitude higher in the Andaman Sea sediments compared to the estimated global average production rates indicate removal of the isotopes at the continental margins. Bottom topography seems to exert control on local 10Be variation, where sediments deposited in valleys or topographic depressions contain higher 10Be concentrations in contrast to the probably erosion-dominated areas at the slopes and troughs.

Surface sediment samples collected from the inner shelf region of the Bay of Bengal, were analysed for the major elements and total and acetic acid available trace elements (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Si, Zn) to evaluate geochemical processes influencing their distribution. Major elemental analysis showed that the sediments had high concentrations of Si and relatively low concentrations of Al and Fe. Both major elemental and trace metal concentrations indicated that the sediments represent weathered products of granite and charnockite. Normalization of metals to Al indicated relatively high enrichment factors for Pb, Cd, Zn and Cr. The higher proportions of nondetrital Pb (66%), Cd (41%) and Co (28%) reveal metal contamination due to anthropogenic inputs. Factor analysis (FA) identified six possible types of sedimentological and geochemical associations. The dominant factor accounting for 26.9% of the total variance identifies an anthropogenic input and accumulation of nondetrital Cd, Co, Cr, Ni and Pb. Association of these metals with CaCO3 reveals that shell fragments in the surface sediments are likely act as a carrier phase for nondetrital metals. The results are discussed in the context of the sources and pathways of elements in the Bay of Bengal.