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The coupling between chemical weathering (including silicate, carbonate and pyrite weathering) and physical erosion is of high interest in active mountain belts. Participation of pyrite weathering which, results in CO2 emission to the atmosphere, also is of great research attention. Nevertheless, the responses of the (de-)couplings to landslide and typhoon are unclear. We used records of riverine TDS (total dissolved solids) and TSS (total suspended solids) with high-frequency sampling during typhoons to estimate chemical denudation rates of silicate (CDRsil), carbonate (CDRcarb), pyrite (CDRpyrite) and physical denudation rates (PDR) in two adjacent catchments, eastern Taiwan. Results show that the CDRsil in the two catchments is approx. 10-fold higher than the global mean, whereas the CDRcarb, CDRpyrite and PDR are over 15-fold higher than the global averages. Landslides likely elevate carbonate and sulfate dissolution, and streamflow is a kinetic control on the CDRs. Among CDRs, CDRsil remains constant with various landslides and typhoons. Yet, CDRcarb and CDRpyrite rapidly respond to typhoons and then contribute more CO2 emission. In sum, landslides expose fresh minerals to enhance chemical weathering; typhoons, which transport the dissolved solids within a short time and prompt new rainwater for weathering, are also dominant agents. We demonstrate the importance of dynamic partitioning of sulfuric and carbonic acid on silicate weathering for quantitative estimation of weathering-associated CO2 budget in active mountain belts.

Increasing anthropogenic nitrogen (N) emission via different pathways has shown prominent impact on aquatic ecosystems for decades, but the effects of interaction among climate-, landscape- and human-associated variables on riverine DIN (dissolved inorganic nitrogen, mainly NO3&minus, and NH4+) export are unclear. In this study, the data of 43 watersheds with a wide range of climate-, landscape- and human-associated gradients across Taiwan were evaluated with partial redundancy analysis (pRDA) to examine their interactive controls on riverine DIN export. Results show that the annual riverine DIN export in Taiwan is approximately 3100 kg-N km&minus, 2 yr&minus, 1, spanning from 230 kg-N km&minus, 1 in less disturbed watersheds (eastern and central Taiwan) to 10,000 kg-N km&minus, 1 in watersheds with intensive human intervention (southwestern and northern Taiwan). NO3&minus, is generally the single dominant form of DIN, while NH4+ renders significance in disturbed watersheds. Nearly all environmental variables display a positive correlation with DIN export, except for landscape setting variables (e.g., slope, area, channel length), which show a negative relationship. In terms of seasonal pattern, climate and human-landscape variables are related to NO3&minus, export independently in the wet season, yet in the dry season climate-human variables jointly dominate NO3&minus, export. Meanwhile, human-landscape (LH) variables (l1 of LH &gt, 0.60) control NH4+ exports in both seasons, and human-associated (H) variables (l1 of H = 0.13) have a minor effect on NH4+ exports in dry season. Precisely, the contribution of controlling variables on DIN export vary with species and seasons, indicating water quality management could be time-dependent, which should be taken into consideration for designing mitigation strategies.

Micro-Raman spectroscopy and petrographic analysis was carried out on ancient potsherds and sediments excavated from the Huagangshan site and river sediments collected from the northern part of eastern Taiwan. The ceramic fragments analyzed, dating back to 1600-2100 B.P., are recognized to be Early Metal Age of Taiwan. The aims of this study are mainly to identify the mineralogical compositions of ceramics, to explore technical processes such as firing temperature and redox state, and to decipher the nature of clays and its raw materials source.The results of micro-Raman analysis for ancient potsherds show the presence of 12 minerals. Quartz, anatase, amorphous carbon, hematite, and pyroxenes are the main components of tempers. In addition, amorphous carbon and hematite are the main constitutes for black- and red- hues pottery, respectively. From the point of view of manufacturing techniques, a large amount of amorphous amorphous carbon indicates that the gray-black pottery is fired under a reducing condition. On the contrary, hematite reveals an oxidizing atmosphere for red-hues pottery. The presence of quartz and anatase implies that the firing temperature is estimated to be 750-950°C. A total of 66 samples, containing 23 ceramic fragments (local and imported products) and 6 sediment from cultural strata of archaeological site and 33 river sediments around the site, is implemented by petrographic analysis of thin sections. Petrographic analytic results of 23 potshards show that the proportion of clay is consistent (60.5~69.1%). The inclusions principally include quartz (polycrystalline and monocrystalline quartz), feldspar, muscovite, and volcanic, sedimentary and metamorphic lithic fragments, and quartz is the main component. In addition, the triangle map with ingredients (volcanic lithics+quartz－sedimentary lithics－metamorphic lithics) shows that the raw materials source of local and main stream pottery recognized by archaeologist is not local, but comes from a distance area (the Coastal Range). On the other hand, imported pottery indicates the raw materials source is indeed from the central and southern Central Range (some distance south of the site). The result further illustrates the vigorous exchange and/or trade activities between the populations of eastern Taiwan during the Early Metal Age (1600-2100 B.P.).

The burial and exhumation history of an orogen can provide insights into the thermal history of rocks in the mountain belt. Asynchronous collision will exhume materials to the surface at different times and expose different metamorphic grades along the orogenic axis. By tracking the thermal signals of eroded materials, it is possible to compare spatial patterns of exhumation along the mountain belt. Previous studies such as bulk mineralogy of sandstones, crystallinity of clay minerals, and fission track thermochronology all suggest that the Pliocene to Pleistocene meta-sedimentary deposits within the preserved basins of the Coastal Range reflect the unroofing history of the Central Range in Eastern Taiwan. In this study, modern sediments from six drainages of the east Central Range (Liwu, Mugua, Laku- Laku, Luye, Jinlun, and Hsuhai Rivers) and three basin sections of meta-sedimentary deposits from the Coastal Range (Shuilien, Chimei, and Madagida sections) were sampled to reconstruct the thermal signals of each drainage along the modern orogenic axis and reconstruct temporal variations of thermal signals in preserved Plio-Pleistocene sedimentary rocks. The temperature index (T.I.) of modern sediments determined by Raman spectroscopy of carbonaceous materials are medium to high (0.4–0.8). In conjunction with bio- and magneto-stratigraphy, our data suggest that the northern Shuilien area has been receiving detritus of medium metamorphic grade from the exhumed orogeny in the north from 3.4 Ma and higher grade since 2 Ma; meanwhile, the southern Madagida section has been mostly taking in juvenile detritus from the south part of the orogen until 1 Ma. The central Chimei section has started collecting mature detritus since 1.24 Ma. The data suggest that the Plio-Pleistocene basins contain a good record of orogen evolution.

Landscape composition and configuration, which runoff flows through, have substantial effects on nutrient export of humid mountainous watersheds. The relationships between landscape metrics and annual and seasonal NO3-N and PO4-P fluxes are developed for 43 watersheds distributed island-wide in Taiwan during 2015–2016. The results show that the watersheds with higher concentrations of NO3-N and PO4-P mainly distributed on western Taiwan whereas watersheds with lower concentrations of NO3-N and PO4-P scattered across mountain regions and eastern Taiwan. Multiple stepwise regression models are used to realize the effects of landscape pattern on NO3-N and PO4-P exports at watershed level and riparian buffers of various width (100 m, 200 m, 500 m, 1000 m, 1500 m, and 2000 m). Our findings show that the average annual exports of NO3-N and PO4-P across various watersheds are 3.8–50.8 and 0.04–7.7 kg ha−1 yr−1, respectively, much higher than reported values worldwide. The class-level metrics IJI (interspersion and juxtaposition) of agricultural land and LPI (largest patch index) of buildup area obtained from 200 m buffer explain 85% of variation of NO3-N flux, and ED (edge of density) of buildup area and LPI of water body or percentage of water body at 200 m buffer combined contribute 90% of variation in PO4-P exports. The highly mixed development of urban and agriculture distributed along with the limited extent of riparian buffers within watersheds in Taiwan make the watershed susceptible to loss of a large quantity of nutrients and sediments into streams. Management practices such as diminishing fragmented agriculture and buildup area are recommended as they should help to reduce water pollution, and better designs of developed area and water body can further improve water quality.

The use of light-emitting diodes (LED) has increased rapidly in Taiwan, because their energy losses are lower than traditional illuminants. Scrap is produced in the manufacturing process for LEDs, which contains valuable metals (i.e., Ga) and harmful component (i.e., As). For sustainable environmental reasons, this study develops a recycling technique for GaAs scrap. The GaAs scrap was firstly ground and sieved to pass 100 mesh sieve. The powder sample was leached, using 1.5 N nitric acid at 40°C for 1.5 h, and the dissolution of Ga and As was close to 100%. Sodium sulfide solution was added into the leachate as a precipitating agent and As was selectively precipitated from the solution. In the optimal conditions, using a 0.1 M of sodium sulfide and a flow rate of 5 mL/min, the precipitation percentages of As and Ga were 98.5 and 1.5%, respectively. The purified Ga solution was recovered, and the As was concentrated in the sediment. The precipitate was examined using X-ray diffraction and the major phase was identified as As2O3 which can be stabilized using the ferrite process or used as a raw material in a related industry. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 471–475, 2015

Micro-Raman spectroscopy is applied for the first time to identify mineralogical characteristics of ceramic bodies and red coatings on decorative cord-marked pottery (ca 2600–1700 B.C.) from an archeological site in northern Taiwan. X-ray diffraction and scanning electron microscopy-energy dispersive X-ray spectrometry were used as complementary techniques. The combined results of mineralogical and elemental composition suggest that the pottery items were produced from illitic clays and fired to a temperature less than 800 °C under oxidizing conditions. The slight discrepancy in composition between the red coatings and ceramic bodies possibly indicates a somewhat different source of raw materials and/or clay refining processes used by ancient potters. Additionally, feldspar, hornblende, and pyroxenes detected in the samples are closely related to the main compositions of nearby volcanic rocks, implying that the raw materials could have come from a local source. Copyright © 2010 John Wiley & Sons, Ltd.