In this work, Raman spectroscopic experiments are conducted on zeolites, including a total of 33 varieties and seven groups with different secondary structural frameworks, for which characteristic vibration modes are studied. Most of the zeolites show prominent Raman peaks in the spectral range between 200–1200 cm⁻¹. Different groups of zeolites can be recognized by differences in the wavenumbers of the T-O-T (T = Si and Al, O = oxygen) modes in the range 379–538 cm⁻¹, the M-O (M = metal,) modes in the range 250–360 cm⁻¹ and the T-O bending modes in the range 530–575 cm⁻¹. All zeolites show characteristic Raman peaks in the range 379–529 cm⁻¹, except for natrolite group (fibrous) zeolites, which are characterized by T-O-T modes in the 433–447 cm⁻¹ range and T-O bending modes in the 528–538 cm⁻¹ range. The analcime group (with singly connected four-ring chains) zeolites show T-O-T modes in the 379–392 cm⁻¹ and 475–497 cm⁻¹ ranges. The gismondine group (with doubly connected four-ring chains) zeolites have T-O-T modes in the 391–432 cm⁻¹ and 463–497 cm⁻¹ ranges. The chabazite group (with a six-cyclic ring) zeolites are characterized by M-O modes in the 320–340 cm⁻¹ range and T-O-T modes in the 477–509 cm⁻¹ range. The Raman modes of mordenite group zeolites (397–410 cm⁻¹ and 470–529 cm⁻¹) overlap with those of heulandite group zeolites (402–416 cm⁻¹ and 480–500 cm⁻¹). Moreover, the mordenite group has a characteristic peak in the 502–529 cm⁻¹ range, and an additional peak in the 800–965 cm⁻¹ range. Another recognizable peak for the heulandite group is in the 612–620 cm⁻¹ range. The unknown zeolites (cowlesite) have unique characteristic peaks at 534 cm⁻¹, which can aid in the verification of their identity.

We investigated the ammonium removal abilities of natural and synthetic zeolites with distinct Si/Al ratios and various surface areas to study how adsorption and ion exchange processes in zeolites perform under different ammonium concentrations and different temperatures. Five zeolites—natural mordenite, chabazite, erionite, clinoptilolite, and synthetic merlinoite—were immersed in 20, 50, and 100 mg/kg ammonium solutions. The results demonstrate that zeolites under high ammonium concentrations (100 mg/kg) possess higher physical adsorption capacity (0.398–0.468 meq/g), whereas those under lower ammonium concentrations (20 mg/kg) possess greater ion exchange properties (64–99%). The ion exchange ability of zeolites is extremely dependent on the cation content of the zeolites, and the cation content is affected by the Si/Al ratio. The surface area of zeolites also has a partial influence on its physical adsorption ability. When the surface area is less than 100 m²/g, the adsorption ability of zeolite increases obviously with surface area; however, adsorption ability is saturated as the surface area becomes larger than this critical value of 100 m²/g. When we placed the zeolites in 50 mg/kg ammonium concentration at different temperatures (5–50 °C), we found that the zeolites exhibited the highest ammonium removal ability at 30 °C and the potassium release was enhanced at 30–40 °C.

The northwestern Pacific Ocean and South China Sea are where tropical cyclones occur most frequently. Many climatologists also study the formation of Pacific Ocean warm pools and typhoons in this region. This study collected data of paleotyphoons found in China's official historical records over the past 2000 years that contained known typhoon activity reports. The collected data are then subjected to statistical analyses focusing on typhoon activity in coastal regions of southeastern China to garner a better understanding of the long-term evolution of moving paths and occurrence frequency, especially regarding those typhoons making landfall in mainland China. We analyzed the data with the year and month of each typhoon event, as well as the number of events in a 10-year period. The result shows that (1) north–southward migration of typhoon paths corresponds to the north–southward migration of the Intertropical Convergence Zone (ITCZ) during the Medieval Warm Period (MWP) and Little Ice Age (LIA) and (2) paleotyphoons made landfall in mainland China 1 month earlier during the MWP than during the LIA. This implies a northward shift in ITCZ during the MWP. Typhoons tend to make landfall in Japan during El Niño-like periods and strike the southern coastal regions of China during La Niña-like stages. According to paleotyphoon records over the last 2000 years, typhoons made landfall in southeastern China frequently around 490–510, 700–850, and after 1500 CE The number of typhoons striking Guangdong Province peaked during the coldest period in 1660–1680 CE; however, after 1700 CE, landfall has migrated farther north. The track of tropical cyclones (TCs) in the northwestern Pacific Ocean is affected by the North Atlantic Oscillation (NAO) and the Pacific Decadal Oscillation (PDO), which shows a nearly 30-year and a 60-year cycle during the LIA.

In studies of paleoclimate change, variations in major and minor elements are often used as proxies for chemical weathering in soil or lake sediments. To prove the suitability of chemical weathering proxies and further discuss the impact of mineral dissolution on element migrations, various parent rocks in Taiwan were chosen to react with sulfuric acid for discussing mineral dissolution rankings and element leaching during chemical weathering processes. The parent rocks include granite, andesite, actinolite schist, slate, quartz sandstone, calcium sandstone, and mudstone. Experimental results show that dissolution rates are mainly controlled by mineral structures and the chemical compositions of rocks. The ranking of rock dissolution rates is as follows: mudstone > slate > actinolite schist > quartz sandstone > granite. Dissolution rates of andesite and calcium sandstone cannot be compared due to secondary minerals being produced in experiments. Moreover, the dissolution sequences of minerals are of the following order: calcite > chlorite > muscovite and illite > augite > hornblende ≈ feldspar > quartz. This result is consistent with the stability of silicate polymerization. Most notable among the results was that the dissolution rates of clay minerals were faster than those of feldspar. Element migration ranking in dissolution processes is as follows: Mg > Ca ≈ Rb > K > Na > Sr > Al > Zr > Fe ≈ Ti. The dissolution rates of univalent elements follow the sequence of bonding forces; however, those of divalent elements are less ordered. This is due to divalent elements being rich in different mineral phases. Therefore, the study suggests that univalent elements are more suitable as chemical weathering proxy candidates. Moreover, whether ratios of Rb/Sr and K/Rb or chemical index of alteration values in sediments are suitable proxies of paleorainfall intensity is discussed in detail.