Distribution and influencing factors of soil selenium and iodine in Limushan-Wanling, Qiongzhong area

Qiongzhong Limushan-Wanling area is located in the middle of Hainan Island, where has an abundance of selenium-rich and iodine-rich soil resources.The distribution characteristics of Se and I contents were analyzed based on the analysis results of soil samples in the topsoil (0-20 cm), middle-layer-soil(80-100 cm), and deep-soil (180-200 cm) of the study area.The correlation characteristics of Se and I in soil and their relationship with elevation potentially indicate that the input of rainfall to soil Se and I is a key factor leading to the enrichment of Se and I.By analyzing the correlation and change law between the contents of Se, I and the contents of pH, soil organic matter, Al2O3 and Fe2O3 in top, middle and deep layer soil, the enrichment and migration of Se and I in the vertical section of soil in the study area was summarized.These results can provide scientific basis for the efficient use of local high-quality land resources and provide new evidence for the study of soil Se source and migration

Petrogenesis of the granitoids related to skarn-type mineralization in the Nyainqentanglha Metallogenic Belt, Tibet

The Nyainqentanglha Metallogenic Belt (NMB) is an economically important lead-zinc ore province located in the Central and Southern Lhasa subterrane, Tibet. The NMB consists mainly of skarn-type lead-zinc polymetallic deposits that form at the contact between Late Cretaceous-Eocene intrusive rocks and carbonatite/volcanic-sedimentary strata. These deposits are generally considered to be related to S-type granites formed by the Indo-Asian continental collision. However, the εHf(t) (ave. −1.6) of zircons from the mineralization-related granitoids indicates that it is crust-mantle mixing products. In addition, the volcanic rocks of the Dianzhong Formation, which have a close spatio-temporal relationship with the skarn-type deposits, typically show mantle-derived features. Therefore, the occurrence of AFC processes in mantle-derived material passing through the thick basement of the Lhasa Terrane may better explain the genesis of the mineralization-related granitoids. In this study, we present results on zircon U–Pb ages, major and trace elements of the granitoids associated with skarn-type mineralization from the Narusongduo district. LA-ICP-MS zircon U–Pb dating shows that the granite formed in the Paleocene (58.6 ± 0.5 Ma). Combined with published regional data, we propose the mineralization age of the skarn-type deposits in the NMB ranges from the Late Cretaceous to Eocene. Detailed petrology and geochemistry of mineralization-related granitoids are evaluated to constrain the magmatic evolution process. The granitoids have high contents of SiO2 (mean 72.8 %), K2O (mean 4.0 %), Rb (mean 186.9 ppm), DI (differentiation index) 84.7, A/CNK (mean 1.3), and low contents of MgO, TFe, suggesting that the granitoids have undergone strong differentiation. In addition, the continuous decrease of P2O5 with progressive differentiation and the lower average P2O5 abundance suggest that the mineralization-related granitoids belong to the I-type granite. The results suggest that the mineralization-related granitoids in the NMB originated from the mantle and is the fractionated I-type granite formed by the process of AFC (Assimilation and Fractional Crystallization). Considering that Pb and Zn often coexist in deposits, we suggest that magmatic differentiation may play an important role in the formation of the granite-related Pb and Zn mineralization

Accumulation and Ecological Risk of Heavy Metals and Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from Typical Estuaries in Hainan Island

BACKGROUND： Heavy metals and polycyclic aromatic hydrocarbons (PAHs) are the ecological research focus because of their teratogenicity, carcinogenicity, and mutagenicity. Hainan Island is China’s first ecological civilization pilot area, and the continuous acceleration of urbanization will increase the pressure on environmental protection in the estuary area. The Changhua River, the Luodai River, and the Sanya River are important seagoing rivers in Hainan Island. At present, there is a lack of reports on heavy metals and polycyclic aromatic hydrocarbons in the sediments of the Changhua and Luodai Rivers, and there are differences in the related research results of the Sanya River. OBJECTIVES： To understand the characteristics, source, and ecological risk of heavy metals and PAHs in surface sediments from the estuary of the Changhua, Luodai, and Sanya Rivers in Hainan Island. METHODS: Sediment samples from the three estuaries were collected. Inductively coupled plasma-mass spectrometry/optical emission spectrometry (ICP-MS/OES) and atomic fluorescence spectrometry were used to determine the content of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn). Gas chromatography-mass spectrometry was used to determine the content of PAHs. Source apportionment was further explored based on the correlation analysis and composition of the contaminants, and the ecological risk evaluation was carried out with the potential ecological risk index (PERI) and sediment quality guidelines (SQGs). RESULTS: The average contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the sediments of Changhua River were 3.24, 0.03, 7.03, 5.33, 0.007, 3.06, 16.9, and 14.1mg/kg, respectively. The corresponding values of these metals in Luodai River were 4.81, 0.02, 7.69, 4.56, 0.010, 3.29, 18.3, and 14.7mg/kg, and the corresponding values in Sanya River were 5.83, 0.05, 15.3, 8.28, 0.021, 4.91, 21.4, and 29.8mg/kg. Exception to As, the concentration of other heavy metals in the sediments were below or close to the Hainan soil baseline, showing little heavy metals accumulation effect. The contents of PAHs in the sediment range from 3.48 to 56.6μg/kg, from 8.72 to 56.8μg/kg, and from 6.41 to 573.9μg/kg for the Changhua, Luodai, and Sanya River, respectively. Compared with other regions, the sediment PAHs content in the study area was relatively low. CONCLUSIONS: Arsenic in the estuarine sediments of the three rivers and Cd, Cu in the Sanya River are strongly influenced by anthropogenic factors, while the regional background mainly influences the remaining elements. PAHs originated mostly from the low-temperature combustion of biomass. The ecological risk evaluation demonstrates that the biotoxic effect of the heavy metals and PAHs is not obvious, mostly with low ecological risk. The present study on heavy metals and PAHs contamination in surface sediments of the three estuaries will provide a reference for future research