RESUMEN
Carbon sink produced during rock weathering is critical to global carbon cycles. In this work, the major ion chemistry and ion sources of Qingshuijiang River Basin were investigated. The principal component analysis, mass balance approach and deduction method were applied for estimating the weathering rate and atmospheric CO2 consumption via the chemical weathering of rocks. The results demonstrated that the chemical weathering of carbonate and silicate rocks within the drainage basin was the main source of the dissolved chemical substances in the Qingshuijiang River Basin, prior to carbonate rock weathering. Some 58.28% of the total dissolved chemical substances were derived from the chemical weathering of carbonate rock, 17.38% from the dissolution of silicate rock, and 17.74% from atmospheric CO2 contribution rates. The chemical weathering rate of this catchment was estimated to be 109.97t·(km2·a)-1, which was comparable to Wujiang River Basin, but higher than the average of global rivers. Furthermore, the atmospheric CO2 consumption rate was estimated to be 7.25×105 mol·(km2·a)-1. The CO2 flux consumed by the rock chemical processes within this catchment was 12.45×109 mol·a-1, of which about 63.13%(7.86×109 mol·a-1) was resulted from carbonate weathering and 36.87%(4.59×109 mol·a-1) from silicate weathering. The CO2 consumed by rock chemical weathering in the Qingshuijiang River reduced the atmospheric CO2 level and constituted a significant part of the global carbon budget. Correlation and spatial distribution analysis of SO42-, F-, NO3- showed that anthropogenic activities contributed remarkably to dissolved solutes and associated CO2 consumption worldwide, and anthropogenic inputs probably contributed some 4.87% to the dissolved solutes in the Qingshuijiang River.
RESUMEN
According to the ion content and chemical characteristic analysis of Qingshuijiang River water during wet season, the result shows that the chemical composition of the river water is dominated by Ca2+, HCO(3-); Mg2+, and SO4(2-). The TDS concentration (213.96 mg · L(-1)) is significantly higher than the average value of rivers worldwide. Seawater correction approach (Cl(-) normalized seawater ratios) was applied to estimate the contribution proportions of local precipitation to the solutes, and it is found that the contribution ratio of precipitation (2.23%) is lower than the average value (3%) of global catchments. Furthermore, Gibbs graph combining major ion element ratio analysis indicates that the catchment hydrochemistry is mainly originated from carbonate rock weathering, which becomes increasingly distinct as the river goes downstream. Both carbonic acid and sulfuric acid play crucial roles in the chemical weathering. Ion source analysis demonstrates that Ca2+, Mg2+, HCO3- are mainly derived from chemical weathering of carbonate mineral (Dolomite and Calcite); Na+, K+ and Cl- are primarily contributed by silicate mineral weathering; SO4(2-) and NO3- stemmed are mainly from acid atmospheric deposition and from urban sewage input. Anthropogenic analysis suggests that the chemical composition of Qingshuijiang River is greatly impacted by the upriver industrial and mining enterprises activities.
Asunto(s)
Monitoreo del Ambiente , Ríos/química , Carbonato de Calcio , Carbonatos , China , Agua Dulce/química , Iones , Magnesio , Minerales , Estaciones del Año , Tiempo (Meteorología)RESUMEN
Among the 5 tested litchi (Litchi chinensis Sonn.) cultivars ("Huaizhi", "Guiwei", "Nuomici", "Hongmili" and "Shuijingqiu", "Nuomici" became deteriorated much faster than other cultivars while "Guiwei" fruit was the slowest in the rotting process (Fig. 1A). Fruit deterioration was accompanied by fruit desiccation (Fig. 2B), but the speed of water loss was not significantly correlated to fruit deterioration rate, indicating that it was not the key factor causing the difference in postharvest performance among cultivars. Fruit deterioration rate was significantly positively correlated to membrane leakage (Fig. 2A), suggesting the capacity to maintain membrane integrity is closely related to the shelflife of litchi. Skin browning potential, uronic acid concentration, degree of methylation of pectin and soluble Ca content in pericarp as well as total Ca content in the pulp were not significantly correlated with fruit deterioration. Content of structural Ca (water-insoluble but acetic acid-soluble calcium, membrane or wall-bound Ca), the major form of Ca in the pericarp, was negatively correlated to fruit deterioration rate (Fig. 2E). The results proved that differences in fruit desiccation rate, browning potential, Ca other than structural form were not the major cause leading to difference in postharvest performance among different cultivars. "Guiwei" being more tolerant to desiccation than other cultivars is likely associated its higher structural Ca concentration in the pericarp.