Reveal the threat of water quality risks in Yellow River Delta based on evidences from isotopic and hydrochemical analyses.

This study aims to evaluate the seasonal and spatial characteristics of hydrochemistry and DO isotopes and identify the eco-environmental threats under the background of saline intrusion and human activities in Yellow River Delta (YRD). Analyses for major ions (i.e., K+, Na+, Ca2+, Mg2+, SO42-, HCO3- and Cl-), nitrate ion (NO3-) and isotopic composition are performed for precipitation, river water, wetland water and sea water. Based on the range of δ2H and δ18O as well as their relations, the mixing between multiple sources and evaporation are confirmed. Electrical conductivity (EC), concentration of NO3-, soluble sodium percentage (SSP) and magnesium hazard (MH) are employed as indicators to reflect the ecological risks from salinity, agricultural pollutants, sodium and magnesium. By hierarchical cluster analysis (HCA), the samples of wetland water are grouped associated with those of river water. The characteristic reflects 3 patterns of risks in wetlands, including saline intrusion, human activities and their mixed influence.

New pregnane glycosides from the roots of Cynanchum otophyllum.

Six new pregnane glycosides with an acyl at C-12 and a straight sugar chain at C-3, namely otophyllosides H-M (1-6), were isolated from the roots of Cynanchum otophyllum (Asclepiadaceae) collected from Eryuan County in Yunnan province of China. Their structures were characterized to be qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-digitoxopyranoside (1), qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-digitoxopyranoside (2), qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-digitoxopyranoside (3), qingyangshengenin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-thevetopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-digitoxopyranoside (4), caudatin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranoside (5), caudatin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside (6), respectively, on the basis of detailed spectroscopic analysis and chemical method.