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The chemistry of major dissolved ions (Ca2+, Mg2+, Na+ + K+, HCO3−, SO42−, Cl−) and dissolved silica (SiO2) in the river water of the Huanghe (Yellow River), China, was studied from historical records at 100 stations in the drainage basin for the period 1958–2000 (not all the parameters were continuously monitored during the entire period). This river system (750,000 km2) presents an exceptional temporal and spatial water chemistry variability compared to other major rivers. The total dissolved solid (TDS) concentration of the Huanghe varied over 2 to 3 orders of magnitude throughout the basin, with a median TDS concentration of 452 mg/L, which is about 4 times the world spatial median value (WSM). In particular, the concentrations of Na+ + K+, SO42−, and Cl− were 10–20 times higher than in other major world rivers. Similar to the Changjiang (Yangtze River) and many other Himalayan rivers, the TDS at a given station is seasonally variable and inversely related to river runoff with a variation factor less than 2.0, despite a water dilution of fourfold to fivefold in the summer flood season. In addition to chemical weathering of sedimentary rocks, evaporation and fractional crystallization were found to be the major natural process controlling the major element chemistry of the Huanghe, owing to the abundance of loess and clastic rocks under arid and semiarid climates. A persistent increasing trend from year to year has been observed in the concentrations of TDS and all the salts except for HCO3− at all main‐channel stations except for the uppermost Lanzhou. The rate of increase in the TDS concentration was the highest in the middle reaches (10.52 mg/L yr−1 at Toudaoguai) and remained to be unusually high in the lower reaches (5.5 mg/L yr−1 at Stations Luokou and Lijin). The increasing trend coincided with a significant decrease in water discharge at most of the main‐channel stations in the past 40 years, and is attributed to increasing regulations of reservoirs and intensive water withdrawal for irrigation and diversions, as well as many other anthropogenic processes. Despite the increasing trend in TDS concentrations, the seaward TDS flux to the sea by the Huanghe has decreased dramatically from more than 20 × 109 kg/yr in the 1960s to less than 10 × 109 kg/yr at present, due to the sharp decrease in water discharge (sometimes completely dried up) in the lower reaches of the river. The significant decreases in sea‐ward fluxes of water and dissolved salts are expected to have profound physical, ecological, and socio‐economic impacts on the lower reaches of the river, the coastal areas and the Bohai Sea.

The aim of the present study was to investigate in vivo the effect of high-mobility group box 1 protein (HMGB1) on activity of regulatory T cells (Tregs) and the influence on T-cell-mediated immunity after thermal injury. Male Wistar rats were randomly divided into four groups as follows: sham burn group, burn group, burn with ethyl pyruvate treatment group, and burn with antireceptor for advanced glycation end products (RAGE) antibody treatment group, and they were killed on postburn days 1, 3, 5, and 7, respectively, with eight animals at each time point. Magnetic cell sorting microbeads were used to isolate splenic Tregs and a column of nylon wool to obtain T cells. Phenotypes, including cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), forkhead/winged helix transcription factor p3 (Foxp3), RAGE, and IL-2Ralpha, were analyzed by flow cytometry. Levels of HMGB1, IL-10, IL-2, IL-4 and interferon gamma were determined by enzyme-linked immunosorbent assay kits, and real-time reverse transcription-polymerase chain reaction was performed to detect mRNA expression of IL-10, IL-2, and IL-2Ralpha. Serum HMGB1 levels were significantly elevated during postburn days 1 to 7. In the burn group, CTLA-4 and Foxp3 expression levels of Tregs were strongly enhanced in comparison to the sham-injured group, and the capacity of Tregs to produce IL-10 was markedly increased. Administration of ethyl pyruvate to inhibit HMGB1 or anti-RAGE antibody could significantly decrease expression levels of CTLA-4, Foxp3 on Tregs, and IL-10 production after burns. Simultaneously, proliferative activity and expression levels of IL-2 and IL-2Ralpha of T cell were restored. The excessively released HMGB1 might stimulate CD4+CD25+Treg activity via binding RAGE on the surface of Tregs and trigger a shift of T(H)1 to T(H)2 with suppression of T-lymphocyte immune function after burn injury.