[Hydrogen and oxygen stable isotope characteristics of water in SPAC system of evergreen broadleaved forest in subtropical region]. / 亚热带地区常绿阔叶林SPACç³»ç»Ÿæ°´åˆ†çš„æ°¢æ°§ç¨³å®šåŒä½ç´ ç‰¹å¾.

Forest soil-plant-atmosphere continuum (SPAC) is an important continuous process of water cycle. In this study, we analyzed hydrogen and oxygen stable isotope compositions of the precipitation, atmospheric water vapor, soil water, branch water, and leaf water to explain the characteristics of the continuous process and the associated controlling factors in a subtropical evergreen broadleaved forest. The results showed that the regression equations between hydrogen and oxygen stable isotopes were δDP=7.97δ18OP+12.68(R2=0.97) for precipitation, δDS=4.29δ18OS-18.62(R2=0.81) for soil water, δDB=3.31δ18OB-29.73(R2=0.49) for branch water and δDL=1.49δ18OL-10.09(R2=0.81) for leaf water of Podocarpus nagi, δDV=3.89δ18OV-51.29(R2=0.46) for atmospheric water vapor, respectively. In the process of water transport from precipitation to soil water to plant water, hydrogen and oxygen isotopes gradually enrich, while water vapor isotopes evaporated from soil and evaporated from plants were depleted. With the influence of precipitation and evaporation, soil water isotopes depleted with depth, and more enriched in the dry season than that in the rainy season. During the observation period, isotope content of branch water was slightly higher than that of soil water, indicating that water might be enriched by transpiration during the transportation process in plants. In the dry season, water isotope in branches of arbor plants was poorer than that of shrubs, indicating that arbor plants with deeper root distribution tended to use deep soil water. Because of the differences of leaf traits, transpiration rate and the response degree of environmental factors, the variation characteristics of water isotope composition in leaves of diffe-rent plants varied with the increases of leaf age. Environmental conditions in rainy season were more conducive to leaf transpiration, which made leaf water isotope enriched in rainy season than in dry season. The isotopic compositions in leaf water of Podocarpus nagi had a positive relationship with leaf water content (LWC), and a negative one with relative humidity, reflecting the water regulation function of plants in response to environmental changes.

[Modeling of Water Quality Response to Land-use Patterns in Taizi River Basin Based on Partial Least Squares].

Land use change in river basin is one of the most significant factors that influence river water quality. Based on remote sensing images and river water quality data of Taizi River Basin, partial least squares (PLS) model was applied to explore the relationship between water quality and land use patterns at sub-watershed scale. In this study, PLS model was established by using the percentage of area of land use patterns from seven different sub-watersheds as the variables and the concentrations of four water quality parameters as the observations. The established model was further tested with the data from other sub-watersheds in Taizi River Basin. The results indicated that total nitrogen (TN) and nitrate (NO3-) were significantly associated with land use types in Taizi River Basin with determination coefficient (R2) greater than 0.62. As for chloride (Cl-) and sulfate (SO42-), measured values and fitted values had a relatively low fitting precision (R2<0.5), which meant land use pattern was not the main factor affecting the concentrations of Cl-and SO42- in river water. Meanwhile, river water quality had a strong correlation with the percentage of area of unused land at the sub-basin scale (influence coefficient>0.24), although unused land area in the Taizi river basin was small.

Behavior, mass inventories and modeling evaluation of xenobiotic endocrine-disrupting chemicals along an urban receiving wastewater river in Henan Province, China.

Historically, the locations of cities mainly depend on the available water source and the urban river not only supplies the fresh water to city but also receives its wastewaters. To analyze the influences of urban zone on its receiving water river, the Jialu River in Henan Province, China, a typical urban river was chosen. Water and sediment samples were collected along the river in 2007 to analyze the concentrations of xenobiotic endocrine-disrupting chemicals (XEDCs) including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in surface water and sediment. The results showed that the concentrations of OP, NP and BPA in surface water were 20.9-63.2 ng L(-1) (mean 39.8 ng L(-1)), 75.2-1520 ng L(-1) (mean 645 ng L(-1)), 410-2990 ng L(-1) (mean 1535 ng L(-1)), respectively. The lowest and highest concentrations of XEDCs in surface water were found in the upper stream and downstream of Zhengzhou urban zone, which was regarded as the major discharge source of these chemicals to this river. The concentrations of OP, NP and BPA in the sediment were 15.9-31.1 ng g(-1), 145-349 ng g(-1) and 626-3584 ng g(-1) with the average concentrations of 21.4 ng g(-1), 257 ng g(-1) and 2291 ng g(-1), respectively. The results of in situ sediment-water partition of XEDCs showed that the partition coefficients (log K(oc)') in the downstream were higher than that in the upstream, which was mainly caused by the retransfer of surface sediment from the upper stream to the downstream. Comparison of measured and theoretical inventories of XEDCs in sediment indicated that the residual time of XEDCs in sediment in the river was about 5 years, which was in the same order of magnitude with its big flood frequency. In order to predict concentration variances of XEDCs in surface water, a fugacity-hydrodynamic model was developed according to the concept of in series completely stirred tank reactors (CSTR). The model results showed that about 29-65% of XEDCs derived from the urban zone (about 2.0 t yr(-1)) would finally dissipate from aqueous phase in the 170 km downstream of the river. Assuming the discharge amount of XEDCs from the urban zone remaining constant, the predicted concentrations of the total XEDCs in the over 90% river reach would be higher than 1.0 µg L(-1) under all normal, high water and low water season in 2007.

Behavior and fate of alkylphenols in surface water of the Jialu River, Henan Province, China.

The behavior and fate of alkylphenols (APs) were studied in surface water from the Jialu River, Henan Province, China. Located at its upper stream, Zhengzhou city is regarded as the major discharge source to this river with its annual effluents containing 726 kg for nonylphenol (NP) and 30.2 kg for octylphenol (OP). The concentrations of NP and OP in surface water ranged from 75.2 to 1520 ngL(-1) and from 20.9 to 63.2 ngL(-1), respectively. To assess the behavior of APs along the river, a mass balance equation based on chloride was adopted, due to its relative conservation. The results showed that dilution effect was prevailing in determining the APs concentrations in surface water along the river. The effect of potential biodegradation was also estimated with an assumption of the optimized biodegradation. The contributions of dilution and biodegradation to the decline of APs concentrations were 38.8%, 23.7% for NP and 57.8%, 24.3% for OP, respectively. The other contribution to the decline of APs concentrations along the river was considered as an integrated effect of adsorption and air-water exchange with the values of 37.5% for NP and 17.9% for OP. The decay half-lives of NP and OP from surface water bodies were 1.6 and 2.4d, respectively. About 70.2% of total NP and 24.1% of total OP were finally eliminated from water phase to surrounding matrix in the downstream. The results suggested that the downstream river channel served as the net sink of APs in the study area.