Abstract:Diatom-based transfer function is established to provide an effective approach for the quantitative reconstruction of lake environmental indicators. Based on the investigation of water quality and surface diatoms from 45 lakes along the middle and lower reaches of Yangtze River, the relationships between diatoms and trophic variables were revealed by Canonical Correspondence Analysis (CCA). The result shown that total phosphorus (TP) can explain the most variation of diatom data, suggesting that it is the most important and significant variable which influenced on the diatom distributions. The inverse deshrinking weighted average model (WA) was chosen to establish the diatom-TP transfer function comparing with a series of WA models. According to the jackknifing statistical test the model gave a relative lower root-mean-square of error (RMSEP_jack=0.157). After deleted outliers, the new model improved the prediction ability greatly, with a higher coefficient of prediction (R²_jack=0.82) and a 21% decrease of predictive error ( RMSEP_jack=0.12). It performed much better comparing to other regional TP models. The establishment of our diatom-TP transfer functions will lay a scientific foundation for the trophic status reconstruction in typical lakes in Yangtze floodplain, which will likely to be an effective technique to set realistic targets for lake environment harnessing.

Abstract:Water resource plays an important role in social and economical activity in China, especially in northern arid or semi-arid regions. In the ungauged Lake Hulun basin, an approach combining two-parameters monthly water balance model and mass balance equation was developed in the study to reconstruct the hydrological and salinity series. 42-years hydrological and salinity monthly series are reconstructed in the Lake Hulun using the model. Simulated water level and salinity are in good agreement with the observed annual mean data. The estimation of water resources and salinity is reliable, and supports the solid base for wise management of water resources in Lake Hulun.

Abstract:Due to the greenhouse effect, the air temperature is now rising, and the changes (drop or rise) of the water level of salt lakes in arid-semi-arid salt lake areas of western China is speeding up. Though there are many lakes in northern Tibetan Plateau, there are no lake level records, except at salt Lake Zabuye, where a long-term field observatory station was established in 1990 by Open Laboratory of Saline Lake Resources and Environment, CAGS, and lake level was recorded monthly. How to forecast the short-term lake-level change accurately and quantitatively according to the historical lake-level records is a major issue concerning the fate of salt lake resource development. In this paper, according to the lake-level records observed during 1991-2003 in salt Lake Zabuye in Tibetan Plateau, we discussed the applications of two forecasting methods of time-serial analysis, the model of Winters linear and seasonal exponent smoothness and the model of ARIMA seasonal multiplication, in forecasting the dynamic lake-level change of salt lakes.

Abstract:The sedimentary course controls the distribution of minerals and source rocks. The characteristics of source rocks in the Member 3 of Shahejie Formation in Dongying Depression revealed the obvious fluctuation of the sedimentary course of lake. Tectonic movement controlled the rise and settle of the whole lake, and with the influence of climate and the other geological factors, the lake deposit was a result of complex sedimentary course which was a main sedimentary cycle contained many hypo-cycles. The heterogeneity and the unstable deposition in the stable deposition of source rocks were believed as a result of the lacustrine cyclothemic sedimentation and the Jake-level fluctuation. The environment of deep water-body and high salinity in the Member 3 of Shahejie Formation was characterized by high content of many trace elements and high value of B/Ca, Sr/Ba. The deposition in fluctuation contributed to the distribution of organic matter in different manners; organic matter was enrichment in the lower part of the Member 3 ol Shahejie Formation, and it was source rocks in high quality; the organic matter was dispersed in the middle part of the Member 3 of Shahejie Formation, whose resource potential for hydrocarbon generation and expulsion was restricted.

Abstract:Bioavailable Phosphorus (BAP) in sediments of Ijake Taihu (6 sites), Lake Chaohu (4 sites) and Lake Longgan (3 sites) was analyzed by chemical extraction method. The mean BAP content in north Lake Taihu was 259.5 mg/kg, 114.6 mg/kg in west of Lake Taihu, 40.6 mg/kg in the middle of the lake and 50. 7 mg/kg in East Lake Taihu. It was very obvious that BAP contents were higher in the north of the lake and lower in the south. The mean BAP content in the west of Lake Chaohu was 254. 2 mg/kg while was 101. 9 mg/kg in the east of the lake. The content is 67. 8 mg/kg in Lake Longgan. All these data showed the more polluted lakes (lake zones) was with higher BAP contents in the sediments. The BAP contents in the sediment cores decreased exponentially that meant the BAP would transform to non-bioavailable form with sedimentation effect. Because of the higher bioactivity in summer, the BAP was more easily transformed to soluble phosphorus and resulted in lower content in the sediment. There was positive correlation between the BAP contents in sediments and soluble reactive phosphorus (SRP) and the correlation was better in the lakes/lake zones with lower BAP contents than in the lakes/lake zones with higher contents.

Abstract:Magnetic study on core sediments from western Lake Chaohu and soils from Hangbu River Catchment suggests that magnetite is the dominant magnetic mineral, and soils from Hangbu River Catchment are the main source of lake sediments. Core ACI near the bank shows higher proportion of sands and higher χ、SIRM values but lower χ_ARM values, indicating higher concentration of magnetite with coarse size. Core AC2 more far away from the bank shows lower proportion of sands and lower χ、SIRM values. The similar variations of χ、SIRM with χ_ARM, and to a lesser degree with clay fraction, in combination with higher χ_ARM/SIRM values, indicating lower concentration of magnetite with fine size. Magnetic properties of soils in the catchments indicate that skeletal soils with abundant sand and gravel fraction are magnetic strong which are contributed by coarse magnetite. Content of sand fraction in core is a reflection of water energy which is dependent on the distance to the bank. Therefore, the distinct magnetic properties of different cores are due to sedimentary dynamics. It is found that χ_ARM/SIRM can be used to indicate the variation of clay contents in sediments

Abstract:It is of great concerns on some pollutants cumulated in lake sediments to become the source of pollution, under certain circumstances, causing serious harm on overlying water quality. In this research, experiment was designed based on the fact of seasonal hypoxia near sediment-water interface (SWI) in Lake Aha,Guizhou Province. By means of the control of redox potential, together with microbiological activities, it was found that microbiological activities has significant influences on the redox reactions happened around SWI; and the overlying water quality can be changed remarkably, along with the variation of redox potential, including transparency, odor and poUutant contents. The cluster analysis of experimental data demonstrated that two main groups with similar geochemical behavior during diagenesis process, could be sorted as Mn,Ga, SO₄^2-,Cu,Cr,Pb and Co,Ni,Fe, Sc,V, Rb. Finally, the maximum release of some metals when lake water turned to hypoxia, were calculated, of which plenty of Fe and Mn found can be released into overlying water.

Abstract:Aggradations are very important for the developing and dying-out of lakes. The aggradations of floods and debris flows are common environmental problems in fault lakes in southwestern China. Investigating the background of the basin of Goose Foot River, the effect of human activities on Lake Qionghai, Sichuan Province, China, and the underwater topography maps of 1988 and 2003 were analyzed. In the past 30 years, turbidity currents were formed by debris flows and floods of Goose Foot River and took huge sediment into Lake Qionghai. The sediment not only pushed the coastline of Lake Qionghai at Goose Foot River fan into lake, but also deposited in the lake to the opposite bank. Debris flows took much more sediment into Lake Qionghai than the soil erosion did in the same basin. There is an underwater levee on the underwater fan. The underwater levee is 2 km in length, 200 m (at south coast) to 600 m (at north coast) in width and the average 2 m in height. The maximum height of sediment deposition at underwater levee is 8. 29 m, or 0. 55 m for every year. There is a channel on the slope of the underwater fan of Goose Foot River mouth eroded by turbidity currents. The main source of sediment is the sediment token by the debris flows in 1996, 1997 and 1998. It should be paid more attention on the environment issues,such as basic characteristics, underwater topography of Lake Qionghai and the effect of Goose Foot River debris flows on Lake Qionghai.

Abstract:Dissolved organic nitrogen is an important component of dissolved organic matter in natural aquatic system. But little is known about its characteristics. This study compared two common methods for DON analysis; persulfate oxidation(PO) and high temperature catalytic oxidation(HTCO). The results showed that both methods had their own merits,but better results were obtained using PO method. PO method resulted in higher recovery for various nitrogen-containing standard compounds(96.0 ±3.0%, excluding heteroyclic nitrogen compounds),and relative standard deviation ranged from 6.2% to 12.5% . The HTCO method yielded relatively low recovery(68.4±13.6%), and needed further impovement. This study would be helpful for the study of nitrogen biogeochemical cycling in aquatic environment.

Abstract:Zooplankton is one of the most important components in lake ecosystems. The zooplankton abundance and P0₄-P released by zooplankton community in Meiliang Bay and Lake Wuli, Lake Taihu were studied from March to May in 2004. The results showed that the cladoceran density in Meiliang Bay was always higher than that in Lake Wuli. However, the abundance of rotifers was higher in Lake Wuli than Meiliang Bay; and the difference of copepods was not significant. P0₄-P releasing rates ranged from 0.20 to 0.43mgP/(g(DW)·h) in Meiliang Bay, and from 0.19 to 0.54 mg/(g(DW)·h) in Lake Wuli. Present study suggests that nutrient release by zooplankton can play an important role in nutrient regeneration in lake ecosystems.

Abstract:In order to analyze the effect of the attachment of suspended matter on the physiological and biochemical characteristics of macrophyte, several indices were tested: fresh weight (FW), chlorophyll content, net primary production, peroxides(POD) activity and catalaes(CAT) activity. Results showed that high loading suspended matter in Miaojia River in Suzhou had significant effect on the growth of Potamageton crispus. After the experiment was finished, its biomass, chlorophyll content, and ratio of chlorophyll a/b of Potamageton crispus being attached with suspended matter were only 63.93%, 66.24% and 63.88% of the reference one respectively. Activities of POD and CAT of Potamageton crispus decreased, which were 61. 25% and 40. 30% of the reference one. Suspended matter was one of the important factors controlling the reconstruction of submerged macrophyte.

Abstract:In order to determine the main types of pollution origins of the heavy metals of sediments of Lake Donghu, Wuhan, based on principle of principal components and the rule of picked-up information which is over 84% of original ones, we have analyzed twelve elements of thirty representative samples of 0 -7 cm sediments of Lake Guozheng and Lake Tanglin, which are the main sub lake of Lake Donghu, Wuhan city. The results indicate that for Guozheng Lake sediments, the first pollution origin (56%) is industry coal dust around the lake, the second origins (16%) are tail gas, domestic sewage and rain flow, and the third parts(12%) are industry sewage with electroplate and press etc. For Lake Tanglin, the first pollution origin (65%) is atmosphere dust which is from industry coal combustion, the second origins (17%) are sewage with household, hospital and soil etc, and the third parts(9%) are disused battery, newspapers and farming materials etc. Employing the comprehensive pollution indexes of heavy metals, which were calculated by root mean square on the background values, to evaluate the pollution degree of sediments of main sublakes of Lake Donghu, it is found that both of them belong to light contamination and the pollution degree of Lake Guozheng is higher than that of Lake Tanglin.

Abstract:Lakes in Yunnan Plateau have undertaken tremendous change due to human activities, especially since 1980s. For the sake of the environmental protection, especially eutrophication control on the main lakes in Yunnan Plateau, the thresholds of different indexes such as transparency and chl. a concentration in lakes are suggested, two of which are not explicitly included in national water quality standards (GB3838-2002) of China. The suggestions offered are obtained based upon document analysis on relevant standards from local and abroad and investigations from typical lake regime in Yunnan Province. For water transparency, the values could be 5.0 m for Grade I, 2.5 m, 1.0 m and 0.5 m for Grade II, HI, IV-V (according to GB3838-2002) respectively. For chl. a, they could be 2 μg/L, 10μg/L,20μg/L,40μg/L and 60μg/L for Grade I, II, M, IV, V respectively. The thresholds suggested could be a substantial implementation of national standard (GB3838-2002) for local management guidance.

Abstract:Based on the water quality investigation in East Lake Taihu from April 2002 to April 2003, a preliminary analysis was carried out on the water quality, its changes and the spatial difference in given districts. The mean value of the water quality parameters ranged as follows: TN, 0.57-3.91 mg/L with a mean value of 1.61 mg/L; NH₄⁺-N, 0.01-0.42 mg/L (0.14 mg/L on the average); N0₃^--N, 0.044-0.549 mg/L, (0.16 mg/L on the average); and the mean TP was 0. 103 mg/L. Compared with the results of earlier investigations, TN, TP and NH₄⁺-N had increased, COD_Mnhad slightly decreased . At present, the water quality was bad, but different sites exhibited different conditions. The water quality in the center of lake was the best. As a whole, East Lake Taihu was meso-eutrophic. Some part of the lake was eutrophic. To improve the water quality of East Lake Taihu, it is important to shut off the external pollution sources, ensure the function of East Lake Taihu, control the scale of pen-culture and recover and protect the aquatic vegetation.