Levels and distributions of organochlorine pesticides in the soil-groundwater system of vegetable planting area in Tianjin City, Northern China.

To study the influence of long-term pesticide application on the distribution of organochlorine pesticides (OCPs) in the soil-groundwater system, 19 soil samples and 19 groundwater samples were collected from agricultural area with long-term pesticide application history in Northern China. Results showed that the composition of OCPs changed significantly from soil to groundwater. For example, ∑DDT, ∑HCH, and ∑heptachlor had high levels in the soil and low levels in the groundwater; in contrast, endrin had low level in the soil and high level in the groundwater. Further study showed that OCP distribution in the soil was significantly influenced by its residue time, soil organic carbon level, and small soil particle contents (i.d. <0.0002 mm). Correlation analysis also indicates that the distribution of OCPs in the groundwater was closely related to the levels of OCPs in the soil layer, which may act as a pollution source.

Analysis of spatial distribution characteristics of dissolved organic matter in typical greenhouse soil of northern China using three dimensional fluorescence spectra technique and parallel factor analysis model.

The aim of the present work is to study the soil DOM characteristics in the vegetable greenhouse with a long-term of cultivation. Results showed that the soil DOM mainly consisted of three components, fulvic acid-like (C1), humic acid-like (C2) and protein-like (C3), with C1 as the majority one. The distribution of DOM in space was also studied. In vertical direction, C1 and C2 decreased significantly with the increase in soil depth, while C3 component decreased after increased. The humification coefficient decreased fast from 0-20 to 30-40 cm, and then increased from 30-40 to 40-50 cm. In the horizontal direction, the level of C2 component varied greatly in space, while that of C1 component changed little, and that of C3 component fell in between the above two. The change in the humification degree of each soil layer significantly varied spatially. Humification process of soil organic matter mainly occurred in the surface soil layer. In addition, the humification degree in space also changed significantly. The new ideas of this study are: (1) Analyze the composition and spatial heterogeneity of soil DOM in the vegetable greenhouse; (2) Use three dimensional fluorescence spectra technology and parallel factor analysis model successfully to quantify the components of soil DOM, which provides a new method for the soil DOM analysis.

[Studies on fluorescence spectral characteristics of fulvic acid (FA) from Xingkai Lake sediments].

Four samples (sample No. HXXD, HXXX, HXDX and HXDB) were taken from Xingkai Lake Sediments in Heilongjiang province and fluorescence spectral characteristics of Fulvic acid (FA) from sediments were studied. Conventional and excitation-emission matrix (EEM) all indicated that FA from HXXD sediment exhibited primary peaks at longer wavelengths. The analysis of fluorescence characteristic parameters indicated that the degree of humification of FA from all sample points were in the order: HXXD > HXDX > HXDB > HXXX. Fluorescence index (f450/500) suggested that FA from HXXD mainly originated from terrestrial sources, while the FA from other samples mainly originated from aquatic organism sources and terrestrial sources. Based on EEM fluorescence regional integration (FIR), the percent fluorescence responses (P(i, n)) of five regions in 3EEMs was calculated. The distributions of P(V, n) (humic acid-like region) and P(III, n) (fulvic acid-like region) were the largest in all samples. The conclusion of the degree of humification of FA based on FIR was consistent with the analysis of conventional fluorescence parameters. The correlation analysis showed that, gamma(A, C) was significantly correlative with P(V, n)/P(III, n), (P(V, n) + P(III, n))/(P(I, n) + P(II, n) + P(III, n)) and P(V, n). The results suggest that gamma(A, C) index is a reasonable tool for assessing humification degree of FA from Xingkai Lake sediments.

[Fluorescence spectroscopic characteristics of dissolved organic matters (DOM) from Jingpo Lake water].

Six samples (sample J1-J6) from Jingpo Lake in Heilongjiang province were analyzed by fluorescence and fluorescence excitation-emission matrix regional integration (FIR) to determine the different characteristics of dissolved organic matters (DOM). The results with the traditional method just analyzing the excitation, emission and synchronous fluorescence spectra indicated that DOM molecular condensation degree was highest at sample J4 and sample J5, however, the study with the three-dimensional-excitation emission matrix spectra (3EEMs) method showed that the content of protein-like material was higher in sample J6 than others. In the second method, 3EEMs was divided into five regions, among which Region I, Region II, and Region IV were related to protein-like material, Region II was related to fulvic acid-like material, Region V was related to humic acid-like organics, and then these regions were integrated named as A(I), A(II), A(III), A(IV) and A(V). The integration results showed that the volume of A(V) occupied the largest proportion of the DOM region integration from all samples, and it exhibited the most prominent both in sample J4 and sample J5, while it's opposite in sample J6. Integral ratio, which means humic acid-like region (A(III), A(V)) divided by protein-like region(A(I), A(II), A(IV)), showed that the value of J4(4. 94) was close to J5 (5.18), J1 (3.52) was close to J2 (3.66), and the minimum value appeared in J6 (2.11). From the above analysis, the DOM humification degree could be confirmed as follows: J4, J5 > J1, J2 > J3 > J6.

[Analysis on the forms and release potential of nutrients in sediments from lakes in the West Jiangsu Province].

To probe the effect of nitrogen and phosphorus (P) in sediment on aqueous nutrient concentrations, forms of phosphorus, sediment water interface diffusion fluxes and phosphorus release and adsorption of 10 lakes in the west Jiangsu province were studied. Sediments were sequentially extracted by the modified Ruttenberg's method, and the result showed that inorganic phosphorus in sediments of the lakes was the major fraction of total phosphorus, but the proportion of bioavailable phosphorus was relatively low. Compared with the lakes in northern Jiangsu, the Fe-P was relatively high in sediments of lakes in southern Jiangsu. The diffusion fluxes of lakes were mainly based on NH4(+) -N diffusion in the west Jiangsu, and ions of most of lakes diffused from overlying water to sediment, NO3(-) -N diffused from sediment to overlying water in lakes except for Lake Hongze, Lake Shijiu and Lake Xuanwu. The condition leaning to acidic (pH < 4) or alkaline (pH > 10) was beneficial to phosphorus release, and except for Lake Xuanwu, the least amount of phosphorus released form sediment was higher in acidic condition than that in alkaline condition. The amount of phosphorus adsorption was increasing with temperature increase. Considering the phosphorus adsorption on native phosphorus polluted (NAP-polluted) sediments. All data of P adsorption on sediment samples collected from 7 lakes were fitted to the modified Langmuir model. And the values of the maximum adsorption capacity (Q(m)), phosphorus binding constant (k), native adsorbed exchangeable phosphorus (Q(NAP)), were subsequently obtained. The results showed that the adsorption amount of P in Lake Hongze and Lake Xuanwu was relatively low, which were liable to release P from sediments.

Strip-based immunoassay for the simultaneous detection of the neonicotinoid insecticides imidacloprid and thiamethoxam in agricultural products.

A semiquantitative strip immunoassay was developed for the rapid detection of imidacloprid and thiamethoxam in agricultural products using specific nanocolloidal gold-labeled monoclonal antibodies. The conjugates of imidacloprid-BSA, thiamethoxam-BSA and goat anti-mouse IgG were coated on the nitro-cellulose membrane of the strip, serving as test lines and control line, respectively. The flow of the complexes of gold labeled antibodies and insecticides along the strip resulted in intensive color formed on the test lines inversely proportional to the concentrations of imidacloprid and thiamethoxam. The visual detection limits of imidacloprid and thiamethoxam in assay buffer were 0.5 and 2 ng mL(-1), respectively. Matrix interference of cucumber, tomato, lettuce, apple, and orange on the strip assay could be eliminated by diluting sample extracts with assay buffer. The strip analysis of imidacloprid and thiamethoxam in these samples was compared to liquid chromatography-mass spectrometry and the results were in good agreement. The strip was stable for storage more than 5 months at 4 °C. The strip assay is a rapid and simple method for the simultaneous screening of imidacloprid and thiamethoxam in agricultural products.

[Regional heterogeneity of lake eutrophication effects in China].

Although biomass of algae (Chl-a) were in variant levels between different lake regions in China under the same nutrients conditions, it demonstrated that efficiencies of TN/TP used by algae had regional differences. In order to clarify the differences, curve estimation in SPSS was used to analyze the linear relationship between Ig Chl-a and Ig TN/lg TP. The slopes of these linear equations were identified as the efficiencies of TN/TP used by algae. The slopes of linear equations from Mengxin Plateau, Yungui Plateau, Northeast Mountain-Plain, lower reach of Yangtze River Plain and North Plain were 1.002, 0.817, 0.761, 0.545, 0.250, orderly. The efficiencies of TN used by algae ranged from the highest to the lowest were lower reach of Yangtze River Plain, Yungui Plateau, North Plain, Northeast Mountain-Plain, Mengxin Plateau, and the slopes of linear equations were 1.401, 1.058, 0.447, 0.239, 0. 099, respectively. Consequently, in Northeast Mountain-Plain, Mengxin Plateau the efficiencies of TP used by algae were higher than those of TN, and in Yangtze River Plain, Yungui Plateau, North Plain, the efficiencies of TN used by algae were higher than those of TP. On the other hand, in order to describe the effects of algae on transparency in different lakes, the relationships between Chl-a and SD were analyzed. The results showed that in Yungui Plateau the effect of algae on transparency was the most obvious as the variation of SD explained by Chl-a was the highest, and Northeast Mountain-Plain, Mengxin Plateau and North Plain followed. However, in lower reach of Yangtze River Plain, the relationship between Chl-a and SD was not significant.

[Occurrence of PFOA and PFOS in the aquatic environments and their ecological toxicities in the aquatic environments].

Based on current researches, described the sources, toxicities, analytical methods and occurrence of PFOA and PFOS in wastewater treatment plants, lakes, rivers, coastal areas and tap waters in different countries in the world. According to the limited concentrations of PFOA + PFOS in effluents of wastewater treatment plants (WTPs) put forward by Germany, the concentrations of PFOA + PFOS in WTP effluents in Singapore, Germany, Korea and England were assessed. The results showed that the concentrations of PFOA + PFOS in WTP effluents in Singapore were higher than the liminted concentration of 300 microg/L. Researches done by China, Japan, USA, and other countries showed that the concentrations of POFA and PFOS in rivers and coastal areas reached to ng/L, and the concentrations in Tennessee River, USA were the highest, reached to 100 ng/L. The risk assessments of PFOA and PFOS in tap water in some cities in China were assessed according to the risk quotients(RQ). The assessment results showed that tap waters from 19 cities in China were all below the risk level.

[Study on ecoregion techniques of lake nutrients in Yunnan-Guizhou plateau Lake regions].

The primary objective of this research is to present an ecoregion model based on the principle components analysis (PCA), the cluster analysis (CA), the discriminant analysis (DA) and the spatial autocorrelation analysis (SAA), which were applied to establish the ecorigion of lake nutrients in Yunnan-Guizhou Plateau Lakes. First, the principle components analysis method was used not only to reduce the dimensionality of the feature space, but also to deal with new indexes. The accumulation contribution ratio of the four new indexes achieved 93.69%, which had the full representation. These complementary indexes which reflect the conditions of lakes were helpful to establish the index system of ecorigion of lake nutrients in Yunnan-Guizhou Plateau Lakes. Second, initial classification of lake drainage area was accomplished by new indicator values and cluster analysis which contained five classes, and then the categories of non-lake drainage area could be identified by the discriminant analysis. Finally, the cluster result was carried on the global statistics, Moran's I was 0.32 which was higher than 0, and the examination value Z was 68.28 which was higher than marginal value (remarkable level 1% correspond 2.58), it was indicated that the cluster result and the space position had the remarkable relativity, afterward spatial distribution pattern of the region was achieved by the quantificational analysis about over score of principle components and application of local spatial autocorrelation method. Then the ecorigion of lake nutrients was accomplished by the association and difference between different districts of the scattered regions' s spatial character. These results indicated that the ecoregion model initiated in the paper was appropriate and feasible to receive objective results and avoid artificial factors. Also it has provided a new method to explore the index system and techniques about the ecoregion of lake nutrients. Scientifically, the model was in favor of the foundation of lake nutrient criteria and eutrophication control standards in China.

[Effects of land management measures on nutrients emission].

The SWAT model, coupled with a GIS, was applied to simulate the effects of fertilizer application, contour planting and returning land for farming to forestry on nutrients discharges. The results showed that when nitrogen fertilizer of agricultural land increased from 630 to 955 kg/hm2, and phosphorus fertilizer increased from 200 to 300 kg/hm2, nitrogen and phosphorus nutrient emissions have shown a growing trend. Nitrate nitrogen loads reached to 3 776.59 kg which increased 19.7% and the rate of changes was the largest. The change rate of inorganic phosphorus was the smallest which increased only 2.7%. The impact of emission loads on nitrogen and phosphorus was the smallest if contour planting was adopted. When slope farmland which slope is greater than 25% all returned land for farming to forestry, the emission loads of various forms of nitrogen and phosphorus decreased, organic phosphorus decreased 16.3% among them. Organic nitrogen, ammonia nitrogen and inorganic phosphorus compared with before returning land for farming to forestry, decreased 22.7%, 25.4% and 27.9% respectively. In small basin of Zhangjiachong, returning farmlands to forests and reducing the amount of chemical fertilizer on the slope farmlands which slopes are larger than 25% have played a prominent role.

[Effects of parameter spatial distribution on non-point pollution source model].

The SWAT model was used to simulate the effects of parameter spatial distribution on flow and nutrients loadings in the Daning river watershed. It was first calibrated and validated using the measured data for the period of 2000 - 2004. Then the model was used to simulate the effects of watershed delineation scenarios on flow and nutrients loadings, using six watershed delineations, each with a different number of sub-watersheds. The max relative error is 19.6% for the annual mean flow under different watershed delineation scenarios. The flow increase first and then decrease with the number of sub-watersheds. The efficiencies coefficient is 0.52 - 0.82 for annual mean flow and 0.80 - 0.83 for monthly mean flow under six delineation scenarios. Outlet nutrients simulations are slightly affected by changes in watershed delineation scenarios. The relative errors of organic nitrogen and organic phosphorous are 16.2% and 7.7% respectively and no explicit trend is observed.

[Simulation of nonpoint source pollution load in Maoping River watershed].

The nitrogen and phosphorous transport in the Maoping River watershed was modelled using the SWAT model, which simulates the water cycle and the transformation of nutrients. The model was first calibrated by comparing the observed and the simulated data from May to October 2004, and then validated. The Nash-Sutcliffe coefficient (R2), the mean square root error (RMSE) and the relative error(CV) were used to test the agreement between observed and simulated data. The validated model was then be used to simulate the nutrients load in Maoping River watershed. The Nash-Sutcliffe coefficient of flow, nitrogen and phosphorous was 0.71, 0.51 and 0.62 with the minimum relative error 1.8%, 1.1% and 10% respectively. Despite achieving the relatively lower resemblance between observed and simulated phosphorous and nitrogen load the model showed good agreement in simulating runoff. The results showed that 102.5t nitrogen and 9.46t phosphorous entered intoYangtze River during May to October 2004. One of the important reason that caused the water quality deterioration can be attributed to the nonpoint source pollution.