Novel perspective on qualitative assessment of swine manure compost maturity using organic carbon density fractions.

Mature compost is safe and stable, yet quality assessments are challenging owing to current maturity indicators' limitations. This study employed density fractionation to separate organic carbon into light and heavy fractions, offering a new perspective for assessing maturity. Results showed that light fraction organic carbon progressively transitioned into heavy fraction during composting, reducing the proportion of total organic carbon from 82.82% to 44.03%, while heavy fraction organic carbon increased to 48.58%. During the first seven days, the reduction rate of light fraction organic carbon decreased slowly, while the increase rate of heavy fraction declined sharply, levelling off thereafter. Light/heavy fraction organic carbon ratio was significantly correlated with existing maturity indicators (carbon/nitrogen ratio, humic acid/fulvic acid ratio, biological growth-related indicators), with the ratio below 1.33 serving as a potential compost maturity marker. Thus, given its simplicity and reliability, organic carbon density fractions is an innovative indicator for compost maturity assessments.

[Determination of estrogenic compounds in water of Jiulong River using polar organic chemical integrative sampler].

Polar organic chemical integrative sampler (POCIS) has been recently documented for the detection of polar organic compounds in the environment to achieve a time weighted average concentration. So it is an important complimentary for spot sampling. POCIS was examined for its sampling efficiency for four kinds of estrogenic compounds (EDCs: estrone, 17alpha-ethynylestradiol, 17beta-estradiol, estriol) in this study. The kinetic studies showed an integrative uptake up to 7 d and the sampling rate decreased as the temperature increased( RSD > 12%). As for different concentrations of target compounds, the sampling rate was not affected by the concentrations (RSD < 5%). After laboratory experiments, an environmental field study was performed in Jiulong River. The results showed that there was a relatively good correlation between the measured and calculated values (r2 = 0.7209, P < 0.001). It demonstrated that POCIS can be used in aquatic field systems.

Levels of endocrine disrupting compounds in South China Sea.

The occurrence of estrogens in the aquatic environment has become a major concern worldwide because of their strong endocrine disrupting potency. In this study, concentrations of four estrogenic compounds, estrone (E1), 17ß-estradiol (E2), 17α-ethynylestradiol (EE2), estriol (E3) were determined with liquid chromatography-tandem mass spectrometry analyses in surface water from South China Sea, and distributions and potential risks of their estrogenic activity were assessed. The estrogenic compounds E1, E2 and E3 were detected in most of the samples, with their concentrations up to 11.16, 3.71 and 21.63 ng L(-1). However, EE2 was only detected in 3 samples. Causality analysis, EEQ values from chemical analysis identified E2 as the main responsible compounds. Based on the EEQ values in the surface water, high estrogenic risks were in the coastal water, and low estrogenic risks in the open sea.

[Occurrence of dissolved polychlorinated biphenyls and organic chlorinated pesticides in the surface water of Haihe River and Bohai ay, China].

Polychlorinated biphenyls (PCBs), hexachlorocyclohexanes (HCHs) and dichlorodiphenyl-trichloroethanes (DDTs) were analyzed in the surface water of Haihe River and Bohai Bay, in north of China. Concentrations of PCBs, HCHs and DDTs were 0.31 - 3.11 microg/L, 0.30 -1.07 microg/L and 0.02 - 0.15 microg/L in river, and in sea were 0.06 - 0.70 microg/L, 0.05 - 0.75 microg/L and 0.01 - 0.11 microg/L respectively. Mostly, the PCBs, HCHs and DDTs in the Bohai Bay are from terrestrial input by Haihe River. PCBs and organic chlorinated pesticides (OCPs) are positively correlated with DOC (dissolved organic carbon). The levels of PCBs and OCPs in Haihe River in this study are quite higher than the similar surface waters in China, while the levels in Bohai Bay are quite consistent with similar waters abroad.

[Residues and distribution characters of chlorobenzenes in soil and plants from Beijing southeast chemical industry zone].

Eleven chlorobenzenes (except MCB of a total of 12 in the congener series, CBs) in soil and plant samples collected from Beijing southeast chemical industry zone were analyzed. The range of total chlorobenzenes was 0.232 - 51.15 ng x g(-1) in soil (dry weight), among which 1,2-DCB, 1,4-DCB and HCB occupy 45.2%, 15.3% and 17.1% respectively; while 5.635 - 31.99 ng x g(-1) in plants (dry weight), among which 1,4-DCB and HCB occupy 51.5% and 14.9%. Total CBs concentrations in soil were positive related with soil organic matter (r = 0.544, p < or = 0.05). Soil-to-spruce needle bioconcentration factors (BCFs) of CBs were calculated and their relationships with CBs' physicochemical properties were investigated. Except for 1,4-DCB and 1,2,4-TCB, the CB BCF into spruce needle generally decreased with increasing volatilization potential [lg (V(p)/K(ow))], and increased with increasing K(OA).

[Photodegradation of hexachlorobenzene in the presence of known organic constituents of atmospheric aerosols].

Hexachlorobenzene photolyzed completely in hexane solvent within several minutes under the radiation of a 500 W high pressure mercury lamp, while its photolysis rate in diisooctyl phthalate solvent, which was chosen as a model for the organic phase of atmospheric combustion aerosols, was over 70 times slower. Anthaquinone and methoxyl phenols that known as aerosol constitutes accelerated the photodegradations of hexachlorobenzene though possible energy transfer and hydrogen abstraction mechanisms, respectively. Pentachlorobenzene was the main photoproduct of hexachlorobenzene.

[Chlorobenzenes in water and surface sediments from Tonghui River of Beijing].

Eleven chlorobenzenes (except MCB of a total of 12 in the congener series) in water and surface sediment samples collected from Tonghui River of Beijing China in November,2003 are analyzed. The range of total chlorobenzenes (CBs) was 0.093 - 6.638 microg x L(-1) in water, among which DCBs occupy 88.8%; while 95.3 - 1 827.7 ng x g(-1) in surface sediments, among which DCBs, TCBs,TeCBs,PeCB and HCB occupy 15.6%, 31.7%, 17.6%, 21.2% and 13.9% respectively. Comparison with the results of other research areas, the pollution of CBs in surface sediments is some serious. Besides, there is no significant correlation between total CBs concentrations in water and those in surface sediments.

Predicting physico-chemical properties of polychlorinated diphenyl ethers (PCDEs): potential persistent organic pollutants (POPs).

Polychlorinated diphenyl ethers (PCDEs) have received more and more concerns as a category of potential persistent organic pollutants (POPs). Modeling its environmental fate and exposure assessment require a number of fundamental physico-chemical properties. However, the experimental data are currently limited due to the difficulty in analysis caused by the complexity of PCDE congeners. As an alternative, the quantitative structure property relationship (QSPR) approach could be used. In this paper, twelve kinds of molecular connectivity indices (MCIs) of all 209 possible molecular structure patterns of PCDEs were calculated. Based on 106 PCDEs with three observed physico-chemical properties-vapour pressure (P0L), aqueous solubility (Sw) and n-octanol/water (Kow) and their MCIs data, a series of QSPR equations were established using multiple linear regression (MLR) method. As a result, three equations with best performance were selected mainly from the view of high regression coefficient (R) and low standard error(SE). All of them showed significant relationship and high accuracy. With these equations the properties of other 103 patterns of PCDEs without the reported observed values were predicted. Furthermore, three partition properties for PCDE congeners-Henry' s Law constants (H), partition coefficients between gas/water (Kgw) and gas/n-octanol (Kgo) were calculated according to the internal relationship among these six properties. These observed and predicted values, in contrast with the criteria listed in the Stockholm treaty about POPs which has been signed by more than ninety countries in May 2001, illustrated that most of PCDEs congeners are potential persistent organic pollutants. As all descriptors/predictors are derived just from the molecular structure itself and without the import of any empirical parameters, this method is impersonal and promising for the estimation of physico-chemical properties of PCDEs.

Application of TLSER method in predicting the aqueous solubility and n-octanol/water partition coefficient of PCBs, PCDDs and PCDFs.

The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n-octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans (PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(alpha), energy of the lowest unoccupied molecular orbit( E(LUMO)), energy of the highest occupied molecular orbit( E(HOMO)), the most positive charge on a hydrogen atom (q+), and the most negative atomic partial charge(q-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n-octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.