This is the first report on using Macleaya cordata for phytoextraction of uranium from the uranium contaminated soil in the greenhouse. Macleaya M. cordata was found to increase uranium concentration in the soil solution by increasing the dissolved organic carbon (DOC). The amendment experiments with citric acid (CA) and [S,S]-ethylenediamine disuccinic acid (EDDS) at the rates of 1.0, 2.5, 5.0, and 10.0 mmol kg⁻¹dry weight (DW) soil showed that EDDS was more efficient to increase uranium concentration in the shoot than CA when they were applied at the same rate. The applications of 5.0 mmol kg⁻¹EDDS and 10.0 mmol kg⁻¹CA were most appropriate for increasing uranium concentrations in the shoot of M. cordata. CA was more efficient to increase the solubility of uranium at the same application rates except for 2.5 mmol kg⁻¹application rate. There was a linear correlation between the uranium concentration in the shoot and the average uranium concentration of one planted pot during 14 days in soil solution after the application of different rates of EDDS and CA, respectively (r² = 0.972, P < 0.01; r² = 0.948, P < 0.01), indicating that uranium uptake was dependent on the soluble uranium concentration. The Fe-U-DOC and Mn-U-DOC complexes were probably formed after the application of CA. Soil solution pH and Fe, Mn, Ca, and DOC concentrations in soil solution were found to be changed by the chelates.

Poor water quality is a serious problem in the world which threatens human health, ecosystems, and plant/animal life. Prediction of surface water quality is a main concern in water resource and environmental systems. In this research, the support vector machine and two methods of artificial neural networks (ANNs), namely feed forward back propagation (FFBP) and radial basis function (RBF), were used to predict the water quality index (WQI) in a free constructed wetland. Seventeen points of the wetland were monitored twice a month over a period of 14 months, and an extensive dataset was collected for 11 water quality variables. A detailed comparison of the overall performance showed that prediction of the support vector machine (SVM) model with coefficient of correlation (R²) = 0.9984 and mean absolute error (MAE) = 0.0052 was either better or comparable with neural networks. This research highlights that the SVM and FFBP can be successfully employed for the prediction of water quality in a free surface constructed wetland environment. These methods simplify the calculation of the WQI and reduce substantial efforts and time by optimizing the computations.

The microbial breakdown of chitosan, a fishery waste-based material, and its derivative cross-linked chitosans, in both non-contaminated and contaminated conditions was investigated in a laboratory incubation study. Biodegradation of chitosan and cross-linked chitosans was affected by the presence of heavy metals. Zn was more pronounced in inhibiting microbial activity than Cu and Pb. It was estimated that a longer period is required to complete the breakdown of the cross-linked chitosans (up to approximately 100 years) than unmodified chitosan (up to approximately 10 years). The influence of biodegradation on the bioavailable fraction of heavy metals was studied concurrently with the biodegradation trial. It was found that the binding behaviour of chitosan for heavy metals was not affected by the biodegradation process.

Due to differences in stereostructure, enantiomeric compositions and enantiomeric ratios (ERs) of chiral compounds can be used to discriminate environmental processes such as abiotic and biotic degradation/transformation. In this study, the ERs of two chiral polycyclic musks, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN), were investigated in the sediments of Zhujiang River and Dongjiang River in the Pearl River Delta (PRD), as well as in those of Suzhou Creek in Shanghai City. The results indicated that ER cᵢₛ of HHCB varied significantly, ranging from 1.09 to 1.53 and 1.40 to 1.48 in the PRD and Suzhou Creek samples, respectively, whereas ER ₜᵣₐₙₛ of HHCB exhibited limited variation, ranging from 0.98 to 1.10 and 0.98 to 1.05 for Pearl River and Suzhou Creek samples, respectively. In addition, ERs of AHTN varied substantially from 1.10 to 1.34 and 1.17 to 1.28 in the PRD and Suzhou Creek, respectively. These results suggest that HHCB in the sediment in the study area underwent biotic degradation and the preferential biotransformation isomer was (4R,7S)-HHCB, while AHTN simultaneously underwent a certain degree of biotic degradation/transformation.

Data distribution is usually skewed severely by the presence of hot spots in contaminated sites. This causes difficulties for accurate geostatistical data transformation. Three types of typical normal distribution transformation methods termed the normal score, Johnson, and Box–Cox transformations were applied to compare the effects of spatial interpolation with normal distribution transformation data of benzo(b)fluoranthene in a large-scale coking plant-contaminated site in north China. Three normal transformation methods decreased the skewness and kurtosis of the benzo(b)fluoranthene, and all the transformed data passed the Kolmogorov–Smirnov test threshold. Cross validation showed that Johnson ordinary kriging has a minimum root-mean-square error of 1.17 and a mean error of 0.19, which was more accurate than the other two models. The area with fewer sampling points and that with high levels of contamination showed the largest prediction standard errors based on the Johnson ordinary kriging prediction map. We introduce an ideal normal transformation method prior to geostatistical estimation for severely skewed data, which enhances the reliability of risk estimation and improves the accuracy for determination of remediation boundaries.

The Indian Himalayan Region (IHR) is one of the important mountain ecosystems among the global mountain system which support wide variety of flora, fauna, human communities and cultural diversities. Surface soil samples collected from IHR were analysed for 23 organochlorine pesticides (OCPs). The concentration of ∑OCPs ranged from 0.28 to 2143.96 ng/g (mean 221.54 ng/g) and was mostly dominated by DDTs. The concentration of ∑DDTs ranged from 0.28 to 2126.94 ng/g (mean 216.65 ng/g). Other OCPs such as HCHs, endosulfan and heptachlor, Aldrin and dieldrin were detected in lower concentration in IHR. Their concentrations in soil samples ranged from ND to 2.79 ng/g for HCHs, ND to 2.83 ng/g for endosulfans, NDto 1.46 ng/g for heptachlor, ND to 2.12 ng/g for Aldrin and ND to 1.81 ng/g for dieldrin. Spatial distribution of OCPs suggested prevalence of DDTs and HCHs at Guwahati and Itanagar, respectively. The close relationship between total organic carbon (TOC) and part of OCP compounds (especially α- and γ-HCH) indicated the important role of TOC in accumulation, binding and persistence of OCP in soil. Diagnostic ratio of DDT metabolites and HCH isomers showed DDT contamination is due to recent application of technical DDT and dicofol, and HCH contamination was due to mixture of technical HCH and lindane source. This was further confirmed by principal component analysis. Ecological risk analysis of OCP residues in soil samples concluded the moderate to severe contamination of soil.

Forty surface sediment samples from the Hunhe River in Northeast China were evaluated for contamination by polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The results showed that decabromodiphenyl ether (BDE-209) was the predominant congener, accounting for >98 % of PBDEs in all sediment. The concentrations of BDE-209 and HBCD ranged from 3.96 to 327 ng/g dry weight and 0.05 to 25.8 ng/g dry weight, respectively, suggesting that BDE-209 was more widely applied in the study area. The mean concentrations of BDE-209 and HBCD in the downstream portion of the Hunhe River (BDE-209 148 ng/g dry weight and HBCD 3.74 ng/g dry weight) were found to be relatively higher than those in the upstream portion of the Hunhe River and the Dahuofang Reservoir, revealing an association with municipal sewage and industrial effluent received from the cities of Fushun and Shenyang. γ-HBCD was the most abundant diastereoisomer of all three analyzed HBCD isomers; however, marked elevations of α-HBCD were also found in most sediment samples. Surprisingly, the relative abundance (mean 38 %) of α-HBCD in sediment from the upstream portion of the Hunhe River was significantly higher (p < 0.006, t test) than those in Dahuofang Reservoir (mean 24 %). Moreover, the severe heavy metal contamination associated with the frequent mining activities in this region was tentatively suggested as being responsible for the increased levels of α-HBCD.