Journal of Environmental Monitoring最新文献

To evaluate critical trace element loads in native vegetation and calculate soil-to-plant transfer factors (TFs), 11 trace elements (Cr, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Pb and Mn) have been determined in leaves of 9 taxonomically verified naturally growing terrestrial plant species as well as in soil samples collected around 3 Ethiopian Rift Valley lakes (Koka, Ziway and Awassa). The Cr concentration in leaves of all the plant species was higher than the "normal" range, with the highest level (8.4 mg per kg dw) being observed in Acacia tortilis from the Lake Koka area. Caper species (Capparis fascicularis) and Ethiopian dogstooth grass (Cynodon aethiopicus) from Koka also contained exceptionally high levels of Cd (1 mg per kg dw) and Mo (32.8 mg per kg dw), respectively. Pb, As and Cu concentrations were low in the plant leaves from all sites. The low Cu level in important fodder plant species (Cynodon aethiopicus, Acacia tortilis and Opuntia ficus-indicus) implies potential deficiency in grazing and browsing animals. Compared to the Canadian environmental quality guideline and maximum allowable concentration in agricultural soils, the total soil trace element concentrations at the studied sites are safe for agricultural crop production. Enrichment factor was high for Zn in soils around Lakes Ziway and Awassa, resulting in moderate to high transfer of Zn to the studied plants. A six step sequential extraction procedure on the soils revealed a relatively high mobility of Cd, Se and Mn. Strong association of most trace elements with the redox sensitive fraction and mineral lattice was also confirmed by partial redundancy analysis. TF (mg per kg dw plants/mg per kg dw soil) values based on the total (TF(total)) and mobile fractions (TF(mobile)) of soil trace element concentrations varied widely among elements and plant species, with the averaged TF(total) and TF(mobile) values ranging from 0.01-2 and 1-60, respectively. Considering the mobile fraction in soils should be available to plants, TF(mobile) values could reflect trace elements transfer to plants in the most realistic way. However, the present study indicates that TF(total) values also reflect the transfer of elements such as Mn, Cd and Se to plants more realistically than TF(mobile) values did.

We examined the spatial and temporal (hourly) variation of aqueous concentrations of mercury in a gold miner's river to determine factors that control transport, retention, and export of mercury. The mercury flux was estimated to account for episodic inputs of mercury through mining tailings, variations in flow rate, and the partitioning of mercury between dissolved and particulate phases. Water samples were collected upstream and downstream of two gold mining sites in the Artiguas river, Nicaragua. The samples were analyzed for dissolved and suspended mercury, total solids, dissolved organic carbon, and total iron in water. Water velocity was also measured at the sampling sites. We found that mercury was mainly transported in a suspended phase, with a temporal pattern of diurnal peaks corresponding to the amalgamation schedules at the mining plants. The concentrations decreased with distance from the mining sites, suggesting dilution by tributaries or sedimentation of particle-bound mercury. The lowest total mercury concentrations in the water were less than 0.1 μg l(-1) and the highest concentration was 5.0 μg l(-1). The mercury concentrations are below the present WHO guidelines of 6 μg l(-1) but are considered to lead to a higher risk to aquatic bacteria and fish in the stream than to humans. The aqueous concentrations exceed the hazard endpoints for both groups by a probability of about 1%. Particulate mercury accounted for the largest variation of mercury fluxes, whereas dissolved mercury made up most of the long-range transport along the stream. The estimated total mass of mercury retained due to sedimentation of suspended solids was 2.7 kg per year, and the total mass exported downstream from the mining area was 1.6 kg per year. This study demonstrates the importance of the temporal and spatial resolution of observations in describing the occurrence and fate of mercury in a river affected by anthropogenic activities.

The development of western China in the past decade has led to increased discharges of wastewater and river pollution. The Wei River is the largest tributary of the Huang He River, but its geochemistry has not been thoroughly investigated. Sixty-three bed-surface sediment samples were collected from the Wei and analyzed for 24 elements by WDXRF; objectives for the study were to investigate the geochemical properties of the sediments; identify sources, and assess pollution levels and environmental risks. Major and trace element concentrations were comparable with those in other large rivers in China, but potentially hazardous trace elements (PHTEs) were lower than in the Yangzi or Pearl Rivers; most likely due to dilution of contaminants by the large sand inflows into the Wei and a lower level of industrialization. Nonetheless, pollution and risk analyses demonstrate slight contamination of Cr, Mn, Nb, Ni and Zn, moderate contamination of Cu and Pb, and strong contamination of As at some locations. Adverse biological effects from Ni and Cu are possible and are likely from As. Statistical and spatial analyses indicate that agriculture runoff and industrial wastewater discharge contribute to the contamination of this river. A comprehensive environmental management strategy, realistic national standards for wastewater discharge, and rigid enforcement are needed to address river pollution in China.

In order to evaluate soil-associated polycyclic aromatic hydrocarbons (PAHs) pollution from coal mine activities in Tiefa coal mine, Northeast China, 16 PAHs identified as priority pollutants by US Environmental Pollution Agency were determined in mining zone soil (MZS), agricultural soil (AS), local lake bank soil (LBS), a vertical soil profile and three coal gangue samples. The total concentration of 16 PAHs (defined as Σ(16)PAH, dry weight) in surface soil ranged from 5.1 to 5642.3 ng g(-1), with an arithmetic mean of 1118.3 ng g(-1). Σ(16)PAH values at the sites from MZS are significantly higher than those found in AS and LBS. The vertical distribution of PAHs indicated that these compounds can penetrate the deeper layers of the soil, especially the low-rings compounds. A complex of petrogenic origin and pyrolytic sources was found within the study area, as suggested by the isomeric ratios of PAHs. According to principal component analysis (PCA), four factors were identified in the source contribution, including coal combustion, unburned coal particulates, coal gangue and vehicular emissions. The degree of contamination and the PAH toxicity assessment suggested that the soils of the study area have been seriously polluted and pose a high potential health risk.

Many metabolites of organic surfactants such as nonylphenol (NP) and perfluorooctanoic acid (PFOA) are ubiquitously found in the environment and are toxic if not sorbed on soils and sediments. In this study, we quantified the sorption of the NP isomer with the highest endocrine activity, [4-(1-ethyl-1,3-dimethylpentyl) phenol] (NP111), and that of PFOA on Yangtze River sediments and its model components illite, goethite and natural organic matter. The sorption experiments were performed with (14)C-labeled NP111 and PFOA by batch or dialysis techniques. The results showed that the sorption isotherms of NP111 and PFOA on the sediments were fitted well by the linear adsorption model. The sorption of NP111 depended largely on the organic carbon content of the sediments. The K(OC) values of NP111 ranged from 6 × 10(3) to 1.1 × 10(4) L kg(-1) indicating that hydrophobic interaction between NP and organic carbon is the main mechanism of sorption. The sorption of NP111 on illite was poor. The sorption of PFOA on the sediments was significantly lower than that of NP111. The affinity of PFOA to adsorb on goethite was slightly higher than on the sediments, but was moderate on illite and negligible on a reference natural organic matter. Principal axis component analysis confirmed that various sediment parameters control the binding of PFOA. This analysis grouped the respective K(d) values to the contents of black carbon, iron oxides and clay, and, hence, to the specific surface area of the sediments.

Contents of trace elements (Cd, Pb, Cu, Zn and Ni) in sediments of river bed and bankside and adjacent agricultural soils along the Zhongxin River, Guangdong, China, were determined to investigate the metal distribution and assess ecological risk of trace element contamination. The results show that Cd and Zn are the two major metal elements contaminating the sediments and riverine farmlands. Geo-accumulation index (I(geo)) also revealed that the river sediments were polluted by Cd at levels from moderate to extreme, and by Zn at levels from moderate to high in most cases. Agricultural soils were generally moderately or highly polluted by Cd, and were unpolluted by Zn in most cases. The trace element contents of the river sediments in the upper and middle reaches of the river were much higher than in the downstream reaches. Agricultural soils in site S3 at Zhongxin Town had the highest amount of all the tested trace elements. Although the contents of the trace elements generally decreased from the upper and middle reaches to the downstream river, there was no obvious trend found for agricultural soils. The trace element contents were less influenced by pH and TOC in the sediments as well as in the soils. Storage in river alluvium and dilution by downstream clean sediments were the main mechanisms responsible for the decrease of the metal contents in the river sediments. The linear fit model depicts the risk of transportation of polluted sediments to Xinfengjiang Reservoir, the largest protection zone for sources of drinking water in Guangdong Province. Torpedo grass and rice plant showed the potential to be used in biomonitoring of metal contamination, however, further investigations are needed before using them in practice.

Two plant species (Paulownia tomentosa and Cytisus scoparius), earthworms (Eisenia fetida), and organic matter (horse manure) were used as an ecological approach to bioremediate a soil historically contaminated by heavy metals and hydrocarbons. The experiment was carried out for six months at a mesoscale level using pots containing 90 kg of polluted soil. Three different treatments were performed for each plant: (i) untreated planted soil as a control (C); (ii) planted soil + horse manure (20:1 w/w) (M); (iii) planted soil + horse manure + 15 earthworms (ME). Both the plant species were able to grow in the polluted soil and to improve the soil's bio-chemical conditions, especially when organic matter and earthworms were applied. By comparing the two plant species, few significant differences were observed in the soil characteristics; Cytisus scoparius improved soil nutrient content more than Paulownia tomentosa, which instead stimulated more soil microbial metabolism. Regarding the pollutants, Paulownia tomentosa was more efficient in reducing the heavy metal (Pb, Cr, Cd, Zn, Cu, Ni) content, while earthworms were particularly able to stimulate the processes involved in the decontamination of organic pollutants (hydrocarbons). This ecological approach, validated at a mesoscale level, has recently been transferred to a real scale situation to carry out the bioremediation of polluted soil in San Giuliano Terme Municipality (Pisa, Italy).

Indoor air quality is important because people are spending an increasing amount of time in the workplace. They are exposed to outdoor pollutants as well as pollutants emitted from products used indoors. Some chemicals, belonging to the category of volatile organic compounds (VOCs), easily release vapors at room temperature by evaporation. These accumulated vapors are often toxic and irritating. They may be alcohols, glycols, ketones, esters, etc., frequently present in the composition of many products for personal care or household purposes. This study suggests that the exposure levels of 2-butoxyethanol play an important role in the level of complaints of people at work. This study has emphasized the necessity of using different active and passive sampling methods for indoor air to avoid evaluation errors.

Indonesian artisanal and small-scale gold mining activities (ASGM) have been described for the islands of Borneo (Kalimantan) and Sulawesi. But the increased gold price over recent years has seen operations extend to the islands of Lombok and Sumbawa. For the current research, an environmental assessment was conducted across three new ASGM locations. Gold is recovered by miners through a two-stage process of whole-ore amalgamation and cyanidation. Waste (tailings) is discharged to land or sea with no concern for contaminants in the tailings. The gold grade of ore is up to 5000 mg kg(-1). The mean gold grade of the amalgamation tailings is 7 mg kg(-1), dropping to 1.2 mg kg(-1) for the cyanidation tailings. The mean mercury concentration of the amalgamation tailings is about 3000 mg kg(-1) and greater than 1600 mg kg(-1) for the cyanidation tailings. Samples of paddy rice grain collected adjacent to cyanidation tailings ponds showed methyl mercury concentrations greater than 100 ng g(-1). This is five times above the Chinese permissible level for total mercury in food crops. The mean total mercury concentration in hair of Lombok ASGM workers was greater than that in a non-exposed population; however there was no difference in methyl mercury concentration. This indicates the primary pathway of mercury exposure is inhalation of volatile mercury in the atmosphere. Future exposure may come from ingestion of methyl mercury contaminated rice where discharge of cyanide tailings to paddies continues. To protect the environment and to enhance the sustainability of ASGM, appropriate tailings management must be implemented. The gold grade of the tailings indicates that the residual value might be recoverable with appropriate technology. Ongoing research is investigating systems such as phytoextraction that might assist ASGM operators in Lombok and Sumbawa to improve their environmental performance.

The paper describes a new and simple method for monitoring volatile organic compounds resulting from a specific industrial indoor process. The method is based on the characteristics of tin dioxide sensors to be sensitive and non-selective to a large variety of gases. We use these characteristics to determine an equivalent concentration of the volatile organic compound mixture, a method which has not been used in other studies or experiments. The value of the equivalent concentration shows the accuracy of the process and the air purity of an industrial environment. A system including a tin dioxide sensor with its conditioning circuits and a temperature compensation circuit, a microcontroller and a graphical interface, was built in order to obtain a versatile, online and user friendly monitoring tool. The system was used for monitoring the volatile organic compound concentrations resulting from leather finishing processes in the Romanian industry.