Potential Risk Of Environmental Pollution Research Articles

Geochemical characteristics of shale gas hydraulic fracturing flowback/produced water in Zheng’an block, northern Guizhou Province, China

Guizhou Province of China is rich in shale gas resources. In recent years, important progress has been made in the exploration and development of shale gas in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in Zheng'an block in northern Guizhou, adjacent to Sichuan Basin. Due to the complex geological conditions and fragile ecological environment in the shale gas distribution area, serious environmental pollution risks may exist in shale gas exploitation. Therefore, this paper conducted element, hydrogen and oxygen isotope analyses for shale gas fracturing flowback/produced water of Well AY7-4 in Zheng'an block. The results showed that the contents of K, Na, Ca, Mg and NH4+ in the flowback/produced water of Well AY7-4 were very high, with an average of 118 mg/L, 7616 mg/L, 266 mg/L, 47 mg/L and 76 mg/L, respectively. The content of Na, Ca and Mg is similar to that of shale gas flowback/produced water in Weiyuan, but lower than that in Changning and Fuling. NH4+ content was similar to that in Changning, but much higher than that in Weiyuan. The average Cl content was 11605 mg/L, which was similar to that in Weiyuan, but lower than that in Changning and Fuling. The average Br content is 48 mg/L, slightly lower than that of Weiyuan, and about half of that of Changning and Fuling. Correspondingly, the Br/Cl value of Well AY7-4 is the lowest, reflecting its relatively low Br content. The average content of Li, B and Sr is 17 mg/L, 10 mg/L and 45 mg/L, respectively, which is similar to that of the Weiyuan, Changning and Fuling shale gas fields. The distribution model of Li and Sr is similar to that of Cl, Br and Na, but the B content and B/Cl value of Well AY7-4 are the lowest. The linear relationship between Br and Cl contents and between δD and δ18O of flowback/produced water of Well AY7-4, freshwater used for hydraulic fracturing and hydraulic fracturing injected fluid indicates that flowback/produced water of Well AY7-4 is mainly the mixed product between low salinity injected fracturing fluid and high salinity brine retained in shale formation. The hydrogen and oxygen isotopic compositions gradually become heavier over time, indicating that the proportion of high salt end formation brine in flowback/produced water is increasing. The contents of Cl, Br, Na and NH4+ in the flowback/produced water of Well AY7-4 are far higher than the allowable discharge value, which is a potential environmental pollution risk and cannot be discharged directly.

Identification of livestock farms with potential risk of environmental pollution by using a model for returning livestock manure to cultivated land.

Livestock farms produce a large amount of livestock manure, which, if not disposed of properly, will become an environmental pollution source. However, limited research has been conducted on identifying livestock farms with a potential risk of environmental pollution. In this study, a model for returning livestock manure to cultivated land was constructed. Livestock manure was returned to cultivated land, and the amount of surplus livestock manure nutrients, including nitrogen and phosphorus, in livestock farms was calculated with pig manure as an example. Then, livestock farms with a potential risk of environmental pollution in Shanggan Town and part of Xiangqian Town in Fuzhou City were identified using phosphorus as an index. Results showed that the spatial distributions of nitrogen and phosphorus from pig manure in the cultivated land varied. All cultivated lands exhibited the maximum carrying capacity for phosphorus, and 1811 cultivated lands exhibited potential nitrogen carrying capacity. A total of 13,958.997kg of phosphorus from pig manure in 144 livestock farms could not be disposed to cultivated lands. In all, 144 livestock farms with surplus phosphorus from pig manure were identified as potential environmental pollution sources. These findings can serve as a scientific basis for the utilization of livestock manure, prevention of environmental pollution caused by livestock farms, and layout planning of livestock farms.

Preparation of polyphosphoric acid and recovery of valuable fluorine resources though a microwave intensification flash evaporation process

Traditional evaporators for the concentration of wet process phosphoric acid (WPA) suffer from concentration, corrosion, and low fluorine yield (less than 40 wt.%). Based on the excellent heating and permittivity properties of phosphoric acid in microwave fields, a microwave intensification flash evaporation (MFE) system is proposed to concentrate highly corrosive WPA for preparing polyphosphoric acid (PPA) and efficiently recovering valuable fluoride resources. A polytetrafluoroethylene tank in a microwave resonant cavity coupled with a vacuum pump is used to facilitate boiling and evaporation. This study reports the evolution of the PPA preparation process by flash evaporation, defluorination, and the boiling phenomenon. In addition, the influencing mechanism of pressure and temperature on PPA preparation and fluorine recovery are investigated. The experimental results indicate the successful preparation of PPA with a P2O5 content higher than 75 wt.% and the cost is considerably much lower than the traditional method. Meanwhile, the recovery yield of fluorine exceeds 90 wt.%, alleviating the depletion of strategic natural resources and potential risk of environmental pollution. This study provides a basis for the efficient preparation of PPA and recovery of fluorine resource from WPA. It is also potentially significant to industries such as metallurgy and sewage treatment.

Mechanical properties and heavy metal leaching behaviors of municipal solid waste incineration bottom ash as road embankment fillings

With the development of economy and urbanization, the natural gravels and sands for new road construction materials encountered severe shortage issues in recent decades. In the meantime, the municipal Solid Waste Incineration bottom ash (MSWIBA) is regarded as a feasible alternative of mined nature aggregates due to its similar mineralogical, physical and chemical characteristics. However, the uncertainties of long-term service performance and potential environmental pollution risk of MSWIBA prevent its widespread applications in road constructions. For these reasons, this paper investigates the resilient modulus and permanent deformation properties by the repeated load triaxial test at different moisture contents, and examines the long-term environment influence using leaching tests on the samples after subjecting to 5 freeze-thaw cycles and samples after one year weathering. Besides, the existing resilient modulus and permanent deformation prediction models of unbounded granular materials are evaluated for their applicability on MSWIBA. The test results indicate that the MSWIBA shows obvious stress-dependence and moisture-dependence in resilient modulus and permanent deformation behaviors. Moreover, the existing resilient modulus and permanent deformation prediction models with stress and moisture dependence are feasible for MSWIBA as well. Additionally, heavy metal leaching concentrations obtained from column test can meet the standard of surface water quality class V in China. This work is expected to benefit the design work and provide the insight of performance of MSWIBA as road embankment material, and promote its further widespread application in road construction.

A Novel Manganese-Rich Pokeweed Biochar for Highly Efficient Adsorption of Heavy Metals from Wastewater: Performance, Mechanisms, and Potential Risk Analysis

A novel manganese-rich pokeweed biochar was prepared at different temperatures from manganese-rich pokeweed plants collected at manganese tailings, resulting in materials identified as BC300, BC400, and BC500. The synthetized biochar materials were investigated as regards their potential for removing Cu2+, Pb2+, and Cd2+, specifically in terms of adsorption performances, adsorption kinetics, adsorption isotherms, and potential environmental pollution risk. The results showed that the sorption process fitted well to the pseudo-second-order kinetic and Langmuir models, and the maximum adsorption capacities of BC500 were 246, 326, and 310 mg·g−1 for Cu2+, Pb2+, and Cd2+ respectively. The physicochemical characteristics of the biochars, and the adsorption mechanisms, were revealed by using scanning electron microscopy-energy spectrometer, elemental analysis, Brunauer–Emmett–Teller techniques, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The sorption mechanism of these three heavy metal ions onto biochars included ion exchange, electrostatic adsorption, chemical adsorption, and precipitation. Besides, the potential pollution risk of manganese-rich pokeweed biochars was significantly reduced after pyrolysis. Therefore, it is feasible to transform manganese-rich pokeweed biomass into manganese-rich pokeweed biochar with potential for heavy metals removal, showing high adsorption capacity, recyclability, and low environmental pollution.

EMULSIONS OF WASTE FATS AND OILS FROM METALWORKING PROCESS AS ENVIRONMENTAL POLLUTANTS

The exploitation of industrial waste oils and fats, along with the influence of physical, thermal, chemical and biological factors, is the reason for their transformation and formation of waste emulsions that pose a potential risk of environmental pollution. This paper provides an overview of reference technological processes which are considered as the sources of environmental pollutants. In addition, this study presents the qualitative and quantitative characteristics of aqueous emulsions of waste fats and oils from metal processing and thus proposes a system for treatment that would minimize the risk of environmental pollution.

An improved method used for evaluating potential environmental pollution risk based on spatial distribution and density of farms.

The livestock manure nitrogen load on farmland (LMNLF) is often used to assess the potential environmental pollution risk of livestock manure nitrogen nutrient (LMN) in a target region. First, the LMNLF of Wuhan city is calculated, and the potential environmental pollution risk of LMN is mainly concentrated in Jiangxia District, Xinzhou District, and Huangpi District, but does not exceed the European Union (EU) standards. Heat map results also certificate this conclusion. Therefore, these three districts are the research emphases. Second, considering spatial distribution of farms, an improved LMNLF method is proposed combining the previous LMNLF and density-based spatial clustering of applications with noise (DBSCAN) methods. Several regions with pollution risks including seven regions in Jiangxia District, one in Xinzhou District, and one in Huangpi District are found out using the improved LMNLF method. Third, to evaluate the carrying capacity of the intensive breeding areas more reasonably, 2km is taken as the farthest transportation distance of manure; there is still one region in Huangpi District which has serious pollution risk on the environment. These above results can help evaluate the pollution degree of livestock manure to the surrounding environment more precisely.

Evaluation of edible bird’s nest processing plant wastewater quality: a factory case study

Edible bird’s nest (EBN) is a rapidly growing industry, especially in Southeast Asia. Cleaning raw EBN is an essential process in an EBN processing plant to remove any contaminant and impurities from the end products. However, this process has introduced a potential risk of environmental pollution through the disposal of the wastewater that may contain contaminants from the EBN. This study was conducted to determine the quality of wastewater from the selected EBN processing plant. Water samples were collected from 4 sampling points (SP) and analysed to determine the water quality index (WQI), metal content, nitrite content and microbiological contamination level. The results showed that the wastewater at SP1 and SP2 was classified as clean, while that of SP3 and SP4 was classified as slightly polluted based on the WQI classification. Metal content analysis results showed that only arsenic was found to exceed the permissible level according to the Environmental Quality Act 1974. The total aerobic count was highest in samples from SP4 with an average reading of 4.72 + 0.47 log CFU/mL. Escherichia coli (E. coli) was only found at all samples from SP4 with an average of 3.20 + 0.05 log CFU/mL. No other coliform readings were obtained from all sampling points. Overall, although the general quality of the wastewater was still at a safe level, the high content of arsenic indicated potential risk to the surrounding environment. Management of wastewater must be improved to ensure an environmentally safe and sustainable EBN production industry.

One-step recovery of REE oxalates in electro-leaching of spent NdFeB magnets

Recovery of rare-earth elements (REEs) from spent NdFeB magnets is receiving great attention because of high amount of neodymium and potential risk of environmental pollution. In this study, a novel environment-friendly hydrometallurgical route is proposed for efficient recovery of REEs during electrochemical leaching with sulfuric and oxalic acids. With proper adjustment of the electrolyte composition and operating conditions, effective separation of different elements is observed; a compact layer of REE oxalates in a purity of up to 93% is obtained on the cathode, while iron remains in the solution and as solid residue for further recovery. The mechanisms during the electro-leaching process were subsequently investigated and we propose that cathodic deposition of the REEs is due to electrostatic attraction of the REE-oxalate particles on the cathode. With this finding, selective recovery of REEs from spent magnets can be achieved. This study provides a new insight on electronic waste recycling by implementing principles of electrochemistry.

Occurrence of antibiotic residues in Apulian honey: potential risk of environmental pollution by antibiotics.

The presence of antibiotic residues in honey is widely documented and is attributed almost exclusively to improper beekeeping practices, due to the frequent use of drugs for the treatment of beehive diseases. Therefore, the aim of our research was to evaluate the presence of antibiotics in honeycomb using the Anti-Microbial Array II (AM II) and IV (AM IV) method and to assess the relationship between environmental context and antibiotic residues in honey. The results show the presence of antibiotic residues in 26/50 honey from brood nests samples, confirming the impact of environmental contamination on the health quality of this food product. In addition, subsequent analyses conducted on positive samples reveal the instability over time of antimicrobial molecules in honey. These results highlight the need for further studies in order to understand all likely sources of contamination and to implement a comprehensive safety management plan for honey.

Investigating the effect of biochar on the potential of increasing cotton yield, potassium efficiency and soil environment

Potassium (K) is an essential macronutrient for plant growth and development. However, in China, available K is relatively low in the soil, and with the extensive use of chemical fertilizer, K use efficiency is constantly reducing, and consequently increasing the potential risk of environmental pollution and economic loss. Therefore, it is essential to reduce the negative impact of over-fertilization on the environment to obtain optimal crop yield. Biochar as a soil amendment has been applied to improve soil fertility and increase crop yield. However, the effects of successive biochar application on cotton yield, agronomy efficiencies and potash fertilizer reduction are not well documented. Our results of a pot experiment showed that the application of 1% biochar to soil under different K levels significantly improved dry mass accumulation and K content of different plant parts, and increased the number of buds, bolls and effective branches of cotton. Particularly, plants treated with 150 mg/kg K2O and 1% biochar had the highest growth parameters. The most important characteristics including the harvest index, K fertilizer contribution index, partial factor productivity, agronomic efficiency and apparent recovery efficiency of K under C1 (1% biochar) were generally greater than those under C0 (without biochar). The 75 mg/kg K2O application was optimal to produce the highest yield with 1% biochar, demonstrating that biochar can increase cotton yield and therefore, reduces chemical K fertilizer application and alleviates agricultural environment risks of chemical fertilizer.

Recovery of gallium from waste light emitting diodes by oxalic acidic leaching

Recovery of gallium from light emitting diodes (LEDs) is receiving great attention due to both high content of gallium and potential risk of environmental pollution. In this study, a novel environment-friendly route was proposed for efficient recovery of gallium from surface mounted device (SMD) of LEDs by using organic acid. Reduction of non-metallic components, selection of lixiviants, optimization of leaching parameters, and possible mechanism of gallium were investigated. Results showed that pyrolysis could reduce non-metallic components effectively, and 22% weight loss was achieved at 733 K. Selection of lixiviant experiments indicated that 83.42% gallium could be extracted from SMD LEDs by oxalic acid, which was much higher than that of 79.89% by hydrochloric acid, 70.62% by citric acid, and 71.69% by DL-malic acid. Further investigation revealed that 90 °C of leaching temperature, 10 g L−1 of pulp density, 0.7 M of oxalic acid and 48–75 μm of particle size were the optimum conditions for effective gallium leaching by oxalic acid. After optimization, the gallium recovery efficiency reached as high as 90.36% in 60 min. Such efficient gallium leaching came from the higher dissociation constant of oxalic acid and the formation of ferrous oxalate which would promote the generation and maintenance of H+. Hence, oxalic acid could be a promising lixiviant for efficient recovery of gallium from SMD LEDs.

Comparative Analysis of Characterization Methods of Potential Environmental Pollution Risk from Livestock and Poultry Breeding

Comparative Analysis of Characterization Methods of Potential Environmental Pollution Risk from Livestock and Poultry Breeding

Characteristics of Nitrogen Deposition in Heilongjiang Liangshui National Nature Reserve

To investigate the nitrogen deposition status in Heilongjiang Liangshui National Nature Reserve, a G78 nitrogen deposition collector was used to monitor dry particulate nitrogen deposition and wet nitrogen deposition during the growing season in 2015, and a bucket was used to monitor bulk nitrogen deposition during non-growing season. The results showed that:①Total nitrogen deposition (wet nitrogen deposition+dry particulate nitrogen deposition during the growing season and bulk deposition during the non-growing season) was 12.93 kg·(hm2·a)-1, inorganic nitrogen deposition was 8.27 kg·(hm2·a)-1 with NH4+/NO3- ratio of 1.3; organic nitrogen deposition was 4.66 kg·(hm2·a)-1, which was equivalent to 36.0% of the total nitrogen deposition. ②Total nitrogen deposition in the growing season (wet+dry particulate deposition) and non-growing season (bulk deposition) were 11.42 kg·hm-2 and 1.51 kg·hm-2respectively, which account for 88.3% and 11.7% of the total nitrogen deposition respectively. ③Total wet nitrogen deposition during the growing season was 9.28 kg·hm-2, contributing to 81.3% of the total nitrogen deposition in the growing season, and was positively correlated with precipitation (R2=0.87, P<0.001); total dry particulate nitrogen deposition in the growing season was 2.14 kg·hm-2, which was 18.7% of the total nitrogen deposition in growing season. Wet nitrogen deposition in this region is moderate compared with other regions in China, and is significantly affected by precipitation. There is a potential risk of environmental pollution in this region. Thus, environmental protection and water quality monitoring are required in the process of production.

Geographical Distribution and Risk Assessment of Heavy Metals in Nearby River of Heap Bioleaching Plant: A Case Study At the Zijin Copper Mine, China

The Zijin heap bioleaching plant was operated at the end of 2005. Concerns about the potential risk of environmental pollution from heap bioleaching plant arise due to the proximity to the Ting River. In this study, a physicochemical analysis, a geo-accumulation index and a high throughput sequencing technology were applied to determine heavy metals, assess the extent of heavy metal pollution, and research the effect of the heap bioleaching plant on the microbes, respectively. Results showed that the heap bioleaching plant had significant influence on the distribution of S, Pb and Cu and no significant influence on the distribution of As, Fe and Cr. Most of the water samples reached the third class standard of the People’s Republic of China for surface water and individual water samples were above the fifth class standard of the People’s Republic of China for surface water (GB3838-2002) because of As. The heap bioleaching plant had some effect on the microbial biomass, diversity and the microbial composition. However, the effect on the microbial biomass and diversity were not significant.

Endocrinologia e controle da vitelogênese em carrapatos

Background : : : : Ticks are distributed worldwide, with impacts on human and animal health. The cattle tick Rhipicephalus (Boophilus) microplus is the main parasite that affects livestock in tropical and subtropical regions of the world, causing large economical losses. Tick control methods are based on the application of chemical acaricides, which has resulted in selection of resistant ticks and a potential risk of environmental pollution and food contamination. Vaccines have showed to be a feasible tick control method that offers a cost-effective, environmental friendly alternative to chemical control. However, more than ten years after the commercialization of the first vaccine against ticks, the identification of tick-protective antigens remains a limiting step in the development of an efficient formulation that would avoid the use of chemical acaricides. So, the study of parasite biology and understanding physiological mechanisms could be a good strategy to find new targets for an efficient vaccine. Review : It was reviewed the main insights about the reproductive process in ticks, emphasizing the hormonal control of vitellogenesis and enzymes involved in vitellin processing during embryogenesis. The processes of vitellogenesis and embryogenesis have been studied in various organisms, particularly in cockroaches, flies and ticks. Although the roles of 20-hydroxyecdysone (20E) and juvenile hormone have been well characterized for vitellogenesis in insects, we know much less about the hormonal control of vitellogenesis in ticks. Initially, it was hypothesized that juvenile hormone was involved in tick vitellogenin-synthesis. However, more critical studies uncovered no evidence for the occurrence of juvenile hormone or juvenile hormone-like molecules in several tick species. Current research shows that in ticks, it appears that ecdysteroids, and not juvenile hormone, regulate the expression of the vitellogenin gene and the synthesis and release of vitellogenin protein into the hemolymph. In general, the carbohydrate, lipid and amino acid composition of tick vitellogenin is similar to that of insect vitellogenin. Once in the hemolymph, oocytes uptake vitellogenin through receptor-mediated endocytosys. However, there are different strategies to control vitellogenin synthesis and uptake by ovary in ixodide ticks. In the oocytes, vitellogenin is partially processed in the endosomal compartment and then stored as vitellin, the main reserve of protein for embryo development, in specialized organelles, the yolk granules. Embryo development depends on the availability of yolk material stored into oocytes. So, the characterization of molecules involved in vitellogenesis and embryo development contribute to a better understanding of the tick parasite physiology. During embryogesesis, acidic enzymes are responsible for the availability of this material and embryo nutrition. The Vitellin-Degrading Cysteine Endopeptidase (VTDCE), Boophilus Yolk Pro-Cathepsin (BYC) and Tick Heme Binding Aspartic Proteinase (THAP) are enzymes involved in vitellin hydrolysis in R. microplus eggs. These enzymes are produced by gut and fat body and transported through the hemolymph to be internalized into the oocytes and then play their role in tick embryo nutrition. As VTDCE, BYC and THAP are involved in an important physiological process, their potential as targets in an anti-tick vaccine is an attractive research topic. With this objective, various enzymes have been tested in native or recombinant forms as candidate immunogens to a multiantigenic anti-tick vaccine. Conclusion : Significant advancements have been made in recent years on understanding the tick reproductive process, and some molecules that can be possible targets for development of new tick control strategies have been characterized.

Recovery of valuable metals from waste cathode materials of spent lithium-ion batteries using mild phosphoric acid

Sustainable recycling of valuable metals from spent lithium-ion batteries (LIBs) may be necessary to alleviate the depletion of strategic metal resources and potential risk of environmental pollution. Herein a hydrometallurgical process was proposed to explore the possibility for the recovery of valuable metals from the cathode materials (LiCoO2) of spent LIBs using phosphoric acid as both leaching and precipitating agent under mild leaching conditions. According to the leaching results, over 99% Co can be separated and recovered as Co3(PO4)2 in a short-cut process involved merely with leaching and filtrating, under the optimized leaching conditions of 40°C (T), 60min (t), 4 vol.% H2O2, 20mLg−1 (L/S) and 0.7mol/L H3PO4. Then leaching kinetics was investigated based on the logarithmic rate kinetics model and the obtained results indicate that the leaching of Co and Li fits well with this model and the activation energies (Ea) for Co and Li are 7.3 and 10.2kJ/mol, respectively. Finally, it can be discovered from characterization results that the obtained product is 97.1% pure cobalt phosphate (Co3(PO4)2).

Prevalence and dissemination of antibiotic resistance genes and coselection of heavy metals in Chinese dairy farms

This study aims to explore prevalence and dissemination of antibiotic resistance genes (ARGs) in dairy farms. A variety of ARGs conferring resistance to most classes of antibiotics were detected in feces and soil samples obtained from dairy farms, using a high-throughput metagenomic sequencing approach. The ARGs observed in the feces and the soil samples were significantly correlated (p<0.01). The abundance of mobile genetics elements, such as transposase, was also examined to evaluate the potential risk of horizontal ARGs transfer. The positive correlation (p<0.001) between the total abundance of transposase genes and ARGs in the soil samples suggested strong dissemination capacity of ARGs in soil. In addition, the ARGs and metal resistance genes (MRGs) were significantly correlated with heavy metals in the feces (p<0.01), suggesting that the heavy metals promoted the emergence of metal resistance, and participated in the coselection processes for ARGs. The prevalence of ARGs with high levels of genetic mobile elements in the dairy farms suggests that cattle excrement is a major reservoir of ARGs with a high risk of dissemination, which increases the potential risk of environmental pollution and threatens public health.

Potential risk of biologic pollution associated to the introduction of Pinus radiata in grassland areas

Afforestation is a recommended practice to mitigate global warming. However, their implementation may generate undesirable impacts, mostly if exotic species are used. Plantations of Pinus radiata D Don in Ventania (Bs. As., Argentina) soils showed notorious increments of extractable P (Pe), which could affect the dynamic of this element as well as the degree of phosphorus saturation (GSPBray). The objectives of this study were: i) to quantify the GSPBray in Mollisols afforested with P. radiata comparing the results with those coming from adjacent, natural grassland areas (base line); ii) to evaluate the potential environmental risk induced by afforestation through the identification of a change point (PC) in the GSPBray indicative of a phosphate leaching increment. Treatments included mature stands of P. radiata (TB) and adjacent areas with natural grassland vegetation (TP). Samples were taken at 0-15; 15-30 and 30-45 cm soil depth, and texture, pH, total organic carbon (COT), Pe, soluble reactive phosphorus (PSR), phosphorus sorption index (ISP) and GSPBray were determined. The results showed a significant acidification in TB and an increase in the COT stock, indicating an additional atmospheric CO2 sequestration by the trees. The Pe and PSR values were notoriously higher in TB, and they were reflected in a significant increment in the GSPBray with respect to TP. The detection of a significant PC in the GSPBray-PSR regression indicates higher chances of phosphate leaching in the forest stands, which could reach water courses, lakes and artificial reservoirs promoting their eutrophication. Because of the potential environmental pollution risk of biologic origin derived from the afforestation with P. radiata in Mollisols areas, their inclusion in clean development practices must be reconsidered.

Groundwater pollution at a pulp and paper mill at Sjasstroj near Lake Ladoga, Russia

AbstractLake Ladoga, situated in north-west Russia, is the main source of drinking water for more than 6 million people in the region of St Petersburg. During recent years eutrophication of Lake Ladoga has increased, with pollution of the lake water and sediments by heavy metals, phenols and chloro-organic substances. This paper reports the influence of effluents from a pulp and paper mill at Sjasstroj situated on the southern shore of Lake Ladoga. At Sjasstroj, contamination of a wide area of land, and the production of large volumes of wastewater requiring treatment and disposal, threaten the sustainability of surface and domestic well supplies and lake ecosystems. A tiered approach to risk assessment was adopted in this investigation beginning with a survey of historical data and an initial field reconnaissance followed by more detailed, targeted hydrogeological and hydrochemical investigations. Concentrations of dissolved organic carbon (DOC) as high as 44 mg 1−1 and adsorbable organic halogens as high as 130 µg 1−1 were found in groundwater samples. The detailed field reconnaissance survey contradicted toxicity index values for the wastewater, sludge and groundwater samples calculated using a Russian method of risk characterization, which would otherwise predict a high potential environmental pollution risk. In reality, there is good evidence for natural attenuation of organic compounds in groundwater, with as much as 40–50% removal of DOC. However, the residual DOC can be problematic when chlorination of raw surface and groundwaters creates organo-chlorine by-products in treated water.