Solomon Islands is rapidly developing its natural resource exploitation sector, but data needed to assess consequent environmental impacts are scarce. We assessed catchments surrounding the Gold Ridge gold mine (Guadalcanal, Solomon Islands) and found that extensive changes in river course, and water and sediment quality have occurred downstream of the gold mine since its development. Sediment run-off from exposed areas associated with the mine pit has increased, elevating turbidity (up to 2450 NTU) and metal and arsenic levels, with levels of the latter being up to 0.141 mg/L in surface waters and 265 mg/kg in sediments. An overfull, inoperative tailings storage facility associated with the currently inactive gold mine with fluctuating arsenic levels (up to 0.087 mg/L in the water; 377 mg/kg in the sediment) presents an ongoing threat to the environment. Arsenic, due to its toxicity, appears to be the greatest threat, with sediment and water guideline levels in rivers exceeded 10-fold and exceeded nearly 20-fold in the tailings dam sediments. Despite elevated metal and arsenic content in the area, no toxic inorganic arsenic was found to have bioaccumulated in locally harvested food. In summary, the natural environment surrounding the Gold Ridge mine has been modified substantially and requires an ongoing monitoring program to ensure the ecosystem services of food and water for the local communities continue to be safe. This study informs not only the local area but also provides a microcosm of the broader global challenges facing the regulation of extractive industries in proximity to subsistence communities.

In recent years, some pigments and chemical products have been reported to contain polychlorinated biphenyl (PCB) congeners as unintentional byproducts, and these have also been detected in residential environments from indoor air and house dust. In this study, using in vitro reporter gene assays, we characterized the agonistic and antagonistic activities of a total of 25 PCB congeners contained in pigments (PCB-1 to -16, -20, -35, -40, -52, -56, -77, -101, -126, and -153) against five nuclear hormone receptors, (estrogen receptor (ER) α/β, glucocorticoid receptor (GR), androgen receptor (AR), thyroid hormone receptor (TR) α1) and aryl hydrocarbon receptor (AhR). In the ERα/β assays, 19 and 13 of the 25 PCBs tested showed ERα/β agonistic and/or antagonistic activities, respectively. Relatively potent agonistic activities against ERα/β were found in PCB congeners possessing chlorides at positions 2 and 3. In the GR and AR assays, five and all of the 25 PCB congeners showed antagonistic activity, respectively. Among the anti-androgenic PCB congeners, the activities were more potent in PCB congeners possessing more than three chlorides including consecutive ortho- and meta- or meta- and para-chlorides. In the AhR assay using a sensitive DR-EcoScreen cell line, five of the 25 PCB congeners showed agonistic activity. We newly found that PCB-1, -35 and -56 can act as AhR agonists. Despite these activities among the PCBs, the effects of PCB-11, mainly detected in pigments and chemical products, against these receptors were found to be weaker than those of other tested PCBs. These results suggest that unintentional PCBs in pigments and chemical products might act as agonists and/or antagonists against ERα/β, AR, GR, and AhR, and some of the PCBs might disrupt endocrine functions via multiple receptors and/or simultaneously induce dioxin-like activity via AhR.

The aim of the study was to investigate abiotic and biotic factors influencing the accumulation of endocrine disrupting compounds (EDCs) such as bisphenol A (BPA), 4-tert-octylphenol (OP) and 4-nonylphenol (NP) in mussels Mytilus trossulus from the Gulf of Gdansk (Southern Baltic). The key abiotic factor influencing BPA, OP and NP accumulation in mussels is their hydrophilicity/lipophilicity, which affects their main assimilation routes - by digestive tract for the more lipophilic OP and NP, and additionally by the gills for the less lipophilic BPA. As a result, high condition index (i.e. higher soft tissue weight) is more often correlated with high concentrations of OP and NP in mussels than with BPA. Furthermore, alkylphenols have 6–8 times greater accumulative potential than BPA. Concentration of the studied compounds was lower in females than in males following spawning, and the effect lasted longer for BPA than for alkylphenols. The influence of season and hydrological conditions on BPA, OP, NP in the mussel was more pronounced than the proximity of external sources of these compounds. An increase in water temperature in summer probably stimulated the solubility of BPA, the least lipophilic of the studied compounds, and led to increased assimilation of this compound from water (through gills). On the other hand, high OP and NP concentrations in mussels occurred in spring, which was caused by increased surface run-off and sediments resuspension.

Much effort has been made to standardise sampling procedures, laboratory analysis, data analysis, etc. for semi volatile organic contaminants (SVOCs). Yet there are some unresolved issues in regards to comparing measurements from one of the most commonly used passive samplers (PAS), the polyurethane foam (PUF) disk PAS (PUF-PAS), between monitoring networks or different studies. One such issue is that there is no universal means to derive a sampling rate (Rs) or to calculate air concentrations (Cair) from PUF-PAS measurements for SVOCs. Cair was calculated from PUF-PAS measurements from a long-term monitoring program at a site in central Europe applying current understanding of passive sampling theory coupled with a consideration for the sampling of particle associated compounds. Cair were assessed against concurrent active air sampler (AAS) measurements. Use of “site-based/sampler-specific” variables: Rs, calculated using a site calibration, provided similar results for most gas-phase SVOCs to air concentrations derived using “default” values (commonly accepted Rs). Individual monthly PUF-PAS-derived air concentrations for the majority of the target compounds were significantly different (Wilcoxon signed-rank (WSR) test; p < 0.05) to AAS regardless of the input values (site/sampler based or default) used to calculate them. However, annual average PUF-PAS-derived air concentrations were within the same order of magnitude as AAS measurements except for the particle-phase polycyclic aromatic hydrocarbons (PAHs). Underestimation of PUF-derived air concentrations for particle-phase PAHs was attributed to a potential overestimation of the particle infiltration into the PUF-PAS chamber and underestimation of the particle bound fraction of PAHs.

A full life-cycle (240 days) bioassay using the terrestrial snail, Cantareus aspersus, allowing exposure during embryogenesis and/or the growth and reproduction phases, was used to assess the effects of Bypass®, a glyphosate-based herbicide (GlyBH), on a range of endpoints, including parameters under endocrine control. As a positive control, a mixture (R-A) made of diquat (Reglone®) and nonylphenols (NP, Agral®), known for its endocrine disrupting effects in other organisms, was tested. At environmental concentrations, both pesticides (R-A mixture and GlyBH) enhanced growth but reduced reproduction. The R-A mixture acted mainly on the fecundity through a delay in egg-laying of approximately 20 days and a strongly reduced number of clutches. This latter dysfunction may be caused by a permanent eversion of the penis, suggesting a disrupting effect at the neuro-endocrine level, which prevented normal mating. GlyBH acted on fertility, possibly due to a decrease in the fertilization of eggs laid by adults exposed during their embryonic development. These results, associated with the absence of observed effects on gonad histology of GlyBH exposed snails, suggested that the underlying mechanisms are neuro-endocrine.

Free amino acid concentrations and nitrogen (N) isotopic composition in new current-year (new), mature current-year (middle-aged) and previous-year (old) Masson pine (Pinus massoniana Lamb.) needles were determined to indicate atmospheric N deposition in Guiyang (SW China). In different areas, free amino acids (especially arginine) concentrations in new and middle-aged needles were higher than in old needles, and the variation of free amino acids (especially arginine) concentrations in new and middle-aged needles was also greater than in old needles. This indicate that free amino acids in new and middle-aged needles may be more sensitive to N deposition compared to old needles. Moreover, concentrations of total free amino acids, arginine, histidine, γ-aminobutyric acid and alanine in middle-aged needles exhibited a strong relationship with N deposition (P < 0.05). Needle δ¹⁵N values showed a strong gradient from central Guiyang to the rural area, with more positive δ¹⁵N (especially in old needles) in the city center (0–5 km) and more negative δ¹⁵N (especially in old needles) in rural area (30–35 km). These suggest that N deposition in the urban center may be dominated by ¹⁵N-enriched NOx-N from traffic exhausts, while it is dominated by isotopically light atmospheric NHx-N from agriculture in rural area. Soil δ¹⁵N decreased slightly with distance from the city center, and the difference in δ¹⁵N values between the soil and needles (especially for old needles) increased significantly with the distance gradient, indicating that atmospheric N deposition may be an important N source for needles. This study provides novel evidence that free amino acids in needles and age-dependent needle δ¹⁵N values are useful indicators of atmospheric N deposition.

Quantifying population exposure level to tobacco smoke is important for investigating its adverse effects on human health. We aimed to investigate the feasibility and application of using population hair concentrations of nicotine and cotinine to indicate their exposure level to tobacco smoke among pregnant women. Our study recruited 256 mothers who delivered healthy babies and collected their hair samples from scalp, of which 172 mothers were self-reported non-passive smokers and the other 84 mothers were self-reported passive smokers. We analyzed nicotine and cotinine concentrations of the hair section grown during the early pregnancy. The linear relationship between cotinine and nicotine was developed and validated by internal cross-validation method. Our results revealed that self-reported passive smokers had higher concentrations of nicotine [2.08 (1.00–4.46) ng/mg hair, i.e. median value (inter-quartile range)] and cotinine [0.063 (0.041–0.148) ng/mg hair] than non-passive smokers [1.35 (0.58–2.59) ng/mg hair of nicotine and 0.049 (0.022–0.087) ng/mg hair of cotinine, respectively]. There existed a linear regression model between hair cotinine and nicotine concentrations, i.e. [cotinine] = 0.024 × [nicotine]+0.0184 (R2 = 0.756) for this population. The internal cross-validation squared correlation coefficient slightly increased from 0.689 to 0.734 with the training subjects varying from 20% to 90%, suggesting that this regression model had high robustness and predictive accuracy. It was concluded that nicotine in maternal hair can evaluate the hair cotinine level and reflect maternal passive exposure level to ambient tobacco smoke with high sensitivity.

Studies have yet to evaluate the effects of water improvement on fluoride concentrations in drinking water and the corresponding health risks to Chinese residents in endemic fluorosis areas (EFAs) at a national level. This paper summarized available data in the published literature (2008–2016) on water fluoride from the EFAs in China before and after water quality was improved. Based on these obtained data, health risk assessment of Chinese residents' exposure to fluoride in improved drinking water was performed by means of a probabilistic approach. The uncertainties in the risk estimates were quantified using Monte Carlo simulation and sensitivity analysis. Our results showed that in general, the average fluoride levels (0.10–2.24 mg/L) in the improved drinking water in the EFAs of China were lower than the pre-intervention levels (0.30–15.24 mg/L). The highest fluoride levels were detected in North and Southwest China. The mean non-carcinogenic risks associated with consumption of the improved drinking water for Chinese residents were mostly accepted (hazard quotient < 1), but the non-carcinogenic risk of children in most of the EFAs at the 95th percentile exceeded the safe level of 1, indicating the potential non-cancer-causing health effects on this fluoride-exposed population. Sensitivity analyses indicated that fluoride concentration in drinking water, ingestion rate of water, and the exposure time in the shower were the most relevant variables in the model, therefore, efforts should focus mainly on the definition of their probability distributions for a more accurate risk assessment.

Cooling tower emissions have become an increasingly common hazard to the environment (air polluting, ice formation and salts deposition) and to the health (Legionella disease) in the last decades. Several environmental policies have emerged in recent years limiting cooling tower emissions but they have not prevented an increasing intensity of outbreaks.Since the level of emissions depends mainly on cooling tower component design and the operating conditions, this paper deals with an experimental investigation of the amount of emissions, drift and PM10, emitted by a cooling tower with different configurations (drift eliminators and distribution systems) and working under several operating conditions. This objective is met by the measurement of cooling tower source emission parameters by means of the sensitive paper technique. Secondary objectives were to contextualize the observed emission rates according to international regulations.Our measurements showed that the drift rates included in the relevant international standards are significantly higher than the obtained results (an average of 100 times higher) and hence, the environmental problems may occur. Therefore, a revision of the standards is recommended with the aim of reducing the environmental and human health impact. By changing the operating conditions and the distribution system, emissions can be reduced by 52.03% and 82% on average. In the case of drift eliminators, the difference ranges from 18.18% to 98.43% on average. As the emissions level is clearly influenced by operating conditions and components, regulation tests should be referred to default conditions. Finally, guidelines to perform emission tests and a selection criterion of components and conditions for the tested cooling tower are proposed.

The effects of humic acid (HA) on interactions between ZnO nanoparticles (ZnO NPs) and Pseudomonas putida KT2440 biofilms at different maturity stages were investigated. Three stages of biofilm development were identified according to bacterial adenosine triphosphate (ATP) activity associated with biofilm development process. In the initial biofilm stage 1, the ATP content of bacteria was reduced by more than 90% when biofilms were exposed to ZnO NPs. However, in the mature biofilm stages 2 and 3, the ATP content was only slightly decreased. Biofilms at stage 3 exhibited less susceptibility to ZnO NPs than biofilms at stage 2. These results suggest that more mature biofilms have a significantly higher tolerance to ZnO NPs compared to young biofilms. In addition, biofilms with intact extracellular polymeric substances (EPS) showed higher tolerance to ZnO NPs than those without EPS, indicating that EPS play a key role in alleviating the toxic effects of ZnO NPs. In both pure ZnO NPs and ZnO-HA mixtures, dissolved Zn²⁺ originating from the NPs significantly contributed to the overall toxicity. The presence of HA dramatically decreased the toxicity of ZnO NPs due to the binding of Zn²⁺ on HA. The combined results from this work suggest that the biofilm maturity stages and environmental constituents (such as humic acid) are important factors to consider when evaluating potential risks of NPs to ecological systems.