Previous studies reported that some species of the family Ceratophryidae are able to produce sounds during premetamorphic tadpole stages. We have now determined the effects of the cholinesterase-inhibiting insecticide chlorpyrifos (CPF) on sounds emitted by tadpoles of Ceratophrys ornata. Tadpoles were exposed individually in order to evaluate the progression of effects. Effects on sound production were complemented with common ecotoxicological endpoints (mortality, behavior, abnormalities and growth inhibition). C. ornata was found to be more sensitive than other native (= 67%, 50%) and non-native species (= 75%, 100%) considering lethal and sublethal endpoints, respectively. Effects on sounds appear along with alterations in swimming, followed by the presence of mild, then severe abnormalities and finally death. Therefore, sound production may be a good biomarker since it anticipates other endpoints that are also affected by CPF. Ceratophrys ornata is a promising new model species in ecotoxicology.

Frequencies and durations of blooms of cyanobacteria are increasing. Some cyanobacteria can produce cyanotoxins including microcystins (MCs). MCs are the most common toxic products of hazardous algal blooms (HABs), with the greatest potential for exposure and to cause toxicity. Recently, MCs have been shown to disrupt endocrine functions. In this study, for the first time, effects of MC-LR on the hypothalamic-pituitary-inter-renal (HPI) axis during early embryonic development (embryos/larvae) of zebrafish (Danio rerio), were investigated. Embryos/larvae of zebrafish were exposed to 1, 10, 100, or 300 μg MC-LR/L during the period of 4–168 h post-fertilization (hpf). Exposure to 300 μg MC-LR/L resulted in significantly greater concentrations of whole-body cortisol than those in controls. Expressions of genes along the HPI axis and mineralocorticoid receptor (MR-) and glucocorticoid receptor (GR-) centered gene networks were evaluated by use of quantitative real-time PCR. Expression of mRNA for crh was significantly down-regulated by exposure to 300 μg MC-LR/L, while expressions of crhbp, crhr1, and crhr2 were significantly up-regulated, relative to controls. MC-LR caused significantly lesser levels of mRNA for steroidogenic genes including hmgra, star, and cyp17, but expression of mRNA for hsd20b was significantly greater than that of controls. Treatment with MC-LR also altered profiles of transcription of MR- and GR-centered gene networks, which might result in multiple responses. Taken together, these results demonstrated that MC-LR affected the corticosteroid-endocrine system of larvae of zebrafish. This study provided valuable insights into molecular mechanisms behind potential toxicity and endocrine disruption of MCs.

Assessing ozone (O3) risk to vegetation is crucial for informing policy making. Soil nitrogen (N) and phosphorus (P) availability could change stomatal conductance which is the main driver of O3 uptake into a leaf. In addition, the availability of N and P could influence photosynthesis and growth. We thus postulated that the sensitivity of plants to O3 may be changed by the levels of N and P in the soil. In this study, a sensitive poplar clone (Oxford) was subject to two N levels (N0, 0 kg N ha−1; N80, 80 kg N ha−1), three P levels (P0, 0 kg P ha−1; P40, 40 kg P ha−1; P80, 80 kg P ha−1) and three levels of O3 exposure (ambient concentration, AA; 1.5 × AA; 2.0 × AA) for a whole growing season in an O3 free air controlled exposure (FACE) facility. Flux-based (POD0 to 6) and exposure-based (W126 and AOT40) dose-response relationships were fitted and critical levels (CLs) were estimated for a 5% decrease of total annual biomass. It was found that N and P availability modified the dose-response relationships of biomass responses to O3. Overall, the N supply decreased the O3 CLs i.e. increased the sensitivity of poplar to O3. Phosphorus alleviated the O3-caused biomass loss and increased the CL. However, such mitigation effects of P were found only in low N and not in high N conditions. In each nutritional treatment, similar performance was found between flux-based and exposure-based indices. However, the flux-based approach was superior, as compared to exposure indices, to explain the biomass reduction when all nutritional treatments were pooled together. The best O3 metric for risk assessments was POD4, with 4.6 mmol m−2 POD4 as a suitable CL for Oxford poplars grown under various soil N and P conditions.

Polycyclic aromatic hydrocarbons (PAHs) are environmental endocrine disruptors, which may modify the bone mineralization. However, epidemiological evidences on this issue were scant. We aimed to investigate the associations of PAHs with bone mass density (BMD) and osteoporosis based on a nationally-representative sample from general U.S. population. Data utilized were extracted from the 2005–2010 National Health and Nutrition Examination Survey (NHANES). Nine urinary PAHs (U-PAHs) metabolites were measured as exposure biomarkers. Associations of specific U-PAHs with BMD and osteoporosis were estimated by multivariable adjusted linear regression models and logistic regression models, respectively. Compared with women at the first tertiles, those at the third tertiles of 1-Hydroxynapthalene, 2-Hydroxyfluorene, 3-Hydroxyphenanthrene, 2-Hydroxyphenanthrene and 9-Hydroxyfluorene had significantly decreased BMD levels [coefficient (β) = −0.023 to −0.014, p < 0.05] or increased likelihoods of osteoporosis [odds ratios (ORs) = 1.86 to 3.36, p < 0.05] at different bone sites. Whereas, elevated BMD levels (β = 0.021, p < 0.05) at trochanter and decreased likelihoods of osteoporosis (OR = 0.33, p < 0.05) at intertrochanter were observed among women at the second tertiles of 1-Hydroxypyrene and 2-Hydroxynapthalene, respectively. Similar results were found for all the population, i.e., combination of men and women. Most of the significant associations disappeared among adult men only. Furthermore, Associations between U-PAHs and BMD were stronger for postmenopausal women when compared with premenopausal group. In conclusion, associations of U-PAHs with BMD and osteoporosis varied by specific U-PAHs and bone sites, as well as menopausal status and genders in U.S. adults.

The combination of emerging antibiotic resistance and lack of discovery of new antibiotic classes poses a threat to future human welfare. Antibiotics are administered to livestock at a large scale and these may enter the environment by the spreading of manure on agricultural fields. They may leach to groundwater, especially in the Netherlands which has some of the most intensive livestock farming and corresponding excessive manure spreading in the world. This study investigates the presence of antibiotics in groundwater in two regions with the most intensive livestock farming in the Netherlands. If so, the hydrochemical conditions were further elaborated. Ten multi-level wells with in total 46 filters were sampled, focusing on relatively young, previously age-dated groundwater below agricultural fields. Twenty-two antibiotics were analyzed belonging to the following antibiotic groups: tetracyclines, sulfonamides, trimethoprims, β-lactams, macrolides, lincosamides, quinolones, nitrofurans and chloramphenicol. The samples were analyzed for these antibiotics by LC-MS/MS ESI-POS/NEG (MRM) preceded by solid phase extraction which resulted in importantly low detection limits. Six antibiotics were found above detection limits in 31 filters in seven wells: sulfamethazine, sulfamethoxazole, lincomycin, chloramphenicol, ciprofloxacin, and sulfadiazine. The concentrations range from 0.3 to 18 ng L−1. Sulfonamides were detected at all measured depths down to 23 meters below surface level with apparent groundwater ages up to 40 years old. No antibiotics were detected below the nitrate/iron redox cline, which suggests that the antibiotics might undergo degradation or attenuation under nitrate-reducing redox conditions. This study provides proof that antibiotics are present in groundwater below agricultural areas in the Netherlands due to the spreading of animal manure.

Arsenic (As) remediation in contaminated water using nanoparticles is promising. However, the fate and transport of As associated with nano-adsorbents in natural environment is poorly understood. To investigate the fate of adsorbed As on nano-TiO₂ in changed redox condition from oxic to anoxic, we added the As(V)-TiO₂ suspension in groundwater to an autoclaved soil column which inoculated a sulfate-reducing bacterium, Desulfovibrio vulgaris DP4. The dissolved As(V) in effluent increased to 798 μg/L for the biotic column and to 1510 μg/L for the abiotic control, and dissolved As(III) was observed only in biotic column. The total As (dissolved plus particulate) in the biotic column effluent (high to 2.5 mg/L) was substantially higher than the abiotic control (1.5 mg/L). Therefore SRB restrained the release of dissolved As, and facilitated the transport of particulate As. Micro-XRF analysis suggested that the nano-TiO₂ with As was mainly retained in the influent front and that its transport was negligible. Our pe-pH calculation and XANES analysis demonstrated that generated secondary iron minerals containing magnetite and mackinawite mainly were responsible for dissolved As retention, and then transported with As as particulate As. The results shed light on the mobilization of adsorbed As on a nano-adsorbent in an anoxic environment.

Due to its high sorption capacity for different kinds of contaminants, biochar is advocated as a novel remediation strategy for contaminated soils. However, it is not clear how long this extraordinary sorption capacity will be maintained after the biochar is applied to the soil. In this study, a commercial biochar was applied to an agricultural soil, and the sorption of atrazine and phenanthrene on biochar amended soils with different aging periods ranging from 0 to 2 y was investigated. The application of fresh biochar in soil led to an obvious enhancement of the sorption coefficients (Kd) of atrazine and phenanthrene (by 3.13 and 2.93 times at Cₑ = 0.01 Sw, respectively) compared with the untreated soil. The surface area of biochar first increased and then decreased with aging time. Correspondingly, the sorption of atrazine and phenanthrene on the biochar amended soils first increased and then decreased markedly. Based on the changing trend of the Kd values with aging time, it could be predicted that the sorption capacity of biochar amended soils will decrease to the level of the untreated soil after 2.5 y.

The effects of the biocide Triclosan, used in personal care products and known as a common environmental contaminant, on byssal apparatus were studied in the marine mussel Mytilus galloprovincialis. Experimental evidences indicated that an exposure for 7 days at a concentration of 10 μg/L induced marked alterations in the byssus gland resulting in a significant delay in byssus regrowth and in a decrease in threads resistance to traction. Such alterations in animals exposed to tidal and waves action would cause a significant loss in ecological fitness and severely impact on mussel survival. Triclosan release in coastal environments therefore should be more carefully monitored to prevent drastic consequences.

It has been suggested that the toxic effects of cadmium (Cd) may disrupt ovarian and uterine functions in adults. However, Cd exposure during gestation and lactation and its effects on the reproductive development in female offspring is still not clear, and the mechanisms underlying exposure toxicology remain mostly unexplored. To investigate how Cd exposure of female rats (F0) during gestation and lactation affects the reproductive development of their female offspring, we studied the steroidogenesis, folliculogenesis, puberty onset, and litter size of the first (F1) and second (F2) filial generations following F0 female rats which had been exposed to CdCl2. The mechanisms related to the early onset of puberty induced by such exposure in female offspring were explored. Maternal exposure to Cd dramatically increased the biosynthesis of steroid hormones in F1 female offspring by the activation of cAMP/PKA pathway and up-regulated expression of steroidogenesis related proteins such as StAR, CYP11A1, 3β-HSD and CYP19A1. The high levels of steroid hormones contributed to an early puberty onset, promoted the differentiation and maturation of follicles, and led to the proliferation of endometrium that resulted in a uterus weight gain. The increased number of antral follicles eventually caused a big litter size. Despite of being free from additional Cd exposure, the levels of CYP11A1 and CYP19A1 in the ovaries of F2 female rats were also high, which resulted in a high concentration of serum progesterone. These results suggested that hormonal changes induced by exposure to Cd in utero might have a lasting effect beyond the first generation. These findings may help to better understand the origin of female sexual dysfunction in the developmental stages in general.

The influence of nitrogen (N) deposition on forest ecosystems largely depend on the N status. Developing threshold and practical indicators for N saturation in subtropical forests, with extremely high N deposition, would both enhance forest management and the assessments of global N balance and carbon (C) sequestration. Here, we quantified the N mass balance and assessed current N status at a number of subtropical forest sites in South China, using both N content, C/N ratio, and 15N natural abundance (δ15N) as potential indicators of N saturation. Among the studied sites, N deposition ranged from 13.8 to 113 kg N ha−1 yr−1 in throughfall, and was dominated by ammonium (NH4+). The threshold for N leaching in subtropical forest was first found to be 26–36 kg N ha−1 yr−1, which was 160% higher than in temperate forest (based on prescribed minimum). This indicates that critical parameter inputs in global models of the impact of N deposition are in need of revision, based on specific ecosystem characteristics. We found a critical C/N ratio of 20 for the O/A horizon as indicator of N saturation. Foliar N content and δ15N were positively correlated with N deposition and were well suited to indicate regional N status. The δ15N enrichment factor (Ɛfoli/So2, δ15Nfoliage - δ15NSoil2) was between −10‰ and −1‰, and had similar trend to those obtained from other regions with increasing N deposition. These suggest that the enrichment factor could be used to investigate the influence of N deposition in forest ecosystems, regardless of spatial heterogeneity in δ15N of N input, soil N availability and geomorphology.