Long-term impact of wastewater effluent discharge on groundwater: Identification of contaminant plume by geochemical, isotopic, and organic tracers' approach

Infiltration of effluents from wastewater treatment plants (WWTP) into groundwater can be a source of Contaminants of Emerging Concern (CECs), such as pharmaceutical compounds, that are not fully removed during the treatment processes. A multi-tracer approach, based on hydrogeochemical, isotopic, and organic tracers, is applied in the Vistrenque Aquifer (Gard, France) to assess the dispersion of such unintentional plumes and its potential implication on groundwater quality for CECs in a small catchment area. In this area, a point source of WWTP effluent causes contaminant infiltration and unintentional transfer to the aquifer. This strong impact of an urban effluent was revealed from the Br/Cl ratio, boron concentrations and δ11B isotopic signature of the groundwater in the direct vicinity of the infiltration point. With increasing distance from that point, dilution with groundwater rapidly attenuates the urban signal from these hydrogeochemical and isotopic tracers. Nevertheless, a gadolinium anomaly, resulting from discharges of urban wastewater containing the contrast agents used for magnetic resonance imaging (MRI), highlights the presence of a wastewater plume further along the flow line, that comes with a series of organic molecules, including pharmaceutical residues. Monitoring persistent or reactive molecules along the plume provides a more detailed understanding of the transfer of CECs into groundwater bodies. This highlights the relevance of pharmaceutical compounds as co-tracers for WWTP plume delineation. The present multi-tracer approach for groundwater resource vulnerability towards CECs allows a more in-depth understanding of contaminant transfer and their fate in groundwater.

A simple distillation method to extract bromine from natural water and salt samples for isotope analysis by multi-collector inductively coupled plasma mass spectrometry

RATIONALE

In natural samples bromine is present in trace amounts, and measurement of stable Br isotopes necessitates its separation from the matrix. Most methods described previously need large samples or samples with high Br/Cl ratios. The use of metals as reagents, proposed in previous Br distillation methods, must be avoided for multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) analyses, because of risk of cross-contamination, since the instrument is also used to measure stable isotopes of metals.

METHODS

Dedicated to water and evaporite samples with low Br/Cl ratios, the proposed method is a simple distillation that separates bromide from chloride for isotopic analyses by MC-ICP-MS. It is based on the difference in oxidation potential between chloride and bromide in the presence of nitric acid. The sample is mixed with dilute (1:5) nitric acid in a distillation flask and heated over a candle flame for 10 min. The distillate (bromine) is trapped in an ammonia solution and reduced to bromide. Chloride is only distilled to a very small extent. The obtained solution can be measured directly by MC-ICP-MS for stable Br isotopes.

RESULTS

The method was tested for a variety of volumes, ammonia concentrations, pH values and distillation times and compared with the classic ion-exchange chromatography method. The method more efficiently separates Br from Cl, so that samples with lower Br/Cl ratios can be analysed, with Br isotope data in agreement with those obtained by previous methods.

CONCLUSIONS

Unlike other Br extraction methods based on oxidation, the distillation method presented here does not use any metallic ion for redox reactions that could contaminate the mass spectrometer. It is efficient in separating Br from samples with low Br/Cl ratios. The method ensures reproducible recovery yields and a long-term reproducibility of ±0.11‰ (1 standard deviation). The distillation method was successfully applied to samples with low Br/Cl ratios and low Br amounts (down to 20 μg).

Stable isotopes of Cu and Zn in higher plants: evidence for Cu reduction at the root surface and two conceptual models for isotopic fractionation processes

Recent reports suggest that significant fractionation of stable metal isotopes occurs during biogeochemical cycling and that the uptake into higher plants is an important process. To test isotopic fractionation of copper (Cu) and zinc (Zn) during plant uptake and constrain its controls, we grew lettuce, tomato, rice and durum wheat under controlled conditions in nutrient solutions with variable metal speciation and iron (Fe) supply. The results show that the fractionation patterns of these two micronutrients are decoupled during the transport from nutrient solution to root. In roots, we found an enrichment of the heavier isotopes for Zn, in agreement with previous studies, but an enrichment of isotopically light Cu, suggesting a reduction of Cu(II) possibly at the surfaces of the root cell plasma membranes. This observation holds for both graminaceous and nongraminaceaous species and confirms that reduction is a predominant and ubiquitous mechanism for the acquisition of Cu into plants similar to the mechanism for the acquisition of iron (Fe) by the strategy I plant species. We propose two preliminary models of isotope fractionation processes of Cu and Zn in plants with different uptake strategies.

[Merkel cell carcinoma: descriptive study of 24 cases (1993-2001)]

INTRODUCTION

Merkel cell carcinoma (MCC) is a rare skin tumor with a highly malignant nature whose appropriate treatment is still debated. Wide surgery is the treatment of choice, but the question concerning protocols for adjuvant radiotherapy or chemotherapy remains open.

PATIENTS AND METHODS

A retrospective analysis of 24 cases of MCC collected over a period of 9 years was performed, focusing on clinical and histologic features, and response to treatment.

RESULTS

There were 17 women and 7 men with a mean age of 74.3 years. The median follow up was 34 months. The annual incidence per 100,000 habitants was 0.378. The head and neck localization was predominant (54%). Fifteen (68%) of patients presented with local disease (stage I), and 32% of patients presented with regional node (stage II) or distant metastases (stage III). Patients with stage I had a 5-years overall survival rate of 73,85%. Among them, five patients (33%) developed a local or nodal recurrence, although two patients were initially treated with surgery and local post-operative radiotherapy. Patients with stage II and III demonstrated a 5-year overall survival rate of 51,43%.

DISCUSSION

Our series illustrates the clinical characteristics of this tumor of the elderly, which is mainly located on head and neck and associated with a poor prognosis. Treatments are discussed.

Stable tracer investigations in humans for assessing the biokinetics of ruthenium and zirconium radionuclides

The interest in the biokinetics of ruthenium and zirconium in humans is justified by the potential radiological risk represented by their radionuclides. Only a few data related to the biokinetics of ruthenium and zirconium in humans are available and, accordingly, the biokinetic models currently recommended by the ICRP for these elements are mainly based on data from animal experiments. The use of stable isotopes as tracers, coupled with a proper analytical technique (nuclear activation analysis with protons) for their determination in biological samples, represents an ethically acceptable methodology for biokinetic investigations, being free from any radiation risk for the volunteer subjects. In this work, the results obtained in eight biokinetic investigations for ruthenium, conducted on a total of three healthy volunteers, and six for zirconium, performed on a total of three subjects, are presented and compared to the predictions of the ICRP models.

Genital squamous cell carcinoma in men treated by photochemotherapy. A cancer registry-based study from 1978 to 1998

BACKGROUND

One single report from the U.S. 16-centre-trial indicated that psoralen and ultraviolet A radiation (PUVA) therapy may induce an increased risk of genital tumours in men, and protection of the genital area is, therefore, recommended.

OBJECTIVES

To evaluate the relevance of this risk in routine clinical practice.

METHODS

Two groups of patients were included in a 1978-98 retrospective study. Case records of men with genital squamous cell carcinoma (SCC) identified from the Cancer Registry of the Doubs area of France were examined for a history of PUVA therapy, topical tar treatment, psoriasis, human papillomavirus infection or genital dermatitis. In addition, all the dermatologists of the Doubs area (in public and private practice) using PUVA therapy were asked to provide information on the number of patients having received PUVA therapy and whether the genital area was exposed during treatment.

RESULTS

Between 1978 and 1998, among the 48 men who had developed a genital SCC in the Doubs area, only one had a history of intensive PUVA therapy. About 150,000 treatments with PUVA therapy had been performed by 15 dermatologists in the Doubs area for 5400 patients since 1978. No case of genital SCC had been reported, despite the fact that the genital area had not been protected during UVA exposure.

CONCLUSIONS

Although retrospective, our study demonstrates that the occurrence of genital SCC in men treated with PUVA therapy is a very rare event in common dermatological practice.