Seasonal, Spatial Variation, and Potential Sources of Organochlorine Pesticides in Water and Sediment in the Lower Reaches of the Dong Nai River System in Vietnam.

The goals of the current study were (1) to examine seasonal and spatial variation of selected OCPs concentrations and (2) to identify potential sources of the pollutants in the lower reaches of the Dong Nai River system. Forty-eight water and sediment samples were taken from 12 stations in the dry and rainy seasons to determine the concentrations of dichlorodiphenyltrichloroethane and its metabolites (total DDTs), hexachlorocyclohexane isomers (total HCHs), heptachlor, aldrin, dieldrin, and endrin. The concentrations of total DDTs (0.30), total HCHs (0.29), Aldrin (0.068), heptachlor (0.04, µg L-1) in water, and total DDTs (8.04), total HCHs (4.51), and Aldrin (1.52, µg kg-1) in sediment were significantly higher in the rainy season than in the dry season (0.14, 0.12, 0.008, 0.009 in water and 3.49, 2.29, and 0.4 in sediment, respectively). Cluster analysis grouped 12 sampling stations into 2 groups, of which group 1 (3 stations) had higher concentrations of total DDTs, total HCHs, Aldrin, heptachlor, and dieldrin in both water and sediment than in group 2. Compositional analysis of total DDTs revealed that DDT residue could be decomposed significantly for the past years and that anaerobic decomposition could be predominant. Principal component analysis/factor analysis (PCA/FA) indicated that the potential sources of OCPs in the study stations could come from residential and agricultural areas located in the upper catchment or areas surrounding the studied stations. In short, OCPs concentration in the studies area could depend on seasonal, spatial variation, and transport of OCPs from upper parts or surrounding areas.

The interactive effect of the season and estuary position on the concentration of persistent organic pollutants in water and sediment from the Cua Dai estuary in Vietnam.

The current study was conducted in the Cua Dai estuary, Vietnam, (1) to assess the status of persistent organic pollutants (POPs) and (2) to examine the interactive effect of season and estuary position on the concentration of the pollutants in surface water and sediment. Fifty-two water and sediment samples were taken in the dry and rainy seasons from inner- and outer-estuary positions to analyze for six POPs, including hexachlorocyclohexane isomers (HCHs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), heptachlor, aldrin, dieldrin, and polychlorinated biphenyl (PCBs). The averaged concentrations of the respective POPs in water samples were 0.07, 0.1, 0.01, 0.03, 0.001, and 0.2 µg L-1 and in sediment samples were 2.6, 3.1, 0.9, 0.2, 0.2, and 121 µg kg-1. Of the six POPs examined, the concentration of DDTs in sediment samples and PCBs in water samples was significantly affected by the interactive effect of the two examined factors. The concentrations of HCHs, DDTs, heptachlor, and aldrin in water samples and of HCHs in sediment samples were significantly higher in the rainy season than in the dry season. Sediment samples collected from the inner position had a significantly higher concentration of HCHs and PCBs than in the outer position. Some mechanisms possibly influenced the varying POP concentration could include (1) greater riverine discharge in the rainy season and (2) the sea dilution effect in the outer position. Therefore, the concentration of the individual examined POPs in water and sediment in the Cua Dai estuary significantly depended on either the season, estuary position, or their combination.

Relative socioeconomic advantage and mood during advanced pregnancy in women in Vietnam.

BACKGROUND: Mental health during pregnancy has not been investigated in Vietnam. Antenatal depression is an established risk factor for postpartum mood disturbance and two representative cohort studies have found rates of depression after childbirth in Vietnam two to three times higher than those in high income countries. AIM: The aim of this exploratory study was to investigate the prevalence and determinants of depression in a cohort of pregnant Vietnamese women. This was the subsidiary aim of an investigation of sexual beliefs and behaviours in pregnancy in Vietnam. METHODS: Participants were recruited from antenatal clinics at Hanoi Obstetric Hospital. Inclusion criteria were to be in advanced pregnancy and appear well educated and confident and therefore potentially be willing to discuss sexual matters. Data were collected by individual structured interviews assessing socio-demographic characteristics, reproductive health, quality of intimate relationship and adequacy of support. Emotional wellbeing was assessed by the Vietnamese translation of the Edinburgh Depression Scale (EDS). RESULTS: In total 61/74 (82%) of women approached to participate were recruited. The mean EDS score of 5.42 +/- 3.8, was similar to that of community cohorts in high income countries and only one participant scored above 15. The cohort was relatively socioeconomically advantaged with high rates of post-secondary education, secure salaried employment, reproductive autonomy and ability to afford higher quality antenatal care. Most participants were able to confide in their husbands and their pregnancies were welcome. Worse mood was associated with insecure casual work, crowded living conditions and experiencing critical coercion in the marital relationship. CONCLUSION: There is an apparently low prevalence of symptoms of depression in relatively socioeconomically advantaged pregnant women in Vietnam.