Emissions of plant protection products from glasshouses to surface water in The Netherlands

Momenteel wordt een vast percentage van 0.1% gebruikt voor de emissie van gewasbeschermingsmiddelen vanuit kassen naar het oppervlaktewater. Metingsgegevens van waterschappen wijzen erop dat de emissie van gewasbeschermingsmiddelen en biociden naar het oppervlaktewater hoger zijn dan aangenomen wordt in de toelatingsprocedure. Dit rapport onderzoekt of nieuwe benaderingen nodig zijn. De onderzoeksresultaten duiden er op dat de werkelijke emissie sterk verschilt tussen verschillende gewassen, teeltsystemen en toedieningswijzen. Dit zou in de evaluatie van de emissie meegenomen moeten worden

Determination and distribution of polycyclic aromatic hydrocarbons in rivers, surface runoff, and sediments in and around Thohoyandou, Limpopo Province, South Africa

Water quality in rural areas is affected adversely by build-up of traffic-generated organic compounds on road surfaces, leading to their presence in water runoff and sediments. Characterising these compounds is a first step in developing measures for the removal of such pollutants from water courses. In this study, liquid-liquid extraction of water samples from several rivers and surface run-off enabled quantification of major PAHs. Soxhlet extraction of sediment samples was followed by clean-up of samples using column chromatography. The PAHs were quantified by gas chromatography. In water and sediment samples, 6 PAHs were identified and quantified. In river water samples, individual PAH levels ranged between 0.1 µg/. and 137 µg/., while in sediment samples levels ranged between 17.9 µg/kg and 9870 µg/kg. For surface run-off, levels ranged between 0.6 µg/. and 2 500 µg/. for water samples and between 112 µg/kg and 34 400 µg/kg for sediment samples. Total levels of PAHs in sediment samples were relatively high (111.6 to 61 764 µg/kg) compared to those in water from both river and surface run-off (29.2 to 3 064.8 µg/.), and PAH levels in surface runoff were much higher than in river waters, implicating tarred roads and parking lots as main point sources of PAHs. PAH ratios also indicate that the PAH content of runoff and sediment is more likely due to pyrogenic sources, i.e. vehicle emissions, although petrogenic sources (mainly oil spills) also play an important role. Toxic Equivalence Quotient (TEQ) values in river and runoff waters ranged from 0.10 to 4.03 µg/. and for sediments the TEQ ranged from 0.50 to 272.23 µg/kg. These results are of concern, as the calculated TEQ is likely to be an underestimate of the actual TEQ, since only 6 PAHs with relatively low toxicities were analysed. Long droughts and low rainfall, and washing of automobiles in and near the rivers are important factors which may have contributed to the observed levels of PAHs in both river water and sediments.Keywords: Polycyclic aromatic hydrocarbon, river water, runoff, sedimen

Rapportage bedrijfsinformatie weidevogelgebieden

Op verzoek van LNV-Directie Kennis heeft Alterra in samenwerking met Sovon en Landschap Noord-Holland een helpdeskvraag beantwoord naar de relatie tussen weidevogels en bedrijfskenmerken. In het onderzoek zijn weinig verschillen gevonden tussen bedrijfsstructuurkenmerken van landbouwbedrijven in stabiele en niet-stabiele weidevogelgebieden. Wel lijkt in stabiele weidevogelgebieden het grondgebruik wat minder intensief en het aandeel gespecialiseerde melkveebedrijven iets kleiner. Mogelijk zijn andere dan de onderzochte bedrijfsfactoren meer van invloed

Psychiatric Diagnosis Revisited:Towards a System of Staging and Profiling Combining Nomothetic and Idiographic Parameters of Momentary Mental States

BACKGROUND: Mental disorders may be reducible to sets of symptoms, connected through systems of causal relations. A clinical staging model predicts that in earlier stages of illness, symptom expression is both non-specific and diffuse. With illness progression, more specific syndromes emerge. This paper addressed the hypothesis that connection strength and connection variability between mental states differ in the hypothesized direction across different stages of psychopathology. METHODS: In a general population sample of female siblings (mostly twins), the Experience Sampling Method was used to collect repeated measures of three momentary mental states (positive affect, negative affect and paranoia). Staging was operationalized across four levels of increasing severity of psychopathology, based on the total score of the Symptom Check List. Multilevel random regression was used to calculate inter- and intra-mental state connection strength and connection variability over time by modelling each momentary mental state at t as a function of the three momentary states at t-1, and by examining moderation by SCL-severity. RESULTS: Mental states impacted dynamically on each other over time, in interaction with SCL-severity groups. Thus, SCL-90 severity groups were characterized by progressively greater inter- and intra-mental state connection strength, and greater inter- and intra-mental state connection variability. CONCLUSION: Diagnosis in psychiatry can be described as stages of growing dynamic causal impact of mental states over time. This system achieves a mode of psychiatric diagnosis that combines nomothetic (group-based classification across stages) and idiographic (individual-specific psychopathological profiles) components of psychopathology at the level of momentary mental states impacting on each other over time

Do subthreshold psychotic experiences predict clinical outcomes in unselected non-help-seeking population-based samples? A systematic review and meta-analysis, enriched with new results

Background The base rate of transition from subthreshold psychotic experiences (the exposure) to clinical psychotic disorder (the outcome) in unselected, representative and non-help-seeking population-based samples is unknown. Method A systematic review and meta-analysis was conducted of representative, longitudinal population-based cohorts with baseline assessment of subthreshold psychotic experiences and follow-up assessment of psychotic and non-psychotic clinical outcomes. Results Six cohorts were identified with a 3-24-year follow-up of baseline subthreshold self-reported psychotic experiences. The yearly risk of conversion to a clinical psychotic outcome in exposed individuals (0.56%) was 3.5 times higher than for individuals without psychotic experiences (0.16%) and there was meta-analytic evidence of dose-response with severity/persistence of psychotic experiences. Individual studies also suggest a role for motivational impairment and social dysfunction. The evidence for conversion to non-psychotic outcome was weaker, although findings were similar in direction. Conclusions Subthreshold self-reported psychotic experiences in epidemiological non-help-seeking samples index psychometric risk for psychotic disorder, with strong modifier effects of severity/persistence. These data can serve as the population reference for selected and variable samples of help-seeking individuals at ultra-high risk, for whom much higher transition rates have been indicate