Adsorption of Pb and Cd on the natural surface coatings (NSCs) in the presence of organochlorine pesticides: a preliminary investigation

Adsorption of Pb and Cd in the presence and absence of organochlorine pesticides (OCPs) on natural surface coatings (NSCs), which were collected in the Nanhu Lake in Changchun, China, was measured in order to investigate the effect of the OCPs on the adsorption of heavy metals on the NSCs. Adsorption of Pb/Cd was carried out under controlled laboratory conditions (mineral salt solution with defined species, ionic strength 0.05 mol/l, 25 degrees C and pH 6.0) with initial Pb and Cd concentrations ranging from 0.2 to 2.5 mol/l. The classical Langmuir adsorption isotherm was applied to estimate the equilibrium coefficients of the adsorption of Pb and Cd on the NSCs. Adsorption interference between Pb/Cd and the OCPs on the NSCs indicated that the adsorption of Pb/Cd on the NSCs was influenced by the OCPs, and competitive adsorption between Pb and the OCPs was observed while adsorption of Cd was enhanced by addition of the OCPs. Adsorption data fit the Langmuir isotherm well for the NSCs treated with the OCPs at different equilibrium concentrations. The results showed that the amount of adsorbed Pb decreased by more than 40% while the amount of adsorbed Cd increased by over 60% with an increase in the initial concentrations of the OCPs ranging from 0 to 5.0 microg/l and that adsorption of Pb/Cd on the NSCs was strongly affected by the OCPs. This preliminary study highlights the importance of the OCPs on the NSCs in controlling the transport, fate, biogeochemistry, bioavailability and toxicity of trace metals in aquatic environments.     

浅谈串联四极杆质谱（GC—QqQ-MS／MS）在土壤样品有机污染物分析中的应用

建立了ASE-GPC—GC-QqQ—MS／MS测定土壤中17种有机氯农药和19种多氯联苯以及MAE-SPE—GC-QqQ—MS／MS测定土壤中16种多环芳烃和18种邻苯二甲酸酯的方法。多环芳烃和邻苯二甲酸酯定量限在0．02～2．81μg／kg之间,有机氯农药和多氯联苯定量限在0．01～0．51μg/kg之间。样品加标浓度在5μg/kg时多环芳烃和邻苯二甲酸酯的平均回收率在66．6％～122．1％之间,相对标准偏差均小于20％;有机氯农药和多氯联苯平均回收率在79．6％～93．2％之间,相对标准偏差均小于15％。     

The Introduction of the Precautionary Principle in Danish Environmental Policy: The Case of Plant Growth Retardants

In this paper, we investigate the Precautionary Principle (PP) in action. Precaution is a fairly new concept in environmental policy. It emerged back in the 1960s but did not consolidate until the 1980s, as it formed part of the major changes taking place in environmental policies at that time. The PP is examined in three contexts. Firstly, we look at the meaning of the concept and how it is disseminated through the media and public discourses to the political arenas of Denmark. Then we examine how the idea is adopted to the political level. Thirdly, we look briefly at the first Danish translation of the principle into a practical context, which includes translations into concrete scientific practices. It is concluded that if the PP shall be more than a simple “idea” or a frequently used “term,” emphasis must be put on the transformation of the concept into concrete practices, like e.g., the alternative testing regimes that we show in the case of plant growth-retarding pesticides presented in this paper.     

Organochlorine pesticides and polychlorinated biphenyl residues in reared and wild Dicentrarchus labrax from the Mediterranean Sea (Sicily, Italy)

The aim of this research was to compare the levels of organochlorine pesticides and PCBs in samples of Dicentrarchus labrax living in the Straits of Messina with samples cultivated in cages in the Mediterranean Sea. Muscles and liver tissues sampled over the months, within the same year, were analyzed. The quantitative determination of the organochlorine compounds was performed by GC-ECD and confirmed with GC–MS. The results showed that the concentrations of DDTs in muscles and livers as such of reared sea bass were in the range 0.2–1.3 μg/kg and 9.6 –48.4 μg/kg, respectively. In wild fish the concentrations of DDTs were very much lower: 0.1 μg/kg in muscles, 5.1–9.0 μg/kg in livers. Total PCBs levels were higher in cultivated sea bass than in wild fish; the concentration ranges were 5.3–59.7 μg/kg and 74.4–267.4 μg/kg in muscle and liver of reared samples, respectively, and 1.1–1.5 μg/kg and 63.2–109.4 μg/kg in muscle and liver of wild samples, respectively.     

Organochlorine pesticide residues in ground water of Thiruvallur district, India

Modern agriculture practices reveal an increase in use of pesticides and fertilizers to meet the food demand of increasing population which results in contamination of the environment. In India crop production increased to 100% but the cropping area has increased marginally by 20%. Pesticides have played a major role in achieving the maximum crop production, but maximum usage and accumulation of pesticide residues was highly detrimental to aquatic and other ecosystem. The present study was chosen to know the level of organochlorines contamination in ground water of Thiruvallur district, Tamil Nadu, India. The samples were highly contaminated with DDT, HCH, endosulfan and their derivatives. Among the HCH derivatives, Gamma HCH residues was found maximum of 9.8 μg/l in Arumbakkam open wells. Concentrations of pp-DDT and op-DDT were 14.3 μg/l and 0.8 μg/l. The maximum residue (15.9 μg/l) of endosulfan sulfate was recorded in Kandigai village bore well. The study showed that the ground water samples were highly contaminated with organochlorine residues.     

Occurrence of Sediment-Bound Pyrethroids in Danish Streams and their Impact on Ecosystem Function

In a total of 189 water samples collected from Danish streams no traces of the pyrethroid esfenvalerate were detected. However, pyrethroids have previously been found in sediments in 9 out of 30 streams investigated. We found that the shredding activity of the Trichopteran Sericostoma personatum and the amphipod Gammarus pulex was significantly reduced with increased concentration of the pyrethroid lambda-cyhalohtrin adsorbed to the leaves on which they fed. Predation rate on the Plecopteran Leuctra nigra by the leech Erpobdella octoculata increased significantly with increasing concentration of lambda-cyhalothrin on the leaves on which L. nigra was fed. Our results clearly indicate that the ongoing monitoring of pesticides is likely to underestimate pyrethroid occurrence and that sediment-bound pyrethroids have a potential negative impact on ecosystem function and biotic interactions in streams.     

REGRESSION MODELS FOR ESTIMATING HERBICIDE CONCENTRATIONS IN U.S. STREAMS FROM WATERSHED CHARACTERISTICS1

ABSTRACT: Regression models were developed for estimating stream concentrations of the herbicides alachlor, atrazine, cyanazine, metolachior, and trilluralin from use‐intensity data and watershed characteristics. Concentrations were determined from samples collected from 45 streams throughout the United States during 1993 to 1995 as part of the U.S. Geological Survey's National Water‐Quality Assessment (NAWQA). Separate regression models were developed for each of six percentiles (10th, 25th, 50th, 75th, 90th, 95th) of the annual distribution of stream concentrations and for the annual time‐weighted mean concentration. Estimates for the individual percentiles can be combined to provide an estimate of the annual distribution of concentrations for a given stream. Agricultural use of the herbicide in the watershed was a significant predictor in nearly all of the models. Several hydrologic and soil parameters also were useful in explaining the variability in concentrations of herbicides among the streams. Most of the regression models developed for estimation of concentration percentiles and annual mean concentrations accounted for 50 percent to 90 percent of the variability among streams. Predicted concentrations were nearly always within an order of magnitude of the measured concentrations for the model‐development streams, and predicted concentration distributions reasonably matched the actual distributions in most cases. Results from application of the models to streams not included in the model development data set are encouraging, but further validation of the regression approach described in this paper is needed.     

长江武汉段水体悬浮物中有机氯农药的残留状况

以α-HCH,β-HCH,γ-HCH,δ-HCH,p,p′-DDE,p,p′-DDD,o,p′-DDT,p,p′-DDT和HCB等9种有机氯农药为目标污染物,采用索氏提取和气相色谱法,对长江武汉段水体悬浮物中有机氯农药的残留进行调查分析。调查发现,在长江武汉段水体悬浮物中,六氯苯(HCB)、六六六(HCHs)和滴滴涕(DDTs)类有机氯农药均被检出,其中六氯苯(HCB)在表层沉积物中的残留量(质量分数)为0 37～9 06ng g,平均为2 89ng g;六六六类农药在悬浮物中的残留量(质量分数)为0 23～1 90ng g,平均为0 76ng g;滴滴涕类在悬浮物中的残留量(质量分数)为0 18～4 67ng g,平均为1 31ng g。在长江武汉段水体悬浮物中,HCB,p,p′-DDE和γ-HCH的被检出率和残留量均最高,为主要污染物。      

东海泥质区表层沉积物中有机氯农药的分布

以GC/ECD内标法定量测定了东海近岸泥质区、远岸济州岛西南泥质区和冲绳海槽共19个表层沉积物样中21种有机氯农药的含量.结果表明,有机氯农药在所有样品中均有检出,东海泥质区已有人类污染物的明显记录.研究区平均总有机氯农药分布特征为沿岸泥质区南部>沿岸泥质区北部>冲绳海槽>济州岛西南泥质区.冲绳海槽中HCHs含量高且其分布特征显著区别于陆架泥质区,显示该区域这一污染物源可能与陆架区有所不同.(DDD+DDE)/DDT比值显示东海泥质区DDT类农药的污染物还比较新.与国内其他地区沉积物中有机氯农药含量相比,东海泥质区有机氯农药污染属较低水平.