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首页> 外文期刊>Environmental Science & Technology >Changes in Surface Area and Concentrations of Semivolatile Organic Contaminants in Aging Snow
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Changes in Surface Area and Concentrations of Semivolatile Organic Contaminants in Aging Snow

机译：积雪中表面积和半挥发性有机污染物浓度的变化

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During the winter of 1999/2000 five snowpacks at Turkey Lake Watershed east of Lake Superior were sampled immediately after falling and again after several days of aging for the analysis of specific snow surface area and the concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The snow surface could be determined with a relative coefficient of variation of 6% using frontal chromatography, measuring the retention of ethyl acetate, a substance with known adsorption coefficient on the ice surface. The snow surface area of fresh snow varied from 1000 to 1330 cm~2/g and was higher for snow falling during colder days. The aged snow samples had consistently lower surface areas ranging from 520 to 780 cm~2/g, corresponding to an average loss of half of the initial surface area during aging. The rate of loss of surface area was faster at higher temperatures. Dieldrin, α-HCH, and γ-HCH were the most abundant OCPs in snowmelt water, but endosulfan, chlordane-related substances, heptachlor epoxide, pp'-DDT, pp'-DDE, and chlorinated benzenes were also consistently present. Three midwinter snowpacks that aged during relatively cold temperatures generally experienced a loss of PCBs and OCPs that was of the same order of magnitude as the observed loss of snow surface area. However, no relationship between the extent of loss and the strength of a contaminants' sorption to snow was apparent. Few significant changes in snowpack concentrations of OCPs and PCBs were observed in a snowpack that fell at relatively high temperatures and aged under colder conditions. Concentrations of OCPs and PCBs increased in a late-winter snowpack that aged while temperatures rapidly increased to above freezing. Concentrations of pp'-DDE and endosulfan-Ⅱ that increased in snowpacks that saw simultaneous decreases in the levels of pp'-DDT and endosulfan-Ⅰ hint atthe occurrence of sunlight induced conversions in snow. While surface area decreases clearly contribute to the loss of semivolatile organic compounds from metamorphosing snowpacks,rnother confounding factors play a role in determining concentration changes, in particular in wet snow.
机译：在1999/2000年冬季，在坠落后立即取样并在苏必利尔湖以东的土耳其湖分水岭上取样了五个积雪，老化后几天对其进行了取样，以分析比雪表面积以及有机氯农药（OCP）和多氯联苯的浓度（ PCB）。可以使用额叶色谱法测定相对表面变化系数为6％的雪面，方法是测量乙酸乙酯的保留率，乙酸乙酯是一种在冰面上具有已知吸附系数的物质。新鲜雪的雪表面积在1000至1330 cm〜2 / g之间，在较冷的日子降雪量更大。老化的雪样品具有始终如一的较低表面积，范围为520至780 cm〜2 / g，对应于老化过程中平均损失了初始表面积的一半。在较高温度下表面积的损失速率更快。狄氏剂，α-六氯环己烷和γ-六氯环己烷是融雪水中最丰富的OCP，但也始终存在硫丹，氯丹相关物质，七氯环氧化物，pp'-DDT，pp'-DDE和氯化苯。在相对较低的温度下老化的三个冬季冬季积雪通常会损失PCB和OCP，其数量级与观察到的积雪表面积的损失数量级相同。但是，损失程度与污染物对雪的吸附强度之间没有明显的关系。在相对较高的温度下降并在较冷的条件下老化的积雪中，观察到的OCP和PCB积雪浓度几乎没有明显变化。在冬季积雪中，OCP和PCB的浓度增加，而雪积雪老化，而温度迅速升高至高于冰点。积雪中pp'-DDE和硫丹Ⅱ的浓度增加，而pp'-DDT和硫丹Ⅰ的水平同时下降，这暗示着雪中阳光诱导的转化的发生。表面积的减少显然会导致变形雪堆中半挥发性有机化合物的损失，而其他混杂因素则在确定浓度变化（尤其是在湿雪中）方面起作用。

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