Volatile organic compounds at swine facilities: A critical review

Volatile organic compounds (VOCs) are regulated aerial pollutants that have environmental and health concerns. Swine operations produce and emit a complex mixture of VOCs with a wide range of molecular weights and a variety of physicochemical properties. Significant progress has been made in this area since the first experiment on VOCs at a swine facility in the early 1960s. A total of 47 research institutions in 15 North American, European, and Asian countries contributed to an increasing number of scientific publications. Nearly half of the research papers were published by U.S. institutions.Investigated major VOC sources included air inside swine barns, in headspaces of manure storages and composts, in open atmosphere above swine wastewater, and surrounding swine farms. They also included liquid swine manure and wastewater, and dusts inside and outside swine barns. Most of the sample analyses have been focusing on identification of VOC compounds and their relationship with odors. More than 500 VOCs have been identified. About 60% and 10% of the studies contributed to the quantification of VOC concentrations and emissions, respectively. The largest numbers of VOC compounds with reported concentrations in a single experimental study were 82 in air, 36 in manure, and 34 in dust samples.The relatively abundant VOC compounds that were quantified in at least two independent studies included acetic acid, butanoic acid (butyric acid), dimethyl disulfide, dimethyl sulfide, iso-valeric, p-cresol, propionic acid, skatole, trimethyl amine, and valeric acid in air. They included acetic acid, p-cresol, iso-butyric acid, butyric acid, indole, phenol, propionic acid, iso-valeric acid, and skatole in manure. In dust samples, they were acetic acid, propionic acid, butyric acid, valeric acid, p-cresol, hexanal, and decanal. Swine facility VOCs were preferentially bound to smaller-size dusts.Identification and quantification of VOCs were restricted by using instruments based on gas Chromatography (GC) and liquid chromatography (LC) with different detectors most of which require time-consuming procedures to obtain results. Various methodologies and technologies in sampling, sample preparation, and sample analysis have been used. Only four publications reported using GC based analyzers and PTR-MS (proton-transfer-reaction mass spectrometry) that allowed continuous VOC measurement. Because of this, the majority of experimental studies were only performed on limited numbers of air, manure, or dust samples. Many aerial VOCs had concentrations that were too low to be identified by the GC peaks.Although VOCs emitted from swine facilities have environmental concerns, only a few studies investigated VOC emission rates, which ranged from 3.0 to 176.5 mg d⁻¹ kg⁻¹ pig at swine finishing barns and from 2.3 to 45.2 g d⁻¹ m⁻² at manure storages. Similar to the other pollutants, spatial and temporal variations of aerial VOC concentrations and emissions existed and were significantly affected by manure management systems, barn structural designs, and ventilation rates.Scientific research in this area has been mainly driven by odor nuisance, instead of environment or health concerns. Compared with other aerial pollutants in animal agriculture, the current scientific knowledge about VOCs at swine facilities is still very limited and far from sufficient to develop reliable emission factors.     

高效液相色谱法测定水环境中壬基酚聚氧乙烯醚及其生物降解产物

应用固相萃取－高效液相色谱法调查了嘉陵江和长江重庆段的壬基酚聚氧乙烯醚(ＮＰｎＥＯ,ｎ＞３)的污染状况．在四月份,长江的Ａ,Ｂ和Ｃ,嘉陵江的Ｄ和Ｅ采样点都测定出了ＮＰｎＥＯ(ｎ＞３)．长江上游Ａ点的浓度最高,为３７．２８μｇ·ｌ－１,嘉陵江的下游Ｄ点的总浓度最低,为７．２１μｇ·ｌ－１．七月的水样中仅在Ａ,Ｄ,Ｅ点检测出ＮＰｎＥＯ(ｎ≥３),其总浓度最高为１．９９μｇ·ｌ－１．但其分解产物ＮＰ的浓度比四月份高．     

响应面法优化测定水体中微囊藻毒素

针对水体中低浓度微囊藻毒素(MC-RR和MC-LR)的富集、淋洗、洗脱等前处理环节,采用单因素响应面优化法探讨微囊藻毒素前处理的最佳条件.结果表明:采用体积分数为25％的甲醇水溶液能够取得最佳淋洗效果,由One Factor设计优化得到体积分数为75％的甲醇水溶液作洗脱剂,MC-RR和MC-LR最佳回收率为89.4％和...