Abstract Gas hazard was evaluated at Lavinio-Tor Caldara, the southernmost gas-discharging zone of the quiescent Albani Hills volcano in central Italy. Also this zone, like the other gas discharges of this volcanic complex, is located above a structural high of the buried Mesozoic carbonate basement, which represents the main reservoir for gas rising from depth. All extensional faults affecting the carbonates are leaking pathways along which gas may rise to the surface creating hazardous conditions. Gas is dominated by CO2 (>90 vol%) and the second component at Lavinio-Tor Caldara is H2S that displays the highest content (4.0–6.3 vol%) of all gas manifestations of the Rome region. This H2S enrichment corresponds to a marked decrease in 3He/4He (R/Ra) isotopic ratio suggesting that gas was contaminated in an upper crustal environment. The main gas discharge occurs at the natural reserve of Tor Caldara, in zones where past sulphur mining excavations removed the surficial impervious cover, or along a ditch. Comparison of the results of four soil CO2 flux surveys carried out in 2005–2018 at Miniera Grande within Tor Caldara, indicates that the highest soil CO2 release occurs shortly after local earthquakes. Continuous monitoring of CO2 and H2S air concentration and of wind speed has been carried out for four months in twelve anomalous gas realising sites of Tor Caldara. Results indicate that only H2S reaches lethal concentration (>250 ppm) near the soil in no wind nights, explaining the presence of small dead animals. At Lavinio, the main soil gas release occurs near old water wells that likely produced a gas blowout during drilling. A total release of over 20 tons/day from 2.93 km2 of gas of endogenous origin, has been estimated for the Lavinio-Tor Caldara area by a detailed soil CO2 flux survey (2572 measurement points over an area of 3.65 km2). The main structural lineaments of the area have N-S and W-E directions, but also NE-SW and NW-SE directions are well represented. Some sectors of the investigated area are exposed to a severe gas hazard for people and animals and precautionary measures should be adopted.

中文翻译：

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Lavinio-Tor Caldara 地区（意大利罗马首都大都会）CO2 和 H2S 排放的来源和危害

摘要 在意大利中部静止的阿尔巴尼山火山最南端的气体排放区拉维尼奥-托尔卡尔达拉 (Lavinio-Tor Caldara) 评估了气体危害。此外，该区域与该火山复合体的其他气体排放一样，位于埋藏的中生代碳酸盐基底的构造高处，这是从深处上升的主要气体储层。影响碳酸盐岩的所有伸展断层都是泄漏通道，气体可能沿着这些通道上升到地表，造成危险条件。气体以 CO2（>90 vol%）为主，而 Lavinio-Tor Caldara 的第二个成分是 H2S，它在罗马地区的所有气体表现形式中显示出最高的含量（4.0-6.3 vol%）。这种 H2S 富集对应于 3He/4He (R/Ra) 同位素比的显着降低，表明气体在上地壳环境中受到污染。主要的气体排放发生在 Tor Caldara 的自然保护区，在过去的硫磺开采挖掘去除了表面不透水覆盖层的区域，或沿着沟渠。比较 2005-2018 年在 Tor Caldara 内的 Miniera Grande 进行的四次土壤 CO2 通量调查的结果表明，最高的土壤 CO2 释放发生在当地地震后不久。在 Tor Caldara 的 12 个异常气体实现地点，对 CO2 和 H2S 空气浓度和风速的连续监测已经进行了四个月。结果表明，在无风的夜晚，土壤附近只有 H2S 达到致死浓度 (>250 ppm)，这解释了小型动物死亡的存在。在拉维尼奥，主要的土壤气体释放发生在旧水井附近，在钻井过程中可能会产生气体井喷。总释放量超过 20 吨/天，从 2. 通过详细的土壤 CO2 通量调查（3.65 平方公里区域内的 2572 个测量点），估计 Lavinio-Tor Caldara 地区有 93 平方公里的内源性气体。该地区的主要构造线有 NS 和 WE 方向，但也有很好的代表 NE-SW 和 NW-SE 方向。调查区部分区域存在严重的人畜气体危害，应采取预防措施。