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Karst terrains are generally regarded as a fragile and vulnerable environment. China's karst is mainly developed in pre-Triassic, old-phase, hard, compact carbonate rock. The lack of soil cover in bare karst land can enhance desertification. Its underground drainage system can aggravate both drought and flooding problems; the interconnected surface and subsurface conditions allow for easy contamination by pollutants. Moreover, karst terrains quite often suffer from a series of engineering problems, such as water infiltrating into mines or transportation tunnels, leakage from reservoirs, and failure of building foundations. As resources and energy exploitation intensified in recent years, karst areas in Southwest China faced some severe geo environmental problems. In order to find out how the problems action and evolution in recent years, field and laboratory investigations were conducted in Guangxi autonomous region, Guizhou, Yunnan, Guangdong, Hunan, Hubei provinces, and Chongqing municipality. About 100 experts from the Provincial Geological Survey and graduate students took part in this project. Several symposiums were held during those 3 years. Besides the in situ survey, data were collected from hydrogeological survey results since 2000 when the new round of land resources investigation began. After analyzing these data, rock desertification, drought and flooding, and contamination and engineering geological environmental problems were considered the most prevalent problems in karst areas in Southwestern China. The status of each problem is elaborated upon in this paper and should be considered for future sustainable development. [ABSTRACT FROM AUTHOR]

This study was directed to ascertain the mortality of a group of arseniasis patients in an endemic rural township in Southwest China, where the residents were exposed for decades to indoor combustion of high arsenic coal. All the diagnosed arseniasis cases registered in 1991 were defined as the target population, which were assigned to three symptom subgroups by the severity of dermal lesions. The death cases were surveyed and checked. The follow-up period was 12.5 years. The standardized mortality ratio (SMR) of all death causes combined, all cancers combined, and the cancers at every site were analyzed. The age standardized mortality rates (ASMRs) were calculated in three subgroups using the procedure of standardization. One hundred and six death cases were recorded. Liver cirrhosis, non-melanotic skin cancer, lung and liver cancer were the four most prevalent death causes and referred to 70.8% (75/106) of the total death cases. The mortality of all death causes combined was not higher than that of the whole of China in 2001 (SMR = 0.76, 95% CI 0.63–0.93). The crude mortality rate of non-melanotic skin cancer in males reached up to 128.66/105. SMRs of lung cancer and larynx cancer in males (SMRs 2.84 and 27.27, 95% CIs 1.51–4.86 and 5.61–79.62, respectively) significantly exceeded the levels for all male Chinese. ASMRs of all death causes combined, all cancers combined and non-melanotic skin cancer in males of the severe dermal symptoms subgroup were significantly higher than those in medium and/or mild dermal symptom subgroups. A significantly increased mortality due to lung cancer and non-melanotic skin cancer was confirmed, alike the situation in other arseniasis endemic areas in the world. No significant elevation of mortality due to liver cancer and bladder cancer was observed. Male arseniasis patients diagnosed with severe skin lesions face higher risks of malignancies and of non-melanotic skin cancer in particular in the following years. [ABSTRACT FROM AUTHOR]