[Source Apportionment and Spatial Distribution Simulation of Heavy Metals in a Typical Petrochemical Industrial City].

Identifying the quantitative source and hazardous areas of heavy metals in soils plays a pivotal role in soil pollution research, and can provide a basis for regional soil risk monitoring and environmental management. For this purpose, a total of 175 samples were collected in topsoils from Linzi, a typical petrochemical industrial city in Shandong Province. Positive matrix factorization (PMF) and factor analysis with non-negative constraints (FA-NNC) receptor models were applied to analyze the sources of the heavy metals. Based on the multivariate statistical simulation methods of min/max autocorrelation factors (MAF) and sequential Gaussian simulation (SGS), the distribution of heavy metal and potential pollution areas were determined. As, Co, Cr, and Mn were mainly affected by natural sources, their concentrations were dominated by the parent materials, and the high-value areas were distributed in the south of the study area. Hg was the most serious pollution element among the 10 heavy metals analyzed in Linzi and originated from atmosphere deposition from industrial emissions and coal combustion, and the highest values were distributed in the northeast of the study area. Cd, Cu, Ni, Pb, and Zn were dominated by natural sources and human activities. The hot-spot areas were mainly concentrated in the middle of the study area. The potentially contaminated areas of Cd and Hg were 580.80 km2 and 666.60 km2, about 85.04% and 97.59% of the total area, and should require more attention. The potential pollution area of most elements was small and scattered across the study area, accounting for less than 1%.

Isolation of both Pseudozyma aphidis and Nocardia otitidiscaviarum from a mycetoma on the leg.

We describe a case of mycetoma which typified the classic presentation of the disease: a male farmer with affection of the lower limbs and a history of trauma. The patient presented with a swollen right lower limb showing multiple discharging sinuses for 25 years. Histopathologically, grains were found by HE stain, and clustered yeast-like cells were observed by PAS stain. The distinctive 'dot-in-circle' sign was found through MRI. Besides Nocardia otitidiscaviarum, Pseudozyma aphidis was isolated from deep tissue culture, and the identification of the etiologic species was ascertained by DNA sequencing. Generally speaking, Nocardia otitidiscaviarum is an infrequent cause of mycetoma, and Pseudozyma species are usually isolated from plant material rather than clinical specimens. This is the first case of mycetoma from which both Nocardia otitidiscaviarum and Pseudozyma aphidis were isolated.