Critical Pollution Value of Heavy Metals Contained in River Sediments

抄録

There are various means of determining the heavy metal critical pollution point of river sediments. This study presents a method for determining a critical point of pollution by using the quantities :
T=_??__??_σ^jj' log₁₀(a+by_j) log₁₀(a+by_j')
where, the suffixes j and j' correspond to the j-th and j'-th metals, respectively, the n×n matrix [σ^jj'] is the inverse of the population variance-covariance matrix of n heavy metals in upstream rivers, and a and b are the arbitrary constants. y_j denotes the average of m independent measurements of the concentration of the j-th metal of the typical downstream river. Values of log₁₀ (a+by_j) are regarded as being distributed as N (μ, ∑), and hence T follows a noncentral chi-square distribution. Using PEARSON'S approximation for a central chi-square distribution, a critical pollution point is obtained. Application to first class rivers in Japan showed a qualitative comparison of the intensity of pollution.